DNA replication and manipulation

Question 1

Where does DNA replication occur

Answer 1

S phase

Question 2

What shape is DNA in

Answer 2

helix w two antiparallel strands

Question 3

Why do hydrogen bonding inbetween DNA strands allow it to unravel

Answer 3

bc they are weaker

Question 4

What direction is DNA made

Answer 4

5’-3’ only

Question 5

DNA replication conservative model

Answer 5

no mixing DNA

Question 6

Semiconservative model

Answer 6

evenly split mixed DNA

Question 7

Dispersive model

Answer 7

random mixing DNA

Question 8

Which experiment showed that DNA replication is semi-conservative

Answer 8

messelsohn and stahl

Question 9

How did messelsohn and stahl do their experiment

Answer 9

growing bacteria in lighter and lighter nitrogens and DNA forms bands when centrifuged

Question 10

Draw out semiconservative model

Answer 10

Dark strand on first, split half on second, and light and half on third

Question 11

If DNA replication was conservative which bands would be observed after one round of replication

Answer 11

heavy and light

Question 12

Complications in DNA replication(4)

Answer 12

1. unwinding tension
2. only add nucleotides to existing nucleotide
3. opposite directions on each strand
4. pieces need to be joined together

Question 13

Helicase

Answer 13

unwinds double helix at replication forks

Question 14

Single-strand binding protein

Answer 14

binds and stabilizes single stranded DNA when it is used as a template

Question 15

topoisomerase

Answer 15

relieves strain of overwinding by breaking, swiveling, and rejoining DNA strands

Question 16

primase

Answer 16

makes RNA primer at 5’ of leading and 5’ of each okazaki fragment of laggiing

Question 17

DNA pol III

Answer 17

uses parental DNA as template and makes new DNA by adding nucleotides to RNA primer

Question 18

DNA pol I

Answer 18

removes RNA primers and replaces with DNA nucleotides

Question 19

DNA ligase

Answer 19

joins okazaki fragments on lagging strand
leading strand: joins 3’ to rest of leading

Question 20

Step 1 of replication (3)

Answer 20

1. helicase unwinds
2. topoisomerase relieves stress
3. single-stranded binding proteins stabilize single strands

Question 21

Step 2 of replication

Answer 21

1. RNA primer attaches to 5’ primer
2. elongation as bases are added
3. RNA primers are replaced with DNA
4. pieces in the lagging strand and put together

Question 22

Prokaryote replication

Answer 22

single origin and moves around the circular c chromosome in both directions

Question 23

Difference between eukaryotic and prokaryotic replication

Answer 23

prokaryotic one origin
eukaryotic many origins of replication

Question 24

Telomeres

Answer 24

protect ends of chromosomes

Question 25

Relation between age and telomere length

Answer 25

As age increases, telomere length decreases

Question 26

End replication problem

Answer 26

few bases at ‘5 end of new strands are missing

Question 27

Telomerase

Answer 27

some cells express this
carries its own RNA template

Question 28

Some types of cancer cells express telomerase to

Answer 28

divide a greater number of times before dying

Question 29

Polymerase Chain Reaction purpose

Answer 29

make many copies of a DNA fragment in vitro

Question 30

Primers

Answer 30

oglionucleotides

Question 31

Things you need in a PCR(5)

Answer 31

1. DNA template
2. Primers
3. DNA polymerase
4. dNTPs
5. Buffer/cofactors

Question 32

Restriction enzymes

Answer 32

recognize and cut specific sequences of DNA

Question 33

EcoRI restriction endonuclease

Answer 33

restriction enzyme

Question 34

restriction enzymes with plasmids

Answer 34

used to insert genes/DNA fragments of interest into a vector

Question 35

agarose gel electrophoresis

Answer 35

used to visualize DNA

Question 36

shorter strands

Answer 36

migrates faster

Question 37

larger strands

Answer 37

migrate slower

Question 38

larger strands

Answer 38

migrate slower

Question 39

CRISPR

Answer 39

used to insert and change gene sequences