DNA- Reynolds

Question 1

____ polymerize to form ____and require

Answer 1

monomers, polymers, enzyme and added energy

Question 2

condensation/ dehydration

Hydrolysis

Answer 2

Condensation: Links monomers to form polymers

Hydrolysis: Polymers broken down into monomers

both can be catalyzed by enzymes

Question 3

DNA carbons

• 5’
• 3’
• 2’
• 1’

Answer 3

• 5’ C= free phosphate attached to 5’ end, 0-3
• 3’ C= OH attached to the 3’ end
• 2’= nothing (Hs)
• 1’ C = Base

Question 4

DNA traits

Answer 4

1. Two antiparallel strands
2. right handed helix
3. Hydrophilic phosphate backbone
4. Hydrophobic bases in the helix
5. dsDNA major and minor grooves
6. H bonding btwn bases
   7.

Question 5

Pyrimidine

Purine

Answer 5

Pyrimidine= one ring

Purine= two rings

Question 6

stabilizing forces of DNA

Answer 6

H bonding

Question 7

Answer 7

one ring= pyrimidine

two ring= purine

Question 8

Pyrimidines

Answer 8

Cytosine

Uracil (RNA)

Thymine (DNA)

Cut the pyi Once

Question 9

Cytosine

Answer 9

-NH2 top

N=C

pyrimidine

Question 10

Thymine

(DNA)

Answer 10

=O

• CH3
• NH

Pyrimidines

Question 11

Uracil

RNA

Answer 11

=O

-HN

CH=CH

pyrimidines

Question 12

Adenine

Answer 12

-NH2 top

N=C

purine

Question 13

Guanine

Answer 13

=O (top)

-H2N

purine

Question 14

Deoxyribosse vs ribose

Answer 14

• Deoxyribose= 2’ carbon has a H
• Ribose= 2’ carbon has an OH

Question 15

• Nucleoside
• Nucleotide
• Ribonucleoside/ribonucleotide
• Deoxyribonucleoside/deoxyribonucleotide

Answer 15

• Nucleoside- N base + 5’ sugar
• Nucleotide- phosphorylated nucleoside
• Ribonucleoside/tide-OH on 2’
• Deoxyribonucleoside/tide- H on 2’

Question 16

Bases within a strand linked via

Answer 16

phosphodiester bonds

(btwn 3’ and 5’ carbon)

Question 17

H bonds bwtn bases…

Answer 17

• A-T 2 H bonds
• G-C 3 H bonds

Question 18

DNA denatiration when…

Answer 18

hydrogen bonds are disrupted

1. Alteration of pH
2. Increased heat
3. DNA replication

Question 19

reanneal

Answer 19

complementary DNA strands can reanneal (hybridize)

Question 20

Tm

Answer 20

temperature that 1/2 of DNA denatures

temp above Tm, DNA is now ss

Question 21

Hershey and Chase

Answer 21

• virus T2 infects E. Coli
• confirmed that DNA is the genetic material

Question 22

human nuclear genome is

mito genome is

Answer 22

3.2 billion bp

16,500 bp

Question 23

Nucleosomes

Answer 23

• DNA associates with histones
• 146 bp of DNA
• then organized to make chromosomes

Question 24

Meselson and Stahl

Answer 24

• proved DNA replicaiton is a semi conservative process
• Bacteria grown in 14N or 15N medium

Question 25

DNA synthesis steps

Answer 25

1. Occurs at the replication fork and is bidirectional 2. Replication fork has leading and lagging (Okazaki fragments) strand synthesis 3. Semiconservative 4. Proceeds in the 5’ to 3’ direction 5. Requires an RNA primer 6. Base selected based on H-bonding and geometry 7. High fidelity (low error rate)

Question 26

DNA A

Answer 26

replication initiation factor that promotes denaturation of DNA at the origin of replication

Question 27

DNA helicase

Answer 27

binds ssDNA near the replication fork and uses ATP to "unzip" DNA

Question 28

single strand DNA binding protein

Answer 28

keeps DNA single stranded

Question 29

Topoisoerase

Answer 29

DNA gyrase * removes torsional strain * relieve coiling strain and changes the supercoiled form of DNA

Question 30

Primase

Answer 30

synthesizes RNA primers to prime DNA synthesis

Question 31

DNA polymerases

Answer 31

replicate DNA

Question 32

DNA ligase

Answer 32

* links DNA by catalyzing phosphodiester bonds * joining of Okazaki fragments * occurs during DNA repair

Question 33

DNA Synthesis

Answer 33

1. DNA is opened via helicase 2. ss DNA proteins stabilize single strands 3. Topoisomerase relieves twisting forces (torsional strain) 4. primase synthesizes RNA primer 5. synthesis of leading strand begins (RNA primer leading strand) 6. DNA polyerase III 5'→3' (need primer) 7. primase synthesizes RNA primer in the lagging strand 8. DNA polymerase III makes Okazaki fragment of lagging strand 9. DNA polymerase I removes RNA primer replacing it w/ DNA 5'→3' 10. DNA ligase closes gap in sugar phosphate backbone

Question 34

You are studying DNA replication in your lab and decide to mutate DNA primase. What is the most likely scenario that you will observe? A. SSBP did not attached to the DNA B. No replication bubble was formed C. DNA polymerase III did not attached to the DNA D. Semiconservative replication occurred …

Answer 34

C. DNA polymerase III did not attached to the DNA

Question 35

DNA pol I

Answer 35

* 5'→3' DNA polymerase activity * 3'→5' exonuclease activity, proofreading * 5'→3' exonuclease activity, RNA primer removal and DNA repair

Question 36

DNA pol III

Answer 36

* main replication enzyme (many subunits) * 5'→3' DNA polymerase activity * 3'→5' exonuclease activity mediates proofreading

Question 37

DNA polymerase adds correct nucleotide via formation of

Answer 37

phosphodiester bond

Question 38

Leading strands

Answer 38

* DNA synthesized in one long molecule * DNA primase makes a dingle RNA primer * DNA polymerase adds nucleotides in 5'→3'

Question 39

Lagging strand

Answer 39

* synthesized discontinuously * lagging strand is looped * DNA polymerase moves away from fork 5' to 3' (okazaki fragments) * Okazaki fragments= RNA primers plus DNA

Question 40

DNA Damage

Answer 40

* DNA are irreplaceable (RNA and proteins are replacable) * if damage is not repaired * point mutation- replacement of one bp * insertion and deletion mutations * due to environmental and normal metabilsm