BSC114 ALL study guides for exam 2
BSC114 ALL study guides for exam 2 BSC 114
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This 15 page Study Guide was uploaded by Lauren Dutch on Friday October 14, 2016. The Study Guide belongs to BSC 114 at University of Alabama - Tuscaloosa taught by Dr. Stephenson in Fall 2016. Since its upload, it has received 147 views. For similar materials see The Principles of Biology 1 in Biology at University of Alabama - Tuscaloosa.
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Date Created: 10/14/16
Chapter 8 Study Guide: 1. Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways. 2. Organisms are thermodynamically open systems because they acquire energy from their surroundings and also lose energy to their surroundings. 3. A farmer’s crops growing over a season must be open system in order to obey the first law of thermodynamics, which states that energy is only converted, not created or destroyed. 4. Energy can be freely transformed among different forms as long as the total energy is conserved. 5. The aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water represents the second law of thermodynamics. 6. According to the second law of thermodynamics, the decrease in entropy associated with life must be compensated for by the increased entropy in the environment in which life exists. 7. If the entropy of a living organism is decreasing, energy input into the organism must be occurring to drive the decrease in entropy. 8. A starch molecule has the most free energy per molecule. 9. ΔG tells you if a process is spontaneous. 10.If, during a process, the system becomes more ordered, then ΔS is negative. 11.When one molecule is broken down into six component molecules, ΔS is positive. 12.From the equation ΔG = ΔH – TΔS it is clear that a decrease in the system’s total energy will increase the probability of spontaneous change, an increase in the entropy of a system will increase the probability of spontaneous change, and an increase in the temperature of the system will increase the probability of a spontaneous change. 13.An exergonic (spontaneous) reaction is a chemical reaction that releases energy when proceeding in the forward direction. 14.Glucose + fructose sucrose is an endergonic reaction. 15.Molecules A and B contain 110 kcal/mol while molecules C and D contain 150 kcal/mol. The reaction that proceeds to convert A and B to C and D is endergonic because the products are more organized than the reactants. 16.The sign of ΔG for a reaction is determined by the free energy of the reactants and the free energy of the products. 17. Metabolic pathways in cells are typically far from equilibrium. To keep metabolic pathways far from equilibrium, the products of one pathway are continuously removed to be used in other reactions, and there is an input of free energy from outside the pathway. 18.Free energy derived from the hydrolysis of ATP can be used to perform many kinds of cellular work. One such example proton movement against the gradient of protons. 19.In general, the hydrolysis of ATP drives cellular work by releasing free energy that can be coupled to other reactions. 20.An example of energy coupling is when ATP hydrolysis is used to drive the active transport of an ion into the cell against its concentration gradient. 21.Much of the suitability of ATP as an energy intermediary is related to the instability of the bond between phosphate groups. These bonds are unstable because the negatively charged phosphate groups vigorously repel one another and the terminal phosphate group is more stable in water than it is in ATP. 22.When 1 mole of ATP is hydrolyzed in a test tube without an enzyme, about twice as much heaet is given off as when 1 mole of ATP is hydrolyzed in a cell. This is because, in the cell, the hydrolysis of ATP is coupled to other endergonic reactions. 23.The free energy released by ATP hydrolysis may be coupled to an endergonic process via the formation of a phosphorylated intermediate. 24.The formation of a glucose-6 phosphate from glucose is an endergonic reaction and is coupled to the hydrolysis of ATP. 25.A chemical reaction is designated as exergonic rather than endergonic when the potential energy of the products is less than the potential energy of the reactants. 26.The activation energy of a reaction is changed by the presence of an enzyme. 27.Neither the sign nor the magnitude of ΔG has anything to do with the speed of a reaction. 28.Enzymes lower activation energy by locally concentrating the reactants. 29.Enzymes speed up the rate of the reaction without changing the ΔG for the reaction. 30.Enzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output. 