Biology 416 Cell Structure and Function Final Exam

SHORT ANSWER The heterochromatin region of chromosomes is mediated by histone modifications. The current model regarding establishment of heterochromatin shows that enzymes initially recruited to the heterochromatin can extend the histone modifications to expand the heterochromatin region. If cells need to stop the expansion of heterochromatin, what mechanism (s) can be used to stop the expansion of heterochromatin at a specific position on chromosomes? Describe TWO possible mechanisms with a couple of sentences each.

1) Remove histone located next on heterochromatin. This will not allow enzyme to extending methylation of H3K9. 2) Modify H3K9 by acetylation. Acetylation of lysine compete to methylation, thus it will block extending H3K9 methylation. 3) Modify H3S10 by phosphorylation. Phosphorylating serine 10 prevent lysine 9 methylation because methylation enzyme for K9 will not work once S10 is phosphorylated. * If you indicated "Barrier DNA", histone acetylation, you got partial points. My expectation was how "Barrier DNA" works as indicated above. Points were given by your reasoning, as such indicating spacing chromatin by the barrier DNA or nucleosome remodeling factor, making open chromatin by Acetylation, etc. Note that methylation is not open the chromatin rather promote heterochromatin. If you specify H3K4 methylation, that is correct answer

BONUS QUESTION Dr. Azuma can drink mile and he likes it. How much milk does he consume per week?

2 gallon (or 3 gallons)

BONUS QUESTION Several topics covered in this exam were awarded the Nobel prize. Indicate one of them.

?

BONUS QUESTION Which KU professor did Dr. Morgan work with as a postdoctoral fellow studying nervous system development in C. elegans?

Answer: Dr. Lundquist

BONUS QUESTION: Which signaling pathway did Dr. Morgan study for about 10 years during her undergraduate and graduate research training?

Answer: Notch Signaling

BONUS QUESTION Who drew a dinosaur (sauropod) and marbles on a birthday cake last weekend?

Answer: Dr. Morgan

BONUS QUESTION Which signaling pathway has a ridiculous naming pattern (in Dr. Morgan's opinion) for pathway members?

Answer: MAP Kinase

Which of the following is an ancient enzyme that was likely an early development in the evolution of energy-generating systems? A) Pyruvate dehydrogenase B) ATPase C) Rubisco D) 3-phosophoglycerate transferase

Answer: B ATPase

Which of the following membrane lipids make membranes stiffer? A) Phosphatidylcholine B) Cholesterol C) Phosphatidylserine D) Phosphatidylethanolamine

Answer: B Cholesterol

Which of the following monomer building blocks is necessary to assemble the membrane structure of eukaryotic cells? A) Sugars B) Fatty Acids C) Amino Acids D) Nucleotides

Answer: B Fatty Acids

Which covalent bond between the following combination of atoms (elements) could be an electrically polar covalent bond? A) Carbon-Carbon B) Hydrogen - Carbon C) Oxygen - Carbon D) Oxygen - Oxygen

Answer: C Oxygen - Carbon

Which modifications on the side chain of Lysine is observed in cells? A) Acetylation B) Ubiquitination C) Methylation D) All of the above

Answer: D All of the above

Related to epigenetic regulation like we discussed in class, which of the following statements is FALSE? A) Methylation of DNA can serve as epigenetic information B) Epigenetic regulation is mainly mediated by specific proteins that recognize epigenetic information C) Combinations of histone modification play an important role in epigenetic regulation D) In each individual, germ-line cells and neurons always have identical epigenetic information

Answer: D In each individual, germ-line cells and neurons always have identical epigenetic information

Where in mitochondria would you find ATP synthase? A) Cytosol B) Outer mitochondrial membrane C) Mitochondrial matrix D) Inner mitochondrial membrane

Answer: D Inner mitochondrial membrane

FILL IN THE BLANK At the translational initiation stage, mRNA binds to the _____ and _____ subunit of the ribosome with aminoacyl-tRNA that carries _____ (amino acid). When tRNA reached that start codon _____ , elongation of the polypeptide will start.

Initiation Factor Small Methionine AUG

BONUS Question: When we discussed disulfide bonds in class, one common activity was introduced as an example of how we control disulfide bonds in a real-life way. What movie was related to that story?

Legally Blonde

FILL IN THE BLANK Whether a protein can localized at a membrane structure in cells can be predicted by _____ of a protein. A stretch of _____ amino acids for 27 residues long can be a signature of that characteristic. Further, the mobility of plasma membrane proteins can be measured by _____ analysis, which use a fluorescently labeled membrane protein. Membrane proteins binding to cellular or extracellular structures, categorized as ____ are _____ mobile than _____ that control ion flux across the membrane.

Primary Structure Hydrophobic FRAP Anchors Less Transporters

BONUS Question: In class, Dr. Azuma indicated his favorite TV/Movie series. What was it?

Star Trek

FILL IN THE BLANK A protein can form its _____ by finding its most energetically favorable conformation. Groups of proteins called _____ aide in this process by binding to newly synthesized proteins. A _____ is one of these proteins which was identified as a critical pathogen in Mad Cow Disease, which is caused by a misfolded protein.

Tertiary Structure Chaperones Prion

Yeast cells can proliferate both in the presence of O2 (aerobically) and in its absence (anaerobically). Under which of the two conditions could you expect the cells to proliferate better? Explain your answer. (6 points)

Yeast cells will proliferate much better aerobically due to the efficiency of ATP production.If the yeast cell is under aerobic conditions, it can utilize oxidative phosphorylation and produce 30 molecules of ATP per glucose molecule oxidized.If the yeast cell is under anaerobic conditions and can only perform glycolysis, it may only produce 2 molecules of ATP.A cell that is short on ATP or making ATP in a less efficient manner is not going to be able to perform its basic cellular functions as easily or quickly.Therefore the cells wouldn't grow and divide as easily or quickly.

FILL IN THE BLANK Microtubules are formed from the tubulin heterodimer, which is composed of the nucleotide-binding _____ protein and the ______ protein. ______ rings are important for microtubule nucleation and are found in the ______ , which is usually found near the cell's nucleus in cells that are not undergoing mitosis. A microtubule that is quickly growing will have a ______ cap that helps prevent the loss of subunits from its growing end. Stable microtubules are used in cilia and flagella; these microtubules are nucleated from a ______ and involve a "______ plus two" array of microtubules.

