INTRO TO BIOLOGY
INTRO TO BIOLOGY BIOL 101
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Chapter 29 Human Reproduction Eggs in females when she is born exist in precursor forms called oocytes Lie within ovaries A pair of walnutshaped organs within the pelvic region Oocytes are expelled approximately every 28 days Ovulation Travels down uterine tube Fallopian tube toward uterus Fertilization may occur during this journey Sperm is produced in unfinished form in sets of tubules in the two male testes They are transported to the epididymis where further development occurs With sexual excitation sperm are transported through the vas deferens to the urethra Secretions from several glands are added to the sperm to form semen Semen is ejaculated into the female vagina Human Reproduction in Outline Sperm move into the uterine tubes Relatively few of the sperm released are likely to encounter a released oocyte A sperm may fertilize an oocyte This fertilized egg divides and ultimately implants into the uterine wall Development continues while implanted into the uterine wall Birth occurs approximately 38 weeks after fertilization Mature egg is the largest cell in the human body Female Reproductive System Mammary glands uterine tubes ovaries uterus vagina external genitalia The female reproductive system must ful ll two different roles Formation is an egg Creation of an environment in which a fertilized egg can develop An important part of the uterine environment is built with each cycle Each 28 days on average Unless an egg is fertilized this uterine environment is dismantled Menstruation 9 cyclical release of blood and uterine tissue from the female reproductive tract This uterine tissue is the endometrium which would have housed an implanted embryo Costs associated with menstruation Discomfort Loss ofblood and other tissue 14 uid ounces of blood amp similar amount of uterine tissue lost Why does menstruation exist Maintaining a permanent embryonic environment in uterus is more costly Inner endometrium changes form near time of ovulation Primary activity switches from growth proliferative phase to secretion of a nutrientrich mucus secretory phase Secretory phase endometrium is required for implantation Secretory phase endometrium cannot perpetuate itself Eggs develop from precursor cells called oocytes Develop in the other portion of ovary Surrounded by a collection of accessory cells Follicle cells Provide the oocyte with nutrients The oocyte and surrounding follicle cells are called ovarian follicle Basic unit of oocyte development Every oocyte maturing into an egg must go through certain developmental stages Begins with several follicles Some follicles develop into primary follicles Some primary follicles develop into secondary follicles A single secondary follicle develops into a tertiary follicle Nurtures an oocyte through its time in the ovary Hormonal in uences cause tertiary follicle to rupture midway through menstrual cycle Oocyte is eXpelled Still surrounded by some accessory cells Ovulation Occurs once with every cycle Ovulated oocyte and accessory cells enter uterine tube Ciliated cells of the uterine tube create liquid current Current carries oocyte about four inches through uterine tube over 4 days Fertilization by sperm can occur during this time Ruptured tertiary follicle develops into corpus luteum Secretes hormones that help prepare female reproductive tract for pregnancy Continued secretion will maintain pregnancy If pregnancy does not occur corpus luteum will disintegrate after about 12 days Male Reproductive System Structures of male reproductive system Sperm begin development in the BU Epididymis is site of sperm maturation and storage Sperm move through vas deferens during ejaculation Both vas deferens empty into urethra Sperm in the form of semen eXit the body through urethra Accessory glands produce secretions that are added to sperm Seminal vesicles Prostate gland Bulbourethral glands Sperm these secretions semen Sperm development requires temperatures slightly cooler than rest of body Testes are eXternal Slightly cooler environment Testes surrounded by a muscle Contraction helps regulate temperature Testes are divided into series of lobes Each lobe contains several convoluted seminiferous tubules Sites of initial sperm development Sperm move toward central cavern of each tubule as they develop Immature sperm are released into central cavity and transported to epididymis Further processing and storage Destruction of older sperm Sperm development takes about 25 months 200 million sperm produced daily 200 million sperm present in average ejaculate Sperm compete with each other to fertilize egg Prior to Birth Union of Sperm and Egg Each sperm has a head Contains haploid nucleus Contains