31.A plot of reaction rate against temperature for an enzyme indicates little activity at 10 degrees C and 45 degrees C with peak activity at 35 degrees C. The most reasonable explanation for the low velocity at 10 degrees C is that there is too little activation energy available. 32.An enzyme is not consumed during the reaction it catalyzes. 33.The active site may resemble a groove or a pocket in the surface of a protein into which the substrate fits. 34.Induced fit means the enzyme changes shape slightly as the substrate binds to it. 35.Heat from the environment is necessary for substrates to get over the activation energy barrier and the kinetic energy of the substrates is increased as the amount of heat in the system is increased. 36.Above a certain substrate concentration, the rate of an enzyme catalyzed reaction drops as the enzymes become saturated. A faster conversion of the substrate into the product under these saturated conditions could occur by increasing the concentration of the enzyme or increasing the temperature by a few degrees. 37.Heating the enzyme, cooling the enzyme, substrate concentration, and pH all affect the rate of an enzyme reaction. 38.Enzyme activity is affected by pH because high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site. 39.The action of competitive inhibitors may be reversible or irreversible. 40.Succinylcholine is structurally almost identical to acetylcholine. If succinylcholine is added to a mixture that contains acetylcholine and the enzyme that hydrolyzes acetylcholine (but not succinylcholine), the rate of acetylcholine hydrolysis is decreased. Subsequent addition of more acetylcholine restores the original rate of acetylcholine hydrolysis. This is because succinylcholine must be a competitive inhibitor with acetylcholine. 41.The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule outside the active site is an example of allosteric activation. 42.Allosteric proteins are sensitive to environmental conditions, are acted on by inhibitors, and exist in active and inactive conditions. 43.Allosteric inhibitors cause a structural change in the enzyme that prevents the substrate from binding at the active site. 44.High levels of ADP result in allosteric activation of catabolic pathways. Chapter 9 Study Guide: 1. A molecule becomes more oxidized when it loses and electron. 2. In the overall process of glycolysis and cellular respiration, glucose is oxidized and oxygen is reduced. 3. Most of the ATP produced in cellular respiration comes from oxidative phosphorylation. 4. The order of cellular respiration is oxidation of glucose to pyruvate, oxidation of pyruvate, citric acid cycle, and oxidative phosphorylation. 5. Oxygen gas is one of the strongest oxidizing agents known because it is very electronegative. 6. The function of cellular respiration is to extract usable energy from glucose. 7. During the reaction of glucose and oxygen to carbon dioxide and water, oxygen is reduced. 8. In a classroom of 300 students, if the air conditioner is shut off and all the doors are kept closed for one hour, temperature and level of carbon dioxide will rise as heat and carbon dioxide are by products of cellular respiration. 9. A small amount of ATP is made in glycolysis when a phosphate group is transferred from a fragment of glucose to ADP by substrate level phosphorylation. 10.Glycolysis occurs in the cytosol of eukaryotic cells. 11.The process by which glucose is oxidized to generate two molecules of pyruvate, ATP and NADH is called glycolysis. 12.A chemist has discovered a drug that blocks phophoglucoisomerase, an enzyme that catalyzes the second reaction in glycolysis. He wants to use the drug to kill bacteria in people with infections. However, he cannot do this because human cells must also perform glycolysis; the drug might also poison them. 13.No carbon dioxide is produced in glycolysis. This is because the products of glycolysis contain the same total number of carbon atoms as in the starting material. 14.Fructose-1, 6-biphosphate contains the most chemical energy in the process of glycolysis. 15.The citric acid cycle generates most of the NADH that delivers electrons to the electron transport chain. 16.In an experiment, mice were fed glucose containing a small amount of radioactive oxygen. The mice were closely monitored, and after a few minutes radioactive oxygen atoms showed up in carbon dioxide. 17.In preparing pyruvate to enter the citric acid cycle, pyruvate is oxidized and a molecule of carbon dioxide is removed. The electrons removed in this process are used to reduce NAD+ to NADH. 18.The citric acid cycle is called a cycle because the four carbon acid that accepts the acetyl CoA in the first step of the cycle is regenerated by the last step of the cycle. 