BIO 109 Exam 4 Review: Chapters 16/21, 17, 18, 19, 22 Chapter 16: Reproduction System and / Chapter 21: Development and Aging The Two Sexes ∙ Male and female gametes (sex cells) combine their genes to form a zygote (fertilized egg) One gamete has motility: sperm (spermatozoon) o ParIf you want to learn more check out What accounts for electrostatic interactions between ions of opposite charge (Na+Cl)?
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ent producing sperm considered male o Parent with a Y chromosome is male Other gamete contains nutrients for developing embryo: egg (ovum) o Parent producing eggs considered female o Anyone lacking a Y chromosome is female o In mammals, female is the parent that provides a sheltered internal environment and prenatal nutrition of the embryo Overview of the Reproductive System ∙ Male reproductive system serves to produce sperm and introduce them into the female body Males have a copulatory organ (penis) for introducing their gametes into the female reproductive tract ∙ Female reproductive system produces eggs, receives sperm, provides for the union of the gametes, harbors the fetus, and nourishes the offspring Females have a copulatory organ (vagina) for receiving the sperm ∙ Reproductive system consists of primary and secondary sex organs Primary sex organs (gonads) o Produce gametes (testes or ovaries) Secondary sex organs: organs other than the gonads that are necessary for reproduction o Male—system of ducts, glands; penis delivers sperm cells o Female—uterine tubes, uterus, and vagina receive sperm and harbor developing fetus ∙ Secondary sex characteristics—features that further distinguish the sexes and play a role in mate attraction Develop at puberty to attract a mate Both sexes o Pubic and axillary hair and their associated scent glands, and the pitch of the voice Male o Facial hair, coarse and visible hair on the torso and limbs, relatively muscular physique Female o Distribution of body fat, breast enlargement, and relatively hairless appearance of the skin Testes produce sperm ∙ Scrotum: sac of skin and smooth muscle that holds the testes Maintains testes at a slightly lower temperature ∙ Seminiferous tubules within testes: produce sperm ∙ Epididymis and ductus deferens: sperm become motile and are stored here ∙ Ductus deferens: transports sperm to where it becomes the ejaculatory duct Male Reproductive System Delivers Sperm ∙ Route of sperm through male reproductive structures Seminiferous tubules Epididymis Ductus deferens Ejaculatory duct Penis Accessory Glands Help Sperm Survive ∙ Semen: mixture of sperm and secretions of accessory glands ∙ Seminal vesicles Secrete fructose (provides source of energy for sperm) and most of seminal fluid ∙ Prostate gland Secretes watery alkaline fluid to raise vaginal pH ∙ Bulbourethral gland Secretes lubricating mucus Cleanses urethraSperm Production Requires Several Cell Divisions ∙ Several cell divisions (mitosis and meiosis) in seminiferous tubules produce sperm ∙ Cell divisions produce a large number of sperm with half the number of chromosomes of somatic cells (haploid) ∙ Sperm (and eggs) are referred to as gametes and are haploid ∙ Sequence of cell types, leading to sperm Spermatogonia (2n), primary spermatocyte (2n), secondary spermatocyte (n), spermatids (n), sperm (n) ∙ Sertoli cells provide support, nourishment Testosterone Affects Male Reproductive Capacity ∙ Testosterone Steroid hormone produced by interstitial cells in testes (between seminiferous tubules) Function: o Controls growth and function of male reproductive tissues o Stimulates aggression and sexual behavior o Controls development of secondary sexual characteristics o Determines rate of sperm formation The Female Reproductive System Produces Eggs and Supports Pregnancy ∙ Ovaries Release oocytes (immature eggs) and secrete the hormones estrogen and progesterone ∙ Oviduct (fallopian tube) Leads from the ovary to the uterus Fertilization occurs in the upper third of the oviduct∙ Uterus: the hollow, pearshaped organ where fertilized egg grows and develops ∙ Layers Endometrium: supports fertilized egg, part of it sloughs off during menstrual flow Myometrium: smooth muscle, expands during pregnancy, constricts during labor Cervix: the narrow opening in the lower part of the uterus that permits sperm to enter the uterus and allows the fetus to exit during birth ∙ Vagina Organ of sexual intercourse and birth canal ∙ External genitalia Labia majora and minora Clitoris Mammary Glands Nourish the Infant Breasts contain mammary glands Mammary glands are modified sweat glands, part of the integumentary system Specialized for lactation (production of milk) Hormonal control of lactation: Prolactin (anterior pituitary hormone)—stimulates milk production Oxytocin (posterior pituitary hormone)—stimulates contractions that eject milk Menstrual Cycle Consists of Ovarian and Uterine Cycles ∙ Pattern of changes, which cycles every 28 days ∙ Controlled by hormones of pituitary gland and ovaries ∙ Begins at puberty and continues until menopause, except during pregnancy ∙ Consists of two linked cycles Ovarian cycle o Series of changes in ovaries associated with oocyte maturation o Controlled by FSH and LH Uterine cycle o Changes in the endometrial lining of the uterus o Controlled by estrogen and progesterone Production of Egg = Ovarian Cycle ∙ Only one female gamete matures each month ∙ At birth, a female’s ovaries contain around 2 million primary oocytes, all of which have begun the first meiotic division. (process starts while still an embryo). ∙ Thus, all the oocytes needed for a lifetime are already present at birth (usually abut 500 are used). ∙ In a holding pattern until receiving a hormonal signal out of the pituitary gland to mature. ∙ During the reproductive cycle, one of these oocytes is initiated to continue their development in a process called ovulation typically with one egg ultimately produced. The Ovarian Cycle: Oocytes Mature and Are Released ∙ If fertilization and pregnancy occurs Chorion (embryonic tissue) secretes human chorionic gonadotropin (hCG) hCG is detected by pregnancy tests hCG causes corpus luteum to continue to produce estrogen and progesterone for another 9–10 weeks After 9–10 weeks, the placenta takes over progesterone and estrogen production High levels of estrogen and progesterone prevent ovulation during