BIOCH200 Lecture Notes - Lecture 1: Pyrimidine, Purine, Energy
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13. The arms of a human and the wing of a bat are _________________ structures, composed of the same bones that have been modified for different functions.
a. | analogous |
b. | vestigial |
c. | homologous |
d. | convergent |
14. Xeroderma pigmentosum is an autosomal recessive genetic disorder. People who are homozygous for the disease-causing allele have skin that is damaged by exposure to ultraviolet radiation; this can lead to skin cancer at an early age. The mutation that causes this disorder is in a gene that functions:
a. | to repair DNA by excising (removing) nucleotides damaged by UV light. |
b. | in lysosomes, to break down lipids that otherwise accumulate in the nervous system. |
c. | to produce the UV blocking pigment melanin in the skin cells |
d. | in red blood cells to carry oxygen to the skin. |
15. The Amish are a religious sect descended from a small group of colonists who came to the United States over 200 years ago. Their religious beliefs have kept them isolated from society. The Amish have a much higher than average incidence of both polydactyly (extra fingers and toes) and dwarfism in their communities. This is most likely explained by:
a. | inheritance of acquired characters. |
b. | the founder effect. |
c. | disruptive selection. |
d. | natural selection. |
16. In the structure of DNA that Watson and Crick proposed, the sides of the "ladder" of the DNA molecule are always the same distance apart, making the molecule a constant width. This occurs because when the bases hydrogen bond to form the rungs of the "ladder", a:
a. | purine always pairs with a pyrimidine. |
b. | purine always pairs with a purine. |
c. | pyrimidine always pairs with a pyrmidine. |
d. | The structure of the double helix is not determined by how the bases pair. |
17. The RNA transcript of DNA that travels to the cytoplasm, carrying the instructions to make a protein, is called:
a. | rRNA. |
b. | tRNA. |
c. | mRNA. |
d. | RNA polymerase. |
18. When DNA is replicated, the error rate is approximately one error for every 10,000 nucleotides copied. However, that error rate is reduced to only 1 error for every 1 billion nucleotides. The DNA sequence is "corrected" by:
a. | repeating S phase to see if the error rate is lower the second time around. |
b. | enzymes that proofread the DNA and repair errors. |
c. | messenger RNA during the process of transcription. |
d. | Any errors made during DNA replication cannot be corrected. If errors are detected after S phase, the cell is destroyed. |
19. Mendel's principle of segregation says that:
a. | when gametes are formed, each gamete receives only one allele for a particular gene. |
b. | some genes are dominant to others. |
c. | a testcross must be used to determine the genotype of an organism with a dominant phenotype. |
d. | all of the above |
20. Tay-Sachs disease is lethal before reproductive age, but the allele persists in Louisiana French Canadians because:
a. | it is a dominant allele. |
b. | new mutations causing this disease are common in that population. |
c. | it is not expressed in the phenotype of heterozygous individuals. |
d. | the disease is contagious and can be transmitted by nonheritable means. |
21. Physical features that are similar in organisms which are not closely related to each other are most likely a result of ____________. A good example of this is the similarities seen between some marsupial and placental mammals.
a. | natural selection. |
b. | adaptation to similar environments |
c. | convergent evolution |
d. | All of the above phrases can be used to correctly fill this blank. |
22. In humans, which of the following sex chromosome compliments could be found in males?
a. | XY |
b. | XX |
c. | Y |
23. The proteins that are associated with eukaryotic chromosomes:
a. | help to package the DNA within the nucleus. |
b. | are involved in gene expression, through binding with the DNA. |
c. | may be replicating or transcribing the DNA. |
d. | All of these are true of proteins that are associated with eukaryotic chromosomes. |
24. A sequence of DNA nucleotides that contains the information to produce a single protein is a(n):
a. | codon. |
b. | gene. |
c. | polypeptide. |
d. | anticodon. |
1. | In addition to identifying the genetic material, the experiments of Avery, MacLeod, and McCarty with different strains of Streptococcus pneumoniae demonstrated that | ||||||||||
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2. | In order to show that DNA in cell extracts is responsible for genetic transformation in Streptococcus pneumoniae, important corroborating evidence should indicate that _______ also destroy transforming activity. | ||||||||||
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3. | Based on what you have learned about the experiments conducted by Griffith and Avery and colleagues with bacteria, which of the following would result in transformation of living R cells? | ||||||||||
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4. | A-T base pairs in a DNA double helix | ||||||||||
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5. | If 23 percent of the bases in a sample of double-stranded DNA are adenine, what percentage of the bases are uracil? | ||||||||||
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6. | The uniform diameter of the DNA structure provides evidence for | ||||||||||
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7. | If a sequence of one strand of DNA is 5â²-TGACTATC-3â², what is the complementary strand? | ||||||||||
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8. | What structural aspect of the DNA facilitates dissociation of the two DNA strands for replication? | ||||||||||
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9. | If the MeselsonâStahl density gradient experiment had resulted in two bands of DNA molecules after only one round of replication, one containing only 15N and the second only 14N, this result would have indicated that replication was | ||||||||||
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10. | The nucleoside analogue acyclovir, which is used to treat herpes simplex virus (HSV) infections, lacks a 3â² hydroxyl group (âOH). Predict what will happen if the host cell DNA polymerase incorporates a molecule of acyclovir into an elongating strand of HSV DNA. | ||||||||||
