3dimensional shape of proteins.
3dimensional shape of proteins.
1. The monomer unit of DNA is:
a. an amino acid
b. a nucleotide
c. a fatty acid
d. glucose
2. Disulfide bridges are a type of covalent bond critical to maintaining the 3dimensional shape of proteins. The amino acid involved in disulfide bridge formation is:
a. tyrosine
b. arginine
c. cysteine
d. glutamic acid
3. Sister chromatids form:
a. during G1
b. during G2
c. during S phase
d. during M phase
4. In a cell containing 10 chromosomes, mitosis results in the formation of daughter cells containing __________ chromosomes.
a. 5
b. 10
c. 20
d. 40
5. Mutant Ras proteins, which are found in many cancer cells, cannot hydrolyze their bound GTP to GDP, and therefore, a. cannot turn themselves on
b. cannot turn themselves off
c. cannot be degraded
6. Checkpoints during the cell cycle process allow cells to:
a. detect DNA damage
b. detect improper spindle formation during mitosis
c. check for unreplicated DNA following DNA synthesis (S phase)
d. all of the above
7. When DNAs from two different organisms are incubated together, some duplexes are formed by DNA strands from the two species. What indicates that such duplexes are less stable than those between strands from the same organism?
(see page 519 of your text for a hint).
a. Heterogeneous duplexes melt at lower temperatures than homogeneous duplexes
b. Heterogeneous duplexes melt at higher temperatures than homogeneous duplexes
c. Heterogeneous duplexes are degraded faster
d. Heterogeneous duplexes are degraded more slowly
e. There is no difference in stability between homogeneous and heterogeneous duplexes
8. Why has the One Gene – One Polypeptide hypothesis had to be modified?
a. Genes can be spliced differently to generate a variety of related polypeptides
b. Enzymes sometimes consist of more than one polypeptide, each of which is coded for by its own gene
c. Enzymes actually code for genes
d. Polypeptides code for genes
9. The first amino acid incorporated into almost all proteins synthesized in eukaryotic cells is a(n) ____________.
a. methionine
b. arginine
c. valine
d. alanine
10. The tails of phospholipids are:
a. hydrophobic
b. hydrophilic
c. amphipathic
11. The organelle(s) in which carbohydrate modifications (glycosylation) of newly synthesized proteins are carried out:
a. nucleus
b. Golgi apparatus
c. lysosomes
d. rough endoplasmic reticulum
e. B and D
f. A and C
12. Multiple RNA transcripts can be generated from a single DNA template.
a. True
b. False
13. Signaling through G coupled proteins leads to a series of intracellular signals.
Choose the letter below that corresponds to the correct order of these signals.
a. activation of protein kinase A (PKA); formation of cyclic AMP (cAMP); activation of adenylyl cyclase
b. formation of cyclic AMP (cAMP); activation of adenylyl cyclase; activation of protein kinase A (PKA)
c. activation of adenylyl cyclase; formation of cyclic AMP (cAMP); activation of protein kinase A (PKA)
14. What is the function of the signal sequence located at the amino terminus of a protein
a. It directs the placement of the RNA on the protein portion of the ribosome.
b. It allows a protein to be directed to the nucleus, where it can function in transcriptional regulation.
c. It allows a protein to be directed and inserted into the endoplasmic reticulum so that it can be secreted by the cell.
15. Lipid bilayers are not permeable to:
a. ions
b. non-polar molecules
c. very small molecules such as CO2
16. Which of the following is not an example of epigenetic inheritance?
a. the inheritance of methylation patterns in DNA
b. the inheritance of a single nucleotide mutation in the DNA
c. the inheritance of patterns of chromosome condensation
17. Which of the following is not a small intracellular signaling molecule (second messenger)?
a. cyclic AMP
b. phospholipase C
c. inositol triphosphate
d. diacylgylcerol
18. DNA replication results in:
a. Two DNA molecules, one with 2 old strands, one with 2 new strands
b. Two DNA molecules, each of which has 2 new strands
c. Two DNA molecules, each of which has 1 new strand and 1 old strand
19. Introns:
a. represent DNA sequences of a gene that are translated into protein
b. represent DNA sequences of a gene that are not translated into protein
c. are found more frequently in eukaryotes than bacteria
d. are found more frequently in bacteria than in eukaryotes
e. a and c
f. b and c
20. The correct order of mitosis is:
a. Metaphase, prophase, telophase, anaphase
b. Prophase, metaphase, anaphase, telophase
c. Anaphase, telophase, metaphase, prophase
d. None of the above