pregnancy The Uterine Cycle Prepares the Uterus for Pregnancy ∙ Series of changes that occur in endometrium as it prepares for the possible arrival of a fertilized egg ∙ Menstrual phase Days 1–5 Estrogen and progesterone decrease Endometrial lining degenerates Menstruation occurs ∙ Proliferative phase Days 6–14 Estrogen and progesterone increase Endometrial lining proliferates ∙ Ovulation Day 14 ∙ Secretory phase Days 15–28 Corpus luteum produces progesterone and estrogen Endometrium continues to proliferate Uterine glands mature Uterus is prepared to accept and nourish a fertilized egg Cyclic Changes in Hormone Levels Produce the Menstrual Cycle ∙ Cycles of hormones of pituitary and reproductive structures Positive feedback o In proliferative phase, increasing estrogen causes surge in LH, which in turn causes ovulation Negative feedback o In secretory phase, steady levels of estrogen and progesterone inhibit LH and FSH release Human Sexual Response, Intercourse, and Fertilization ∙ Human sexual response Excitement: increased sexual awareness and arousal Plateau: intense and continuing arousal Orgasm: peak of sexual sensations Resolution: abatement of arousal Male sexual response: orgasm, marked by ejaculation, refractory period Female sexual response: orgasm, marked by rhythmic muscular contractions Fertilization: One Sperm Penetrates the Egg ∙ Fertilization Ejaculate: may contain several hundred million sperm Sperm may reach egg within hours to a day or more One sperm penetrates egg within the oviduct Sperm may be viable for up to 5 days within the female reproductive tract Takes place in 624 hrs after intercourse if an egg is present Fertilization = Sperm Penetrates Egg ∙ First sperm that penetrates zona pellicida (with help from enzymes in acrosome), egg blocks polyspermy ∙ Sperm nucleus only into egg and nuclear fusion occurs (2N zygote)Twins May Be Fraternal or Identical • Fraternal twins Ovulation of more than one oocyte, each of which is fertilized by different sperm No more similar than two siblings May be different genders Fraternal twins arise when two eggs are ovulated and fertilized in the same monthly cycle • Identical twins One oocyte fertilized Split into two preembryos before 16cell stage Same gender, look alike Identical twins arise when a zygote divides in two during development Development: Cleavage, Morphogenesis, Differentiation, and Growth 1. Cleavage Series of cell divisions without cell growth Produces a ball of identical cells Occurs up to about day four after fertilization Occurs entirely within the oviduct 2. Morphogenesis Changes in shape and form o Physical development of organism o Ongoing o At implantation, growth in size 3. Differentiation Individual cells take on specialized forms and functions 4. Growth Begins significantly at implantation Single cell at fertilization to >trillion cells at birth Growth in number of cells and size of cells results in increase in overall size PreEmbryonic Development: The First Two Weeks ∙ Conceptus travels through oviduct ∙ Growth, differentiation, and morphogenesis begin Morula (ball of 32 identical cells)—results from cleavage Blastocyst (hollow ball with inner cell mass that will become the embryo)— results from differentiation Implantation occurs as the blastocyst burrows into the endometrium day six or seven postfertilization Embyronic disk (destined to become the embryo) develops—end of pre embryonic period PreEmbryonic Development ∙ Ectopic pregnancy Occurs when blastocyst implants in an oviduct prior to reaching the uterus Oviduct is not large enough to support the development of a fullterm baby Ectopic pregnancies are often terminated to protect the health of the mother Embryonic Development: Weeks Three to Eight ∙ Rapid growth, differentiation, morphogenesis ∙ All organs, organ systems established by end of embryonic period ∙ Embryonic development: beginning of week three until end of week eight The Placenta and Umbilical Cord ∙ Umbilical cord: twoway life line, connects placenta to embryo’s circulation ∙ Functions Filters nutrients, waste, and antibodies for the fetus without mixing mother and fetal circulations Site of nutrient and gas exchange between embryo and mother Some toxins or viruses may pass through o Alcohol, cocaine, HIV Endocrine o Initially produces hCG (human chorionic gonadotropin o Later produces estrogen and progesterone The Embryo Develops Rapidly ∙ Day 15 Embryonic disk elongates along one axis Primitive streak appears in embryonic disk ∙ Days 19–24 Neural tube develops: becomes brain and spinal cord Pharyngeal arches develop Somites (segments): bone, muscle, skin ∙ End of week four Heart is beginning to develop Eye development begins Limb buds appear Gender Development Begins at Six Weeks ∙ Y chromosome gene for sexdetermining region Y (SRY) activated ∙ Testesdetermining factor synthesized from SRY gene—will initiate development of the testes ∙ Testes secrete two hormones 1. Testosterone stimulates the further development of male genitalia 2. AntiMullerian hormone suppresses development of female external and internal genitalia ∙ Absence of Y chromosome results in female developmentEnd of when you stop calling it an embryo and start calling it a fetus is at week 8 Months Three and Four ∙ Eight weeks: marks the transition from embryonic to fetal development ∙ Months three and four Organ development Beginnings of organ function o Kidneys, liver, spleen Cartilaginous skeleton replaced with bone Bone marrow begins producing red blood cells Face develops Rapid growth Months Five and Six ∙ Months five and six Fetal movement begins Fetal heartbeat can be heard with stethoscope Fetus responds to external sounds Lungs produce surfactant—significant for survival outside of mother Survival possible outside mother ∙ End of six months marks end of second trimester Months Seven through Nine ∙ Months seven through nine (third trimester) Rapid growth and maturation Fetal activity increases Fetus prepares for life “on the outside” o Lungs and digestive tract ready to function ∙ Average size at birth 20 inches in length, 6–7.5 lbs Birth and the Early Postnatal Period ∙ Labor initiated by hormones secreted by maturing fetus ∙ Uterus begins to contract and contractions strengthen with continuous positive feedback ∙ Stages of labor Stage 1: dilation of cervix Stage 2: expulsion of fetus (delivery) Stage 3: