BIOL Chapter 11 Review
Which of the following is a characteristic of double-stranded DNA?
2 nanometers in width, 10 base pairs per turn and 0.34 nanometers per base pair.
Arrange the following proteins in the proper order in which they participate in DNA replication. 1 = Primase 2 = Helicase 3 = Single-strand binding proteins 4 = DNA polymerase I
2, 3, 1, 4.
Which of the following DNA sequences is complementary to 5' TAGAC 3'?
3' ATCTG 5'.
In the Meselson and Stahl experiment, the starting Escherichia coli culture was grown in heavy (15N) medium; the DNA was 15N15N. After TWO generations of growth in light (14N) medium, the DNA of the E. coli cells contained
50% 15N14N DNA and 50% 14N14N DNA.
According to Chargaff's rule, which of the following statements about double-stranded DNA is TRUE?
A = T and C = G and A + G = C + T.
Why is the lagging strand synthesized in a discontinuous fashion?
DNA synthesis must occur in a 5' to 3' direction, which imposes spatial constraints on the synthesis of the lagging strand.
DNA pol III can initiate DNA synthesis.
False
Which of the following DNA molecules is the most stable?
GCGTGCAC CGCACGTG.
What data would Meselson and Stahl have expected if DNA replication was conservative, rather than semiconservative?
In the first generation, there would be two bands, one of light density and one of heavy density. In the second generation there would still be two bands, one of light density and one of heavy density.
Which of the following is required to replicate the lagging strand of DNA?
Okazaki fragments, primase and DNA ligase.
Why were Griffiths' 'S' strains able to produce a polysaccharide coat while the 'R' strains could not?
The 'S' and 'R' strains carry differences in their genetic material.
Griffiths (1928) mixed heat-killed 'S' bacteria with 'R' bacteria and injected a mouse with both types of bacteria. As a result, the mouse died and Griffiths obtained living 'S' bacteria from the dead mouse. How can you explain this phenomenon?
The DNA from the 'S' bacteria with the gene responsible for capsule formation was transferred to the 'R' bacteria when the strains were mixed. This gene transformed the 'R' bacteria into 'S' bacteria, allowing it to produce a capsule and evade the mouse's immune system.
In Meselson and Stahl's experiment, what was the purpose of centrifuging DNA in a solution of cesium chloride.
The cesium chloride provided a medium of variable density, so that DNA of different density would aggregate in specific regions.
What statement about the major and minor grooves is TRUE?
The major and minor grooves are important for DNA binding proteins to attach to the DNA.
Select the statement that best explains why the replication machinery is found at the replication fork.
The replication machinery must be able to open and stabilize the template DNA, and it must have access to both template strands for replication.
Complete the sentences about the process of DNA replication with the correct terms.
When replication starts, an origin of replication forms, consisting of two replication fork(s) moving in opposite directions. DNA double helix is separated into single strands by the enzyme DNA helicase. Newly-exposed, unreplicated DNA is protected by single-strand binding protein. Short segments of RNA are synthesized, called RNA primers. The enzyme that synthesizes the short segments of RNA is called a primase. The short RNA segments provide a free 3' OH for replication. New DNA is synthesized in the 5' to 3' direction. The enzyme that removes tightened coils ahead of the replication fork is topoisomerase. The enzyme that catalyzes new DNA synthesis is DNA polymerase. DNA synthesis occurs continuously on the leading strand. DNA synthesis occurs in small sections on the lagging strand. Fragments of discontinuous DNA synthesis are called Okazaki fragments. Gaps in the sugar-phosphate backbone of DNA are closed by DNA ligase.
Match the experimental procedures and findings with the correct scientific investigators. Match the experimental procedures and findings with the correct scientific investigators.
Wilkins and Franklin (1953) - X-ray diffraction of DNA showed it was a helix - Determined that DNA had a repeating structure and a uniform diameter Watson and Crick (1953) - Used the biochemical modeling approach of Pauling - Built models of DNA structure Chargaff (1950) - Measured A, C, T, G in different species, found A=T, C=G
The pairing of nitrogenous bases in DNA is specific because
functional groups on each of the bases form hydrogen bonds with functional groups on only one other base.
The Meselson-Stahl experiment demonstrated that DNA replication produces two DNA molecules each composed of
one old and one new strand.
Griffiths (1928) mixed heat-killed 'S' bacteria with 'R' bacteria and injected a mouse with both types of bacteria. As a result, the mouse died and Griffiths obtained living 'S' bacteria from the dead mouse. He called this process
transformation.
RNA primers are removed by the action of the enzyme
DNA pol I.
DNA polymerase occasionally makes errors and adds an incorrect base. A new strand of DNA is being produced, and the template strand contains a G. Based on your knowledge of the structure of DNA, why is it more likely that DNA polymerase would accidently add a T to the new strand instead of a G or an A.?
Because the structure of T and C are similar as they both have a single ring.
Suppose actively dividing eukaryotic cells were treated with a chemical that blocks the activity of the enzyme telomerase. What would happen to these cells?
Cells would lose DNA at the ends of the chromosomes over many generations.
Which of the following statements about the DNA double helix is TRUE?
Complementary base pairing across the double helix allows information to be transferred via DNA replication.
