AP Bio Unit 6 DNA and Gene expression review
34. Since Watson and Crick described DNA in 1953, what best explains why the function of small RNAs is still being explained?
Changes in technology as well as our ability to determine how much of the DNA is expressed have now made this possible.
A frameshift mutation results from what? A) a base deletion only. B) a base substitution only. C) deletion of three consecutive bases. D) either an insertion or a deletion of a base.
D
A strand of DNA that is AGCCTTA will bond with which RNA? A.TCGGAAT TCGGUUT UGCCUUA D.UCGGAAU
D
Mutations in which set of genes(special type of genes that regulate body parts)lead to transformations in the identity of entire body parts? A) morphogens B) segmentation genes C) egg-polarity genes D) homeotic genes
D
Regulatory genes produce proteins called ________________. A) operon B) inducer C) promoter D) repressor
D
Transcription in eukaryotes requires what other molecules besides RNA polymerase to begin? A) the protein product of the promoter B) start and stop codons C) ribosomes and tRNA D) several transcription factors
D
Why can a new DNA strand elongates only in the 5' to 3' direction? A) Okazaki fragments prevent elongation in the 3' to 5' direction. B) the polarity of the DNA molecule prevents addition of nucleotides at the 3' end. C) replication must progress toward the replication fork. D) DNA polymerase can only add nucleotides to the free 3' end.
D
10. If a cell were unable to produce histone proteins, how would this affect the DNA? A) There would be an increase in the amount of "satellite" DNA produced during centrifugation. B) The cell's DNA couldn't be packed into its nucleus. C) Spindle fibers would not form during prophase. D) Amplification of other genes would compensate for the lack of histones.
B
Allolactose, an isomer of lactose, is formed in small amounts from lactose. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. What does the lactose do when it enters the cell? Hint: Remember Lac operon A) The repressor protein attaches to the regulator. B) Allolactose binds to the repressor protein. C) Allolactose binds to the regulator gene. D) The repressor protein and allolactose bind to RNA polymerase.
B
Alternative RNA splicing is defined as? A) is a mechanism for increasing the rate of transcription. B) can allow the production of proteins of different sizes and functions from a single mRNA. C) can allow the production of similar proteins from different RNAs. D) increases the rate of transcription.
B
If a newly made polypeptide is to be secreted from a cell, what must occur before it is secreted? A) It must be translated by a ribosome that remains free of attachment to the ER. B) Its signal sequence must target it to the ER, after which it goes to the Golgi. C) Its signal sequence must be cleaved off before the polypeptide can enter the ER. D) Its signal sequence must target it to the plasma membrane, where it causes exocytosis.
B
If a researcher could decrease methylation of histone tails what affect would this have on the chromatin that surrounds it. A) increased chromatin condensation B) decreased chromatin condensation C) activation of histone tails for enzymatic function D) decreased binding of transcription factors
B
How is eukaryotic gene expression regulated that requires additions to the mRNA? A) mRNA, tRNA, and rRNA are transcribed. B) RNA polymerase binds to the promoter. C) A poly-A tail is added to the 3' end of an mRNA and a cap is added to the 5' end. D) Transcription can begin as soon as translation has begun even a little.
C
If you were to observe the activity of methylated DNA, you would expect it to have what effect? A) be replicating nearly continuously. B) be unwinding in preparation for protein synthesis. C) have turned off or slowed down the process of transcription. D) be very actively transcribed and translated.
C
What is the effect of a nonsense mutation in a gene? A) It changes an amino acid in the encoded protein. B) It has no effect on the amino acid sequence of the encoded protein. C) It introduces a premature stop codon into the mRNA. D) It alters the reading frame of the mRNA.
C
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? A) It synthesizes RNA nucleotides to make a primer. B) It catalyzes the lengthening of telomeres. C) It joins Okazaki fragments together. D) It unwinds the parental double helix.