acrosome lled with enzymes Enzymes are released eXtemally to break down cells and material surrounding the oocyte Digestive juices of dozens of sperm are required to break down layers surrounding oocyte A single sperm binds with receptors on the surface of the oocyte Sperm and oocyte plasma membrane fuse Sperm and egg nuclei combine Fertilization is complete Binding by a single sperm prevents binding and fertilization by additional sperm May sperm reach the cells that surround the oocyte Only rst sperm that binds with receptors on the oocyte can fertilize it Nucleus of sperm unites with nucleus of oocyte The two nuclei fuse together Fertilization initiates development Stepwise process by which fertilized egg is transformed into functioning organism After fertilization the fertilized egg divides multiple times 5gtwr Multicellular embryo is formed Embryo reaches uterus about 4 days after fertilization This embryo will transform into a hollow blastocysi and implant into uterine wall within 2 days Implantation in uterine tube or on cerviX constitutes ectopic pregnancy In general embryos do not survive these implantations Blastocyst consists of two parts Inner cell mass Portion that develops into baby Trophoblast Present on periphery of blastocyst in uterine wall Facilitate implantation Release enzymes that carve out cavity in uterine wall Form fetal portion of placenta Placenta Network of maternal and embryonic blood vessels and membranes Facilitates exchange of nutrients gases and wastes between mother and embryo Linked to fetus through umbilical cord Identical Twins Genetically identical Develop during early stages of pregnancy Within rst 7 days postfertilization Embryo separates into two parts eg two cells separate after rst division and each implants separately eg blastocyst s inner mass separates into two masses each developing into a separate individual Fraternal Twins Produced through multiple ovulations followed by separate fertilizations Each implants separately No more alike than any siblings All of the cells within a blastocyst s inner mass are identical None are specialized yet Embryonic stem cells These cells show promise in the treatment of Parkinson s disease spinal cord injuries and countless other conditions Able to differentiate into any type of cell in the adult body Birth Fetal head lodges near base of mother s spine late in pregnancy Labor soon follows Regular contractions of uterine muscles sweep over fetus from legs to head Pressure dilates cerviX Continued contractions eXpel baby Continued contractions eXpel placenta Afterbirth Often desirable to avoid pregnancy Various forms of contraception eXist with varying levels of effectiveness Condom Birth Control Pill Diaphragm Intrauterine Device IUD Tubal Ligation Vasectomy STDs Many microorganisms can be transmitted from one individual to another during seX Some cause disease Risk of an STD is dependant upon many factors Number of sexual partners The disease itself Type of sexual activity Precautions taken to avoid transmission Chlamydia Caused by Chlamydia trachomatis bacterium Possible consequences spread to uterine tubes in women causing pelvic in ammatory disease PID which can lead to sterility Treatment curable with timely use of antibiotics Gonorrhea Caused by Neisseria gonnorhoeae bacterium Possible consequences arthritis pelvic in ammatory disease PID Treatment curable with timely use of antibiotics though antibioticresistant strains now eXist Syphilis Caused by Treponema pallidum bacterium Possible consequences heart nervous system and bone damage if allowed to progress Treatment curable with timely use of antibiotics though antibioticresistant strains now eXist Genital Herpes Caused by Herpes simpleX virus Possible consequences recurrent skin lesions eye damage and pregnancy complications Treatment occurrence and severity of outbreaks can be lessened with treatment but no cure eXists Genital Warts Caused by Human papilloma virus Possible consequences cervical cancer in women association with increased risk of cervical and penile cancer Treatment several treatments eXist for removing warts but virus may persist AIDS Caused by Human immunode ciency virus HIV Possible consequences death dementia and injury from variety of opportunistic infections Treatments treatments to reduce symptoms eXist but no cure Chapter 25 The Human Bodv and Three of its SVstems Cell 7 basic unit of life Tissue 7 a group of cells performing a common function Organ 7 combined tissues Organ System 7 group of organs Human body has 11 organ systems Organism 7 multiple organ systems 4 Basic Tissue Types in Human Body Epithelial Tissue Covers internal and external body surfaces Outer layer of skin lining of blood vessels lining of stomach etc Comprised of mostly tightly