Test 3 Flashcards
In the context of early studies of molecular biolofy performed to decipher the properties and the identity of the genetic material, Griffith et al. demonstrated which of the following?
A. The property of transformation or uptake of genetic material in bacteria
B. The chemical nature of the transforming material in bacteria
C. The chemical nature of the genetic material in T2 bacteriophage
D. All of the above are correct
E. A. and B.
A. The property of transformation or uptake of genetic material in bacteria
A nucleoside is defined as ? A. A sugar linked to a base B. A sugar linked to a phosphate group C. A base linked to a phosphate group D. A sugar linked to a base linked to a phosphate group E. None of the above
A. A sugar linked to a base
At the replication fork, _____ catalyzes the synthesis of DNA.
DNA polymerase
Ahead of the replication fork, ____ diminishes the tension that is created as the double helix supercoils.
Gyrase
______ is complexed with helicase and creates short RNA primers
Primase
_____ breaks the hydogen bonds between the bases at the replication fork
Helicase
The replication of DNA proceeds in what direction? A. 3' to 5' B. 5' to 5' C. 3' to 3' D. 5' to 3' E. None of the above
D. 5’ to 3’
Eukaryotic cells use the same DNA polymerase to replicate mitochondrial DNA and nuclear DNA. A. True B. false C. Sometimes D. Unknown
B. false
In the context of DNA recombination, crossing over takes place:
A. Before DNA synthesis, resulting in all the products that are recombinants
B. During DNA synthesis, resulting in products that are recombinant and nonrecombinant
C. After synthesis, resulting in products that are recombinant and nonrecombinant
D. B. and C.
E. All of the above
C. After synthesis, resulting in products that are recombinant and nonrecombinant
Eukaryotic chromosomes require an RNA primer to initiate all new DNA synthesis. However, this poses a problem’, eukaryotes have unique features at the end of their ____ chomosomes called telomeres that recruit a specialized DNA polymerase called telomerase. Telomerase is composed of both protein and ____ that extends the ends of the chomosome, thus solving the ‘end replication problem’.
Linear
RNA
Acetylation of the histone proteins would have which effect on its interaction with DNA?
A. The DNA would bind more tightly to the histones
B. The DNA would loosen its interaction with the histones
C. The DNA would become more accessible
D. The DNA would become less accessible
E. B. and C.
E. B. and C.
Methylation of the histone proteins would have which effect on its interaction with DNA?
A. The DNA would bind more tightly to the histones
B. The DNA would loosen its interaction with the histones
C. The DNA would become more accessible
D. The DNA would become less accessible
E. B. and C.
D. The DNA would become less accessible
Deacetylation of the histone proteins would have which effect on its interaction with DNA?
A. The DNA would bind more tightly to the histones
B. The DNA would loosen its interaction with the histones
C. The DNA would become more accessible
D. The DNA would become less accessible
E. A. and D.
E. A. and D.
In the context of eukaryotic transcription, there are several proteins that come together to form the ‘basal transcription apparatus’. What is the role of the basal transcription machinery?
A. To recognize the transcription start site
B. To bind to the TATA box with the promoter
C. To stabilize the interaction between the proteins and the DNA
D. To unwind the DNA so that it may be used as a template
E. All of the above
E. All of the above
There is one profound difference between replication and transcription that reflects the different purposes served by these distinct molecular processes - what is it?
A. Transcription selectively copies certain parts of the genome
B. Replication selectively copies certain parts of the genome
C. Transcription randomly copies certain parts of the genome
D. Replication randomly copies certain parts of the genome
E. There are no difference between replication and transcription.
A. Transcription selectively copies certain parts of the genome
Which of the following is not required for transcription?
A. Ribonucleotides B. RNA primers C. DNA template D. RNA polymerase E. All of the above are required
B. RNA primers
Bacterial cells posses one RNA polymerase that is a large, multimeric enzyme composed of five subunits that make up the core enzyme. What is the role of the subunit called sigma factor (σ)? A, Promiscuity B. Selectivity C. Precision D. Specificity E. None of the above
D. Specificity
In prokaryotes, rho-independant transcription termination depends on a secondary structure formed in - ?
A. The RNA polymerase that is transcribing the gene
B. The DNA template
C. The RNA that is being transcribed
D. A protein factor that binds to RNA polymerase
E. A protein factor that binds to the RNA that is being transcribed
C. The RNA that is being transcribed
Which of the following human cells contain a gene that specifies eye color?
A. Cells in the eye B. Cells in the heart C. Gametes D. Cells in the eye and gametes E. All of the above
E. All of the above
How many copies of the H1 histone protein would be found in chromatin containing 60 nucleosomes?
A. 15 B. 30 C. 60 D. 120 E. 240
C. 60
_____ undergoes the normal process of condensation and decondensation in the cell cycle, represents the majority of chomosomal material, is where most transcription takes place, and is considered to be ‘active DNA’.
A. Heterochromatin
B. Euchromatin
C. All chromatin
D. None of the above
B. Euchromatin
Suppose that a single DNA base change of an A to a T occurs and is copied during replication. Is this change necessarily a mutation?
