UNIT 2 : Chapter 4-6 Study Guide
UNIT 2 : Chapter 4-6 Study Guide BIOL 1014
Arkansas Tech University
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This 8 page Study Guide was uploaded by Surani Notetaker on Wednesday February 17, 2016. The Study Guide belongs to BIOL 1014 at Arkansas Tech University taught by Dr. Jacqueline Bowan in Spring 2016. Since its upload, it has received 25 views. For similar materials see Introduction to Biological Sciences in Biology at Arkansas Tech University.
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Date Created: 02/17/16
Chapter 4 Review Questions Answer Key 1. To establish the link between sickle cell anemia and malaria, Dr. Allison collected data on 290 children living in areas of Africa that had a high incidence of malaria. He found that only 28% of children with sickle cell trait were infected with malaria, while 46% of children without the trait were infected with malaria. 2. The blood cells of individuals with malaria collapse into a sickle shape when under oxygen stress. 3. If an individual inherits an allele for the HbS and for the HbA protein they are likely to have some resistance to malaria and will be unlikely to develop full- blown sickle-cell disease. (c) 4. Linus Pauling and his colleagues learned that an individual with two normal hemoglobin genes would be unlikely to exhibit sickle cell disease. (a) 5. Pangenesis, a discounted theory, was the idea that each part of the body produces a characteristic seed that is released by males and females during mating, resulting in offspring with blended traits. (d) 6. The principal discoveries Mendel made using his monohybrid crosses were that genes come in more than one form (alleles), the alleles of a gene sort individually into gametes during meiosis, and that some traits are dominant while others are recessive. (b) 7. The primary reason that Mendel was successful in understanding the rules of inheritance was that he quantified and developed ratios with his data. 8. An allelic interaction occurs in heterozygotes when the two different alleles produce a phenotype different from the homozygotes. Examples of allelic interaction include codominance and incomplete dominance. 9. Gene interactions occur when two or more gene proteins contribute to an overall phenotype. Examples include polygenic traits like hair and skin color and those with a considerable contribution from both genetic and environmental influences like height. 10.An example of environment influencing the expression of genes is the coloring of Siamese cats. Even though all of their cells contain the gene for pigmented fur, the gene is only expressed in areas of the cat that are exposed to cold, like ears, feet, face, and tails. Siamese kittens are white when they are born. 11.DNA is a polymer of the four nucleotides; adenine, thymine, guanine, and cytosine. It is a double helix with a deoxyribose-phosphate backbone and the nitrogenous bases hydrogen-bonded to each other in the middle. Adenine pairs with thymine and guanine pairs with cytosine. 12.For the DNA sequence GCATTTGCCAACTGA the (a) complementary DNA sequence is CGTAAACGGTTGACT. (b) The complementary transcribed mRNA sequence would be CGUAAACGGUUGACU. (c) The specific anticodons are GCA, UUU, GCC, AAC, UGA. 13.Evidence that DNA is the transforming substance found in Frederick Griffith’s 1929 pneumonia experiment comes from the work of Avery, McLeod, and McCarty. They used the same two bacterial strains that Griffith used and made cell-free extracts of the heat-killed S (virulent) strain. They made five solutions from the extract. Each solution had a macromolecule removed from it. They removed carbohydrates, fats, proteins, DNA, and RNA. They combined each of these solutions with the live R (nonvirulent) strain. All of the solutions transformed the bacteria except for the one which had no DNA. This provided convincing evidence that DNA is responsible for the transformation process. 14.DNA transcribes an RNA copy which is translated into the amino acid sequence of a protein. 15.Protein structure is essential for function. Proteins that have lost their structure, liked sickled hemoglobin, can no longer carry out their function. 16.This cross is between two heterozygotes, Aa and Aa. A A A AA Aa a Aa aa The likelihood their children will have sickle cell anemia is ¼ or 25%. The likelihood they will be carriers is ½ or 50%. Chapter 5 Review Questions Answer Key 1. Cancer makes you sick because large tumors affect the organs they are in negatively, metastasis spreads cancer to other organs, and tumors deprive other cells of oxygen and therefore nutrients. 2. Creating extra cells does not cause serious health consequences when tumors are benign. 3. Cancer is a breakdown in cell communication and community, because it is a disease where the cancer cells ignore communication from the community they live in. Cancer cells ignore normal chemical signals which would result in organized growth with a definite halt to cell proliferation. Cancer cells grow uncontrollably and at random. 4. The three checkpoints are located at the end of G1, just before mitosis begins and at metaphase of mitosis. 5. 5. Proto-oncogenes are cell cycle control genes that make proteins that activate the cell cycle. Oncogenes are mutated cell cycle control genes that continuously tell cells to divide. 6. Oncogenes contribute to tumor formation through (a) telling cells to divide; they are like an accelerator stuck in the “on” position. 7. Tumor suppressors are genes that produce proteins that tell cells not to divide. Changes in tumor suppressor genes cause cells to ignore communication from other cells and the cells continue to divide instead of stopping. 8. Cells usually do not divide unless told to do so by the p53 tumor suppressor gene. The protein produced by this gene tells cells to begin replicating their DNA, this occurs when cells move from G1 to S in the cell cycle. During the M phase the cell divides its DNA into two separate parcels. At this point it is important to check on whether or not this has occurred properly. Cells without the appropriate DNA will behave erratically and probably become cancerous. 9. Lack of exercise, poor diet, smoking and excessive exposure to UV radiation are all risk factors for cancer. Young age is not a risk factor. 