C
41. Embryonic stem cells are better to use than adult stem cells. What makes them so special?
41. Embryonic stem cells are better to use than adult stem cells. What makes them so special?
What is the function of topoisomerase? A) relieving strain in the DNA ahead of the replication fork B) elongating new DNA at a replication fork by adding nucleotides to the existing chain C) adding methyl groups to bases of DNA D) unwinding of the double helix
A
What is the significance of the TATA box in eukaryotic promoters? A) It is the recognition site for a specific transcription factor. B) It sets the reading frame of the mRNA. C) It prevents supercoiling of the DNA near the start site. D) It is the recognition site for ribosomal binding.
A
Cytosine, adenine, guanine and thymine are always in specific proportions. Please explain.
A always combines with T C always combines with G
43. What is product of the lytic cycle?
A large number of phages are released at a time.
22. What happens when the wrong amino acid is added in a polypeptide chain?
A protein may not be functional or may create a mutated protein
5. Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction?
DNA Polymerase III
49. How are plasmids (DNA) different than proteins in structure? Come up with a list to compare - here are a few things
DNA Proteins Made of nucleotides made of amino acids Sugar base and phosphate primary, secondary Double stranded tertiary and quartenary Helical structure in euk made from DNA Circular structure in prok
What is meant by the description "antiparallel" regarding the strands that make up DNA?
DNA is double stranded, one side runs from the 5' end of a sugar to the 3' and the other runs the opposite direction - they connect with hydrogen bonds
37. Genomic imprinting, DNA methylation, and histone acetylation are all examples of what term that explains how expression of our traits goes above and beyond what our DNA code actually says?
Epigenetics
29. The tryptophan operon is a repressible operon which means what?
It is always on unless it becomes repressed when tryptophan is in excess it will bind to the operator and cause a conformational change in the operator region on the DNA and it will TURN OFF the making of the enzymes which produce tryptophan
50. Why do you need a promoter (origin of replication) sequence to make a transformed bacteria.
It is the starting place for binding of Polymerase which starts the replication process or making of RNA
After mixing a heat-killed, phosphorescent (light-emitting) strain of bacteria with a living, nonphosphorescent strain, you discover that some of the living cells are now phosphorescent. How can this be explained?
Just like in Griffith's experiment there was a transformation.
14. What evidence that RNA probably evolved before DNA?
RNA acts as a primer to MAKE DNA, without it no DNA would get copied
15. What causes the termination of transcription in prokaryotes?
RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.
11. What affects the RATE DNA fragment moves through a gel during electrophoresis?
The SIZE of the DNA LARGER is slower
44. The lysogenic cycle of a viral phage often doesn't immediately express the virus, how does the lysogenic cycle work compared to the lytic cycle?
The phage genome replicates along with the host genome.
In his transformation experiments, what did Griffith observe?
Transforming factor DNA from heat killed Inserted itself into living Nonpathogenic strain
45. Vaccines are used to stop the onset of what type of infection in humans?
Viruses
42. The first cloned cat, called Carbon Copy, was a calico, but she looked significantly different from her female parent. What is special about how CALICO cats express their genes?
X inactivation in the embryo is random and produces different patterns.
19. In order for a eukaryotic gene to be engineered into a bacterial colony what must be included in addition to the coding region of the gene?
a bacterial promoter sequence
26. Which type of small-scale mutation would be most likely to have a catastrophic effect on the functioning of a protein at the very start of the gene?
a base deletion
13. How does a bacterial cell protect its own DNA from restriction enzymes?
by adding methyl groups to adenines and cytosines
32. What would occur if the repressor of an inducible operon were mutated so it could not bind the operator?
continuous transcription of the operon's genes
12) Assume that you are trying to insert a gene into a plasmid. Someone gives you a preparation of genomic DNA that has been cut with restriction enzyme X. The gene you wish to insert has sites on both ends for cutting by restriction enzyme Y. You have a plasmid with a single site for Y, but not for X. How can you do this?
cut the DNA again with restriction enzyme Y and insert these fragments into the plasmid cut with the same enzyme.
40. In 1997, Dolly the sheep was cloned. What was the first step in the process of cloning the sheep?
fusion of an adult cell's nucleus with an unnucleated sheep egg, followed by incubation in a surrogate
20. A eukaryotic transcription unit has several nucleotides that don't code for the protein. Explain what these other nucleotides are for.
many noncoding stretches of nucleotides are present in eukaryotic DNA and may actually code for all types of RNA's rather that proteins.
