lecture 28

Question 0

DNA

Answer 0

genetic material

Question 1

what happened in the early 20th century:

Answer 1

the identification of the molecules of inheritance loomed as a major challenge to biologists

Question 2

Genetic alphabet

Answer 2

T,A,C,G

Question 3

DNA has directionality from

Answer 3

the sugars

Question 4

Carbons join from the

Answer 4

3’ end and the 5’ end

‘=prime

Question 5

5’ connects to the

Answer 5

phosphate

Question 6

3’ connects to

Answer 6

nitrogenous bases

Question 7

Maurice Wilkins and Rosalind Franklin were using a technique called

Answer 7

x-ray crystallography to study molecular structure

franklin produced a pic of the DNA molecules using this technique

Question 8

Franklin’s x-ray crystallographic images of DNA enabled Watson to ..

Answer 8

deduce that DNA was helical and the width of the helix and the spacing of the nitrogenous bases

Question 9

The width suggested that the DNA molecule was

Answer 9

made up of 2 strands, forming a double helix

Question 10

5’ and 3’ run________to each other

Answer 10

antiparallel

Question 11

Chargaff’s rule states:

Answer 11

many species there is an equal number of A and T bases, and an equal number of G + C bases

Question 12

there are two antiparallel sugar-phosphate backbones…

Answer 12

with the nitrogenous bases paired in the molecules interior

Question 13

Adenine (A) paired only with

Answer 13

thymine (T)

Question 14

Guanine (G) paired only with

Answer 14

Cytosine (C)

Question 15

the Watson-crick model explains Chargaff’s rules

Answer 15

in any organism the amount of A=T and G=C
A+G=2 rings
T+C=1 ring

Question 16

parental

Answer 16

2 strands that are identical

Question 17

the relationship between the structure + function is

Answer 17

manifest in the double helix

Question 18

Watson and crick notes that the specific base pairing suggested a

Answer 18

possible copying mechanism for genetic material

Question 19

Since the two strands of DNA are complementary,

Answer 19

each strand acts as a template fore building a new strand in replication

Question 20

in DNA replication…

Answer 20

the parent molecules unwinds and 2 new daughter strands are built based on base-pairing rules

Question 21

the copying of DNA is remarkable in its

Answer 21

speed and accuracy

Question 22

more than a dozen enzymes and other proteins participate in ..

Answer 22

DNA replication

Question 23

Replication begins at special sites called

Answer 23

organisms of replication, where the two DNA strands are separated, opening up a replication “bubble”

Question 24

replication proceeds in both directions from each origin, unit…

Answer 24

the entire molecule is copied

Question 25

at the end of each replication bubble is a

Answer 25

replication fork, a y shaped region where new DNA strands are elongating

Question 26

DNA polymerases cannot initiate synthesis or a polypeptide, they can only

Answer 26

add nucleotides to the 3’ end.

Question 27

the initial nucleotide strand is a short..

Answer 27

RNA primer

Question 28

the primer is short__________, and the 3’ end serves as the starting point for the _______.

Answer 28

(5-10 nucleotides long)

new DNA strand

Question 29

Enzymes called DNA polymerases catalyze the elongation of the new DNA at a

Answer 29

replication fork

Question 30

Most DNA polymerases require a primer and a

Answer 30

DNA template strand

Question 31

The rate of elongation is about ___________ in human cells

Answer 31

50 per second