19.In the citric acid cycle, for each pyruvate that enters the cycle, one ATP, three NADH and one FADH2 are produced. For each glucose molecule that enters glycolysis, two ATP, 6 NADH, and 2 FADH2 are produced in the citric acid cycle. 20.The reactions of the citric acid cycle occur in the matrix of the mitochondrion in eukaryotic cells. 21.Four ATP molecules are gained by substrate level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen. 22.Formation of NADH and FADH2 is a major energy accomplishment of the citric acid cycle. 23.After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of NADH. 24.The release of carbon dioxide and NADH accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle. 25.The energy given up by electrons as they move through the electron transport chain is used to pump H+ across a membrane. 26.Energy for synthesizing ATP is obtained by the flow of H+ across the inner mitochondrial membrane through the ATP synthase enzyme. 27.When a poison such as cyanide blocks the electron transport chain, glycolysis and the citric acid cycle also eventually stop working because NAD+ and FAD are no longer available from the electron transport chain to power glycolysis and the citric acid cycle. 28.Most of the electrons removed from glucose by cellular respiration are used to reduce NAD+ to NADH in glycolysis and the citric acid cycle and to produce the proton gradient for ATP synthesis in the mitochondria. 29.Each ATP molecule contains about 1% of the amount of chemical energy available from the complete oxidation of a single glucose molecule. Cellular respiration produces about 32 ATP from one glucose molecule. The rest of the energy is converted to heat. 30.During aerobic respiration, molecular oxygen is used at the end of the electron transport chain to accept electrons and form water. 31.ADP, oxygen, and ATP are all involved in oxidative phosphorylation. 32.In the electron transport chain, electrons are passed from one carrier to another, releasing a little energy at each step. 33.If a compound that allows protons to freely diffuse across membranes is added to cells that are actively metabolizing via cellular respiration, ATP synthesis, glycolysis, and electron transport would continue. 34.The movement of electrons down the electron transport chain is the source of energy that produces the chemiosmotic gradient in mitochondria. 35.In eukaryotic cells, the components of the electron transport chain are located in or on the innermembrane of the mitochondrion. 36.The overall efficiency of respiration (the percentage of energy released that is saved in ATP) is approximately 35%. 37.When solid tumors of animals reach a certain size, the center of the tumor begins to die. To prevent this, the tumor can recruit new blood vessels to supply oxygen so that aerobic cellular respiration can occur instead of fermentation and it supplies glucose to the rapidly dividing cells of the tumor. 38.Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol or carbon dioxide. This last step enables the cell to recycle the reduced NADH to oxidized NAD+. 39.Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of lactate. 40.In glycolysis in the absence of oxygen, cells need a way to regenerate NAD+. 41.Muscle tissues make lactate from pyruvate to regenerate NAD+. 42.In brewing beer, maltose is the substrate for alcoholic fermentation. 43.If muscle cells in the human body consume oxygen faster than it can be supplied, the muscle cells will have more trouble making enough ATP to meet their energy requirements, the cells will not be able to carry out oxidative phosphorylation, and the cells will consume glucose at an increased rate. 44.Glycolysis is the only pathway found in all organisms. 45.When protein molecules are used as fuel for cellular respiration, amino groups are produced as waste. 46.A gram of fat oxidized by respiration produces approximately twice as much ATP as a gram of carbohydrate. This is because fats are better electron donors to oxygen than sugars. 47.If significant amounts of materials are removed from the citric acid cycle to produce amino acids for protein synthesis, less ATP will be produced, less carbon dioxide will be produced, and the four carbon compound that combines with acetyl CoA will have to be made by some other process. Chapter 10 Study Guide: 1. In photosynthesis, plants use carbon from carbon dioxide to make sugar and other organic molecules. 2. Fungi are heterotrophs. 3. Carbon dioxide enters the leaf through the stomata. 4. In a rosebush, chlorophyll is located in thylakoids, which are in chloroplasts in the mesophyll cells of a leaf. 5. Chlorophyll molecules are in the thylakoid membranes of chloroplasts. 6. The source of oxygen produced by photosynthesis comes from water. 