10.Cancer is more prevalent in the elderly, because as you age you accumulate errors and DNA damage. This damage increases the likelihood of cancer. The poor are more likely to suffer from cancer due to increase smoking rates, poor nutrition, increased likelihood of exposure to carcinogens in the workplace, increased risk of exposure to infectious agents, and poor access to health care. 11.Accurate DNA repair leads to less DNA damage which decreases the likelihood of developing cancer. 12.Warning signals of cancer include lumps in the breast or testes, changes in warts and moles, changes in bowel or bladder habits, persistent indigestion or heartburn, difficulty swallowing and unusual bleeding. 13.Some of the routine cancer screening tests are mammograms, colonoscopies, Pap tests, prostate exams, and other periodic health exams. 14.A false positive test shows that a condition is present when it is not, while a false negative test shows that a condition is not present when it is actually present. 15.An oncologist might use radiation therapy to reduce the metastasized cancer spreading throughout a person before removing or destroying the primary tumor through surgery or chemotherapy. 16.You can reduce your chances of getting cancer by not smoking, eating diets rich in fiber and low in saturated fat, avoid exposure to UV light, exercise and maintain a healthy weight, avoid risky sexual behavior, avoid excessive alcohol, avoid known carcinogens, and get regular check-ups. Chapter 6 Review Questions Answer Key 1. Three methods for determining sex in species include: temperature of egg incubation (many reptiles), place of permanent attachment (Bonellia marine worms), and presence of Y chromosome (mammals). 2. See attached 3. See Attached 4. Primary sex determination is a step in sexual development that determines whether ovaries or testes form. (C) 5. Androgen-insensitivity syndrome is a disorder of sexual development in which an individual who is XY does not develop as a male because their cells lack receptors to bind to testosterone. (A) 6. In males sperm form as a result of even meiotic division in which one germ cell divides to become 4 sperm. Sperm are relatively small, highly motile cells. In females eggs form as a result of uneven meiotic division which results in one functional egg cell and 3 non-functioning polar bodies. Eggs are very large nonmotile cells. Both egg and sperm are the result of meiosis. 7. Sex Hormone Table Hormone Produced by Effect on males Effect on females GnRH Hypothalamus Signals release by Signals release by pituitary gland of pituitary gland of FSH and LH FSH and LH FSH Pituitary gland Binds to Sertoli Stimulates cells triggering estrogen secretion spermatogenesis and follicle growth (egg) LH Pituitary gland Directs interstitial Stimulates cells (found near estrogen secretion seminiferous tubules) to secrete testosterone Testosterone Testes in men, Promotes Muscle ovaries in women development of development and male sex organs, maintenance sperm development, and muscle development Estrogen Corpus luteum and Initiation of sperm Promotes ovaries in women, production development of adrenal glands in female sex organs, men menstruation, maintenance of pregnancy Progesterone Corpus luteum and Maintains male sex Promotes ovaries in women, organs and development of adrenal glands in initiation of sperm female sex organs, men production menstruation, maintenance of pregnancy 8. Hormones carefully regulate sperm production by carefully balancing the level of the important hormones, testosterone, GnRH, FSH, and LH. Low levels of testosterone increase the release of GnRH by the hypothalamus. This triggers the pituitary glands to release FSH and LH. LH increases the production of testosterone, while FSH stimulates sperm production. High levels of testosterone cause the level of GnRH to drop which decreases sperm production. 9. For women it’s all about the estrogen. The presence of high levels of estrogen and progesterone signal pregnancy. The process of oogenesis begins with GnRH, as GnRH levels increase the pituitary gland releases FSH and LH. FSH triggers oogenesis by stimulating follicle growth, while both LH and FSH trigger estrogen secretion. When oogenesis is complete the egg bursts from the follicle which becomes the corpus luteum. The corpus luteum also produces estrogen and progesterone. If pregnancy does not occur the corpus lutem deteriorates, estrogen and progesterone levels drop and that triggers menstruation. 10.When pregnancy occurs the corpus luteum is maintained and it will continue to produce estrogen and progesterone for the duration of the pregnancy. If pregnancy does not occur the corpus luteum deteriorates. 11.Bipotential embryos are triggered along either the male or female pathway by the presence of the SRY gene. The SRY gene triggers the production of testosterone which causes the development of the Wolffian duct and the degeneration of the Müllerian duct system resulting in a male. If the SRY gene is not present estrogen is produced which promotes the formation of the Müllerian duct system while the Wolffian duct system degenerates. 12.Pregnancy can be prevented by a variety of methods including surgery, hormones, and barrier contraceptives. Surgeries are 99 % effective, hormones are 99 % effective, and barrier methods are about 85% effective. 13.Cervical caps, diaphragms, male condoms, and female condoms are all barrier devices. The intrauterine device is not a barrier device. (D) 14.Possible causes of infertility in men include low sperm count or low numbers of healthy sperm. This may be due to elevation of temperature (failure to wear boxers) or exposure to harmful pollutants. Possible causes of infertility in women include poor hormonal levels, endometriosis, and pelvic inflammatory disease. 15.Intrauterine insemination is the infertility treatment that involves placing the sperm directly into the uterus. (B) 16.The prenatal tests performed during pregnancy include blood and urine tests, amniocentesis, chorionic villus sampling, and ultrasounds. 17.The health of newborns is first assessed through the APGAR scale (activity, pulse, grimace response, appearance, and respiration) and blood samples to look for genetic disorders. Human Sex Determination Female Male Testosteron Estrogen e Promotes Promotes developmen developmen t t Wolffian Mϋllerian ducts ducts Become Become Testes. Ovary, epididymi oviduct, s, Wolffian uterus, At At puberty puberty Pituitary Pituitary gland gland Releases Releases Hormones Hormones Which Which cause cause Larynx Breast enlargem developm ent, hair ent, hair
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