dna replication - exam 1

Question 1

nucleotide

Answer 1

phostphate gtoup, pentose sugar, nitrogenous base

5 nitrogenous bases – ACTUG
what the nucleotide is named after

Question 2

deoxyribonucleic acid

Answer 2

dna

contains instructions used in development & functioning of all living organisms

Question 3

ribonucleic acid

Answer 3

crucial for tkaing instructions in dna & making proteins that wn the cell

Question 4

dna bases

Answer 4

ATGC

Question 5

rna bases

Answer 5

AUGC

Question 6

dna sugar

Answer 6

deoxyribose

Question 7

rna sugar

Answer 7

ribose

Question 8

dna # of strands

Answer 8

2, double helix

Question 9

rna # of strands

Answer 9

1

Question 10

dna location in cell

Answer 10

nucleus

Question 11

rna location in cell

Answer 11

nucleus, cytosol

Question 12

ATGGCTA

Answer 12

TACCGAT

dna

Question 13

ACUGCA

Answer 13

UGACGU

rna

Question 14

hydrogen bonds

Answer 14

2 bonds in TA
3 bonds in GC

Question 15

genome

Answer 15

complete set of dna in an orgnaism

every cell in the body contains a complete set of the genome

contains all of the info needed for an organsim to develop & grow

no correlation between size of genome & complexity of organism

Question 16

helicase

Answer 16

unwinds double helix at replication fork

Question 17

single stranded binding protein

Answer 17

stabilize replication bubble

keep single strands from re pairing

Question 18

topoisomerase

Answer 18

relieves supercoiling ahead of helicase

allows helicase to keep moving

Question 19

dna polymerase III

Answer 19

makes dna strand complementary to template

but dna needs a 3’-OH to get started so it needs a primase

Question 20

primase

Answer 20

makes a primer

now dna pol III can make dna complementary to template strand

the compl. strand is built in 5’ –> 3’ direction

dna can only build by adding nucleotides to 3’ end

Question 21

primer

Answer 21

short strand of rna complementary to template

provides 3’-OH for dna pol III

Question 22

dna polymerase I

Answer 22

removes primers

fills in gap w/ dna nucleotides

it cannot make the phosphdiester bond to connect dna fragments

Question 23

dna ligase

Answer 23

makes phosphodiester bond to connect dna fragments

Question 24

continous synthesis

Answer 24

leading strand

moving towards inside of fork

Question 25

discontinous synthesis

Answer 25

lagging strand moving towards open end of fork has to keep making small strand as the fork opens up

Question 26

why can't dna syntehsis occur after primer is removed

Answer 26

no 3' - OH available

Question 27

what happens because the primer is removed

Answer 27

gap doesn't get filled cell hates single stranded dna single stranded ends get chopped off the chromosome gets shorter

Question 28

telomeres

Answer 28

ends of chromosomes stretches of repeated bases do not contain genes

Question 29

what happens when telomere repeats are gone

Answer 29

start losing genes chromosomes fall apart (shoelace w/out aglet) chromosomes fuse cells die

Question 30

hayflick limit

Answer 30

40-60 divisions before cell death more than this & the cells start to mutate, can become harmful

Question 31

telomerase

Answer 31

enzymes that can "fill in the gap" in cells that need to replicate over the hayflick limit - embryo & stem cells chromosomes maintain length upon each cell divsion

Question 32

telomere & aging

Answer 32

telomere length correlates with age longer telomere = longer life span telomeres shorten w age

Question 33

too much telomerase

Answer 33

overexpression of telomerase expands lifespan compromises fertility did not lead to longer telomeres mutations = cancer

Question 34

3' --> 5' exonuclease activity

Answer 34

pol. adds incorrecct nt pol. detects mispaired bases uses 3'-5' exonuclease to remove incorrect nt

Question 35

nuclease

Answer 35

chops up nucleic acid

Question 36

exonuclease

Answer 36

chops up nucleic acid starting at an end

Question 37

3'-5' exonuclease

Answer 37

chops up from 3' end

Question 38

mismatch repair system

Answer 38

remove/replace incorrectly pair nts, later mismatch detacted endonuclease cuts out mismatch dna pol. fills in the correct nts dna ligase makes the last phophodiester bond

Question 39

endonuclease

Answer 39

chops up internal mistakes

Question 40

excision repair system

Answer 40

similar to mismatch but works later uv light can cause thymine dimer to become misshapen endonuclease cuts out the damage dna pol fills in the gap ligase connects pieces