afterbirth—expulsion of placenta ∙ Cesarean delivery Surgical delivery of baby The Transition from Fetus to Newborn ∙ Taking the first breath Pulmonary surfactants necessary for alveoli to expand and fill with air ∙ Changes in cardiovascular system Umbilical circulation cut off Ductus venosus regresses to connective tissue Foramen ovale and ductus arteriosus close in days/weeks, cause blood to go through the lungs instead of bypassing them All blood from the digestive tract goes to liver Lactation Produces Milk to Nourish the Newborn ∙ Endocrine control of lactation Estrogen and progesterone cause breast enlargement during pregnancy Prolactin stimulates milk production Oxytocin stimulates smooth muscle contractions that cause ejection of milk ∙ Colostrum Watery milk produced the first few days after birth Rich in antibodiesFrom Birth to Adulthood ∙ Neonatal period (first month) Helpless period—movement by reflex rather than by conscious control ∙ Infancy (2 to 15 months) Rapid development and maturation of organ systems Rapid brain growth, particularly cerebral cortex ∙ Childhood (16 months to 12 years) Continued development and growth ∙ Adolescence (15 to 20 years) Growth spurt Sexual maturation Death Is the Final Transition ∙ Failure of critical organ systems leads to rapid death Brain Respiratory system Cardiovascular system ∙ Death is a process; defining the moment of death is a challenge ∙ Legal and medical criteria of death Irreversible cessation of circulatory and respiratory functions Irreversible cessation of all functions of the entire brain, including the brain stem Birth Control Methods: Controlling Fertility ∙ Abstinence: not having intercourse ∙ Surgical sterilization Vasectomy in males: cut and tie off both ductus deferens Tubal ligation in females: cut and tie off both oviducts Hysteroscopy in females: cauterize the oviducts to seal themHormonal Methods: Pills, Injections, Patches, and Rings ∙ Birth control pills (oral contraceptives) Combination of synthetic progesterone and estrogen Inhibit release of FSH and LH ∙ Hormone injections DepoProvera, Lunelle ∙ Hormone patch Ortho Evra ∙ Vaginal ring NuvaRing ∙ Implant Implanon; progesteronecontaining rod under skin ∙ Block ovulation—quite effective Advantages: o May reduce cramps and menstrual flow o Some protection against ovarian and uterine cancers Disadvantages: o Side effects include acne, headaches, fluid retention, high blood pressure, blood clots Do not protect against sexually transmitted diseases (STDs) Other Birth Control Methods ∙ IUDs: Intrauterine devices Small plastic or metal piece inserted into uterus Create mild chronic inflammation that prevents fertilization or implantation Mirena: includes progesteronelike drug ∙ Diaphragms and cervical caps Prevent sperm from entering the cervix Effectiveness improved when used with spermicides ∙ Chemical spermicides Kill sperm cells ∙ Condoms Trap ejaculated sperm ∙ Natural alternatives Rhythm method, withdrawal ∙ After intercourse pills Preven, o Four pills within 72 hours of intercourse o Prevents ovulation or fertilization Plan B (morning after pill) Mifeprex (RU486) o Prevents implantation of preembryo o Causes regression of endometrial lining o May be prescribed to induce an early abortion, up to seven weeks afterElective Abortion ∙ Methods: Mifiprex can be used up to seven weeks Vacuum suctioning of uterus Surgical scraping of uterine lining Infusion of strong saline solution The Future in Birth Control ∙ Currently in research and development: Male birth control: reduces sperm production Vaccines for women o Vaccine against hCG (human chorionic gonadotropin) o Vaccine against sperm Infertility: Inability to Conceive ∙ Infertility: inability to achieve pregnancy after a year of trying ∙ Many causes of infertility Number and quality of sperm o <60 million/ejaculation is considered infertile Pelvic inflammatory disease (PID) o Scarred, blocked oviducts Abnormal production of FSH and/or LH Irregular menstrual cycles Endometriosis Strongly acidic vaginal secretions Decreased reproductive capacity with age Miscarriage (spontaneous abortion) Enhancing Fertility ∙ Artificial insemination ∙ Artificial reproductive technologies (ART) Both sperm and eggs are handled outside of the body Method of choice for women with blocked or damaged oviducts Immature eggs must be first harvested from a woman Once eggs are harvested, there are a variety of different techniques ∙ In vitro fertilization (IVF) Fertilization in test tube outside of the body After several cell divisions, embryo is inserted into the uterus via the vagina ∙ GIFT (gamete intrafallopian transfer) Unfertilized eggs and sperm placed directly in oviduct ∙ ZIFT (zygote intrafallopian transfer) Fertilized egg is placed in oviduct ∙ Fertilityenhancing drugs Boost production of developing eggs May result in multiple births ∙ Surrogate motherhood Sexually Transmitted Diseases (STDs) ∙ Transmitted by sexual contact, including Genital, oralgenital, analgenital ∙ Can be very damaging or deadly ∙ May affect organs outside of the reproductive system ∙ Some are not treatable Bacterial STDs ∙ Gonorrhea Caused by bacteria Neisseria gonorrhoeae Male symptoms: penile discharge, painful urination Female symptoms: vaginal discharge, burning sensation when urinating o Females are often asymptomatic Can be passed to newborn during birth causing a serious eye infection If untreated, can lead to inflammation, scarring, and infertility Usually can be treated with antibiotics ∙ Syphilis Caused by bacteria Treponema pallidum Three phases o Primary: lesion in genital area o Secondary: rash Bacteria invades blood, lymph nodes, nervous system, bones o Tertiary: widespread damage to nervous system and cardiovascular system Congenital syphilis: transmitted by infected mother to fetus Treatment: penicillin ∙ Chlamydia Caused by bacteria Chlamydia trachomatis Often goes undiagnosed due to mildness of symptoms o Men: penile discharge, burning upon urination o Women: vaginal discharge, burning and itching sensation If untreated, may lead to pelvic inflammatory disease in women Can infect newborn during birth Treatment: antibiotics Viral STDs ∙ HIV and Hepatitis B HIV: one of the most dangerous STDs o Slowly destroys the immune system causing AIDS (acquired immunodeficiency syndrome) o Treatments, but no cure Hepatitis B virus o More contagious than HIV, but not