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.
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%
Which of the following cells have reduced or very little active telomerase activity?
most normal somatic cells
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 f
5' A C G U U A G G 3'
How does the enzyme telomerase meet the challenge of replicating the ends of linear chromosomes?
It catalyzes the lengthening of telomeres, compensating for the shortening that could occur during replication without telomerase activity.
For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to
Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
What is a major difference between eukaryotic DNA replication and prokaryotic DNA replication?
Prokaryotic chromosomes have a single origin of replication, while eukaryotic chromosomes have multiple origins of replication.
In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5' ? 3' direction?
DNA polymerase III
DNA replication is said to be semiconservative. What does this mean?
Each new double helix consists of one old and one new strand.
Telomere shortening puts a limit on the number of times a cell can divide. Research has shown that telomerase can extend the life span of cultured human cells. How might adding telomerase affect cellular aging?
Telomerase eliminates telomere shortening and retards aging.
A new DNA strand elongates only in the 5' to 3' direction because
DNA polymerase can add nucleotides only to the free 3' end
Which of the following help(s) to hold the DNA strands apart while they are being replicated?
single-strand DNA binding proteins
What is the difference between the leading strand and the lagging strand in DNA replication?
The leading strand is synthesized continuously in the 5' ? 3' direction, while the lagging strand is synthesized discontinuously in the 5' ? 3' direction.
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
What is the function of helicase in DNA replication?
It untwists the double helix and separates the two DNA strands.
Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons?
Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.
Who conducted the X-ray diffraction studies that were key to the discovery of the structure of DNA?
Franklin
What is a telomere?
the ends of linear chromosomes
Which of the following statements describes a eukaryotic chromosome?
a single linear molecule of double-stranded DNA plus proteins