β-tubulin α-tubulin γ-tubulin Centrosome GTP Basal Body Nine

Unlike mitochondria, chloroplasts do not have a transporter that allows them to export ATP to the cytosol. How, then, do plant cells obtain the ATP that they need to carry out energy-requiring metabolic reactions in the cytosol? (7 points)

Answer: Plant cells also have mitochondria and the mitochondria and chloroplasts are working together as collaborators to address the cell's energetic needs. The cell is not using the ATP produced by photosynthesis but is instead using ATP from mitochondriaMitochondria will produce ATP by oxidative phosphorylation. ATP is then able to be made because of the glyceraldehyde-3-phosphate that is made via photosynthesis in the chloroplast. That sugar moves out of the chloroplast, into the cytosol and will be used by the Citric Acid Cycle and oxidative phosphorylation to make ATP, which can then be pumped out of the mitochondria into the cytosol of the plant's cell.

Which of the following statements is true? A) G-protein-coupled receptors will act directly on calcium channels to open them. B) G-protein-coupled receptors are typically seven pass transmembrane proteins. C) G-protein-coupled receptors activate their associated G proteins by phosphorylating GDP to create GTP. D) G-protein-coupled receptors are typically coupled to monomeric GTP-binding proteins.

Answer: B G-protein-coupled receptors are typically seven pass transmembrane proteins.

Which of the following statements is NOT true) A) Enzymes will not change conformation before and after catalysis B) Enzymes lower the activation energy for a specific reaction C) Enzymes cannot control direction or specificity of the reaction D) Enzymes can be regulated by allosteric mechanism

Answer: C Enzymes cannot control direction or specificity of the reaction

FILL IN THE BLANK The second law of thermodynamics state that events of the universe will follow the direction of increasing _______ , which means increasing disorder. The cellular activity of making biomolecules by a ______ reaction foes against that statement. To overcome this, the cell generates _____ which is released into the environment and increases disorder.

Entropy Condensation Heat

SHORT ANSWER You discover that the underlying cause of a disease is decreased expression of the protein X due to a lower amount of the mRNA encoding protein X in cell. You find the corresponding mutation in the genome related to this disease. What kind of defect caused by this mutation can create the defective expression of the protein X? Describe two possible mechanisms (there are many possibilities). The best answers will include the nature of the mutation and how it impacts each step of gene expression for each of the two mechanisms you select to describe.

The mutation reduced "mRNA amount of gene X", therefore the mutation affects transcription of gene X or stability of mRNA coding protein X. The possible defect that mutation can make will be: 1) Mutation on promoter or regulatory sequence of gene X that inhibit transcriptional activator binding or promote transcriptional repressor binding 2) Mutation on transcriptional regulator gene that control transcription of gene X 3) Mutation created more micro RNA that binds to mRNA of protein that induces degradation of the mRNA. (Or mutation on gene X or micro RNA make the mRNA targeted by micro RNA.) *Some of you indicated how the mutation created during DNA replication, etc. But that is no the question asked. Other idea as such silenced by histone methylation, HDAC, are graded based on how you explained for specific role of mutation on genome in gene X mRNA level. Note, Ubiquitin/proteasome is for "Protein degradation" not for mRNA regulation. Also, micro RNA for translational inhibition is not correct since that will not affect mRNA level. The key point is how mRNA level of specific gene can be controlled in cells. If the mechanism you explained has broad impact on the many mRNA (such and modification of mRNA, general transcription factors), I gave points case by case.

SHORT ANSWER You found a mutation in the voltage-gated Na+ channel gene. Because of the mutation, the channel CAN NOT form its inactive (resting) conformation. With this mutation, what will you expect the action potential to be like for the signaling neuron? You may draw and describe in a few sentences. Label any important features of your drawing.

"Inactive (resting) conformation" allows channel close even at membrane potential is favorable to keep open. That conformation is most critical to directional movement of action potential. With this mutation, the directional movement of action potential will be compromised. (If you indicated this by drawing, that is fine.) *Partial points were given based on what you indicated for channel defect and explanation of "consequence of not forming inactive conformation". Especially, "Directional movement of action potential", which was discussed in class in a key. Note that channel still could go back to "closed conformation" when membrane potential returned because of other ions movement. Also, action potential will not keep rising because environmental factors (Osmosis and electrochemical gradient) will reach to equilibrium. Slower recovery of action potential is reasonable so that you get partial points by that.

Which of the following statements is TRUE? A) A mutation is passed on to offspring only if it is present in the germ-line cells B) A heritable mutation that causes a disease, such as in the breast cancer gene BRCA1, initially happened in somatic cells of the individual then was inherited by offspring C) A mutation that arises in a mother's somatic cells often causes a disease in her daughter D) In an evolutionary sense, a mutation in somatic cells plays an important role in evolution of a species

Answer: A A mutation is passed on to offspring only if it is present in the germ-line cells

Which of the following statements is TRUE? A) Gas such as CO2 and O2, can diffuse across the cell membrane but not an artificial lipid bilayer B) Electrically charged molecules, such as Ions, can diffuse through an artificial lipid bilayer C) Direction of passive transport of molecules across membrane is not only controlled by osmosis D) Active transport always uses energy from ATP hydrolysis to move a molecule across the plasma membrane against osmosis

Answer: C Direction of passive transport of molecules across membrane is not only controlled by osmosis

Which of these proteins is a key target of Ca2+ signaling? A) Delta B) Acetylcholine C) Notch D) Calmodulin

Answer: D Calmodulin

Which of the following statements about human chromosomes is FALSE? A) Each chromosome occupies discrete territories in the nucleus during interphase B) Chromosomes isolated from cancer patients often show an abnormality in the number of chromosomes and in the shape of the chromosomes C) Condensation of chromatin to chromosomes is required for separation of the genome in mitosis D) Each chromosome has a distinctive DNA sequence at its telomere

Answer: D Each chromosome has a distinctive DNA sequence at its telomere

If a protein is being transported to this organelle, will transport happen when the protein is folded, unfolded, or mid-synthesis? Possible answers: folded, unfolded, mid-synthesis. Answers for this question may be used more than once. Nucleus: [Blank1] Mitochondria: [Blank2] Peroxisome: [Blank3] Endoplasmic Reticulum: [Blank4]

Blank 1 = Folded Blank 2 = Unfolded Blank 3 = Folded Blank 4 = Mid-Synthesis

SHORT ANSWER You found two enzymes that catalyze the same hydrolysis reaction in the same substrate. You analyzed their activities and obtained results shown in the graphs below (Graphs are from Exam 1). Based on these results, which enzyme (Enzymes #1 or Enzyme #2) will be more effective at hydrolyzing the substrate in the following cell? Explain your reasoning in a couple of sentences. Cell: Contains approximately 2 micro M of the substrate.

Enzyme #1 will be more effective. From the kinetics data (graphs), enzyme #1 has catalytic rate approximately 10 mol/sec at 2 micro M and enzyme #2 has approximately 2 mol/sec at 2 micro M. If cell has 2 micro M substrates, enzyme #1 work higher catalytic rate than enzyme #1. * Note that explaining Km difference and V max difference are not important justification for the answer. Catalytic rate at given substrate concentration is the reason for choosing the enzyme. If I see that justification in your statement, you got full point.

