Lecture 2

Question 1

Where are covalent bonds in DNA

Answer 1

Sugar-Phosphate

Question 2

Which H bonds are easiest to break in dna

Answer 2

A-T, double bonded, G-C are triple bonded

Question 3

What do h bonds hold together in DNA

Answer 3

2 strands of DNA

Question 4

What differs on the 2’ carbon of Deoxyribose and ribose

Answer 4

Deoxyribose has Hydrogen on 2’carbon
Ribose has Hydroxyl group on 2’ carbon

Question 5

Are purines and pyrimidies double or single ringed

Answer 5

Purines: Double (A/G)
Pyrimidines: Single (C/T)

Question 6

Nucleoside vs nucleotide

Answer 6

Nucleoside: sugar and base
Nucleotide: Sugar, base, phosphate

Question 7

Features of DNA

Answer 7

5’–>3’
Right handed
Complementary
Antiparallel

Question 8

What happens in gap phase

Answer 8

growing and getting ready for what’s next- make proteins and get ready to split to 2 cells

Question 9

What happens in S phase

Answer 9

SECOND (S) copy- DNA replication

Question 10

What happens in G0 phase

Answer 10

Cells have stopped dividing

Question 11

What happens in M phase

Answer 11

Mitosis

Question 12

What phase is where chromosomes condense so you can see them clearly

Answer 12

Metaphase

Question 13

Phases of mitosis

Answer 13

IPMAT

Question 14

What is different about meiosis from mitosis

Answer 14

one round of replication, 2 rounds of division, total of 4 haploid cells

Question 15

Where do sister chromatids get seperated

Answer 15

metaphase 2

Question 16

What kind of cell do you start with for both mitosis and meiosis

Answer 16

a diploid cell

Question 17

Which phase results in recombinant chromosomes

Answer 17

Prophase- crossing over in prophase leads to recombinent chromosomes

Question 18

How many chromosomes in gametes

Answer 18

23- haploid

Question 19

What do you end up with Mitosis vs meiosis

Answer 19

Mitosis: 2 identical daughter/sister cells
Meiosis: 4 haploid daughter cells

Question 20

What unzips the 2 strands of dna

Answer 20

helicase

Question 21

What starts Transcirption

Answer 21

primase

Question 22

Which direction can DNA bases be added

Answer 22

5’–>3’

Question 23

How is DNA replicated in terms of new and old strands

Answer 23

semi-conservative- keep 1 strand as base

Question 24

What direction can replication occur in

Answer 24

5’–>3’

Question 25

Why can dna only replicate 5’–>3’

Answer 25

Have to have OH group to replicate
Can only add to Hydroxyl

Question 26

What does DNA ligase do

Answer 26

seal two strands of DNA together where there were bubbles

Question 27

How many replication sites can be going at one time?

Answer 27

MANY- can do it in many places at the same time

Question 28

What does Topoisomerase do

Answer 28

unwind supercoils on DNA

Question 29

What do cancer drugs commonly inhibit

Answer 29

topoisomerase- they inhibit DNA replication

Question 30

Which strand (leading/lagging) can be synthesized continuously

Answer 30

leading

Question 31

What are okazaki fragments associated with

Answer 31

lagging strand

Question 32

What polymerase helps add on to RNA primer (adds DNA on to RNA primer)

Answer 32

DNA polymerase 3- adds in DNA

Question 33

What polymrease recognizes a mutation and takes it out/corrects it

Answer 33

exopolymerase

Question 34

What does DNA polymerase 1 do

Answer 34

remove RNA, put in DNA

Question 35

What does DNA ligase do

Answer 35

Seals nick after last nucleotide of RNA primer with phosphodiester bond bewtween 5’ P group and 3’ OH group

Question 36

What are telomeres

Answer 36

DNA at end of chromosomes

Question 37

is telomere shortening in gametes or somatic cells

Answer 37

somatic cells

Question 38

What does telomerase

Answer 38

prevent telomeres from shorteining in every single round (has RNA so DNA can add onto it, gives artificial template)

Question 39

Which enzyme aids with coiling and uncoiling in the tertiary structure

Answer 39

Topoisomerases

Question 40

What is a nucleosome

Answer 40

repeating unit of DNA that wraps around a protein and makes up chromatin

Question 41

What charge are histones and how does this compare to DNA

Answer 41

histones are positive, attracts DNA, which is negative

Question 42

Why do we visualize DNA in metaphase

Answer 42

It is highly wound together and easily visible, most condensed

Question 43

What does DNA repair prevent

Answer 43

1. Delay senescence
2. prevent apoptosis
3. prevent uncontrolled cell division

Question 44

What does nucleotide excision repair do

Answer 44

remove many DNA pairs (24 ish).
Seen in the case of skin cancer from sun

Question 45

What does double strand break repair fix

Answer 45

non-homologous end joining/homologous recombination
Most detremental

Question 46

What is mismatch repiar

Answer 46

take out mismatch, put in right strand, seal with ligase

Question 47

What is lynch syndrome

Answer 47

-Autosomal dominant, mismatch repair gene not functioning
- Tied to colon cancer.
-A different mismatch repair gene not functioning causes breast cancer

Question 48

What is exroderma pigmentosum

Answer 48

• Something in nucleotide exision repair is not working, early and frequent skin cancers, cannot fix mistakes on cells

Question 49

What is homologous recombination associated with

Answer 49

breast cancer - BRCA1/2
Born with this is problematic

Question 50

DNA polymerase 1 vs polymerase 3

Answer 50

1: removes and replaces primers
3. elongates DNA