DNA (exam 2 q 2)

Question 1

DNA was discovered by

Answer 1

Rosalind Franklin

Question 2

what did Rosalind Franklin do?

Answer 2

 Took x ray photos of DNA.
 Discovered double helix structure and measured many more DNA parameters

Question 3

Watson and Crick:

Answer 3

made a model that fit data using some of Franklin’s work. they got credit for discovering DNA structure.

Question 4

DNA is composed of

Answer 4

sugar backbones and there are 4 nitrogenous bases: A, T, G, C

Question 5

base pair between DNA strands

Answer 5

 A and T
 C and G
 * Forms 3 rings across middle

Question 6

combination of bases and sugar is called a

Answer 6

nucleotide

Question 7

5’ end has

Answer 7

phosphate

Question 8

3’ end has

Answer 8

hydroxyl

Question 9

new nucleotides are always added to the ___ end.

Answer 9

3’

Question 10

direction of strand:

Answer 10

5’ to 3’

Question 11

complementary strands

Answer 11

each strand has letters that fit with the other strand

Question 12

antiparallel strands

Answer 12

strands run in opposite directions
*5’ and 3’ are on opposite ends for each strand

Question 13

genes are instructions to make

Answer 13

proteins and useful RNA

Question 14

linked genes:

Answer 14

on same chromosome

Question 15

DNA replication

Answer 15

making a DNA copy

Question 16

DNA replication is accomplished by

Answer 16

DNA polymerase

Question 17

since DNA cannot start itself…

Answer 17

you cannot copy the first section of information on the strand and DNA gets shorter each time it is copied

Question 18

telomeres

Answer 18

sections of DNA at end of chromosomes that act as pointless information that is okay to be lost

Question 19

telomeres prevent…

Answer 19

loss of important information

Question 20

when telomeres are used up…

Answer 20

cells may lose ability to divide

Question 21

how are mistakes made as DNA is copied handled?

Answer 21

1. Proteins search for mistakes in DNA
2. Tags are added to mistakes
3. Repair polymerase cuts out damaged section of strand
4. Damaged section is discarded
5. Repair polymerase recreates damaged section

Question 22

how are long stands of DNA handled?

Answer 22

they are packed into chromosomes to take up less space

Question 23

DNA is wrapped around spools called

Answer 23

histones

Question 24

histones twist around each other to form

Answer 24

a chromatin fiber

Question 25

chromatin fiber (formed from twisted histones) twist around

Answer 25

other structures

Question 26

DNA compacts into ___ ____ if cell is dividing

Answer 26

sister chromatids