1. What problem is encountered in replicating DNA at the ends of chromosomes (telomeres)?
  2. Usually exhaust supply of NTPs before the ends of the chromosomes are reached.
  3. Run out of template to prime DNA synthesis on the lagging strand
  4. Overshoot the ends in the synthesis of the leading strand
  1. What is the difference between DNA polymerase proofreading and excision repair?
  2. Proof reading happens during DNA synthesis
  3. Proof reading generally replaces a single mismatched base
  4. Excision repair may excise a segment of damaged DNA
  5. All of the above
  1. Recently scientists have developed two new bases that can be incorporated into DNA and that base pair with each other – bringing the total number of DNA bases to six. If a new code was developed for such DNA, how many bases would be needed in a codon to code for all 20 amino acids?
  2. One (a singlet)
  3. Two (a doublet)
  4. Three (a triplet)
  5. Four (a quadruplet)
  1. What type of mutation does this represent?
  1. Frameshift
  2. Missense
  3. Nonsense
  4. Silent
  1. Sigma
  2. Is a regulatory subunit of prokaryotic RNA polymerase
  3. Makes the initial contact with the promoter during the initiation of transcription
  4. Binds to the -35 and -10 boxes in bacterial promoters
  5. All of the above
  1. There are as many different aminoacyl tRNA synthetases as there are different tRNAs.
  2. True
  3. False
  1. The first aminoacyl tRNA initiating protein synthesis
  2. Is usually an alanine tRNA
  3. Enters at the acceptor (A) site
  4. Is placed at the peptidyl (P) site
  5. Binds to the large ribosome subunit and not the mRNA
  1. The first aminoacyl tRNA initiating protein synthesis
  2. Is usually an alanine tRNA
  3. Enters at the acceptor (A) site
  4. Is placed at the peptidyl (P) site
  5. Binds to the large ribosome subunit and not the mRNA
  1. A peptide bond is formed between the growing polypeptide on the tRNA at the ……… and the amino acid on the incoming aminoacyl-tRNA at the ……..
  2. E site, P site
  3. A site, P site
  4. A site, E site
  5. P site, A site
  1. What would be the characteristics of a lacI- (loss of function) mutant?
  2. b-galactosidase would not be produced in the presence of lactose
  3. b-galactosidase would be produced even in the absence of lactose
  4. b-galactosidase would not be produced in the presence or absence of lactose
  1. To what DNA element does the lac repressor bind in the absence of lactose?
  2. b-galactosidase gene (lacZ)
  3. lac promoter
  4. lac operator
  5. All of the above
  1. How does the lac repressor prevent the expression of the lacZ and lacY genes? By …..
  2. Breaking down lactose
  3. Blocking transcription of the lac operon
  4. Interfering with the translation of bgalactosidase mRNA
  5. Why do eukaryotes have more transcription factors (regulatory subunits) than prokaryotes?
  6. Because there is a different RNA polymerase for each gene
  7. Because eukaryotic genes are bigger
  8. Because eukaryotes have more genes that are controlled differently
  9. All of the above
  1. A G protein-linked receptor has been activated by a hormone. What is the likely downstream signaling event that transduces the signal?
  2. Importation of the receptor into the nucleus
  3. Activation of a protein phosphorylation cascade
  4. Production of cyclic AMP (cAMP)
  5. All of the above
  1. Within an organism, what makes one cell type different from another?
  2. Each cell type expresses different genes
  3. Each cell type inherits different genes
  4. Each cell type discards different genes
  5. Each gene codes different proteins in different cells.
  1. What makes each insect body segment different from another?
  2. Each inherits different genes
  3. Each expresses different genes
  4. Each discards different genes
  5. Each gene codes different proteins in different segments
  1. What group of proteins plays a key role in controlling the program of developmental changes?
  2. Motor proteins
  3. Transporter proteins
  4. Transcription factors
  5. Cyclin dependent kinases
  6. Restriction endonucleases
  1. Which of the following contribute to the resting potential of a neuron?
  1. Bulk flow
  2. Voltage-gated Cl- channels
  3. Ungated ion specific “leak” channels
  4. Anions in the cytoplasm
  5. Na+/K+ pump
  6. Ligand-gated Na+ channels
  1. 2 and 3
  2. 1, 2, 5
  3. 3, 4, 5
  4. 4, 5, 6
  5. 1, 4, 5
  6. 2, 5, 6
  1. In rod cells of the vertebrate eye, when retinal has not been activated by light, _.
  2. phosphodiesterase enzymes are active
  3. sodium channels in the rod’s plasma membrane are open
  4. cyclic guanosine monophosphate (cGMP) levels are low
  5. sodium channels in the rod’s plasma membrane are closed
  1. What is the name of the cellular process that generates haploid gametes, such as eggs and sperm?
  2. Mitosis
  3. Cytokinesis
  4. Spindle formation
  5. Meiosis
  6. Diplogenesis