Chapter 16: The Molecular Basis of Inheritance Flashcards
In his transformation experiments, what 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.
Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?
8%
In an analysis of the nucleotide composition of DNA, which of the following will be found?
A + C = G + T
What is meant by the description “antiparallel” regarding the strands that make up DNA?
The 5’ to 3’ direction of one strand runs counter to the 5’ to 3’ direction of the other strand.
An Okazaki fragment has which of the following arrangements?
5’ RNA nucleotides, DNA nucleotides 3’
Which enzyme catalyzes the elongation of a DNA strand in the 5’ → 3’ direction?
DNA polymerase III
At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork:
3’ C C T A G G C T G C A A T C C 5’
An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?
5’ A C G U U A G G 3’
What is the function of DNA polymerase III?
to add nucleotides to the 3’ end of a growing DNA strand
The leading and the lagging strands differ in that
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.
A new DNA strand elongates only in the 5’ to 3’ direction because
DNA polymerase can only add nucleotides to the free 3’ end.
What is the function of topoisomerase?
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 help(s) to hold the DNA strands apart while they are being replicated?
single-strand binding proteins
Which of the enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3’ end of Okazaki fragments?
DNA Polymerse I
Which of the enzymes separates the DNA strands during replication?
Helicase
Which of the enzymes covalently connects segments of DNA?
Ligase
Which of the enzymes synthesizes short segments of RNA?
Primase
Which of the following statements describes the eukaryotic chromosome?
It consists of a single linear molecule of double-stranded DNA plus proteins.
Once the pattern found after one round of replication was observed, Meselson and Stahl could be confident of which of the following conclusions?
Replication is not conservative. It is semiconservative.
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’ end of a growing strand.
In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?
A+G = C+T
The elongation of the leading strand during DNA synthesis
depends on the action of DNA polymerase.
In a nucleosome, the DNA is wrapped around
histones.
The DNA double helix model is based on whose X-ray crystallography studies?
Rosalind Franklin
T or F: Each nucleotide in DNA is composed of a 5-carbon ribose sugar, a nitrogenous base, and a phosphate group.
False
If the % of guanine in the DNA of an organism is 26%, what would be the % of thymine in the DNA of the organism based on Chargaff’s base pairing rule?
24%
DNA in the chromosomes of eukaryotic cells is tightly coiled around which of the following structures, so that it can be packed inside the tiny microscopic nucleus of a human cell?
Histone Proteins
Which of the following bases is present in RNA instead of thymine?
Uracil
Which one of the following enzymes catalyzes the untwisting of the two strands of a DNA molecule when DNA replication is initiated?
Helicase Enzyme
T or F: During DNA replication, multiple replication bubbles form on the single circular chromosome of a prokaryotic cell.
False
Which one of the following enzymes catalyzes the joining of the Okazaki fragments of the newly synthesized lagging strand of DNA during DNA replication?
DNA ligase enzyme
Which of the following enzymes proofread newly made DNA, replacing any incorrect nucleotides?
DNA polymerases
To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?
Nuclease, DNA polymerase, DNA ligase
The chemical bond that joins the nitrogenous base pairs in a DNA double helix.
Hydrogen bond
Single-ringed pyrimidine bases
Thymine, Cytosine and Uracil
The ________ is the total genetic material of an organism.
genome
Which of the following are purine bases
Guanine and Adenine