packed cells One or several cell layers thick Functions Barrier skin prevents microorganisms from entering body Transport sugars are transported across the epithelium lining the sm intestine Production of Various Substances glands within the stomach epithelium produce and secrete digestive juices Connective Tissue Stabilizes and supports other tissues eX bone tissue Most are composed mainly of extracellular material with widely separated cells Muscle Tissue Specialized in its ability to contract Three types Skeletal eX bicep striated and voluntary Cardiac present only in heart striated and involuntary Smooth eX blood vessels uterus etc nonstriated and involuntary Nervous Tissue Specialized for rapid conduction of messages electrical impulses Two main types of cells Neurons conduct impulses Glial cells perform support functions for neurons Tissues Present in Stomach Inner surface lined by epithelial tissue supported by underlying connective tissue Smooth muscle underlies the connective tissue Nervous tissue controls the release of digestive juices and controls contractions of smooth muscle Blood vessels present also contain all four tissue types Organs and Tissues Make up Organ Systems Body Support and Movement The Integumentary System Skin hair nails secretory cells Protection regulation of body temperature The Skeletal System Bones cartilage ligaments tendons Support protection storage of fat and minerals The Muscular System Skeletal muscles provide movement posture support heat generation Coordination Regulation and Defense The Nervous System Brain spinal cord other nerves sense organs Rapid communication system The Endocrine System Pituitary thyroid parathyroid thymus adrenals pancreas gonad Hormone communication system The Immune System Thymus lymph nodes spleen lymphatic vessels Collection of cells and proteins Protection from invading microbes Returns uid to circulatory system Transport and Exchange with the Environment Cardiovascular System Bone marrow heart capillaries arteries veins Transports materials in body Respiratory System Nasal cavity pharynx larynx trachea bronchi lung Facilitates exchange of Oz and C02 Digestive System Salivary gland pharynx esophagus liver stomach gall bladder sm intestine lg intestine anus Breakdown and absorption of food Urinary System Kidney ureter urinary bladder urethra Elimination of wastes from blood Retains useful molecules in blood Reproductive System Male production of sperm Seminal vesicles prostate sperm duct urethra epididymis testis penis scrotum Female production of eggs nourishment to offspring in utero mammary glands Mammary glands uterine tube ovary uterus vagina external genitalia Integumentary System Skin is the primary component along with hair nails glands Primary function is protection Skin is organized into two parts Thin outer epidermis Cells in deepest layer divide and new cells are pushed outward Outermost layers are dead because they are too far away from blood supply Filled with waterresistant protein keratin Thicker underlying dermis Touch and pressure receptors provide sensation Hair follicles start deep in dermis Hypodermis lies below dermis NOT part of skin Contains abundant fat cells subcutaneous fat Skeletal System Contains three structural elements Bone Connective tissue providing support Ligaments Connective tissue linking bones together Cartilage Connective tissue serving as padding in joints and other places Tendons Connective tissues joining bone to muscle Each Bone is a separate organ Calcified osseous tissue Nerves and blood vessels Cells comprise only 2 of bone tissue Structure of long bone Compact bone forms outer portion Spongy bone lls expanded ends Porous contains marrow redride to blood cells yellowenergy storing Marrow cavity contains yellow marrow Bone is dynamic Bone Remodeling involves three types of cells One builds up bone one maintains bone one breaks down bone Entire skeleton is replaced every ten years Osteoporosis 7 thinning of bone tissue Joints exist wherever two bones meet Suture Hinge BallandSocket Gliding Muscular System Muscles move scaffolding of bones Fibers at ends of muscles form tendons which attach bone to muscle Each skeletal muscle is a separate organ Collectively comprise 40 of body weight Each muscle contains bundles of cells called fascicles Each fascicle contains multiple muscle cells Each muscle ber contains 10000 sarcomeres fundamental units of contraction Muscle fibers contain numerous long thin strands called myofibrils Run entire length of cell Myofibrils contain filaments of two types that are responsible for muscle contraction Thick filaments are protein myosin Center of sarcomere Thin filaments are protein actin Attached to both ends of sarcomeres Overlap with thick filaments Thin