A. Yes, it is a change in the DNA sequence.
B. Yes, if the base change occurs in a gamete (sperm or egg cell); otherwise no.
C. Yes, if the base change occurs in the coding part of a gene; otherwise no.
D. Yes, if the base change occurs in the coding part of a gene and alters the amino acid sequence of a protein; otherwise no.
E. Yes, if the base change alters the appearance of the organism (phenotype); otherwise
no.
A. Yes, it is a change in the DNA sequence.
In a population of genetically identical mice, you discover two independent mutant strains in which all of the animals have epileptic seizures. In both strains, you know that the epileptic seizures are due to a single DNA mutation. You cross a mutant mouse from one strain to a mutant mouse from the second strain and find out that none of their offspring undergo spontaneous seizures. From this experiment you would conclude that the two mutant strains of mice most likely have mutations in:
A. the same DNA base (A, T, C, or G) within a particular gene.
B. the same gene, but not necessarily the same DNA base.
C. Two different genes.
C. Two different genes.
The MLH1 gene is important in colorectal cancer. This gene is located on chromosome 3, and four different alleles of the gene have been identified in humans. The maximum number of alleles a single normal individual can have is: A. 1 B. 2 C. 3 D. 4
B. 2
Use the following mRNA codon key as needed to answer the next two questions: GCC Alanine AAU Asparagine CCU Proline GGA Glycine UGG Tryptophan UGA “Stop” (no amino acid) GAA Glutamic acid GAG Glutamic acid AGG Arginine CCC Proline CAU Histidine
The following DNA sequence (coding strand) occurs near the middle of the coding region of a gene.
DNA
50 55 60 65
5’—A A T G A A T G G G A G C C T G A A G G A G –-3’
The corresponding mRNA sequence is shown below. Note that the coding strand of DNA has the same sequence as the mRNA, except that there are U’s in the mRNA where there are T’s in the DNA. The first triplet of nucleotides AAU (underlined) is in frame for coding, and encodes Asparagine as the codon table above indicates.
mRNA
50 55 60 65
5’—A A U G A A U G G G A G C C U G A A G G A G –-3’
Which of the following DNA mutations is almost certain to result in a shorter than normal mRNA?
a) A→G at position 50 b) G→A at position 53 c) C→A at position 58 d) None of the above
d) None of the above
For the same DNA sequence, which of the following DNA mutations is almost certain to result in a shorter than normal protein?
a) T→C at position 59 b) A→G at position 61 c) Insertion of a G after the G at position 54 d) None of the above
c) Insertion of a G after the G at position 54
You have identified a previously unknown human gene that appears to have a role in autism. It is similar enough in DNA sequence to a known mouse gene that you believe the two genes may be evolutionarily related. You determine and compare the DNA sequences, the predicted mRNA sequences, and the predicted amino acid sequences corresponding to the two genes. You would expect to find the greatest sequence similarity from comparisons of the two:
a) DNA sequences.
b) mRNA sequences.
c) amino acid sequences.
d) All three comparisons are likely to show the same degree of sequence similarity.
c) amino acid sequences.
You are interested in studying a gene called CFTR because mutations in this gene in humans cause cystic fibrosis. You have made a line of mice that lack the mouse CFTR gene. These mice are unable to clear bacteria from their lungs, so they get lung disease. You put a normal human CFTR gene into some of these mice and discover that the mice with the human gene are able to clear bacteria from their lungs and no longer get lung disease. From this experiment, you can conclude that:
a) The DNA sequences of the mouse CFTR gene and human CFTR gene are identical.
b) The amino acid sequences of the mouse CFTR protein and the human CFTR protein are identical.
c) The mouse CFTR gene and human CFTR gene both encode proteins that are similar in function.
d) Both answers b) and c)
e) All of the above
c) The mouse CFTR gene and human CFTR gene both encode proteins that are similar in function.
A collection of clones containing DNA fragments that have been produced by reverse transcription of cellular mRNA
cDNA library
An ordered set of DNA fragments fixed to a solid support, which serve as probes to detect the presence of complimentary sequences; often used to assess the expression of genes in various tissues and under different conditions.
microarray
A collection of clones containing DNA fragments that consist of an entire genome of an organism
Genomic library
The molecular genetic technique by which a short DNA or RNA sequence is amplified by means of oligonucleotide primers used in repeated cycles of in vitro DNA synthesis
PCR
The molecular genetic technique by which DNA is transferred to a membrane and hybridized with gene-specific probes to detect a specific DNA amongst a heterogeneous mixture of DNA
Southern blot
If a DNA molecule is 40% cytosine (C) what is the percentage of guanine (G)?
A. 20% B. 40% C. 60% D. 80% E. unknown
B. 40%
If a DNA molecule of 80 base pairs contains 45 adenosine bases (A), how many guanine (G) bases will it have?
A. 15 B. 35 C. 45 D. 90 E. unknown
B. 35
Which of the following statements below does not accuratley describe a difference between DNA and RNA?
A. RNA molecules are usually single-stranded
B. The bases in RNA contain uracil instead of thymine
C. The sugar in RNA is deoxyribose instead of ribose
D. RNA molecules often take on secondary or tertiary structures for proper function
E. All of the above
C. The sugar in RNA is deoxyribose instead of ribose
siRNAs and miRNAs are needed in which process?
A. Transcription B. Translation C. Replication D. RNA splicing E. RNA interference
E. RNA interference
