Question

Question 2a

Deoxyribonucleic acid (DNA) is made up of nucleotides.

Which part of the nucleotide stabilizes the structure of DNA using weak van der Waals interactions (stacking) and using hydrogen bonds?

(Note that covalent bonds are not included in that sentence.)

	a.	the deoxyribose sugar
	b.	the ribose sugar
	c.	the phosphate
	d.	the nitrogenous base
	e.	the amino acid

Question 2b

This ability of the nitrogenous bases to exist in more than one form can lead to incorporation of the wrong nucleotide during DNA replication. For example, a "C" might be matched to an "A" where a "T" would normally be added.

What is the name for the spontaneous, although infrequent, change of a nitrogenous base to a slightly different chemical form?

	a.	proton exchange
	b.	tautomerization
	c.	ketomerization
	d.	perambulation
	e.	farnesylation

Question 2c

When you consider how DNA replication occurs, there is a problem with the ends of linear chromosomes. The lagging strand cannot copy the last ten nucleotides (approximately) at the end of the chromosome.

Research has shown that chromosomes contain telomere sequences at their ends.

Telomere sequences are...

	a.	special DNA sequences that do not require priming for replication.
	b.	noncoding, repetitive sequences that are entirely unable to be replicated during DNA replication.
	c.	protein-based structures at the ends of chromosomes that protect the chromosome end by allowing the replisome to initiate DNA replication without an RNA primer.
	d.	noncoding, repetitive sequences that can be copied independent of the replisome.
	e.	equivalent to a poly-A tail on an mRNA; it is a long repeated A-T pairing.

Answer 1

1. d. the nitrogenous base

the nitrogenous bases are part of the nucleotide that stabilizes the structure of DNA using weak van der Waals interactions (stacking) and using hydrogen bonds.

2. b. tautomerization

Tautomerization is the name for the spontaneous, although infrequent, change of a nitrogenous base to a slightly different chemical form

3. c. protein-based structures at the ends of chromosomes that protect the chromosome end by allowing the replisome to initiate DNA replication without an RNA primer

Telomeres are capping proteins that protect the end of chromosomes from DNA damage or from fusion with neighbouring chromosomes.