SHORT ANSWER: You enjoyed learning about the dynamic instability of microtubules and join a lab that works on microtubule polymerization. You learn to grow microtubules in culture using conditions that allow you to watch individual microtubules under a microscope. You can see the microtubules growing and shrinking, as you would expect. The professor who runs the lab gets in a new piece of equipment, a very fine laser beam that can be used to sever microtubules. After she confirms the laser beam is working, she asks you to sever growing microtubules at their middle, using the laser beam. A. Do you expect that the newly exposed microtubule plus ends from the middle of the microtubule will grow or shrink? Explain your answer in complete sentences. (4 points) B. What do you predict would happen to the newly exposed plus ends if you did the same experiment, but were to grow the microtubules in the presence of an analog of GTP that cannot be hydrolyzed, and you then severed the microtubules in the middle with a laser beam? Explain your answer. (4 points)

Answer: A.) If you cut a microtubule in the middle, you will create new "plus ends " and "minus ends". A microtubule will most likely grow at the plus end if you add GTP-carrying subunits to the plus end, where β-tubulin is exposed. BUT, over time, GTP is hydrolyzed, which leaves only a cap of GTP-carrying subunits at the newly created plus end along with the remainder of the tubulin filament containing GDP-carrying subunits. A plus-end that contains GDP-carrying subunits is then created. The GDP carrying subunits are less tightly bound than the GTP carrying subunits. The GDP carrying subunits would eventually peel away from each other, leading to depolymerization of the microtubule, leading to SHRINKAGE of the microtubule. B.) On the other hand, if a non-hydrolyzable analog of GTP containing microtubule is severed with a laser, the newly exposed plus end would contain GTP-carrying subunits. This GTP would NOT hydrolyze to GDP carrying subunit and the microtubule would continue to grow. Therefore, when severed in the middle, the newly exposed microtubule plus ends with non-hydrolyzable GTP analog will continue to grow. *Notes: Since the GTP is hydrolyzed over time, in part A the microtubule would shrink, since it would not have the GTP cap in the middle where it was cut, it would now be GDP.

Ciliopathies are diseases caused by the dysfunction of cilia. Based on what we learned about the normal function of cells in the human respiratory tract, in your own words, what respiratory-related outcomes would you expect in patients with ciliopathies? The best answers will start by explaining what we know about healthy cells in the respiratory tract - their features and functions - and then will explain what could occur in the disease state. (5 points)

Answer: Healthy ciliated cells in the respiratory tract use the cilia to move along the layers of mucus that have trapped dust particles, dead cells, debris, and pathogens up toward the throat where we will swallow or cough out the mucus for elimination from the body.If a person has ciliopathy, their cilia are not able to move the mucus along and are not able to clear out debris or pathogens. This leads to a higher liability for bronchial infections.

FILL IN THE BLANK The cell cycle consists of an alternation between ______ , which appears as a period of dramatic activity under the microscope, and a preparative period called ______ , which consists of three phases called G1 phase, ______ , and ______ . During M phase, the nucleus divides in a process called ______ , and the cytoplasm splits in two in a process called ______ . The cell-cycle control system relies an increase in the activity of ______ to trigger DNA replication. Inactivation of ______ is required to exit from M phase after chromosome segregation.

Answer: M Phase Interphase S Phase G2 Phase Mitosis Cytokinesis S-Cdk M-Cdk

Induced pluripotent stem (iPS) cells: A) Can be created by the expression of a set of key genes in most somatic cell types, including cells derived from adult tissues B) Require a supply of donor egg cells, as is the case for embryonic stem cells C) Can differentiate into a greater variety of adult tissues than embryonic stem cells D) Cannot yet be used to generate organoids

Answer: A A is CORRECT B is INCORRECT because iPS cells do not require donor egg cells and are made from adult (and not embryonic) cells C is INCORRECT because embryonic stem cells can differentiate into all tissue and cell types D is INCORRECT because iPS cells (in addition to ES and Lgr5+ adult stem cells) can be induced to produce organoids in vitro

Which of the following statements about transposons is FALSE? A) All transposons need to be transcribed first to change position in the genome B) Retrotransposons contain the reverse transcriptase gene C) They are initially inserted into genomes by viral infection D) Transposons contain the transposase (recombination enzyme) gene

Answer: A All transposons need to be transcribed first to change position in the genome

Which of these is a process by which cells harvest the energy stored in food molecules; usually accompanied by the uptake of O2 and release of CO2? A) Cellular Respiration B) Photosynthesis C) Oxidative Phosphorylation D) Glycolysis

Answer: A Cellular Respiration

Which of the following statements is true? A) GTP-binding proteins are active when bound to GTP, and inactive when bound to GDP. B) GDP is phosphorylated to form GTP by a GAP in order to active GTP-binding proteins. C) GEFs promote hydrolysis of GTP to GDP D) Protein phosphatases add phosphate groups to proteins.

Answer: A GTP-binding proteins are active when bound to GTP, and inactive when bound to GDP.

Which of the following statements is true about the formation of clathrin-coated vesicles? A) If a cell did not produce dynamin, you would expect to observe deeply invaginated clathrin-coated pits along the membrane, but no clathrin-coated vesicles. B)If a cell did not produce adaptins, you would expect that more clathrin-coated endocytic vesicles than usual would form. C) If a cell did not produce clathrin, you would expect that adaptins would coat all endocytic vesicles. D) If a cell did not produce adaptins, you would expect that clathrin-coated endocytic vesicles would take longer to form.

Answer: A If a cell did not produce dynamin, you would expect to observe deeply invaginated clathrin-coated pits along the membrane, but no clathrin-coated vesicles.

Action potential is created by the movement of ions across the plasma membrane through a channel. The ion channel for _____ is critical to create an action potential. A) Na+ B) K+ C) Ca2+ D) Cl-

Answer: A Na+

You are studying nuclear lamins and use recombinant DNA technology to alter the coding sequence of a nuclear lamin gene. The alteration you make creates a situation such that the gene now codes for a nuclear lamin protein that can no longer be phosphorylated when the nuclear envelope is broken down during mitosis. What do you predict would happen if the cell only had the altered nuclear lamin gene (and not the unaltered version) A) Nuclear lamins will no longer disassemble properly during mitosis. B) Disassembly of the nuclear lamins will occur prematurely because the lamins cannot be phosphorylated. C) Mitosis should proceed as usual because the dephosphorylation of the lamin is what is important for nuclear lamina assembly during mitosis, so phosphorylation will not be necessary. D) Nuclear lamins will be unable to produce dimers, as the coiled-coil formation will be disrupted.

Answer: A Nuclear lamins will no longer disassemble properly during mitosis.

