ch 16

Question 1

What is the significance of the 5’ and 3’ carbons between two different nucleotides?

Answer 1

gives the orientation of the nucleotides and gives directionality

Question 2

If one strand of DNA is running 5’ to 3’, what direction is the other running? What is this orientation called?

Answer 2

opposite directions to each other- antiparallel

Question 3

Nitrogenous bases (what kinds of bonds hold them together?)

Answer 3

hydrogen

Question 4

Nitrogenous bases (what kinds of bonds hold them together?)

Answer 4

hydrogen bond

Question 5

“DNA replication is semiconservative” – what does semiconservative mean in this context?

Answer 5

each daughter DNA molecule consists of one new strand and one parent strand of nucleotides- 2 daughter cells identical in sequence to the parent

Question 6

In what phase of the cell cycle is DNA replication taking place?

Answer 6

S phase

Question 7

Nucleosome

Answer 7

(10nm fiber) DNA coiled around histones

Question 8

30nm fiber

Answer 8

10nm fiber coiled

Question 9

Histone proteins

Answer 9

A small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA and plays a key role in chromatin structure.

Question 10

“Metaphase chromosome”: Note, this chromosome will be well packed in other stages of mitosis as well.

Answer 10

(700nm)300nm fiber folds and loops

Question 11

helicase

Answer 11

An enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands.

Question 12

DNA polymerases

Answer 12

binds new DNA nucleotides to complementary bases on parental strands (5’»>3’)

Question 13

prokaryote chromosome structure

Answer 13

circular DNA w/ small amount of protein > supercoiled

Question 14

eukaryote chromosome structure

Answer 14

linear DNA w/ lots of protein

Question 15

Monomers for the synthesis of DNA are called __________.

Answer 15

nucleotides

Question 16

In DNA, the two purines are __________, and the two pyrimidines are __________.

Answer 16

adenine and guanine … cytosine and thymine

Question 17

The two antiparallel strands of nucleotides that form the DNA double helix are held together by __________.

Answer 17

hydrogen bonds between nucleotide bases

Question 18

The role of DNA polymerases in DNA replication is to __________.

Answer 18

attach free nucleotides to the new DNA strand

Question 19

DNA polymerase adds nucleotides to the __________ of the leading strands, and to the __________ of the lagging strands (Okazaki fragments).

Answer 19

3′ end … 3′ end