7. In photosynthesis, the oxygen atoms in carbon dioxide end up in sugar molecules and water. 8. Molecular oxygen is produced during linear electron flow during the light reactions. 9. The reactions of the Calvin cycle are not directly dependent on light but they usually do not occur at night because the Calvin cycle requires products only produced when the photosystems are illuminated. 10.The Calvin cycle occurs in the stroma. 11.The role of NADP+ in photosynthesis is to form NADPH to be used in the Calvin cycle. 12.A blue photon would carry the most energy. 13.The most important role of pigments in photosynthesis is to capture light energy. 14.Blue-violet and red-orange wavelengths are absorbed by pigments in the thylakoid membranes. 15.Based on the work of Engelmann, a plot of photosynthetic activity versus wavelength of light is referred to as an action spectrum. 16.When chloroplast pigments absorb light, the pigments’ electrons become excited. 17.A photosystem consists of a reaction center, light harvesting complexes, and primary electron acceptors in the thylakoid membrane. 18.The electrons entering photosystem II come from water. 19.During photosynthesis in chloroplasts, oxygen is produced from water via a series of reactions associated with photosystem II. 20.Electrons are cycled in the cyclic variation of the light reactions. 21.Both mitochondria and chloroplasts used chemiosmosis to produce ATP. 22.You could distinguish a thylakoid membrane from an inner mitochondrial membrane because the thylakoid membrane would have photosynthetic pigments. 23.During photosynthesis in a eukaryotic cell, an electrochemical gradient is formed across the thylakoid membrane. 24.The light reactions of photosynthesis generate high energy electrons which end up in NADPH through linear electron flow. The light reactions also produce ATP and oxygen. 25.The energy used to produce ATP in the light reactions of photosynthesis comes from movement of H+ through a membrane. 26.NADP+ is reduced and carries electrons to the Calvin cycle. 27.Carbon dioxide is reduced during the Calvin cycle. 28.During the Calvin cycle, ATP is hydrolyzed and NADPH is oxidized. 29.Rubisco is the enzyme in plants that captures carbon dioxide to begin the Calvin cycle. 30.In the Calvin cycle, carbon dioxide is combined with a five carbon compound to form an unstable six carbon compound, which decomposes into two three carbon compounds. 31.Glyceraldehyde-3-phosphate is produced in the stroma of chloroplasts. It is produced from glucose during glycolysis. It is a 3 carbon sugar. For every three molecules of carbon dioxide reduced in the Calvin cycle, six molecules of G3P are formed but only one of these molecules exits the cycle to be used by the plant cell. For every three molecules of carbon dioxide, six molecules of G3P are formed but five must be recycled to regenerate three molecules of RuBP. 32.The light reactions produce ATP and NADPH, both of which are used in the Calvin cycle. 33.If plants close their stomata, water loss is reduced; carbon dioxide is prevented from entering the leaf; in a process called photorespiration, rubisco binds oxygen instead of carbon dioxide and oxygen from the light reactions in the leaf builds up. 34.C4 plants are more suited to hot climates than C3 plants because they keep fixing carbon dioxide even when the concentration of carbon dioxide in the leaf is low. 35.You have a large, healthy philodendron that you carelessly leave in total darkness while you are away on vacation. You are surprised to find that it is still alive when you return. It is still alive because, while it did have access to light, the plant stored energy in the form of sugars or starch, and it was able to derive energy from the stored molecules during your vacation. Chapter 11 Study Guide: 1. Evidence that cell signaling evolved early in the history of life comes from the similarity of cell signaling mechanisms in organisms that have a very distant common ancestor. 2. When a platelet contacts a damaged blood vessel, it is stimulated to release thromboxane A2. Thromboxane A2 in turn stimulates vascular spasm and attracts additional platelets to the injured site. In this example, thromboxane A2 is acting as a local regulator. 3. Early work on signal transduction and glycogen metabolism by Sutherland indicated that the signal molecule did not interact directly with the cytosolic enzyme, but required an intact plasma membrane before the enzyme could be activated. 4. Certain yeast cells secrete a molecule called the a factor. The purpose of this molecule is to stimulate cells of the opposite mating type, A yeast cells, to grow toward the a cell. 5. Cells use different signaling strategies to achieve different goals. In hormonal signaling, specialized cells release hormone molecules into the circulatory system, permitting distant cells to be affected. 