filaments slide toward center during contraction Sarcomeres and muscle shorten Length of filaments don t change Myosin heads bind to thin filaments Create crossbridges Myosin heads pivot at base Thin filament pulled toward center REPEAT Two varieties of muscle fibers exist Fast twitch Faster generate more power Generate power only for brief periods Sprinting primarily uses fast twitch Slow twitch Slower more sustained power Distance athletics use slow twitch Chapter 28 Transport and Exchange Transport and Exchange Systems of the body Respiratory Moves 02 into and C02 out of the body Cardiovascular Transports materials to and from all other systems Digestive Transforms food into a form that can be transported throughout the body Urinary Filters bodily uids removes waste while conserving water and other materials The Cardiovascular System Fluid transport system Three components Heart blood vessels and blood Transports many different materials throughout the body Nutrients vitamins waste products hormones immune system cells and proteins oxygen C02 heat Centrifugation will separate blood into two layers 55 plasma 92 water 7 plasma proteins 1 other solutes 45 formed elements 999 red blood cells Red blood cells Most numerous of the formed elements Transport 02 to and C02 from every part of the body 1 white blood cells and platelets White blood cells Critical players in the immune system Platelets Small fragments of cells Important in the bloodclotting process Red blood cells Erythrocytes filled with the ironcontaining pigment hemoglobin Gives blood its red color Binds to 02 in the lungs which is required for metabolism Releases 02 in other body tissues Binds to C02 in body tissues produced during metabolism Releases C02 in the lungs Present in large concentration 48 7 54 million per cubic millimeter of blood l3 of all cells in the body Odd structure Lost nucleus and organelles Cannot maintain themselves very well Average life span of 120 days 180 million new RBCs made each minute Cell membrane lled with hemoglobin White Blood Cells Leukocytes Possess standard cellular organelles Central to body s immune system operation 6000 per cubic millimeter ofblood Platelets Fragments of cells Broke away from large cells in bone marrow Enzymebearing packets Aid in blood clotting at sites of injury Plasma 92 water Proteins and other materials are dissolved in this water Plasma proteins are most numerous EX Antibodies transport proteins clotting proteins etc Nonprotein materials are all present EX Hormones nutrients wastes ions etc The Heart Muscular pump Roughly the size of a clenched fist Located near the back of the chest wall directly behind sternum Heart moves blood through blood vessels Blood exits and enters through two circulation loops Pulmonary circulation Picks up 02 from lungs Systemic circulation Delivers 02 to other body tissues 4 Chambers 2 associated with pulmonary right atrium right ventricle 2 associated with systemic circulation left atrium left ventricle Pulmonary Circulation Blood enters the right atrium through two veins Superior and inferior vena cava This blood is returning after distributing 02 throughout the body This blood is deoxygenated Ozpoor Right ventricle pumps blood out of the heart through pulmonary arteries Systemic Circulation Newly oxygenated blood returns to the left atrium The left atrium pumps blood to the adjacent left ventricle Left ventricle pumps blood out of the heart through the aorta Ventricles contract with great force Blood move out of the heart only Valves between the atria and ventricles prevent back ow into the atria A heart murmur is back ow into the atria Valves between the ventricles and arteries prevent back ow into the ventricles Lubdub heart sounds correspond to each of the valves closing Blood is supplied to the heart through coronary arteries branching from aorta Heart Attack LDL Groups of the heartmuscle cells do not receive blood Cholesterol carrying molecules can lodge within the innermost tissue later of a coronary artery Oxidation of LDLs causes the immune system to recognize them as foreign In ammatory response causes tissue to swell into the space through which blood normally ows Partial blockage is rarely sufficient to cause heart attack Some of this swollen tissue ruptures forming clot Combination of swelling and clotting can cause complete blockage of artery Can result in heart attack Lowering of LDLs and increasing of HDLs can lessen chance of heart attack Capillaries Diameters average 3 tenthousandths of an inch Red blood cells must travel in sing file Possess only a single layer of epithelial cells Smooth muscle and connective tissue layers are absent Central function is to allow materials to pass into them and out of them Smallest blood vessels Consist of