BIOCHEM

Question 1

are the chemical basis of heredity.

Answer 1

Nucleic Acids

Question 2

_______ is organized into genes, the fundamental unit of genetic information.

Answer 2

DNA

Question 3

directs the synthesis of RNA.

Answer 3

DNA

Question 4

directs and regulates protein synthesis

Answer 4

RNA

Question 5

DNA contains four distinct deoxynucleotides, what are these?

Answer 5

1. Deoxyadenylate (A)
2. Deoxyguanylate (G)
3. Deoxycytidylate (C)
4. Deoxythymidylate (T)

Question 6

These monomeric units of DNA are held in polymeric form
by____________________ constituting a single strand.

Answer 6

3′,5′-phosphodiester bonds

Question 7

The polymer possesses a polarity: one end has a 5′-
_________ or ________________ while the other has a 3′-
________________ or ___________________

Answer 7

hydroxyl, phosphate terminus, phosphate, hydroxyl terminus.

Question 8

The two strands of this double-stranded helix are held in
register by both ______________ between the purine and pyrimidine bases of the respective linear molecules and by_______________ and ________________ between the stacked adjacent base pairs.

Answer 8

hydrogen bonds (H-bonds), van der Waals, hydrophobic interactions

Question 9

This common form of DNA is said to be _______________
because as one looks down the double helix, the base
residues form a spiral in a clockwise direction.

Answer 9

right-handed

Question 9

A-T and G-C base pairs are often referred to as ____________________

Answer 9

Watson- Crick base pairs.

Question 10

The two strands of the double-helical molecule, each of
which possesses a polarity, are _________________; that is, one
strand runs in the 5′ to 3′ direction and the other in the 3′
to 5′ direction.

Answer 10

antiparallel

Question 11

This is the strand of DNA that is copied, or
transcribed, during ribonucleic acid (RNA)
synthesis.

Answer 11

Template Strand

Question 12

the template strand is also referred to as _____________

Answer 12

non coding strand

Question 13

A single turn of B-form DNA about the long axis of the
molecule contains _______

The distance spanned by one turn of B-DNA is__________________

Answer 13

10 bp, 3.4 nm (34 Å).

Question 14

______________ hold the deoxyguanosine
nucleotide to the deoxycytidine nucleotide.

By contrast, the other canonical base pair, the A- T pair, is held together by _______________

Answer 14

Three H-bonds, two H-bonds.

Question 15

The midpoint of the measured DNA denaturation
is called the __________________, or _____.

Answer 15

melting temperature, Tm

Question 16

is often referred to as renaturation or hybridization.

Answer 16

Reannealing

Question 17

are formed
when the molecule is twisted in
the direction opposite from the
clockwise turns of the right-
handed double helix found in B-
DNA.

Answer 17

Negative Supercoils

Question 18

Enzymes that catalyze topologic changes of DNA are
called ____________________

Answer 18

topoisomerases.

Question 19

can relax or insert supercoils,
using ATP as an energy source.

Answer 19

topoisomerases.

Question 20

In RNA, the sugar moiety to which the phosphates and purine and pyrimidine bases are
attached is _____________ rather than the 2′-deoxyribose
of DNA.

Answer 20

ribose

Question 21

This class is the most heterogeneous in
abundance, size, and stability;

Answer 21

Messenger RNA

Question 22

serve as adapters
for the translation of the information in
the sequence of nucleotides of the
mRNA into specific amino acids.

Answer 22

The tRNA molecules

Question 23

DNA rich in _________ melts at a higher temperature than
DNA rich in________, due to differences in hydrogen bond
content and base stacking.

Answer 23

G-C pairs, A-T pairs

Question 24

ribosome is a cytoplasmic nucleoprotein
structure that acts as the machinery for the
synthesis of proteins from the mRNA templates.

Answer 24

Ribosomal RNA

Question 25

A large number of discrete, highlyA large number of discrete, highly conserved
small RNA species are found in eukaryotic cells;
some are quite stable.conserved
small RNA species are found in eukaryotic cells;
some are quite stable.

Answer 25

Small Nuclei RNA’s

Question 26

These RNAs are typically transcribed
from the large regions of eukaryotic
genomes that do not encode for protein
(ie, the mRNA encoding genes).

Answer 26

LncRNAs,

Question 27

play many roles ranging from
contributing to structural aspects of
chromatin to regulation of mRNA gene
transcription

Answer 27

ncRNAs