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Cell Biology - Solved Questions for Exam 1 | BIOL 4374, Exams of Cell Biology

University of Houston (UH)Cell Biology

Material Type: Exam; Class: Cell Biology; Subject: (Biology); University: University of Houston; Term: Spring 2014;

Typology: Exams

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Cell$Biology/Cell$Biochemistry:$Exam%#1%
Choose&the&single&best&answer.&
!
1) A!molecule!that!has!both!hydrophobic!and!hydrophilic!regions!is!known!as!___________________.!
!
A. Helical!
B. Lipophobic!
C. Striated!
D. Lipophilic!
E. Amphipathic!
!
2) A!common!laboratory!method!used!to!separate!the!components!of!cells!on!the!basis!of!their!
size!AND!density!is!called!___________________.!
!
A. Differential!centrifugation!
B. Affinity!chromatography!
C. Gel!electrophoresis!
D. A!northern!blot!
E. Sonication!
!
3) A!species!of!fruit!fly!commonly!used!for!studies!of!animal!genetics!and!development!is!called!
____________________.!
!
A. Caenorhabditis!elegans!
B. Saccharomyces!cerevisiae!
C. Drosophila!melanogaster!
D. E.!coli!
E. Arabidopsis!thaliana!
!
4) Something!that!is!soluble!in!water!is!said!to!be!__________________________.!
!
A. Hydrophobic!
B. Hydrophilic!
C. Lipophilic!
D. Lipophobic!
E. B!and!D!
!
5) What!organelles!are!responsible!for!the!synthesis!of!the!majority!of!eukaryotic!cellular!ATP!via!
oxidative!phosphorylation?!
!
A. Peroxisomes!
B. Nuclei!
C. Mitochondria!
D. Lysosomes!
E. Chloroplasts!
!
!
!
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Download Cell Biology - Solved Questions for Exam 1 | BIOL 4374 and more Exams Cell Biology in PDF only on Docsity!

Cell Biology/Cell Biochemistry: Exam

Choose the single best answer.

