Ch 16: The Molecular Basis of Inheritance

Question 1

What is transfromation?

Answer 1

a change in genotype and phenotype due to assimilation of foreign DNA

Question 2

What are bacteriophages (or phages)?

Answer 2

viruses that infect bacteria

Question 3

What is a virus?

Answer 3

DNA (sometimes RNA) enclosed by a protective coat, often simply protein

Question 4

Who discovered the genetic role of DNA?

Answer 4

Frederick Griffith

Question 5

What is the first Chargaffs rule?

Answer 5

the base composition of DNA varies between species

Question 6

Who was involved in discovering the role of DNA in inheritance?

Answer 6

Maurice Wilkins and Rosalind Franklin came up with the first image of DNA and then James Watson stole the image and deduced his findings off of it

Question 6

What is the second Chargaffs rule?

Answer 6

in any species the number of A and T bases is equal and the number of G and C bases is equal

Question 7

What were the findings from Watson and Crick?

Answer 7

DNA has a structure of a double helix and the backbones are antiparallel

Question 8

What type of unit is adenine and guanine?

Answer 8

they are both purine

Question 9

What type of unit is cytisine and thymine?

Answer 9

they are both pyrimidine

Question 10

What is DNA replication?

Answer 10

the copying of DNA

Question 11

What is a semiconservative model?

Answer 11

it predicts that when a double helix replicates, each daughter molecule will have one old strand (derived or “conserved” from the parent molecule) and one newly made strand

Question 12

What are origins of replication on DNA?

Answer 12

where the two DNA strands ae separated, opening up a replication “bubble”

Question 13

What is a replication fork?

Answer 13

a Y-shaped region where parental DNA strands are being unwound

Question 14

What are helicases?

Answer 14

enzymes that untwist the double helix at the replication forks

Question 15

What are single-strand binding proteins?

Answer 15

proteins that bind to and stabilize single-stranded DNA

Question 16

What is topoisomerase?

Answer 16

it relieves the strain of twisting of the double helix by breaking, swiveling, and rejoining DNA strands

Question 17

What are DNA polymerases?

Answer 17

they are enzymes that catalyze the synthesis of new DNA at a replication fork

Question 18

What is the function of a primer?

Answer 18

DNA polymerases require a primer so they can add nucleotides

Question 19

What is the function of a primase?

Answer 19

to synthesize the short RNA primer

Question 20

What do DNA polymerases require?

Answer 20

they require a primer and a DNA template strand

Question 21

What is the difference between dATP and ATP?

Answer 21

dATP has deoxyribose while ATP has ribose

Question 22

Which way does DNA polymerases add nucleotides?

Answer 22

DNA polymerases add nucleotides only to the free 3’ end of a growing strand, therefore a new DNA strand can elongate only in the 5’ –> 3’ direction

Question 23

What does the DNA polymerase synthesize?

Answer 23

the DNA polymerase synthesizes a leading strand continuously, moving toward the replication fork

Question 24

Besides the leading strand, what is the other strand called?

Answer 24

the lagging strand

Question 25

How is the lagging strand elongated?

Answer 25

the DNA polymerase must work in the direction away from the replication fork

Question 26

What are Okazaki fragments?

Answer 26

the series of fragments that are synthesized for the lagging strand

Question 27

What are Okazaki fragments joined by?

Answer 27

they are joined together by DNA ligase

Question 28

What occurs during mismatch repair?

Answer 28

repair enzymes replace incorrectly paired nucleotides that have evaded the proofreading process

Question 29

What happens during nucleotide excision repair?

Answer 29

a nuclease cuts out and replaces damaged stretches of DNA

Question 30

What is the function of telomeres?

Answer 30

telomeres do not prevent the shortening of DNA molecules, but they do postpone the erosion fo genes near the ends of DNA molecules

Question 31

What are chromatin?

Answer 31

in the eukaryotic cell, DNA is precisely combined with proteins in a complex

Question 32

What are histones responsible for?

Answer 32

these proteins are responsible for the main level of DNA packing in interphase chromatin

Question 33

What are nucleosomes?

Answer 33

the unfolded chromatin which resembles beads on a string, the bead being the nucleosomes

Question 34

What are nucleosomes composed of?

Answer 34

they are composed of DNA wound twice around a core of eight histones

Question 35

What is euchromatin?

Answer 35

loosely packed chromatin

Question 36

What is heterochromatin?

Answer 36

highly condensed chromatin