a single layer of cells Small diameter forces red blood cells to travel in single file Link smallest arteries to smallest veins Capillary Beds Oxygen glucose and other nutrients move through the capillary wall into the interstitial uid Liquid in which the capillaries and surrounding cells are immersed These materials move to nearby cells No viable cell is more than two or three cells away from a capillary C02 and other wastes move from these cells into the capillaries from the interstitial uid Blood pressure is rather high in the arteries Propels blood into the capillaries Blood pressure is rather low in veins Skeletal muscles and oneway valves work together to move blood through veins back to the heart Skeletal muscles squeeze blood along Valves prevent backward movement in veins The Respiratory System Breathing has two central functions Capturing and distributing 02 Without 02 out cells lack energy required to function 5 7 6 minutes without breathing generally results in death Disposal of C02 C02 produced during metabolism must be removed C02 disposal also regulates blood pH Components of respiratory system Nose nasal cavity sinuses pharynx throat larynx voice box trachea wind pipe bronchi and bronchioles air conducting passageways lungs Lungs are comprised mainly of grapelike clusters of tiny hollow sacs at the end of each bronchiole Alveoli Air exchanging chambers of lungs 300 million present in set of lungs Surface area equivalent to a tennis court Tightly linked with capillary networks Ventilation is the first step in respiration Physical movement of air into and out of the lungs Contraction of the diaphragm decreases the volume of the thoracic cavity Reduces the pressure inside the lungs Air moves into lungs Relaxation of diaphragm increases volume of thoracic cavity Increases pressure inside lungs Air ows from lungs Digestive System Digestive tract is a muscular tube Alimentary canal or gastrointestinal tract Mouth 9 anus Mouth tongue pharynx esophagus stomach small intestine large intestine Various accessory organs exist along the length of the digestive tract Salivary glands gall bladder liver pancreas Central function is to convert ingested food into a form the body can use These molecules enter the circulatory system and are distributed throughout body Involved in removal of waste remaining after useful materials have been removed Carbohydrates and proteins are broken down into sugars and amino acids Carbs and amino acids diffuse across inner lining of small intestine into adjacent capillaries Fat digestion is more complicated Large molecules are broken down into small molecules that ultimately enter the cardiovascular system Tube has several layers Inner lining is epithelial tissue Mucosa Next layer is connective tissues Blood vessels and nerves present Nerves coordinate muscular contraction and secretion of digestive juices Next layer has 2 sets of smooth muscle Alternating contractions move food through the digestive tract by peristalsis Outermost layer is connective tissue Numerous folds in mucosa increase surface area available for absorption of digested food Also permit expansion Villi are smallerscale projections of mucosa Further increase surface area available for absorption Food moves into adjacent capillaries Fats move into lymphatic vessels then blood Steps in Digestion Mouth Entry place for food Mechanical breakdown by chewing Chemical breakdown of carbs by enzymes secreted by salivary glands Food moved by tongue into pharynx Pharynx Muscles push food to esophagus Esophagus Muscles push food into stomach Stomach Functions in digestion and temporary storage Mechanical digestion by churning food Chemical digestion by digestive juices Mainly protein digestion Glands secrete gastric juice into stomach through gastric pits 45 ounces of gastric juice per day Contains hydrochloric acid and enzymes Low pH aids in digestion kills bacteria and other microorganisms Protecting mucus protects cells lining the stomach Few substances pass directly from stomach into circulation Ex Alcohol and some drugs After several hours food is converted into soupy mixture Chyme A circular muscle regulates ow of chyme into small intestine Pyloric Sphincter Small Intestine Small in diameter 16 inches at start 9 1 inch at end Large in length 20 feet long 80 of nutrients are absorbed in small intestine 10 are absorbed in stomach 10 are absorbed in large intestine 3 Regions Duodenum 10 inches closest to stomach Receives chyme and secretions from pancreas liver gall bladder Jujenum 8 feet long Site of majority of absorption Ileum 12 feet long Some nutrient absorption Ends at sphincter muscle which controls ow of chyme into large intestine Pancreas Pinkishgray organ about 6 inches long Lies behind stomach Produces