as deadly o Affects liver o Vaccine available for prevention ∙ Genital Herpes and Human Papillomavirus (HPV) Genital herpes: Herpes simplex virus o Painful blisters may recur periodically o Drugs will suppress outbreaks and contagious phase, but no cure o May infect infants during birth Human papillomavirus (HPV) o Many strains can cause warts in genital area o 2 types cause cervical cancer Vaccines to prevent cervical cancer: Gardasil, Cervari Other STDs ∙ Yeast Infections Candida albicans (yeast): normally present but may overgrow o Pain, inflammation, discharge o Can be passed sexually o May follow antibiotic treatment for bacterial infections o Treatment: topical or oral antifungal medication ∙ Trichomoniasis Trichomoniasis: caused by protozoan Trichomonas vaginalis o Women: Vaginitis—inflammation of vagina Frothy foulsmelling discharge o Men: Inflammation of penis, discharge o Treatment: Flagyl (metranidazole) ∙ Pubic Lice Tiny arthropod, related to spiders Commonly called “crabs” Prefer to live on pubic hair Cause intense itching and skin irritation Treatment: antilice medication Clothes and bedding should be thoroughly washed in hot water Protecting Yourself Against STDs Choose partner wisely Communicate Use suitable barriers Get tested and treated Get vaccinated (Hepatitis B and HPV)Which is the female primary sex organ? Ovary Which gland secretes an alkaline fluid to neutralize the acidic pH of the vagina? Prostrate The presence or absence of which hormone determines the sex of the fetus? Testosterone What is the proper order of the stages of intercourse? Excitement, Plateau, Orgasm, Resolution What is the age of the youngest recorded birth mother? 5 years old Chapter 17: Cell Reproduction and Differentiation An Overview of Replication, Transcription, and Translation ∙ Human DNA is organized into 46 separate chromosomes ∙ DNA replication Process of copying DNA prior to cell division This involves making exact copies of all 46 chromosomes ∙ Gene Short segment of DNA that contains the code, or recipe, for a protein Smallest functional unit of DNA ∙ Transcription Process of copying DNA of a gene into mRNA (messenger ribonucleic acid) Occurs within the cell nucleus ∙ Translation Process of converting the mRNA template into one or more proteins Occurs in the cytoplasm at ribosomes ∙ Structure of a chromosome ∙ Replication, transcription, and translation Replication: Copying DNA Before Cell Division ∙ Process DNA strands uncoil and “unzip” Each single strand serves as a template for the creation of a new complementary strand DNA nucleotides are positioned and linked by DNA polymerase Precise basepairing (AT, CG) assures that an exact copy is made Centromere holds duplicate daughter chromosomes (sister chromatids) togetherMutations Are Alterations in DNA ∙ Mutations Alterations or “mistakes” in the DNA code Occur most frequently during DNA replication Causes o Chemical and physical forces Effects of mutations o Silent mutations: have no effect o Many mutations are harmful, may result in cell death or cancer o Some mutations are beneficial Some mutations are repaired by repair enzymes Mechanism of DNA Repair Enzymes recognize errors Errors are cut out with enzymes Damaged section is replaced DNA backbone is reconnected Numerous different DNA repair enzymes Repair enzymes are most active between the time of DNA replication and the beginning of mitosis For an Organism to Grow and Develop, Cells Have to Reproduce So what happens when your skin epidermis cells produce new a cell? Goes through the cell cycle as it grows. Nucleus and cell divide = mitosis. We started life as a single cell – father’s sperm (N) + mother’s egg (N) Each body cell nucleus has 46 chromosomes (2N) – 23 from father and 23 from mother Cleavage in an echinoderm embryo Cells Reproduce by Dividing in Two Unicellular organisms: cell division is the mechanism of reproduction Multicellular organisms: cell division enables growth from a fertilized egg to a multicellular individual Mechanism of cell division is the same in all eukaryotes Cell Reproduction: One Cell Becomes Two ∙ Two types of cell reproduction processes Mitosis: generates new diploid cells o Diploid—cell has two sets of chromosomes, one from the mother and one from the father Meiosis: generates haploid gametes o Haploid—cell has only one set of chromosomes Mitosis Produces Diploid Cells and Meiosis Produces Haploid Cells ∙ All cells in human body divide by mitosis, with the exception of the cells that form sperm and eggs ∙ All body cells other than sperm and eggs have 46 chromosomes (are diploid) These represent 23 pairs of chromosomes ∙ Gametes (sperm, eggs) have 23 chromosomes (are haploid) ∙ Reduction in chromosome number from diploid to haploid is accomplished by meiosis, a special cell division process that occurs in ovaries and testes The Cell Cycle Creates New Cells ∙ Cell cycle includes two major phases Interphase (between cell division) Mitotic phase (cell division) ∙ Interphase Long growth period between cell divisions o G1 (first gap): primary growth phase, very active growth o S (synthesis): synthesis of DNA for next cell division o G2 (second gap): final growth phase before cell division ∙ Mitotic phase (cell division phase) Mitosis o Nuclear division duplicated DNA is distributed between two daughter nuclei, nucleus divides Cytokinesis o Cytoplasm divides o Two new daughter cells are formed ∙ Complete cell cycle takes 18–24 hours ∙ Mitosis and cytokinesis takes less than one hour of the complete cell cycle ∙ Many cells enter a nondividing state, G0, either temporarily or permanently Neurons, osteocytes enter G0 after adolescenceEnvironmental Factors Influence Cell Differentiation ∙ All body cells have the same DNA, yet there are great differences between the shape and function of different cell types ∙ Differentiation Process by which a cell becomes different from its parent or sister cell Differentiation is based on different gene expression Differentiation in Early Development ∙ After fertilization of egg by sperm, zygote begins several cell divisions during which cells divide but don’t grow (up to 16 or 32 cells), and form a ball ∙ After eightcell stage, cells are exposed to different environments inside versus outside the ball ∙ Cloning Can occur by embryo splitting at eightcell stage because cells are not yet differentiated Differentiation