6. Sutherland discovered that the hormone epinephrine binds to a specific receptor on the plasma membrane of the liver cell to metabolize glycogen in liver cells. 7. Testosterone and estrogen are lipid soluble signal molecules that cross the plasma membrane by simple diffusion. Only specific cells respond to their presence, however, because nontarget cells lack the intracellular receptors that, when activated by the signal molecule, can interact with genes in the cell’s nucleus. 8. Different types of cells can respond differently to the same signaling molecule because different types of cells possess different proteins. 9. Steroid hormones can enter a cell by simple diffusion. Therefore steroids do not initiate cell signaling by interacting with a receptor in the plasma membrane. 10.Steroid hormones can enter a cell by simple diffusion. 11.A small molecule that specifically binds to a larger molecule is called a ligand. 12.Receptors for signal molecules may be found embedded in the plasma membrane, or found within the cytoplasm or nucleus. 13.Testosterone does not affect all cells of the body because not all cells have cytoplasmic receptors for testosterone. 14.G protein coupled receptors are not enzymes whereas receptor tyrosine kinases have enzymatic function. 15.Receptor tyrosine kinases are activated when the binding of a single molecule causes it to form a dimer. 16.The binding of a signal molecule to a ligand gated ion channel affects the membrane potential. 17.Nitric acid is unusual among animal signal molecules in that it is a gas. 18.A G protein is active when a GTP is bound to it. 19.If a modified form of GTP that cannot by enzymatically converted to GDP were added to a culture of cells, the likely result would be that the activated G proteins would remain locked in the “on” position, transmitting signal even in the absence of a signaling molecule. 20.Replacement of GDP with GTP would activate a G protein. 21.Ras, a small G protein located at the plasma membrane, is often mutated in different types of cancer. Ras normally signals to a cell that it should divide. Cancer cells divide uncontrollably. This mutation of Ras is one in which it cannot hydrolyze GTP to GDP. 22.The cellular response of a signal pathway that terminates at a transcription factor would be the synthesis of mRNA. 23.Cholera develops when the bacterial toxin prevents G protein inactivation, which leads to the continuous production of cAMP. 24.The general name for an enzyme that transfers phosphate groups from ATP to a protein is protein kinase. 25.ATPgammaS is a form of ATP that cannot be hydrolyzed by enzymes. If this compound were introduced to cells so that it replaced the normal ATP, there would be a decrease in phosphorylated proteins in the cell. 26.Phosphorylation can either activate or inactivate a protein. 27.The source of phosphate for a phosphorylation cascade is ATP. 28.Second messengers tend to be water soluble and small. This accounts for their ability to rapidly move throughout the cell by diffusion. 29.The molecule cAMP usually directly activates protein kinase A. 30.A mutation in the active site of adenylyl cyclase that inactivates it would most likely lead to lower activity of protein kinase A. 31.Domoic acid is a neurotoxin produced by some species of alga. Domoic acid binds to the kainite receptor on neurons in parts of the brain. The kainite receptor facilitates the movement of calcium into the cell. Excess domoic acid induced stimulation of the neural kainite receptors causes neural damage and short term memory loss. The kainate receptor is a ligan gated ion channel and domoic acid is a ligand. 32.In a typical cell, calcium ions are often concentrated within the ER. 33.During the transduction of a signal, one molecule or ion may be closely associated with the activity of another. Some combinations include calcium and IP3, cAMP and adenylyl cyclase, cAMP and protein kinase A, and DAG and IP3. 34.A difference between the mechanisms of cAMP and Ca2+ in signal transduction is that cAMP is synthesized by an enzyme in response to a signal and Ca2+ is released from intracellular stores. 35.IP3 is produced as a result of the cleavage of a specific phospholipid in the plasma membrane. 36.IP3 acts by opening Ca2+ channels. 37.In eukaryotic cells, cyclic AMP is a second messenger that is produced as a response to an external signal such as a hormone. 38.In the inherited disorder Wiskott-Aldrich syndrome, a multifunctional relay protein involved with the proliferation of immune cells is defective. 39.In liver cells, epinephrine stimulates the breakdown of glycogen. As the signal transduction pathway progresses, the signal is amplified. 