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11. | Which of the following does not demonstrate the stability of the DNA double helix? | ||||||||||
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12. | What effect would a primase inhibitor have on DNA replication? | ||||||||||
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13. | To replicate their DNA in a timely manner, most eukaryotic chromosomes | ||||||||||
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14. | Which statement about DNA replication is false? | ||||||||||
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15. | In many eukaryotes, there are repetitive sequences called telomeres at the ends of chromosomes. After successive rounds of DNA replication, the _______ strand becomes shorter. In some cells, an enzyme called _______ repairs the shortened strand. | ||||||||||
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16. | A researcher studies normal human fibroblast cells. They can be maintained in culture but die off after about 30 cell generations. Unexpectedly, a colony of cells continues to survive and divide past 30 generations. Which scenario is most likely true for these cells? | ||||||||||
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17. | If DNA polymerase III introduces an incorrect nucleotide, what is the first corrective action made by the DNA repair system? | ||||||||||
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18. | Choose the correct order of the following four events in the excision repair of DNA: (1) Base-paired DNA is made complementary to the template. (2) Damaged bases are recognized. (3) DNA ligase seals the new strand to existing DNA. (4) Part of a single strand is excised. | ||||||||||
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19. | Six complete cycles of PCR should result in a _______-fold increase in the amount of DNA. | ||||||||||
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20. | When double-stranded DNA is heated to temperatures above 90°C, it denatures. Denaturation is a process that | ||||||||||
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Multiple answers to each question might be possible!
You decide to identify the CFTR mutation by analyzing the genomic DNA of your patients compared to healthy individuals. You specifically are looking to see whether a specific 3' gene truncation has occurred in the patients. You will determine this using hybridization techniques with samples from healthy and CF patients. Which of the following will allow you to accomplish this?
Using an RNA probe complementary to the region not removed by the truncation. | |
Using an RNA probe complementary to the region removed by the truncation. | |
Using an DNA probe complementary to the region not removed by the truncation. | |
Using an DNA probe complementary to the region removed by the truncation. |
To conduct the hybridization experiment, you are trying to decide between using a DNA or RNA probe. Which would be ideal to use and why?
As both are composed of nucleic acids, using either would result in identical results. | |
An RNA probe because RNA has uracil bases. | |
An RNA probe because it could also be used in a translation experiment. | |
A DNA probe because it is more stable than RNA. | |
A DNA probe because RNA cannot bind to DNA. |
One step of the Hershey/Chase experiment involved blending the virus/cell mixture before centrifugation and probing the pellet for radioactivity. Why was the blending step necessary?
To collect the bacteria at the bottom of the tube. | |
To break open the bacteria to release the genome. | |
To separate the bacteria from the bacteriophages. | |
To be able to detect the radioactivity. |
Imagine Hershey/Chase had used an RNA virus (genome composed of RNA) instead of a DNA virus in their experiment. Would radioactivity still have been found in the pellet?
No, because only DNA can be labeled with radioactivity. | |
No, because the RNA genome would not enter the bacteria upon infection. | |
No, because while DNA and RNA nucleotides are similar, they are not identical. | |
Yes, because DNA and RNA nucleotides are similar. | |
Yes, because genome in any form (DNA, RNA, protein) would be labeled similarly. |
The human genome consists mostly of non-coding DNA. Which of the following are benefits of this?
Random DNA mutations generally won't affect RNA and protein function. | |
It is faster to duplicate the genome when these are present. | |
The existence of introns can lead to multiple variations of proteins encoded by a single gene. | |
It is unlikely transposons would exist in the genome if there was too much protein coding DNA. |
Explain the 5â to 3â directionality of a DNA stand.
It is due to the fact that the free 5â carbon is on one end and the free 3â carbon is on the other | |
It is due to the fact that new nucleotide are added to the 5â carbon of the previous nucleotide | |
It is due to the fact that there are 3 phosphate groups attached to the 5â carbon | |
It is due to the fact the complementary strand is 3â to 5â | |
More than one of the above explain the 5â to 3â directionality |
You accidentally add a mutant dNTP (which has an H instead of an OH connected to the 3â carbon) to a reaction where DNA is being replicated. Which of the following is true of this mutant dNTP?
It can be incorporated into DNA strand but cannot form a phosphodiester bond with an incoming wild type dNTP | |
It can be incorporated into a DNA strand but cannot base pair with a complementary nucleotide | |
It can be incorporated into a DNA strand and can form a phosphodiester bond with an incoming dNTP, but only if it is another mutant dNTP | |
It cannot be incorporated into a DNA strand. |
Why does DNA polymerase utilize an RNA primer?
DNA polymerase is unable to initiate strand synthesis but RNA polymerase can | |
DNA polymerase can only add a dNTP to an rNTP | |
DNA synthesis proceeds in the 3â to 5â when initiating strand synthesis | |
Chromosomal DNA contains interspersed RNA fragments | |
The RNA primer increases stability of the newly synthesized strand |