Later in Development ∙ Two factors Developmental history of earlier cells Local environment ∙ Genes are “turned on” or “turned off” at various stages of development ∙ External substances harmful to fetuses: Cigarette smoke: retards growth Alcohol: fetal alcohol syndrome Medications: pass through placenta Illegal drugs: child born addicted Environmental chemicals: in air, water, soil Radiation: radon, Xrays Intrauterine infections: HIV, syphilis, rubella Reproductive Cloning Requires an Undifferentiated Cell ∙ Reproductive cloning Producing a “copy” of an entire organism Requires a completely undifferentiated cell as the starting point Two methods o Embryo splitting o Somatic cell nuclear transfer Embryo Splitting: Producing Identical Offspring ∙ Procedure Egg is fertilized in vitro, and allowed to divide to the eightcell stage Cells of eightcell stage are carefully separated and each is implanted into a different surrogate mother in which it develops ∙ Results: clones are genetically identical to each other but not to either parent ∙ Process has not been attempted with humansSomatic Cell Nuclear Transfer Produces a Clone of an Adult ∙ Somatic cell: any cell other than a gamete ∙ Each somatic cell has a full diploid set of chromosomes ∙ Procedure Somatic cell from the adult organism to be cloned is inserted into an enucleated fertilized egg An electrical current is used to fuse the cells Fused cell is implanted into uterus of surrogate mother and allowed to develop ∙ Result Offspring is a clone of the adult organism that provided the somatic cell Therapeutic Cloning: Creating Tissues and Organs ∙ Therapeutic cloning The cloning of human cells specifically for treating patients Ideally, remove a single cell from a patient and nurture it to develop and differentiate into the cell type needed to treat the disease Potential for creating new cells, tissues, or organs—as yet unrealized Chapter 18: Cancer: Uncontrolled Cell Division and Differentiation Cancer: An Introduction ∙ 100 different types of cancer ∙ All cancers are diseases of cell division and differentiation ∙ Normal Cells Have regulatory mechanisms that maintain an appropriate rate of cell division o Internal “clock” o Hormones o Inhibitory signals from nearby cells Remain in one location throughout their lifespan ∙ Abnormal Cells Malfunctions in growth monitoring that allow for overproduction of cells Can migrate to several different locations throughout lifetime Loose function and structure over time Tumors Can Be Benign or Cancerous ∙ Hyperplasia Substantial increase in the rate of cell division ∙ Tumor Also known as a neoplasm A discrete mass of cells resulting from hyperplasia ∙ Benign tumors Noncancerous Remain in one location Single, welldefined mass May be surrounded by connective tissue Often can be readily removed surgically Cancerous Cells Lose Control Over Their Functions and Structures ∙ Dysplasia Abnormal change in cell structure Considered a precancerous state ∙ Cancerous tumors Abnormal cell structure Loss of regulation of cell growth ∙ In situ cancer Tumor stays in one place ∙ Malignant tumor Tumor invades normal tissue and compromises organ function Tumor may undergo metastasis o Spread of the cancer to another organ or body region o Secondary, malignant tumors at other locations may developHow Cancer Develops ∙ Two things must happen simultaneously for cancer to develop: 1. Cell must divide uncontrollably 2. Cell must undergo physical changes and break away from surrounding cells ∙ These changes usually correlate with specific mutations in the cell’s genes Mutant Forms of ProtoOncogens, Tumor Suppressor Genes, and Mutator Genes Contribute to Cancer ∙ Protooncogenes Normal regulatory genes that promote cell growth and differentiation, division, or adhesion ∙ Oncogenes Mutated or damaged protooncogenes May cause cells to grow and divide more quickly than normal May result in a cell failing to respond to inhibitory signals ∙ Cancer develops only when multiple oncogenes are present ∙ Tumor suppressor genes Regulatory genes repress cell growth, division, differentiation, and adhesion May be turned off, damaged, or mutated in cancers Example: If the p53 tumor suppressor gene is mutated, a variety of cancers will develop more readilyo p53 mutations have been found in cervical, colon, lung, skin, bladder, and breast tumors ∙ Mutator genes Involved in DNA repair during replication May be mutated themselves and not function A Variety of Factors Can Lead to Cancer ∙ Age: single most important factor in development of cancer The longer we live, the more likely we are to die of cancer ∙ Some genes may be inherited that increase susceptibility to cancer ∙ Multigene basis of cancer ∙ Carcinogenesis: process of transforming a normal cell into a cancer cell Carcinogen: any substance or physical factor that causes cancer ∙ Viruses and bacteria (<15% of all cancers) Human papillomavirus (HPV): cervical cancer Hepatitis B and C viruses: liver cancer HIV: Kaposi’s sarcoma EpsteinBarr virus: Hodgkin’s disease ∙ Chemicals in the environment Asbestos, benzene, some pesticides, dyes ∙ Tobacco Responsible for 30% of all cancer deaths ∙ Radiation Ultraviolet radiation (sun exposure): skin cancer o Causes >80% of all skin cancers ∙ Diet and obesity Likely involved in approximately 30% of cancers Red meat, saturated animal fat: increased risk of cancer of colon, rectum, prostate Alcohol consumption: increased risk of breast, rectal, colon, and liver cancer High salt consumption associated with stomach cancer Type II diabetics have a much higher risk of dying of cancer Aflatoxin present in raw peanut butter ∙ Internal factors Free radicals produced by metabolism may damage DNA Antioxidants (vitamins A,C,E) may neutralize free radicals o Antioxidant containing foods: blueberries, spinach, tomatoes The Immune System Plays an Important Role in Cancer Prevention ∙ Immune system normally defends the body against cancers ∙ Cancer cells may not be recognized as “self” and may be destroyed by the immune system ∙ Anything that suppresses the immune system may make an individual more susceptible to cancerAdvances in Diagnosis Enable Early Detection ∙ Tumor imaging Xrays o Example: mammogram Positron emission tomography (PET) Magnetic resonance imaging (MRI) ∙ Genetic testing Identify mutated genes Privacy and treatment issues ∙ Enzyme tests for cancer markers