All of the above were important considerations in the elucidation of the structure of DNA.
1) Watson and Crick elucidated the structure of DNA in 1953. Their research built on and helped explain the findings of other scientists, including ________.
DNA is the molecular substance of genetic inheritance.
2) The transduction experiments done by Hershey and Chase, and the transformation experiments done by Griffith, supported the same conclusion, which was ________.
complementary base pairing
3) The fact that within a double-stranded DNA molecule, adenine forms two hydrogen bonds with thymine and cytosine forms three hydrogen bonds with guanine is known as
semiconservative replication.
DNA is synthesized through a process known as
Meselson and Stahl
5) Who performed the classic experiments that proved DNA was copied by semiconservative replication?
DNA polymerase
6) DNA contains the template needed to copy itself, but as you learned in Chapter 4, it has no catalytic activity. What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in the DNA polymer being formed?
? he deoxyribonucleotide triphosphate substrates
7) What provides the energy for the polymerization reactions in DNA synthesis
2, 1, 3, 5, 4
8) Put the following steps of DNA replication in chronological order. 1. Single-stranded binding proteins attach to DNA strands. 2. hydrogen bonds between base pairs of antiparallel strands are broken. 3. Primase binds to the site of origin. 4. DNA polymerase binds to the template strand. 5. An RNA primer is created.
Telomerase ensures that the ends of the chromosomes are accurately replicated and eliminates telomere shortening.
Bodnar et al. (1998) used telomerase to extend the life span of normal human cells. Telomere shortening puts a limit on the number of times a cell can divide. How might adding telomerase affect cellular aging?
most normal somatic cells
Which of the following cells do not have active telomerase activity?
on average, 6 times each time the entire genome of a cell is replicated
DNA replication is highly accurate. It results in about one mistake per billion nucleotides. For the human genome, how often would errors occur?
The proofreading mechanism of DNA polymerase was not working properly.
Researchers found E. coli that had mutation rates 100 times higher than normal. What is a possible explanation for these results?
The parent strand is methylated.
In the mismatch repair process, enzyme complexes replace bases that were incorrectly inserted into the newly synthesized DNA strand. To function, they must be able to distinguish between the parent DNA strand and the new strand. How is this accomplished?
pyrimidine dimers
In humans, xeroderma pigmentosum is a disorder of the nucleotide excision repair mechanism. These individuals are unable to repair DNA damage caused by ultraviolet light. Which of the following are the most prominent types of mutations in individuals suffering from xeroderma pigmentosum?
adjacent pyrimidines on the same DNA strand that join by covalent bonding
What are pyrimidine dimers?
There are several enzymes involved in the nucleotide excision repair process.
Recent studies have shown that xeroderma pigmentosum (an error in the nucleotide excision repair process) can result from mutations in one of seven genes. What can you infer from this finding?
decreased ability to repair certain DNA mutations
) Hereditary nonpolyposis colorectal cancer (HNPCC) is an inherited disorder. The genetic defect identified is an error in the mismatch repair mechanism. Which of the following would be an expected result of this mutation?