insulin which is secreted into blood Secretes materials through pancreatic duct into duodenum of small intestine Digestive enzymes Lipases proteases and carbohydrates Break down food molecules Chemical buffers neutralizing acidity of chyme Accessory Organs Gall Bladder Muscular sac Lodged in a recess beneath liver Stores and concentrates bile Liver Produces bile Facilitates digestion of fats Blood carrying nutrients from digestive system ows into the liver First stop for most nutrients Controls which nutrients are stored and which are sent to rest of the body First stop for toxins such as alcohol Packages waste products for removal by kidneys Large Intestine NS feet long Begins at the end of the small intestine and ends at anus Receives material from small intestine Regulated by ileocecal valve Holds and compacts material that is large waste produces feces Returns water to general circulation Absorbs vitamins produced by resident bacteria Divided into 3 regions Cecum Contains pouch called appendix Nonessential arm of immune system Can become infected appendicitis Colon Longest section of large intestine Rectum Storage site of feces Urinary System Function in elimination of liquid waste Digestive system removed retained waste from digestion Urinary system removes waste generated through cellular activity throughout body Filters waste from blood Passes waste to the urinary bladder for elimination Filters waste from blood Regulates blood volume Controls ion concentrations Maintains pH balance in body Conserves bodily resources Organs in Urinary System Kidneys Located on either side of vertebral column Shaped like kidney beans About size of small pears Blood arrives via renal arteries Blood exits via renal veins Urine exits via ureters One input two outputs CHAPTER 11 NOTES Mendel and His Discoveries Inheritance is viewed as a black box Genetics 7 the study of inheritance Study began with Gregor Mendel Austrian Monk and naturalist Had no knowledge of chromosomes meiosis or DNA Used scienti c method Experimental Organism 7 Pisum sativum common garden pea Performed in presentday Czech Republic Genes 7 elements of NA located on chromosomes ake up 2 of DNA BASES A 7 Adenine T 7 Thymine C 7 Cytosine G 7 Guanine Cycle of a Pea Plane Selfpollination 2 Fertilization 3 Germination 4 Development For each character of the plant there are two traits Dominant represented by CAPITAL letters Recessive represented by lower case letters Genotype 7 genetic makeup of an individual Phenotype 7 features and characteristics of an individual Determined by its genotype under some conditions and its environment under others Yellow seeds were dominant Y Green seeds were recessive y Parental generation 9 P generation Offspring of P 9 F1 generation rst lial generation Offspring of F1 9 F2 generation second lial generation What did Mendel learn No blending of characteristics Heredity is due to the transmission of discrete elements Green seeds were absent from F1 Green seeds reappeared in F2 F1 individuals retained a greenseed element Traits are caused by PAIRS of elements F1 individuals must possess a yellowseed element F1 individuals also possess a greenseed element Pairs of elements represent genes Paired genes exist on pair of homologous chromosomes Alternative forms of genes are called alleles Homozygous 7 having two identical alleles of a gene for a given character Genotype YY 9 Homozygous Dominant Genotype yy 9 Homozygous recessive Chapter 11 Part II Heterozygous 7 possessing two different alleles of a gene for a given character Genotype Yy 9 Heterozygous F2 generation has 3 different genotypes YY Y F2 generation also has 2 different phenotypes Yellow and green F2 generation displays 2 different ratios Genotypic ratio 121 YYYyyy Phenotypic ratio 31 YellowGreen YY and Yy have same phenotype Mendel s Law ofSegregalian Individuals possess two alleles for each gene These alleles separate during gamete production Dominant allele 9 an allele that is phenotypically eXpressed in a heterozygote Recessive allele 9 an allele that is NOT phenotypically eXpressed in a heterozygote Yy genotype is yellow phenotype Mendel s Law ofIndependentAssartment During gamete formation gene pairs assort independent of one another The transmission of one character does NOT in uence the transmission of another The eld of genetics is founded upon Mendel s work Polygenic Inheritance 9 many other traits governed by multiple genes more than 2 alleles for many genes Blood types are determined by types of glycoprotein on the surface of the red blood cells Type of glycoprotein is genetically determined by single gene on chromosome 9 Human blood types 9 A B AB 0 Type A has most glycoprotein Type O has no glycoprotein A allele 9 A molecule B allele 9 B molecule 0 allele 9 