Screening large numbers of people Cancer Treatments ∙ Conventional treatments Surgery: has improved with better imaging techniques Radiation: targets the tumor, but sometimes damages healthy cells Chemotherapy: use of cytotoxic drugs to destroy cancer cells o Side effects: nausea, hair loss, anemia o Often kills normal cells as well Often a combination of two or more of the above treatments is used ∙ Magnetism Magnet is placed at the tumor Tiny magnetic beads coated with chemotherapy drugs are injected and pulled to the tumor ∙ Photodynamic therapy Uses lightsensitive drugs that are taken up by cancer cells and lasers, which activate the toxicity of the drug ∙ Immunotherapy Boosts the immune response of patient Development of antibodies that specifically recognize cancer cells Tagging antibodies with radioactive molecules or chemotherapeutic drugs Development of vaccines against specific cancers ∙ Starving cancers Antiangiogenic drugs prevent the development of a good blood supply to the tumor ∙ Molecular treatments Target oncogenes Common Cancers ∙ Lung Cancer Smoking: leading risk factor No simple screening test, so the cancer is often more advanced when detected Early symptoms are nonspecific o Persistent coughing o Bronchitis o Recurrent pneumonia o Voice change Treatment o Surgery, often combined with radiation and chemotherapy ∙ Colon and Rectal Cancers Symptoms o Blood in stool, rectal bleeding Risk factors: o Sedentary lifestyle, obesity, smoking, family history, lowfiber diet, high fat diet Start as polyps (benign tumors), which gradually become malignant Screening tests can detect cancer early o Detection of blood in stool specimens o Colonoscopy: examining interior of colon with flexible fiberoptic scope Treatment: polyp removal, tumor removal ∙ Breast Cancer Early detection is crucial for survival o Mammogram: low dose Xray used for early detection o Detection of a lump on breast exam Risk factors o Genetics: two different genes increase risk BRCA1 and BRCA2 o Age o Early onset of menstruation, late menopauseo Obesity after menopause o Oral contraceptives o Hormone replacement after menopause ∙ Prostate Cancer Most common after age 50 Biggest risk factor: advancing age Symptoms o Urination difficulties, blood in urine, pain in pelvic area Diagnosis o Digital rectal exam o Blood test for PSA (prostatespecific antigen) o Biopsy Treatment o Surgery, radiation therapy, hormones ∙ Leukemia Cancer of immature white blood cells in the bone marrow Risk factors: Down syndrome, exposure to ionizing radiation, benzene, infection with HTLV1 virus Childhood forms of leukemia as well as adult forms of leukemia Symptoms: nonspecific Diagnosis: blood tests and bone marrow biopsies Treatment: chemotherapy, or chemotherapy plus bone marrow transplant ∙ Lymphoma Cancer of lymphoid tissue o Includes Hodgkin’s and nonHodgkin’s lymphoma Symptoms o Enlarged lymph nodes, intermittent fever, itching, weight loss, night sweats Risk factors o Altered immune function Transplant recipients HIV infection Occupational exposure to herbicides Treatment: radiation, chemotherapy, bone marrow transplant ∙ Urinary Bladder Cancer Symptoms o Blood in the urine Risk factors o Smoking, urban living, exposure to arsenic in water supply, occupational exposure to leather, dye, rubber Diagnosis o Microscopic examination of urine for cancer cells o Cystoscopy: direct examination of bladder wall with cystoscope (thin flexible tube with lens) Treatment o Surgery with chemotherapy ∙ Kidney Cancer Risk factors o Genetics, smoking, exposure to certain toxic chemicals, age, gender (female) No direct screening tests o Usually detected during examination for a renalrelated problem Diagnosis o CT scan or ultrasound Treatment o Surgical removal of affected kidney ∙ Skin Cancer Three major types 1. Basal cell carcinoma o Involves basal cells in base layer of epithelium o Rarely metastasizes, but should be removed 2. Squamous cell carcinoma o Involves epithelial cells o May metastasize slowly 3. Melanoma o Deadliest, but least common of skin cancers o Cancer of the melanocytes o Metastasizes quickly Early Signs of Skin Cancer—ABC’s o Observe skin lesions for ∙ A = Asymmetry Two halves of the affected area don’t match ∙ B = Border Border is irregular in shape ∙ C = Color Varies or is black ∙ D = Diameter Greater than 6 mm (size of pea) ∙ E = Evolution Change in size, shape, color or elevation; new symptom such as bleeding, itching, or crusting∙ Uterine, Cervical Cancers Uterine cancer o Involves the endometrium o Symptom: abnormal bleeding o Risk factors Early onset of menstruation, late onset of menopause, not having children, estrogen use after menopause Cervical cancer o Caused by human papilloma virus (HPV) infection o Detection: Pap test o Prevention: Gardasil or Cervarix vaccines Treatment: surgery, chemotherapy, radiation, hormones Most Cancers Can Be Prevented Know family history Know your own body ∙ Learn selfexamination techniques Get regular medical screenings Avoid direct sunlight 10 a.m. to 4 p.m., sunlamps, and tanning salons Watch diet and weight Don’t smoke Drink alcohol in moderation, if at all Stay informed Ch. 19: Genetics and Inheritance Genes: DNA sequences that contain instructions for building proteins Genetics: study of genes and their transmission from one generation to the nextGenome: sum total of all of an organism’s DNA Your Genotype Is the Genetic Basis of Your Phenotype ∙ Chromosomes: structures within the nucleus, composed of DNA and protein ∙ The genes are located on the chromosomes ∙ Humans have 23 pairs of chromosomes 22 pairs of autosomes 1 pair of sex chromosomes: determine gender 1 of each pair of autosomes and 1 sex chromosome is inherited from each parent ∙ Homologous chromosomes One member of each pair is inherited from each parent Look alike (size, shape, banding pattern) Not identical: may have different alleles of particular genes ∙ Alleles: alternative forms of a gene Alleles arise from mutation ∙ Homozygous: two identical alleles at a particular locus ∙ Heterozygous: two different alleles at a particular locus ∙ Genotype: an individual’s complete set of alleles ∙ Phenotype: observable physical and functional traits Examples: hair color, eye color, skin color, blood type, disease susceptibility Phenotype is determined by inherited alleles and environmental factors Genetic Inheritance Follows