midterm 2

Question 1

__________ are the building blocks of dna and rna?

Answer 1

nucleotides

Question 2

purines are______ and _______ while pyridimines are _________, ___________ and _________.

Answer 2

adenine and guanine

cytosine, thymine, and uracil

Question 3

what bonds interactions between gc and at

Answer 3

hydrogen bonds

Question 4

what stabilizes the dna double helix?

Answer 4

nucleotide base stacking

Question 5

what are the three conformations of the dna double helix?

Answer 5

A B Z

Question 6

melting point is influenced by?

Answer 6

strand length and ionic strength

Question 7

how is supercoiled dna generated?

Answer 7

twisting of the double stranded helix

Question 8

when is dna supercoiling induced?

Answer 8

transcription by rna polymerase

Question 9

what are the 4 secondary structures of rna in the ribosome RNaseP?

Answer 9

Duplex, Hairpin, Bulge, Loop

Question 10

Interaction between hsitones and DNA is sequence specific ? (t or f)

Answer 10

False

Question 11

Dna wraps around the histone proteins to form what?

Answer 11

a nucleosome

Question 12

what binds to dna sequence specifically?

Answer 12

lac repressor protein

Question 13

what protects the end of chromosomes from degredation?

Answer 13

telomeres

Question 14

______ is used to discover the function of an unkown gene?

Answer 14

bioinformatics

Question 15

what facilitates the propagation of recombinant molecules in antibiotic resistance?

Answer 15

plasmid vectors

Question 16

what recognizes palindromic sequences in dna and cleave double stranded dna?

Answer 16

restriction endonucleases

Question 17

what is an in vitro method of dna amplification?

Answer 17

polymerase chain reaction

Question 18

what are the 3 pcr amplification temperature phases?

Answer 18

95–> denature
60–> anneal
72–> synthesize dna

Question 19

luciferase conerts d-luciferin to _____ in a reaction to produce light

Answer 19

oxyluciferin

Question 20

the first step in protein purification is to ?

Answer 20

prepare a cell extract

Question 21

what is used to separate proteins based on density?

Answer 21

centrifuge

Question 22

gel filtration separates proteins based on?

Answer 22

basis of size

Question 23

ion exchange cromatography separates proteins based on?

Answer 23

basis of charge

Question 24

afffinity chromatography proteins based on?

Answer 24

specific ligand interactions

Question 25

what is the difference between nucleotides and nucleosides?

Answer 25

nucleosides lack a phosphate

Question 26

complementary base pairs are held by?

Answer 26

h bonds

Question 27

what happens to absorbance as it denatures?

Answer 27

it increases

Question 28

why are type II topoisomerase enzymes important in DNA replication and transcription?

Answer 28

they relieve the positive supercoiling

Question 29

protein conformation is determined by two factors in an aqueous solution, what are they?

Answer 29

1. formation of maximun number of h bonds

2. placement of hydrophobic amino acid residues within the interior of the protein

Question 30

what functional group is present in all 20 amino acids except proline?

Answer 30

amino group

Question 31

what best represent sthe backbone of two peptide bonds?

Answer 31

C-C-N-C-C-N

Question 32

where are there h bonds located in a protein right handed alpha helix?

Answer 32

they are parallel to the axis of the helix