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1-20: Chapter 13 - DNA; 21-
In his transformation experiments, which of the following did Griffith observe?
Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.
Which of the following statements correctly describes one of Chargaff’s rules regarding DNA?
The percentages of adenine and thymine are roughly equal, as are the percentages of guanine and cytosine in the DNA of a given species.
Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in the sample will be thymine?
8%
Which of the following characteristics of the structure of DNA was determined directly from X-ray diffraction photographs of crystallized DNA?
The double helical structure
What is meant by the description “antiparallel” regarding the two strands of nucleic acids that make up DNA?
The 5’ to 3’ direction of one strand runs counter to the 5’ to 3’ direction of the other strand
Which of the following statements correctly describes one characteristic of DNA replication in eukaryotes?
In the lagging strand, DNA is replicated in short pieces called Okazaki fragments, which are then joined together at the end of the process.
Which of the following statements correctly describes how the leading and lagging strands of DNA formed during DNA replication differ?
The leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction.
What is the function of topoimerase
Relieving strain in the DNA ahead of the replication fork.
What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?
It joins Okazaki fragments together
Which of the following molecule(s) help(s) to hold the DNA strands apart while being replicated?
single-strand binding proteins
During DNA replication, which of the following enzymes separates the DNA strands during replication?
helicase
During DNA replication, which of the following enzymes covalently connects segments of DNA?
ligase
Which of the following mechanisms removes nucleotides that are paired incorrectly during DNA replication?
mismatch repair
In a linear eukaryotic chromatin sample, which of the following strands is looped into nucleosomes?
DNA without attached histones
Which of the following statements best describes the eukaryotic chromosomes?
It consists of a single linear molecule of double-stranded DNA plus proteins
If a cell were unable to produce histone proteins, which of the following effects would likely occur?
The cell’s DNA couldn’t be packed into it’s nucleus
Which of the following lists of structures correctly represents the order of increasingly higher levels of organization of chromatin?
NUCLEOsome, 30-NM CHROmatin fiber, LOOPed domain.
What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized
DNA polymerase can join new nucleotides only to the 3’ of a preexisting strand
In a nucleosome, the DNA is wrapped around
histones
The elongation of the leading strand during DNA synthesis
depends on the action of DNA polymerase
Which of the following statements correctly defines the process of gene expression?
Gene expression is the process by which DNA directs the synthesis of proteins
The nitrogenous base adenine is found in all members of which of the following groups of molecules?
ATP, RNA, and DNA
A particular triplet of bases in the template strand of DNA is 5’-AGT-3. The corresponding codon for the mRNA is transcribed as
UCA
Which of the following is not true of a codon?
It extends from one end of a tRNA molecule
The genetic code is essentially the same for all organisms. Based on this information, one can logically assume which of the following statements to be correct?
A gene from an organism can theoretically be expressed by any other organism
Which of the following statements best describes the termination of transcription in bacteria?
RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.
Which of the following processes only occurs in eukaryotic gene expression?
A poly-A tail is added to the 3’ end of an mRNA, and a cap is added to the 5’ end
Which of the following statements best describes the function of the TATA box in eukaryotic promoters?
It is the recognition site for a specific transcription factor.
A eukaryotic mutation upstream of a particular gene has been identified that changes the sequence of the TATA box to GATA. How would you predict the mutation would affect the transcription of this gene?
Transcription factor binding would be reduced or eliminated, and transcription of the gene would decrease dramatically
Which of the following is a function of a poly-A tail in mRNA
It helps protect the mRNA from degradation by hydrolytic enzymes
A eukaryotic transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. Which of the following statements best explains this fact?
Many noncoding stretches of nucleotides are present in eukaryotic DNA
During the process of alternative RNA splicing, where on a pre-mRNA does a spliceosome bind?
on certain sequences of an intron
Which of the following experimental procedures is most likely to speed up mRNA degradation in a eukaryotic cell?
Removal of the 5’ cap
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the tRNA that binds the mRNA codon is
AAA
Accuracy in the translation of mRNA into the sequence of amino acids in a polypeptide depends on specificity in which of the following characteristics?
Bonding of the anticodon to the codon and the attachment of amino acids to tRNAs
There are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. This is best explained by the fact that
The rules for base pairing between the third base of a codon and tRNA are flexible
In what way could a point mutation in DA make a difference in the function of a protein?
It might substitute a different amino acid in the protein, which could change its function
Which oWhat is the effect of f the following types of mutation, resulting in an error in the mRNA just after the 5’ AUG start codon, is most likely to have the most serious effect on the polypeptide product?
A deletion of two nucleotides
What is the effect of a nucleotide pair substituion that results in a nonsense mutation in a gene?
It introduces a premature stop codon into the mRNA
Which of the following types of mutations could result in a frame shift mutation?
Either an insertion or deletion of a base
Which of the following mutations is most likely to cause a phenotypic change?
A single nucleotide deletion in an exon coding for an active site of a protein
Examine the table of codons in the figure above. A possible sequence of nucleotides in the template strand of DNA that would code for polypeptide sequence phe-leu-ile-val
AAA-GAA-TAA-CAA
Examine the table of codons in the figure above. What amino acid sequence will be produced based on the following mRNA codon sequence? AUG-UCU-UCG-UUA-UCC-UUG
met-ser-see-leu-ser-leu