When a terminally differentiated cell in an adult body dies, it can typically be replaced in the body by a stock of A) proliferating precursor cells B) cells more apically located than the terminally differentiated cells C) Wnt proteins D) induced pluripotent cells

Answer: A Proliferating precursor cells already within the tissue are typically used to replace terminally differentiated cells. Induced pluripotent cells are produced in the laboratory and are not typically used to replace adult terminally differentiated cells within the body

Which of the following statements is true? A) Proteins destined for mitochondria and chloroplasts must translocate across two membranes, requiring close proximity of the two membranes during this process. B) Nuclear import is powered by hydrolysis of GDP to GTP. C) Proteins destined for the nucleus are marked by a nuclear localization signal which binds in the cytosol to the nuclear basket. D) The signal recognition particle binds to the mitochondrial signal sequence and enables proteins to embed in the membrane.

Answer: A Proteins destined for mitochondria and chloroplasts must translocate across two membranes, requiring close proximity of the two membranes during this process.

The inherited disease xeroderma pigmentosum causes serious problems with lesions on skin and often people with this disease develop skin cancer with repeated exposure to sunlight. Which of the following repair mechanisms do you expect is defective in the cells of the individuals who have this inherited disease? A) Repair of thymine dimers created by UV irradiation B) Repair of double strand break created by X-ray irradiation C) Repair of chemical damage of base by base excision repair D) Repair via proofreading mechanisms during DNA replication

Answer: A Repair of thymine dimers created by UV irradiation

Which of the following are true statements about skeletal muscle fibers? A) Skeletal muscle fibers include a specialized portion of the endoplasmic reticulum called the sarcoplasmic reticulum B) Skeletal muscle fibers are a string of multiple cells with single nuclei. C) Skeletal muscle fibers rely on release of sodium ions for contraction. D) Each skeletal muscle fiber will include one myofibril within its cytoplasm.

Answer: A Skeletal muscle fibers include a specialized portion of the endoplasmic reticulum called the sarcoplasmic reticulum

Which of the following statements about microscopic analysis is FALSE? A) The electron microscope has less resolution than the confocal microscope B) Fluorescently labeled antibodies can be used to visualize specific molecules in cells by using fluorescence microscopy C) Confocal microscopy can increase the resolution of signals by limiting the light path with a pinhole D) Fluorescent proteins can be used to visualize movements of proteins in cells

Answer: A The electron microscope has less resolution than the confocal microscope

Which of the following events does NOT usually occur during interphase? A) The nuclear envelope breaks down. B) Cells grow in size. C) DNA is replicated. D) The centrosomes are duplicated.

Answer: A The nuclear envelope breaks down.

Apoptosis differs from necrosis in that necrosis... A) causes cells to swell and burst, whereas apoptotic cells shrink and condense. B) requires the reception of an extracellular signal. C) involves a caspase cascade D) causes DNA to fragment

Answer: A causes cells to swell and burst, whereas apoptotic cells shrink and condense.

Which of the following statements is TRUE? A) rRNAs and mRNAs are transcribed by different RNA polymerases B) RNA polymerase II is mostly located in the nucleolus C) Non-protein-coding RNAs, except tRNA and rRNA, do not have any function in cells D) RNA polymerase II only makes mRNAs, which encode proteins, but no other functional RNAs

Answer: A rRNAs and mRNAs are transcribed by different RNA polymerases

Organisms that reproduce sexually... A) undergo a sexual reproductive cycle that involves an alternation of haploid cells with the generation of diploid cells. B) must be haploid, unlike organisms that reproduce asexually. C) create zygotes that are genetically identical to each other. D) can reproduce only with a partner that carries the same alleles.

Answer: A undergo a sexual reproductive cycle that involves an alternation of haploid cells with the generation of diploid cells.

Carbohydrate (Sugar) molecules are used in cells in many ways. Which of the following statement is FALSE? A) Condensed sugar (polysaccharide) is a major way of storing energy for cells B) 6-carbon sugar (Hexose) is a part of the building blocks of a nucleotide C) Sugar can be structural support in cells D) Sugars used in DNA and RNA are different

Answer: B 6-carbon sugar (Hexose) is a part of the building blocks of a nucleotide

A major distinction between the connective tissues in an animal and other main tissue types such as epithelium, nervous tissue, or muscle is the: A) Ability of connective-tissue cells such as fibroblasts to change shape B) Amount of extracellular matrix in connective tissues C) Ability of connective tissues to withstand mechanical stresses D) Numerous connections that connective-tissue cells make with each other

Answer: B A is INCORRECT because cells in non-connective tissues can change shape (for example, muscle cells when they contract) B is CORRECT C is INCORRECT because cells in non-connective tissues can withstand mechanical stress (for example, cells of the epidermis) D is INCORRECT because cells in connective tissue tend to be scattered throughout the extracellular matrix and make few or no contacts with each other, unlike nerve cells or epithelial cells

Which of the following statements about microtubule organizing centers is FALSE? A) Centrosomes typically contain a pair of centrioles, which is made up of a cylindrical array of short microtubules. B) Centrosomes serve as the microtubule organizing centers for cilia. C) Centrosomes are the major microtubule-organizing center in animal cells. D) Microtubules emanating from the centrosome have the same polarity such that all have their minus end attached to the centrosome and their plus end away from the centrosome.

Answer: B Centrosomes serve as the microtubule organizing centers for cilia.

Which of the following statements is true about the role of enzymes in the oxidation of sugars: A) An enzyme must be able to function in all steps of cellular respiration in order to be involved B) Enzymes allow reactions to proceed in a stepwise manner at appropriate temperatures for the cell C) Enzymes lower the energy released from the reaction D) Without enzymes, the oxidation of sugar will produce AND capture the same amount of energy

Answer: B Enzymes allow reactions to proceed in a stepwise manner at appropriate temperatures for the cell

Which of the following statements is true? A) Phagocytosis is used by some viruses to invade host cells. B) Exocytosis would be used during a cell's release of a hormone into the extracellular space. C) Pinocytosis is used by a macrophage engulfing a bacterial cell. D) Endocytosed materials are delivered directly to lysosomes.

Answer: B Exocytosis would be used during a cell's release of a hormone into the extracellular space.

Which organelle is responsible for sorting transport vesicles, modifying proteins, has cis and trans faces, and appears as flattened, membrane-enclosed sacs? A) Lysosomes B) Golgi Apparatus C) Endosomes D) Endoplasmic Reticulum

Answer: B Golgi Apparatus

Which one of the following statements is NOT true? A) Post-translational modification of a protein can regulate interactions between this protein and its binding partner B) Methylation of Lysine affects its electrical charge at its side chain C) Binding affinity of a motor protein to its track can be changed during its ATP hydrolysis reaction D) The shape of the GTP bound form of small GTPase proteins is distinct from the shape of the GDP bound form

Answer: B Methylation of Lysine affects its electrical charge at its side chain

Which of the following observations is false and does NOT support the theory that mitochondria are descendants of prokaryotic ancestors? A) Mitochondria have DNA based genomes. B) Mitochondria are found within bacteria and archaea. C) Mitochondria have ribosomes. D) Chemiosmotic coupling happens similarly in plasma membranes of mitochondria, bacteria, and archaea.