Certain Patterns ∙ Punnett square analysis Predicts patterns of inheritance ∙ To set up a Punnett square: Possible alleles of one parent are placed on one axis Possible alleles of other parent are placed on the other axis Possible combinations of parental alleles are written in the squares within the gridMendel Established the Basic Principles of Genetics ∙ Worked with pea plants in the 1850s in Austria ∙ Did multiple genetic experiments to develop basic rules of inheritance ∙ Law of segregation Gametes carry only one allele of each gene Each gamete produced from meiosis gets only one set of genes ∙ Law of independent assortment Genes for different traits are separated from each other independently during meiosis o Applies in most cases The combination of alleles that make up that set are random Dominant Alleles Are Expressed Over Recessive Alleles ∙ Dominant allele Masks or suppresses the expression of its complementary allele Always expressed, even if heterozygous ∙ Recessive allele Will not be expressed if paired with a dominant allele (heterozygous) Will only be expressed if individual is homozygous for the recessive allele ∙ Dominant alleles are not always more common than recessive; sometimes they may be rare in a population TwoTrait Crosses: Independent Assortment of Genes for Different Traits ∙ Outcome of twotrait crosses can be predicted by Punnett square analysis ∙ Law of independent assortment The alleles of different genes are distributed to gametes independently during meiosis This law applies only if the two genes in question are on different chromosomes Incomplete Dominance: Heterozygotes Have an Intermediate Phenotype ∙ Examples Hair o Straight hair: HH o Wavy hair: Hh o Curly hair: hh Familial hypercholesterolemia o HH: Normal o Hh: blood cholesterol 2×–3× normalo hh: blood cholesterol >6× normal, heart attacks in childhood Codominance: Both Gene Products Are Equally Expressed ∙ Examples Genes for ABO blood types o A gene and B gene are codominant o An individual heterozygous for the A and B genes will be blood type AB, expressing both A and B antigens on red blood cells Sicklecell gene o Two different alleles of hemoglobin gene ∙ HbA: encodes normal hemoglobin ∙ HbS: encodes sickle cell hemoglobin o Sicklecell anemia: HbS HbS (homozygous) ∙ HbS will crystallize if O2 is slightly decreased, resulting in bending of red blood cells into crescent shapes ∙ Multiorgan damage may result o Sicklecell trait: HbA HbS (heterozygous) ∙ Affected individual makes both types of hemoglobin ∙ Rarely symptomaticPolygenic Inheritance: Phenotype Is Influenced By Many Genes ∙ Inheritance of phenotypic traits that depend on many genes ∙ Examples Eye color, skin color Height, body size and shape ∙ Polygenic traits are usually distributed within a population as a continuous range of values Both Genotype and the Environment Affect Phenotype ∙ Phenotype isn’t determined by genotype alone ∙ Environmental factors can profoundly influence phenotype Example: nutrition affects height, body size Linked Alleles May or May Not Be Inherited Together ∙ Linked alleles: physically located on the same chromosome ∙ May be inherited together ∙ May be “shuffled” during crossing over during meiosis SexLinked Inheritance: X and Y Chromosomes Carry Different Genes∙ Sex chromosomes 23rd pair of chromosomes Not homologous X and Y chromosomes carry different genes ∙ Males: have one X and one Y chromosome ∙ Females: have two X chromosomes ∙ Male 50% Xcarrying gametes, 50% Ycarrying gametes Male parent determines the gender of offspring ∙ Karyotype A composite visual display of all of the chromosomes of an individual Shows all 23 pair of chromosomes lined up sidebyside SexLinked Inheritance Depends on Genes Located on Sex Chromosomes ∙ Sexlinked genes are located on sex chromosomes Sexlinked or Xlinked inheritance Characteristics o More males than females express the disease o Passed to sons by mother o Father cannot pass the gene to sons, but daughters will be carriers ∙ Examples Redgreen color blindness Hemophilia: an Xlinked recessive disease o Female carriers pass the hemophilia allele to half their daughters and the disease to half their sons o Males with the disease pass the hemophilia allele to all their daughters (if they survive long enough to have children), but never to their sons Duchenne muscular dystrophy SexInfluenced Traits Are Affected by Actions of Sex Genes ∙ Sexinfluenced traits Genes encoding these traits are located on the autosomes (not the sex chromosomes) Expression of the trait is affected by presence of testosterone, estrogen ∙ Example Baldness o Several genes influence hair patterns, but also influenced by the presence of estrogen or testosterone Chromosomes May Be Altered in Number or Structure ∙ Nondisjunction during meiosis Failure of homologous chromosomes or sister chromatids to separate A gamete may end up with two copies of a chromosome, instead of just one Examples o Down syndrome: trisomy 21 o Alterations of the number of sex chromosomes Down Syndrome: Three Copies of Chromosome 21 ∙ Three copies of chromosome number 21 Also referred to as trisomy 21 ∙ Distinct physical features ∙ Developmental disabilities ∙ 1/1000 live births in the United States ∙ Increased risk of trisomy with increasing maternal age ∙ Can be detected by fetal testing Alterations in the Number of Sex Chromosomes ∙ Nondisjunction affecting sex chromosomes can produce a variety of combinations ∙ Jacob syndrome: XYY Males, tall, otherwise fairly normal ∙ Klinefelter syndrome: XXY Males, tall, sterile, mild mental impairment, some breast enlargement ∙ Turner syndrome: XO Female, short, normal intelligence, sterileDeletions and Translocations Alter Chromosome Structure ∙ Deletions Piece of a chromosome breaks off Example: Criduchat syndrome ∙ Translocations Piece of chromosome breaks off and attaches to a different chromosome Many Inherited Genetic Disorders Involve Recessive Alleles ∙ Many genetic disorders involve recessive alleles To develop these diseases, one recessive allele is inherited from each parent, who most often are themselves heterozygous (carriers) Phenylketonuria (PKU) o Lack enzyme to metabolize phenylalanine o May cause mental retardation o Treatment: limit phenylalanine in diet TaySachs disease o Lack enzyme to metabolize a brain lipid o Leads to brain dysfunction and death by age four Dominant