  1. A molecule that has both hydrophobic and hydrophilic regions is known as ___________________. A. Helical B. Lipophobic C. Striated D. Lipophilic E. Amphipathic
  2. A common laboratory method used to separate the components of cells on the basis of their size AND density is called ___________________. A. Differential centrifugation B. Affinity chromatography C. Gel electrophoresis D. A northern blot E. Sonication
  3. A species of fruit fly commonly used for studies of animal genetics and development is called ____________________. A. Caenorhabditis elegans B. Saccharomyces cerevisiae C. Drosophila melanogaster D. E. coli E. Arabidopsis thaliana
  4. Something that is soluble in water is said to be __________________________. A. Hydrophobic B. Hydrophilic C. Lipophilic D. Lipophobic E. B and D
  5. What organelles are responsible for the synthesis of the majority of eukaryotic cellular ATP via oxidative phosphorylation? A. Peroxisomes B. Nuclei C. Mitochondria D. Lysosomes E. Chloroplasts
  1. The process by which cells harness energy from sunlight and synthesize glucose from CO 2 and water is called _____________________________. A. Differentiation B. Autophagy C. Oxidative phosphorylation D. Photosynthesis E. Cellular respiration
  2. The phospholipid bilayer with associated proteins that surrounds the cell is also known as the _____________________________. A. Cell wall B. Plasma membrane C. Flux capacitor D. Perimeter of defense E. Nuclear envelope
  3. Which model organism most closely resembles the human? A. Mouse B. Yeast C. Bacterium D. Zebrafish E. Arabidopsis
  4. Archaea are more closely related to bacteria than eukaryotes? A. True B. False
  5. By definition, all eukaryotic cells have ______________________? A. a plasma membrane B. DNA C. a nucleus D. emotional issues E. mitochondria
  6. What is a major disadvantage of electron microscopy? A. Samples must be dead. B. Requires expensive equipment. C. Requires great expertise. D. All of the above.
  1. Isotopes of the same element have different numbers of what type of subatomic particle? A. Electrons B. Protons C. Neutrons D. Quarks
  2. Which type of bond is the strongest? A. Ionic B. Hydrogen C. Covalent D. van der Waals
  3. The amino acid histidine is often found in enzymes. Depending on the pH of its environment, sometimes histidine is neutral and at other times it acquires a proton and becomes positively charged. Consider an enzyme with a histidine side chain that is known to have an important role in the function of the enzyme. It is not clear whether this histidine is required in its protonated or its unprotonated state. To answer this question you measure enzyme activity over a range of pH, with the results shown in the figure below. Which form of histidine is necessary for the active enzyme? A. Protonated B. Unprotonated
  4. How do protein, nucleic acid and polysaccharide molecules polymerize (grow)? A. By condensation reactions B. By hydrolysis reactions C. By oxidation reactions
  5. Δ G ° indicates the change in the standard free energy as a reactant is converted to product. Given what you know about these values, which reaction below is the most favorable? A. ADP + Pi → ATP Δ G ° = +7.3 kcal/mole B. glucose 1-­‐phosphate → glucose 6-­‐phosphate Δ G ° = – 1.7 kcal/mole C. glucose + fructose → sucrose Δ G ° = +5.5 kcal/mole D. glucose → CO 2 + H 2 O Δ G ° = – 686 kcal/mole activity (% of maximum) 4 5 6 7 8 9 10 0 100 120 80 60 40 20 pH
  1. The ability of a protein to bind selectively and with high affinity to specific molecules is due to which types of bonds? A. Weak, noncovalent B. Strong, covalent
  2. Why are α helices and β sheets common folding patterns in polypeptides? A. The unique amino acid sequences that generate these folding patterns are common in polypeptides. B. Molecular chaperones tend to fold polypeptides in these common folding patterns. C. Amino acid side chains are not involved in forming the hydrogen bonds, allowing many different sequences to adopt these folding patterns.
  3. Phosphorylation of a protein: A. Increases a protein’s activity. B. Decreases a protein’s activity. C. Can either increase or decrease a protein’s activity.
  4. The nucleotide sequence of one DNA strand of a DNA double helix is 5’-­‐GGATTTCG-­‐3’. What is the sequence of the complementary strand? A. 5’-­‐GGATTTCG-­‐3’ B. 5’-­‐GCTTTAGG-­‐3’ C. 5’-­‐CGAAATCC-­‐3’ D. 5’-­‐CCTAAAGC-­‐3’
  5. Because hydrogen bonds hold the two strands of a DNA molecule together, the strands can be separated without breaking any covalent bonds. Every unique DNA molecule “melts” at a different temperature. In this context, T m, melting temperature, is the point at which two strands separate, or become denatured. Which of the DNA sequences listed below has the highest melting temperature. A. GGCGCACC B. TATTGTCT C. GACTCCTG D. CTAACTGG
  6. The N-­‐terminal tail of histone H3 can be extensively modified, and depending on the number, location, and combination of these modifications, these changes may promote the formation of heterochromatin. What is the result of heterochromatin formation? A. increase in gene expression B. gene silencing C. recruitment of remodeling complexes D. displacement of histone H
  1. How does an allosteric inhibitor affect the active site of an enzyme? A. It binds to the active site, preventing substrate molecules from binding there. B. It binds to a second site, causing a conformational change in the enzyme that makes the active site less accommodating to the substrate.
  2. Which is the more reduced member of the pair below? A B
  3. The graph in the figure below illustrates the relationship between reaction rates and substrate concentration for an enzyme-­‐catalyzed reaction. What does the K m value roughly indicate with respect to enzyme substrate interactions? A. the maximum rate of catalysis B. the number of enzyme active sites C. the enzyme–substrate binding affinity D. the equilibrium rate of catalysis
  4. Which statement is true about the removal of a terminal phosphate from ATP? A. The reaction is a condensation reaction. B. The reaction is associated with a positive change in ΔG°. C. The reaction is energetically favorable. Fe3+ H 2 C CH 2 (i) (C) (D) (B) (A) C C N C C N C CH 2 C C O O O O– O O– H H O O H H H SH +H 3 N H H H CH 2 Fe2+ H 3 C CH 3 (ii) C C N C C N C CH 2 C C O O O O– O O– H H O H H H S +H 3 N H H H CH 2 C C N C C N C CH 2 C C O O O O– O O– H H S H +H 3 N H H H CH 2 K m rate of reaction substrate concentration V max ½ V max
  1. The correct folding of proteins is necessary to maintain healthy cells and tissues. Unfolded proteins are responsible for such neurodegenerative disorders as Alzheimer’s, Huntington’s, and Creutzfeld–Jacob disease (the specific faulty protein is different for each disease). What is the ultimate fate of these disease-­‐causing, unfolded proteins? A. They are degraded. B. They bind a different target protein. C. They form structured filaments. D. They form protein aggregates.
  2. Which of the following compounds is the most flexible? A. B. C.
  3. The Ras protein is a GTPase that functions in many growth-­‐factor signaling pathways. In its active form, with GTP bound, it transmits a downstream signal that leads to cell proliferation; in its inactive form, with GDP bound, the signal is not transmitted. Mutations in the gene for Ras are found in many cancers. Of the choices below, which alteration of Ras activity is most likely to contribute to the uncontrolled growth of cancer cells? A. a change that prevents Ras from being made B. a change that increases the affinity of Ras for GDP C. a change that decreases the affinity of Ras for GTP D. a change that decreases the rate of hydrolysis of GTP by Ras
  4. What is X referring to? A. A-­‐T base pair B. G-­‐C base pair C. deoxyribose D. phosphodiester bonds E. purine base O O O O O O O O O P P O O O O _ O_ O O P O_^ O O O O _ O_ P O O O O _ O^ P P O O O O P O (^) O O_^ O P O (^) O O O _ 5 ¢ end 3 ¢ end 3 ¢ end 5 ¢ end X