Answer: B Mitochondria are found within bacteria and archaea.

Which of the following transporters use energy from a Na+ gradient for its transport reaction? A) Na+/K+ pump B) Na+/Glucose Symport C) Voltage gated Ca2+ channel D) Bacteriorhodopsin

Answer: B Na+/Glucose Symport

Which of the following is true of photosynthesis? A) Electrons transferred along Photosystem II and then Photosystem I are eventually donated to O2 as the final step B) Photosynthesis takes place in two stages: the light reactions and the light-independent (or dark) reactions. C) Photosynthesis takes place in the inner chloroplast membrane. D) ATP and FADH are products of Stage 1 of photosynthesis, which go on to be consumed in Stage 2 of photosynthesis.

Answer: B Photosynthesis takes place in two stages: the light reactions and the light-independent (or dark) reactions.

Which of the following statements is true? A) All enzyme-coupled receptors are receptor tyrosine kinases. B) Receptor tyrosine kinases often dimerize upon binding of their ligand, resulting in their activation. C) Receptor tyrosine kinases often activate Ras directly by exchanging its GDP for GTP. D) Receptor tyrosine kinases remove phosphate groups from the tyrosine amino acids of proteins.

Answer: B Receptor tyrosine kinases often dimerize upon binding of their ligand, resulting in their activation.

Which of the following statements is true? A) An N-terminal NLS is necessary, but not sufficient to trigger protein sorting to the nucleus B) Signal sequences governing protein transport can be as short as 3 amino acids long C) Stop transfer sequences for ER transport are cleaved off of a single pass transmembrane protein once the protein is embedded in the membrane D) A nuclear localization signal at the 3' end of an mRNA, will trigger nuclear import of that mRNA

Answer: B Signal sequences governing protein transport can be as short as 3 amino acids long

Which of the following statements about small noncoding RNAs, such as microRNAs, is FALSE? A) Some small noncoding RNAs can regulate translation efficiency of mRNA B) Small noncoding RNAs never bind to protein for their function C) Some small noncoding RNAs originated from introns D) Some small noncoding RNAs reduce stability of mRNA in the cytoplasm

Answer: B Small noncoding RNAs never bind to protein for their function

Which of the following statements is true? A) Notch signaling requires the diffusion of an extracellular ligand from a distance and would be classified as endocrine signaling. B) Steroid hormones move across the plasma membrane in order to bind to their receptors. C) Notch signaling is a pathway used in very few organisms. D) Steroid hormone-induced signaling pathways require the activation of a series of effector proteins and second messengers.

Answer: B Steroid hormones move across the plasma membrane in order to bind to their receptors.

Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? A) The cell would pass through M phase more slowly than normal cells. B) The cell would enter M phase under conditions when normal cells would not. C) The cell would be unable to enter M phase. D) The cell would be unable to enter G2.

Answer: B The cell would enter M phase under conditions when normal cells would not.

Which of the following is FALSE regarding the structure and function of telomeric sequences? A) Telomere repeat sequences allow a T-loop structure to form B) The non-homologous end joining repair mechanism can fuse intact telomeres (telomeres with T-loop structure) C) If a cell expresses telomerase, that cell can extend telomeric DNA D) Loss of T-loop structure can be mediated by loss of TRF2 protein

Answer: B The non-homologous end joining repair mechanism can fuse intact telomeres (telomeres with T-loop structure)

Which of the following statements about splicing is FALSE? A) The spliceosome, containing small non-coding RNAs, mediates splicing reactions in the nucleus B) The spliceosome attaches to DNAs to cut an intron C) The overall reaction of splicing does not require energy even though it contains a condensation reaction D) Alternative splicing contributes to increased variation of mRNAs from an initial transcript

Answer: B The spliceosome attaches to DNAs to cut an intron

Which of the statements below about intermediate filaments is true? A) They easily disassemble. B) They can be found in the cytoplasm and the nucleus. C) They are freely floating in the cell. D) Each filament is about 10 μm in diameter.

Answer: B They can be found in the cytoplasm and the nucleus.

Which of the following statements about nucleosomes is FALSE A) The position of core histones with respect to the transcription factor binding site on the DNA can influence efficiency of binding of the transcription factor B) When the histone tail of nucleosomes is NOT modified, DNA is less tightly bound to a histone C) The combination of histone modifications (histone code) at nucleosomes is key epigenetic information D) Heterochromatin binding proteins bind to Histone H3 methylated at Lysine 9

Answer: B When the histone tail of nucleosomes is NOT modified, DNA is less tightly bound to a histone

During recombination: A) one crossover event occurs for each pair of human chromosomes. B) chiasmata hold chromosomes together. C) sister chromatids undergo crossing-over with each other. D) the synaptonemal complex keeps the sister chromatids together until anaphase II.

Answer: B chiasmata hold chromosomes together.

Levels of Cdk activity change during the cell cycle, in part because: A) the Cdks phosphorylate each other. B) cyclin activity and concentrations change during the cycle. C) Cdk degradation precedes entry into the next phase of the cell cycle. D) the Cdks activate the cyclins.

Answer: B cyclin activity and concentrations change during the cycle.

The plasmodesmata in plants are functionally most similar to which animal cell junction? A) Tight Junction B) Adherens Junction C) Gap Junction D) Desmosome

Answer: C

Proteins are made by a condensation reaction of amino acids. If a protein has 100 amino acids, how many variations in the primary structure could it have? A) 20 x 100 B) 4 x 100 C) 20^100 D) 100^20

Answer: C 20^100

Which of the following statements about actin filaments is true? A) Actin filaments can only be found in the cell in bundles of filaments. B) Actin filaments, similar to microtubules, are composed of actin dimers. C) Actin filaments are found in the cell in microvilli, contractile bundles, lamellipodia, filopodia, and contractile rings. D) Actin filaments, similar to intermediate filaments, do not have a polarity to their structure.

Answer: C Actin filaments are found in the cell in microvilli, contractile bundles, lamellipodia, filopodia, and contractile rings.