Disorders ∙ Some human genetic disorders are dominant Achondroplasia is a form of dwarfism Huntington’s disease is a fatal dominant disorder where neurons in the brain cells degenerate Huntington Disease Is Caused by DominantLethal Allele ∙ Caused by lethal dominant allele ∙ Always expressed in heterozygote Not expressed until midlife ∙ Always lethal ∙ Has persisted in the human population Isn’t expressed until midlife so affected individuals have often had children prior to onset of symptoms Each child of an affected individual has a 50% chance of inheriting the lethal gene Genes Code for Proteins, Not for Specific Behaviors ∙ Genes: encode specific proteins ∙ Proteins have specific functions leading to phenotypes ∙ Protein functions Hormones Enzymes Structural Neurotransmitters Chapter 22: Evolution and the Origins of Life Three Key Concepts of Evolution ∙ Evolution involves descent over time Populations undergo slow changes over generations ∙ Evolution involves genetic modification Changes in the DNA ∙ Evolution is unpredictable and natural ∙ Microevolution: result of genetic changes, gives rise to new species ∙ Macroevolution: largescale changes or trends that apply to groups of species Evidence for Evolution Comes from Many Sources ∙ Incomplete but valuable ∙ Preserves only hard tissues ∙ Determining the age of fossils Stratification of sedimentary rocks in which fossils are located can help determine age of fossils Radiometric dating Comparative Anatomy and Embryology Provide More Evidence ∙ Homologous structures: body structures that share a common origin Example: vertebrate forelimbs ∙ Analogous structures: body structures that share a similar function but very different origins Example: bird wing and insect wing ∙ Vestigial structures: body structures that no longer have a function but are homologous to structures in other organisms Example: human coccyx ∙ Compare structures of embryos of different vertebrate species ∙ Striking similarities Gill or pharyngeal slits Postanal tail Notochord Body segmentation (somites) Comparative Biochemistry Examines Similarities Between Molecules ∙ Examines similarities between molecules ∙ Estimates divergence of species from a common ancestor Example: cytochrome C ∙ Similarities in RNA, DNA, and proteins are used as indicators of common ancestry Biogeography: The Impact of Geographic Barriers and Continental Drift on Evolutionary Processes ∙ Study of the distribution of different plants and animals worldwide ∙ Impact of geographic barriers such as mountains, deserts, large bodies of water ∙ Continental drift due to movement of earth’s tectonic plates—related groups of organisms were isolated from each other and evolved separately Random Mutations Underlie Evolution ∙ Random mutations Mutations are rare accidental events that change the nucleotide sequence of a gene Alleles: different forms of a gene that result from mutations in a gene Nonlethal alleles may be passed to the next generation and future generations Without mutations there would be no evolution Natural Selection Encourages Changes in the Gene Pool ∙ Natural selection “Survival of the fittest” by means of natural selection Individuals with certain traits are more likely to survive, reproduce, and pass the genes that encode those traits to their offspring Mass Extinctions Eliminate Many Species ∙ Extinction: a lifeform dies out completely ∙ Mass extinctions Five mass extinctions in the last 530 million years These have eliminated 50% or more of species Largest mass extinction: during the Triassic period Most recent mass extinction: during the Cretaceous period—end of the dinosaurs We may be entering the 6th mass extinction now— due to human activity Evolutionary Trees Trace Relationships Between Species ∙ Also called a phylogenetic tree ∙ Purpose Trace evolutionary change and relationships between species ∙ Adaptive radiation Short bursts of evolutionary activity Many new species develop within a short time The Young Earth Was Too Hot for Life ∙ Earth originated 4.6 billion years ago (bya) ∙ Inhospitable to life Hot and steamy ∙ Early atmosphere Consisted of carbon dioxide, water vapor, hydrogen, nitrogen, methane, and ammonia No liquid water, oxygen, or ozone Bombarded with UV radiation Organic Molecules Formed from Atmospheric Gases ∙ Selfreplicating RNA and, later, DNA formed on clay templates or under the dry conditions and intense heat near volcanoes ∙ Early cells were formed as selfreplicating DNA and other organic molecules became enclosed in lipid/protein membranes ∙ First living cells were anaerobic ∙ As photosynthesis evolved, O2 began to accumulate in the atmosphere Photosynthetic Organisms Altered the Course of Evolution ∙ Photosynthesis Caused an increase in atmospheric oxygen Oxygen is produced as a byproduct of photosynthesis ∙ Evolution of aerobic organisms Oxygen toxic to anaerobic organisms Survivors had to possess chemical pathways to make needed organic compounds Aerobic metabolism evolved as pathways that could harness the reactive power of oxygen The Rise of Animals and Our Human Ancestors ∙ 1.7 billion years ago Nucleus formed, eukaryotes develop ∙ 1.3 billion years ago First multicellular organisms (seaweed) ∙ 600 million years ago Animals appear ∙ 65 million years ago Dinosaurs extinct ∙ 5 million years ago Distinctly human ancestors Modern Humans Came from Africa Humans Are Primates ∙ Mammals Vertebrates with hair and mammary glands that produce milk ∙ Primates Hands with five digits Fairly flat fingernails and toenails Forwardfacing eyes Includes lemurs, monkeys, apes, humans ∙ All primates share a common ancestor that lived about 60 million years ago ∙ Hominoid group diverged from other primates about 25 million years ago ∙ Hominoids Larger brains No tail More complex social behavior ∙ Includes orangutans, apes, chimpanzees, humansDifferences Within the Human Species ∙ Racial differences are slight differences in phenotypes between subgroups of a common species ∙ Differences helped populations adapt to environments Dark skin: provides protection from ultraviolet (UV) damage in intense sunlight Light skin: allows adequate UV radiation for vitamin D production in less intense sunlight ∙ Racial differences are no more significant than individual differences Final on scantrons in the Biology Building lecture room where we have class on Tuesday at 8am – don’t be late