40.Cells of the gastrointestinal tract and cells of the heart respond differently to epinephrine because there are different proteins found in the two types of cells. 41. Apoptosis is essential for the normal development of the nervous system. 42.Some apoptotic signals originate from outside the cell. Some apoptotic signals come from the nucleus when DNA has suffered irreparable damage. Some apoptotic signals come from the ER when a lot of protein misfolding has occurred. Some apoptotic signals come from mitochondria. Chapter 12 Study Guide: 1. The person credited with first recognizing (in the 1860s) that living cells cannot arise spontaneously, but arise only from previously existing cells, is Rudolf Virchow. 2. The function of the mitotic cell cycle is to produce daughter cells that are genetically identical to the parent cell. 3. Sister chromatids end up in separate daughter cells after cytokinesis has occurred. 4. The complex of DNA and protein that makes up a eukaryotic chromosome is properly called chromatin. 5. The region of a chromosome in which the two double strands of replicated DNA are held together is called a centromere. 6. The centromere is a region in which sister chromatids are attached to one another in prophase. 7. 23 maternal chromosomes are present in somatic human cells not engaged in cell division. 8. A cell entering the cell cycle with 32 chromosomes will produce two daughter cells, each with 32 chromosomes. 9. Cytokinesis refers to the division of the cytoplasm. 10.Chromatids are identical copies of each other if they are part of the same duplicated chromosome. 11.If a cell contains 60 chromatids at the start of mitosis, there will be 30 chromosomes in each daughter cell at the completion of the cell cycle. 12.A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in the cells doubled between the G1 and G2 phases. 13.A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. In the G1 phase of a grasshopper daughter cell, there would be 100 units of DNA. 14.During interphase, the genetic material of a typical eukaryotic cell is dispersed in the nucleus as long strands of chromatin. 15.DNA replication occurs in the S phase of interphase. 16.If a human somatic cell is just about to divide, it has 92 chromatids. 17.Down syndrome is characterized by cells having three copies of chromosome 21. As a cell in an individual with Down syndrome prepares to enter mitosis, there would be 94 chromatids present. 18.Replication of chromosomes does not occur during mitosis. It occurs during interphase. 19.G2 has the most DNA per cell in the cell cycle. 20.In telophase of mitosis, the mitotic spindle breaks down and the chromatin uncoils. This is essentially the opposite of what happens in prophase. 21.Telophase is essentially the opposite of prometaphase in terms of the nuclear envelope. 22.Assume that you are dealing with a species in which the number of chromosomes in each somatic cell is 14. There would be 0 chromatids present in the early telophase of mitosis. 23.Centrosomes separate in prophase. 24.Following cytokinesis in an animal cell, each new daughter cell has two centrioles. 25.The phase of mitosis during which the chromosomes move toward separate poles of the cell is anaphase. 26.One event occurring during prophase is the beginning of the formation of a spindle apparatus. 27.During anaphase, cohesions joining sister chromatids at the centromeres are cleaved; the centrioles are at opposite poles; a spindle made of microtubules is present; and genetically identical chromosomes move to opposite poles. 28.The nuclear envelope does not disappear during metaphase. It disappears earlier than that. 29.Sister chromatids separate during anaphase. 30.In animal cell mitosis, the cleavage furrow forms during cytokinesis. 31.During metaphase, chromosomes line up in one plane in preparation for their separation to opposite poles of the cell. 32.You would know that a dividing cell was a plant cell rather than an animal cell if you saw that it had formed a cell plate. 33.Mitosis does not occur in dividing bacteria. 34.During binary fission in a bacterium, the origins of replication move apart. 35.During binary fission, one copy of the single parental chromosome is distributed to each daughter cell. 36.When a cell in S phase is fused with a cell in G1, DNA synthesis begins immediately in the original G1 nucleus. 37.Tissue culture experiments with PDGF demonstrate that without this substance fibroblasts fail to divide. 38.Nerve cells don’t divide. 39.Observing cancer cells in culture shows that cancer cells do not exhibit density dependent inhibition. 40.Cells of benign tumors do not metastasize; those of malignant tumors do. Chapter 13 Study Guide: 1. There are tens of thousands genes present in the human genome. 