Which of the situations below will enhance microtubule shrinkage? A) Addition of a drug that blocks the ability of a tubulin dimer to bind to γ-tubulin B) Addition of a drug that increases the affinity of tubulin molecules carrying GDP for other tubulin molecules C) Addition of a drug that inhibits GTP exchange on free tubulin dimers D) Addition of a drug that inhibits hydrolysis of the GTP carried by tubulin dimers

Answer: C Addition of a drug that inhibits GTP exchange on free tubulin dimers

Which of the following statements about DNA replication of a human chromosomes is FALSE? A) The template DNA sequence is incompletely replicated B) It is synthesized from multiple origins by a mixture of continuous and discontinuous DNA synthesis C) After replication of entire genome, it is expected to have 300 mutations even with combining all DNA repair mechanisms D) Modification of both DNA and histones on template will be maintained after DNA replication

Answer: C After replication of entire genome, it is expected to have 300 mutations even with combining all DNA repair mechanisms

At the end of DNA replication, the sister chromatids are held together by the: A) Histones B) Securins C) Cohesins D) Kinetochores

Answer: C Cohesins

Which of the following statements about the phases of mitosis is true? A) During pro-metaphase, the nuclear envelope is still intact. B) During metaphase, duplicated chromosomes are attached to the spindle microtubules by centrosomes. C) During prophase, the duplicated chromosomes condense and the mitotic spindle begins to assemble in the cytoplasm D) During telophase, the nuclear envelope remains unassembled although the microtubules return to their interphase configuration.

Answer: C During prophase, the duplicated chromosomes condense and the mitotic spindle begins to assemble in the cytoplasm

Which of the following mechanisms contributes the most in creating multi-functional domain proteins? A) Point mutation in an exon B) Point mutation in the promoter region of genes C) Exon shuffling by transposon activity D) None of the above

Answer: C Exon shuffling by transposon activity

Which of the following statements fits in the blank? "A DNA double helix _____." A) Contains uridine B) Is formed by hydrophobic bonds between bases C) Has a negative charge originating from phosphate backbone D) Is made by two DNA strands that run parallel

Answer: C Has a negative charge originating from phosphate backbone

Which of the following statements about chromatin is FALSE? A) Chromatin is a chain of nucleosomes composed of a Histone core and DNA B) Each nucleosome contains 8 Histone proteins and approximately 147 base pairs of DNA C) Histones in nucleosomes are composed of two molecules each of H1, H2A, H2B, and H3 D) A DNA fragment wrapped around a nucleosome is not easily accessible by a sequence specific DNA binding protein, such as a transcription factor.

Answer: C Histones in nucleosomes are composed of two molecules each of H1, H2A, H2B, and H3

Which of the following non-covalent interactions will contribute the most to form the core of globular proteins in the water? A) Ionic Bond B) Hydrogen Bonds C) Hydrophobic Interactions D) Van der Waals attractions

Answer: C Hydrophobic Interactions

Which of the following statements about chemical bonding is TRUE? A) The strength of a non-polar covalent bond is much lower in water than in a vacuum B) Polar covalent bonds can be formed between two atoms which have similar electronegativity C) Hydrophobic interactions are mediated by exclusion of hydrophobic molecules by water D) The strength of polar covalent bonds is the same as non-polar covalent bonds in water

Answer: C Hydrophobic interactions are mediated by exclusion of hydrophobic molecules by water

Which of the following statements is true? A) All enzyme-coupled receptors must bind to an associated enzyme to become activated B) G-protein coupled receptors only bind to monomeric G proteins. C) Ion-channel-coupled receptors are often found on neurons and muscle cells. D) All receptors are located on the cell surface of a target cell.

Answer: C Ion-channel-coupled receptors are often found on neurons and muscle cells.

Which of the following statements about the human genome is FALSE? A) About 2-3% of DNA sequences across the entire genome are protein-coding exons B) About 50% of the genome is repeated sequence elements C) Mobile elements are categorized as unique sequences D) Genes (intron plus exon) occupy about 22% of the DNA sequence across the entire genome

Answer: C Mobile elements are categorized as unique sequences

Phosphorylation of amino acids is used on many occasions in cells, such as signal transduction and regulation of enzyme activity. Which amino acids are known to be phosphorylated in eukaryotes? A) Histidine, Serine, and Tyrosine B) Arginine, Lysine, and Threonine C) Serine, Threonine, and Tyrosine D) Histidine, Threonine, and Tyrosine

Answer: C Serine, Threonine, and Tyrosine

Membrane lipids are capable of many different types of movement. Which of these movements require energy to happen in biological membranes? A) Rotation B) Lateral movement C) Switching between lipid layers D) Flexing of hydrocarbon chains

Answer: C Switching between lipid layers

Which combination of words fits correctly into the blanks? "All living organisms on Earth use energy initially provided from _____, which is captured by ______." A) the Sun, Mitochondria B) Carbon, Chloroplast C) the Sun, Chloroplast D) Oxygen, Mitochondria

Answer: C The Sun, Chloroplast

Which of the following statements is FALSE? A) The cleavage furrow often forms in the middle of the cell, but can be positioned differently to produce two daughter cells of different sizes. B) The cleavage furrow will not begin to form in the absence of a mitotic spindle. C) The cleavage furrow always forms parallel to the interpolar microtubules. D) The cleavage furrow is a puckering of the plasma membrane caused by the constriction of a ring of filaments attached to the plasma membrane.

Answer: C The cleavage furrow always forms parallel to the interpolar microtubules.

Which following statements about Eukaryotic cells is FALSE? A) Eukaryotic cells have more complex membrane structures than Prokaryotes B) The genome of Eukaryotic cells is stored in the nucleus during interphase C) The genome size of Eukaryotic cells is always larger than that of prokaryotic cells (such as Bacteria) D) The Nucleus of Eukaryotic cells has a high density so it can be separated from other cellular organelles by spinning cell extracts at low speed.

Answer: C The genome size of Eukaryotic cells is always larger than that of prokaryotic cells (such as Bacteria)

Ras is a GTP-binding protein that is often defective in cancer cells. A common mutation found in cancer cells causes Ras to behave as though it were bound to GTP all the time, which will cause cells to divide inappropriately. From this description, the normal Ras gene is a/an: A) Tumor Suppressor B) Oncogene C) Proto-oncogene D) Gain-of-Function Mutation

Answer: C The normal Ras gene is a proto-oncogene. Only the mutated form of Ras is an oncogene and a gain-of-function mutation.

Which statement is FALSE about protein structure? A) Primary structure of the protein can be determined by the DNA sequence of the gene coding that protein B) Proline is typically located in unstructured regions (outside of secondary structured regions) of the proteins C) The tertiary structure of proteins will not be affected whether proteins are in an organic solvent or in water D) Disulfide bonds can link two proteins

Answer: C The tertiary structure of proteins will not be affected whether proteins are in an organic solvent or in water

Which of the following statements is true? A) During constitutive exocytosis, selected proteins are diverted into secretory vesicles where the proteins are stored until an extracellular signal stimulates their secretion. B) Regulated exocytosis continually supplies the plasma membrane with newly synthesized lipids and proteins. C) Vesicles resulting from pinocytosis are small, whereas vesicles resulting from phagocytosis are relatively larger to accommodate large particles such as bacteria. D) Pinocytosis takes place in some specialized cell types, whereas phagocytosis happens in all eukaryotic cells.