inactive no molecule encoded SiX combinations of alleles for four blood types Blood Type Genotype I u Present Type A AA or A0 Type B BB or B0 Type AB AB Type O 00 A molecule present B molecule present A and B present neither is present Codominant 9 neither molecule is dominant over the other Polygenic traits 9 governed by multiple genes Several genes contribute to a character EXAMPLES human height skin color etc Bell curve 9 a distribution of values that is symmetrically largest around the average CHAPTER 6 All living things require a constant supply of energy Energy is derived from the sun Sugars possess energy because they contain high energy electrons Like a roller coaster on top of a hill ATP 9 Adenosine TriPhosphate Comes from energy released from chemical reactions ATP can release energy when needed ADP 9 Adenosine DiPhosphate lSt Law of Thermodynamics Energy cannot be created or destroyed Energy can be transformed Energy can be converted Example Chemical bond energy 9heat energy9mechanical energy 2nd Law of Thermodynamics Energy transfer always results in a greater amount of disorder entropy in the universe Energy transformations will run spontaneously in one direction only With energy transformation a portion of the energy is converted to heat Biological systems are relatively efficient at energy conversion ATP and ADP can be interconverted ADP P ATP 6 requires energy ATP ADP P 6 releases energy Enzymes are protein catalysts The production of enzymes is encoded by unis of DNA called genes For any chemical reaction to occur an initial input of energy is required Enzymes function by reducing the required energy input Enzymes only accelerate reactions that would occur anyway Many activities are multi stepped Series of reactions called a metabolic pathway Metabolic pathway 9 set of enzymatically controlled steps resulting in the completion of a product or process Each enzyme performs a specific task Substrate 9 9 9 9 Product Chapter 14 amp 15 Notes Chapter 14 How Proteins are Made Proteins have many diverse roles Cell signaling hastening chemical reactions cellular transport transporting substances through the blood etc Genetic code is stored in DNA Information used to produce proteins Proteins are main players in most cellular processes Proteins are made from AMINO ACIDS Hundreds of thousands of different proteins made by living things are similar in construction 20 different amino acids are assembled to make proteins Strung together in different orders Different lengths made different proteins Linear chain forms a polypeptide which can be more than 20 amino acids in length Some amino acids are used multiple times One or more polypeptide chains are folded into a single protein Each protein has a particular 3D shape protein conformation Shape is stabilized by chemical bonds Covalent ionic and hydrogen Shape determines how it binds to other molecules How is a protein made DNA 9 mRNA 9 protein DNA 9 mRNA 7 Transcription mRNA 9 protein 7 Translation DNA is organized into genes Each gene directs the synthesis of a single protein gene expression Transcription 7 the process in which DNA s information is copied onto mRNA Takes place in the nucleus ofthe cell a section ofDNA unwinds and nucleotides on itform base pairs with nucleotides of mRNA creating a tape This segment omeNA then leaves the cell nucleus headedfor a ribosome in the cell s cytoplasm where translation takes place A gene s two strands of DNA are separated by RNA polymerase One DNA strand is copied to form an mRNA molecule messenger RNA mRNA is transported to the cytoplasm Translation 7 the process by which the information encoded in mRNA is used to assemble aprotein at a ribosome Takes place in the cytoplasm Joining the mRNA tape at the ribosome are amino acids brought there by tRNA The length of mRNA is then read within the ribosome The result is a chain ofamino acids linked together in the order specified by the mRNA tape When the chain isfinished andfolded up aprotein has been made A ribosome reads the mRNA and assembles amino acids in the appropriate order Assistance of transfer RNA tRNA is required The polypeptide folds into a protein DNA and RNA are similar in structure M polymer of deoxynucleotides polymer of nucleotides sugar 7 deoxyribose sugar 7 ribose bases 7 A T G C bases 7 A U G C phosphates phosphates Transcription Takes place in the nucleus Following the production of an mRNA molecule it must be transported to the cytoplasm Transport is through a nuclear pore Translation is ready to begin at this point Takes many players 7 mRNA ribosomes tRNA amino acids mRNA molecules groups of three consecutive nucleotides are the functional units within mRNA molecules codon 7 an mRNA triplet that codes for a single amino acid or a start or a stop