2. A locus is the precise location of a gene on a chromosome. 3. Sexual and asexual reproduction are alike in that they can both occur in multicellular organisms. 4. A clone is the product of asexual reproduction and mitosis. 5. Unless the chromosomes were stained to show band patterns, a karyotype would be least likely to show part of a chromosome turned around. 6. A karyotype is a photograph of all the chromosomes in a single cell from an individual. 7. Fertilization produces a diploid zygote. 8. Diploid cells can divide by mitosis or meiosis; haploid cells can divide by mitosis but not by meiosis. 9. Alteration of generations includes multicellular haploid stage, multicellular diploid stage, zygote, and spores. 10.The sexual cycle of the diploid, multicellular algal genus Fucus involves mitosis, meiosis, and fertilization. 11.A life cycle in which the only multicellular form is haploid is most typical of fungi. 12.In sexually reproducing species, the chromosome number remains stable over time because meiosis and fertilization always alternate. 13.The egg of a rabbit contains 22 chromosomes. There are 44 chromosomes in the somatic cells of a rabbit. 14.In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing 5 chromosomes. 15.Humans have 22 pairs of autosomes. 16.Sister chromatids are identical copies of each other formed through DNA synthesis. 17.Homologous chromosomes have genes for the same traits at the same loci. 18.When we say that an organism is haploid, we mean that its cells have a single set of chromosomes. 19.Mitosis multiplies body cells in humans. 20.Somatic cells in humans contain two sets of chromosomes and are therefore termed diploid. 21.Nearly all life cycles have both haploid and diploid phases. Usually, the transition from haploid to diploid takes place at fertilization, when gametes fuse. 22.Spores and gametes are different in that gametes can fuse to form a zygote but spores can develop into independent organisms without first forming a zygote. 23.Humans have 46 chromosomes. This number of chromosomes will be found in liver cells. 24.Meiosis results in cells that contain half the parental chromosome number. 25.At the end of telophase I of meiosis and the first cytokinesis, there are two haploid cells. 26.When a diploid cell has completed meiosis, there are four haploid cells. 27.Synapsis occurs during prophase I. 28.During anaphase II, sister chromatids separate and migrate toward opposite poles. 29.During anaphase I, homologs separate and migrate toward opposite poles. 30.Cytokinesis is the division of cytoplasm to create two cells. 31.Meiosis creates cells with a haploid number of chromosomes. 32.Crossing over occurs during prophase I. 33.Regions of chromosomes where nonsister chromatids cross over are called chiasmata. 34.The synaptonemal complex physically connects homologous chromosomes during prophase I. 35.If an organism has a haploid chromosome number of 4, 4 tetrads will form during meiosis. 36.Synapsis of homologous pairs occurs only during prophase I of the first meiotic division. 37.Homologous chromosomes only separate during meiosis, not mitosis. 38.Meiosis is longer and more complex than mitosis because it decreases the chromosome number to haploid, introduces genetic variation among daughter cells, ensures that each daughter cell gets a single complete set of chromosomes and undergoes two rounds of cytokinesis. 39.An organism with a diploid number of 8 can produce 16 kinds of gametes. 40.Genetic variation is caused by random fertilization, independent assortment and crossing over. 41.In humans the haploid number of chromosomes is 23. Independent assortment has the possibility of producing 2^23 different types of gametes. 42.The diploid number of chromosomes in a certain animal is 8. The four pairs of homologs align and assort independently to form any of 16 different combinations. 43.In a diploid set of chromosomes, one member of each pair of homologs is derived from the father and one comes from the mother. If 2n = 6, 1/8 of a particular gamete will contain only paternal chromosome. 44.The major contribution of sex to evolution is that it provides a method to increase genetic variation. 45.The random alignment of homologs at metaphase I does not have to do with crossing over. 46.Although energetically more costly than asexual reproduction, sexual reproduction leads to different combinations of alleles that could provide adaptability in a changing environment. 47.Although sexual reproduction is nearly universal among animals, bdelloid rotifers reproduce asexually but can increase genetic variation present in a population by means of the uptake of DNA from other rotifers.
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