Answer: C Vesicles resulting from pinocytosis are small, whereas vesicles resulting from phagocytosis are relatively larger to accommodate large particles such as bacteria.

Which of the following statements about the regulation of Cyclin-Cdk complexes is false? A) Ubiquitylation of cyclin is mediated by the Anaphase Promoting Complex/Cyclosome (APC/C) B) Ubiquitylation of cyclin leads to its destruction. C) Wee1 removes inhibitory phosphates from the cyclin-Cdk complex immediately upon its formation D) Cdc25 is responsible for removal of inhibitory phosphates from the Cdk component of the M-Cdk complex.

Answer: C Wee1 removes inhibitory phosphates from the cyclin-Cdk complex immediately upon its formation

The gene information stored in DNA is the sequence of _____ in a DNA strand, which is transcribed into _____ to be translated into ____. A) bases, proteins, RNA B) Amino acid, RNA, proteins C) bases, RNA, proteins D) sugar, RNA, lipids

Answer: C bases, RNA, proteins

The concentration of mitotic cyclin (M cyclin) A) is activated by phosphorylation. B) is highest in G1 phase. C) falls toward the end of M phase as a result of ubiquitylation and degradation. D) rises markedly during M phase.

Answer: C falls toward the end of M phase as a result of ubiquitylation and degradation.

Which of the following about bacterial transcription is FALSE? A) RNA polymerase requires sigma factor for initiating transcription B) Sigma factor recognizes promoter sites in the DNA C) mRNA transcribed from one promotor always codes one gene (protein) D) It can be controlled by environmental factors, for example, available sugar source

Answer: C mRNA transcribed from one promotor always codes one gene (protein)

Which of the following statements about the structure of microtubules is FALSE? A) Microtubules are built from protofilaments that come together to make a hollow structure. B) The two ends of a protofilament are chemically distinct, with α-tubulin exposed at one end and β-tubulin exposed at the other end. C) α-Tubulin and β-tubulin are covalently bound to make the tubulin dimer that then assembles into protofilaments. D) Within a microtubule, all protofilaments are arranged in the same orientation, giving the microtubule structural polarity.

Answer: C α-Tubulin and β-tubulin are covalently bound to make the tubulin dimer that then assembles into protofilaments.

A malignant tumor is more dangerous than a benign tumor because A) its cells are proliferating faster B) it causes neighboring cells to mutate C) its cells attack and phagocytose neighboring normal tissue cells D) its cells invade other tissues

Answer: D

In the absence of recombination, how many genetically different types of gametes can an organism with five homologous chromosome pairs produce? A) 10 B) 64 C) 5 D) 32

Answer: D 32

Both multicellular plants and animals have: A) Cells capable of locomotion B) Cells with cell walls C) A cytoskeleton composed of actin filaments, microtubules, and intermediate filaments D) Tissues composed of multiple different cell types

Answer: D A is INCORRECT because plants are not capable of locomotion B is INCORRECT because animal cells do not have cell walls C is INCORRECT because plant cells do not have intermediate filaments D is CORRECT

Which of the following is an example of endocrine cell signaling? A) A membrane-bound signal molecule binds to a receptor on a neighboring cell B) A neurotransmitter binding to a receptor on a target cell at a synapse C) A secreted signal acts locally in the extracellular fluid to influence nearby cells. D) A secreted signal is available to interact with cells in the whole body via the bloodstream

Answer: D A secreted signal is available to interact with cells in the whole body via the bloodstream

Which of the following statements about the cytoskeleton is TRUE? A) The cytoskeleton provides a rigid and unchangeable structure important for the shape of the cell. B) All prokaryotic cells have actin, microtubules, and intermediate filaments in their cytoplasm. C) The three cytoskeletal filaments perform distinct tasks in the cell and act completely independently of one another. D) Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end.

Answer: D Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end.

Eukaryotic chromosomes contain sequence elements that are required for the faithful transmission of genetic information from a mother cell to each daughter cell. Which of the following is known to be one of these required elements in eukaryotes? A) Centromeres B) Origins of replication C) Telomeres D) All of the above

Answer: D All of the above

Which of the following protein functions can be predicted from the primary structure of proteins? A) Whether the protein can bind to cAMP (Cyclic AMP) or not B) Whether the proteins can form helix turn helix motif or not C) Whether the protein can bind to GTP or not D) All of the above

Answer: D All of the above

Which of the following will be essential in intestinal epithelial cells to absorb glucose from the gut lumen and to release glucose to the inside of our body? A) Position of Na+/Glucose symport on apical side of plasma membrane B) Na+/K+ pump to create Na+ gradient C) Glucose transporter positioned at the basal side of the plasma membrane D) All of the above

Answer: D All of the above

Which of the following statements is true? A) Vesicle fusion to its destination organelle requires adaptin molecules on the vesicle to bind to Rab on the destination membrane. B) Transport vesicles only deliver lipids to the cell surface. C) Clathrin remains on the outside of a vesicle for its entire journey from origin to destination. D) All transport vesicles in the cell must have a v-SNARE protein in their membrane.

Answer: D All transport vesicles in the cell must have a v-SNARE protein in their membrane.

As we discussed in class, linear genomes (eukaryotes) have problems replicating DNA completely. In theory, which of the following (enzyme) activities can solve this problem? A) DNA primase that can synthesize DNA primers for initiation of DNA replication. B) DNA polymerase that can extend DNA strands from the 5' end C) DNA polymerase that does not require an initial RNA primer D) Any of the above

Answer: D Any of the above

Which of the following statements about apoptosis is TRUE? A) Cells that constitutively express Bcl2 will be more prone to undergo apoptosis. B) The procaspases are catalytically active upon initial expression in the cell. C) Bax and Bak promote apoptosis by binding to procaspases in the apoptosome. D) Apoptosis can be promoted by the release of cytochrome c into the cytosol from mitochondria.

Answer: D Apoptosis can be promoted by the release of cytochrome c into the cytosol from mitochondria.