command in the translation stage of protein synthesis Each codon corresponds to a speci c amino acid eg AUG 9 methionine tRNA molecules Encoded by genes Functional as RNA molecules but NOT translated into protein Translates information from mRNA to protein One region binds to the mRNA molecule Anticodon Base pairs with mRNA codon Another region is linked to a speci c amino acid Ribosomes Organelles that are NOT surrounded by a membrane 2 components Ribosomal RNA rRNA Encoded by gene Not translated Forms the ribosome s Proteins Attached to the rRNA scaffolding When these subunits are joined there are 3 binding sites skeleton E P A tRNA bind to these sites during translation Steps of Translation A messenger RNA transcript binds to the small subunit of a ribosome as the rst transfer RNA is aniving The mRNA codon AUG is the start sequence for most polypeptide chains The tRNA with its methionine met amino acid attached then binds this AUG codon The large ribosomal subunit joins the ribosome as a second tRNA arrives bearing a leucine leu amino acid The second tRNA binds to the mRNA chain within the ribosome s Asite A bond is formed between the newly anived leu amino acid and the met amino acid thus forming a polypeptide chain The ribosome now effectively shifts one codon to the right relocating the original Psite tRNA to the Esite the Asite tRNA to the Psite and moving a new mRNA codon into the Asite The Esite tRNA leaves the ribosome even as a new tRNA bonds with the Asite mRNA codon and the process of elongation continues Equot W 5 Chapter 15 Biotechnology Biotechnology 7 the use of technology to control biological processes as a means of meeting societal needs Transgenic organisms have been produced Transgenic organism 9 An organism having stably integrated one or more genes for another species Requires carious tools of molecular biology Restriction enzymes were discovered in the early 1970s Restriction enzymes 9 a type of enzyme occurring naturally in bacteria that recognizes a speci c series of DNA bases and cuts the DNA strand at that site Restriction enzymes are used in biotechnology to cut DNA in speci c places Many bacteria possess plasmids asmid 9 a ring of DNA that lies outside the chromosome in bacteria Plasmids can move into bacterial cells in the process called transformation thus making them a valuable tool in biotechnology 1 Use restriction enzymes to snip gene of interest from the isolated human genome 2 Insert gene into plasmid complementary sticky ends will t together 3 Transfer the plasmid back into bacterial cell 4 Let bacterial cells replicate Harvest and purify the human protein produced by the plasmids inside the bacterial cells Transgenic varieties of many crop plants have been produced Genetically modi ed food crops Many crops in the US are transgenic Genetically modi ed crops are engineered to produce higher yields with reduced use of chemical pesticides and herbicides Examples virus resistant crops insect resistant crops herbicide tolerant crops Reproductive Cloning Reproductive cloning 9 the cloning of whole complex living things Biotechnology has greatly expanded the range of organisms that can be cloned Clone 9 exact genetic copy A single gene or a whole complex organism can be cloned Ian Wilmut cloned dolly the sheep in 1997 l a cell was taken from the udder of a sixyearold white sheep and then allowed to divide many times in the laboratory Meanwhile an egg was taken from a second blackfaced sheep 2 One of the resulting udder cells was selected to be the donor cell for the cloning Meanwhile using a slender tube called a micropipette researches sucked the DNA out of the egg 3 The donor cell and egg were put next to each other and an electric current was applied to the egg cell 4 This caused the two cells to fuse and prompted an activation that reprogrammed the donorcell DNA This caused the fused cell to start developing as an embryo 5 After some incubation the embryo was implanted in a third sheep which served as the surrogate mother 6 The mother gave birth to Dolly the sheep which grew into an adult She died in 2000 Many other large mammals have been cloned since 1997 DNA evidence can help establish innocence as well as guilt DNA testing regularly exonerates suspects DNA testing has also exonerated people wrongly convicted of crimes DNA typing can also be used to establish paternity Controversies Biotechnology has generated some ethical issues Is it acceptable to advance the techniques necessary to bring about human reproductive cloning The production of genetically modi ed food plants has raised commotion Recumbent DNA 9 two or more segments of DNA that have been combined by humans into a sequence that does not eXist in nature
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