DNA Structure and Synthesis COPY

Question 1

Describe transformation

Answer 1

when one bacteria changes the characteristics of another

Question 2

How did transformation lead to the discovery of DNA?

Answer 2

It was discovered that DNA was the transforming factor

Question 3

What is a bacteriophage?

Answer 3

a virus that uses a bacteria to replicate itself

Question 4

How did bacteriophage help confirm the role of DNA?

Answer 4

the virus injects DNA into the bacteria to replicate itself which showed that DNA stored genetic information

Question 5

What is X-ray crystallography?

Answer 5

early technique used to get a visual of DNA

Question 6

How does X-ray crystallography work?

Answer 6

it diffracts light through a DNA crystal which creates an image

Question 7

Describe DNA structure

Answer 7

double helix which runs anti-parallel

Question 8

Describe double helix

Answer 8

two strands twisted around each other

Question 9

Describe anti-parallel

Answer 9

3’ and 5’ ends run opposite directions

Question 10

What makes up a nucleotide

Answer 10

base, sugar, phosphate

Question 11

What makes up a nucleoside

Answer 11

base, sugar

Question 12

Pyrimidines have ___ ring (s)

Answer 12

one

Question 13

Purines have ___ ring (s)

Answer 13

two

Question 14

Pyrimidines consist of what bases?

Answer 14

cytosine, thymine, uracil

Question 15

Purines consist of what bases?

Answer 15

adenine, guanine

Question 16

What do Chargaff’s rules state

Answer 16

in any species there is an equal number of A and T bases, and an equal number of G and C bases

Question 17

Purine + purine would impact the DNA structure how?

Answer 17

too wide

Question 18

Pyrimidine + pyrimidine would impact the DNA structure how?

Answer 18

too narrow

Question 19

What is the correct model of DNA replication?

Answer 19

semiconservative model

Question 20

Describe the semiconservative model

Answer 20

replicated DNA will have one old and one new strand of DNA

Question 21

Describe the conservative model

Answer 21

the two parent strands rejoin

Question 22

Describe the dispersive model

Answer 22

each strand is a mix of old and new

Question 23

Describe origins of replication

Answer 23

where the two DNA strands are separated forming a “bubble”.

Question 24

Describe the replication fork

Answer 24

the ends of the bubble where new DNA strands begin elongating.

Question 25

Bacterial DNA is what shape?

Answer 25

circular

Question 26

Describe helicases

Answer 26

enzymes that untwist the double helix at the replication forks

Question 27

Describe topoisomerase

Answer 27

goes ahead of replication forks, cuts, unwinds, and rejoins DNA strands

Question 28

Why is topoisomerase needed?

Answer 28

to keep the DNA strands from being too twisted

Question 29

Describe single-strand binding protein

Answer 29

holds the DNA strand straight so it can be used as a template

Question 30

What is a primer

Answer 30

a short strand of RNA that is laid down at the origin of replication

Question 31

What is primase?

Answer 31

enzyme that lays down the primer

Question 32

Describe DNA Polymerase III

Answer 32

adds DNA nucleotides to the 3’ end of the primer

Question 33

The new strands grow in ________ directions.

Answer 33

opposite

Question 34

DNA polymerases add nucleotides only to the __ ___of a strand

Answer 34

3' end

Question 35

a new DNA strand can elongate only in the __ to __ direction

Answer 35

5' to 3'

Question 36

Leading strand grows _______the origin of replication

Answer 36

in front of

Question 37

Lagging strand grows _______ of the origin of replication

Answer 37

behind

Question 38

Describe Okazaki fragments

Answer 38

a series of primers and new DNA segments

Question 39

Describe DNA polymerase I

Answer 39

removes the RNA primers and replaces them with DNA nucleotides

Question 40

Describe DNA ligase

Answer 40

connects the new DNA nucleotides

Question 41

___ ___________ proofread DNA as it is added

Answer 41

DNA Polymerases

Question 42

________ can repair __________ based pairs or ________ DNA

Answer 42

enzymes; mismatched; damaged

Question 43

Describe nucleotide excision repair.

Answer 43

cutting out damaged DNA and replacing it with new DNA

Question 44

Describe nuclease

Answer 44

an enzyme that cuts out damaged DNA

Question 45

In nucleotide excision repair, what happens after DNA is cut out?

Answer 45

1. DNA Polymerase adds new nucleotides | 2. Ligase seals the new nucleotides

Question 46

Why is DNA cut short after every replication?

Answer 46

DNA can’t be added to 5’ end new strands

Question 47

How is DNA code protected from being cut?

Answer 47

meaningless code protects the real code

Question 48

Describe telomeres

Answer 48

repetitive nucleotide sequences at the end of DNA that do not contain genes

Question 49

Describe telomerase

Answer 49

an enzyme that lengthens telomeres in gamete DNA

Question 50

Why is telomerase needed?

Answer 50

so a zygote can start off with a full set of telomeres

Question 51

Describe histones

Answer 51

DNA wrapped around bead like proteins

Question 52

Describe chromatin

Answer 52

DNA and histones together

Question 53

What happens into DNA packaging after histones are made?

Answer 53

the Chromatin is coiled together into a larger fiber