Which of the following statements does NOT fit in the blank? "Chromatin-remodeling complexes (Nucleosome remodeling proteins) _____." A) Are motor proteins that use DNA as a track B) Can move core histones in chromatin to allow a specific DNA sequence to be more accessible for sequence specific DNA binding proteins C) Use the energy of ATP hydrolysis to move nucleosomes D) Are capable of efficiently moving Histones that have no modification on their tails

Answer: D Are capable of efficiently moving Histones that have no modification on their tails

Which of the following molecules is a common second messenger in cell signaling pathways that regulate early development as well as key functions of nerve, muscle, and secretory cells? A) Na+ B) K+ C) Acetylcholine D) Ca2+

Answer: D Ca2+

Which of the following mechanisms MAY NOT be used by cells to change patterns of gene expression during development (differentiation of cells)? A) Expression of a transcriptional regulator that can increase its own expression B) Changing histone modifications C) Eliminating DNA methylation D) Changing DNA sequence during DNA replication

Answer: D Changing DNA sequence during DNA replication

Which of the following statements about stem cell niches is false? A) The Paneth cells serves as a stem cell niche for the stem cells of the mammalian intestine B) Wnt signaling is required for a functional stem cell niche in the mammalian intestine C) Dr. Judith Kimble identified the first stem cell niche in an animal, which relied on Notch signaling D) Paneth cells are not required for maintenance of the stem cells in the mammalian intestine

Answer: D D is incorrect because Paneth cells serve as the stem cell niche and are therefore required to maintain stem cells in the intestine

Consider a protein that contains an ER signal sequence at its N-terminus and a nuclear localization sequence in its middle. Where will this protein's final destination be in the cell? A) Nucleus B) Golgi Apparatus C) Cytosol D) Endoplasmic Reticulum

Answer: D Endoplasmic Reticulum

Which of the following DOES NOT fit for regulating membrane structure in eukaryotic cells? A) At the Golgi apparatus, membrane lipid species will be distributes unevenly between the lumen side and cytoplasmic side B) Acquisition of new lipids from the cytoplasm happens at the ER C) Membrane lipids facing the Golgi lumen will be exposed extracellularly after trafficking to the plasma membrane D) Flip-flop reactions of membrane lipids only occur at the ER

Answer: D Flip-flop reactions of membrane lipids only occur at the ER

Which of the following statements about eukaryotic transcription regulators is TRUE? A) All transcription regulators, which bind to specific DNA sequences, are specified to either repress gene expression or activate gene expression B) Transcription repressors bind to HAT either directly or indirectly C) The binding sequence of transcription regulators is always located close (within 200bps) to the TATA box D) General transcription factor contains a TBP

Answer: D General transcription factor contains a TBP

ΔG indicated the change in the standard free energy as a reactant and is converted to a product. Given what you know about these values, which reaction below os the most favorable? A) ATP → ADP + Pi (ΔG = -7.3 kcal/mole) B) Glucose 1-Phosphate → Glucose 6-Phosphate (ΔG = -1.7 kcal/mole) C) Glucose + Fructose → Sucrose (ΔG = +5.5 kcal/mole) D) Glucose → CO2 + H2O (ΔG = -686 kcal/mole)

Answer: D Glucose → CO2 + H2O (ΔG = -686 kcal/mole)

Which of the following compartments has a lower pH compared to other compartments and carries a positive charge along the membrane following oxidative phosphorylation? A) Mitochondrial Matrix B) Outer Mitochondrial Membrane C) Inner Mitochondrial Membrane D) Intermembrane Space

Answer: D Intermembrane Space

Which statement is true regarding mitochondria? A) Mitochondria remain in the same location throughout the life of the cell. B) All cells have roughly the same number of mitochondria. C) Mitochondria never divide or fuse. D) Mitochondria can be either small and round in shape or long continuous tubules.

Answer: D Mitochondria can be either small and round in shape or long continuous tubules.

Which of the following statements is FALSE? A) Asexual reproduction typically gives rise to offspring that are genetically identical. B) Sexual reproduction allows for a wide variety of gene combinations. C) Gametes are specialized sex cells. D) Mutations in somatic cells are passed on to individuals of the next generation.

Answer: D Mutations in somatic cells are passed on to individuals of the next generation.

Which of the following statements about genetic model organism is FALSE? A) Fission yeast mutants were used to study how mitosis is induced B) The study of the fruit fly mutant called "Sevenless) revealed the EGFR/Ras pathway C) Most genetic model organisms have established mutant strains available to any researcher D) No plant is established as genetic model organism

Answer: D No plant is established as genetic model organism

Which of the following statements is true? A) Synaptic vesicles containing neurotransmitters will fuse to the presynaptic membrane when Na+ concentration increases B) The presynaptic membrane has ligand-gated Ca2+ channels C) Transmitting signals at synapses between the presynaptic membrane and post synaptic membrane is medicated by releasing ions from presynaptic membrane D) Opening the Cl- channel in the postsynaptic membrane can antagonize induction of action potential by competing with the opening of a Na+ channel

Answer: D Opening the Cl- channel in the postsynaptic membrane can antagonize induction of action potential by competing with the opening of a Na+ channel

Which of the following statements fits in the blank? "An ionic bond between two atoms, such as NaCl, is formed as a result of the ______? A) sharing of electrons B) loss of electrons from both atoms C) loss of a proton from an atom D) transfer of electrons from one atom to the other

Answer: D Transfer of electrons from one atom to the other

During fertilization in humans, A) a sperm moves in a random fashion until it encounters an egg. B) several sperm pronuclei compete in the cytoplasm to fuse with the egg nucleus. C) only one sperm binds to the unfertilized egg. D) a wave of Ca2+ ions is released in the fertilized egg's cytoplasm.

Answer: D a wave of Ca2+ ions is released in the fertilized egg's cytoplasm.

During sexual reproduction, novel mixtures of alleles are generated. This is because: A) a diploid individual has two different alleles for every gene. B) every gamete produced by a diploid individual has several different alleles of a single gene. C) in all diploid species, two alleles exist for every gene. D) during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene.

Answer: D during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene.

Label these epithelial tissues using the following terms: columnar, cuboidal, squamous. Then identify the yellow layer. Are these tissues stratified or simple?

Answers: A is columnar B is squamous C is cuboidal The yellow layer is the basal lamina These tissues all appear simple - one layer. If they had many layer, they would be stratified.

Indicate whether the following are found in plants, animals, or both: A) Intermediate filaments B) Cells walls C) Microtubules D) Cellulose E) Collagen

Answers: A. Animals B. Plants C. Both D. Plants E. Animals

The endomembrane system is composed of a series of organelles. The _____ separates the nucleus from the cytosol and _____ within it govern import and export of materials to and from the nucleus. The ______ is continuous with the nuclear envelope and is the most extensive membrane system in a eukaryotic cell. The ______ is a system of flattened membranous sacs that can modify proteins and sort vesicles to either the cell surface or to the ______. From there, a transport vesicle containing a protein may then be passed along to the ______ for degradation.

Answers: Nuclear Envelope Nuclear Pores Endoplasmic Reticulum Golgi Apparatus Endosomes Lysosomes