DNA

Question 1

Structure of DNA

Answer 1

• phosphate group
• deoxyribose sugar
• organic base (A,G,C,T)

Question 2

2 Macromolecules in Chromosomes

Answer 2

• proteins

- DNA

Question 3

Griffith Experiment

Answer 3

• Frederick Griffith 1928

- experimented with pathogenic bacteria

Question 4

Virulent Strain

Answer 4

• S form (smooth)
• coated with polysaccharide capsule
• killed mice

Question 5

Non-Virulent Strain

Answer 5

• R form (rough)
• lacked capsule
• mice alive

Question 6

Griffith Experiment Cases

Answer 6

#1 - live S = dead mouse
#2 - live R = alive mouse
#3 - heat killed S = alive mouse
#4 - live R killed S = dead mouse

Question 7

Case #4 (Griffith Experiment)

Answer 7

live R took remains pieces of heat killed S and mutated

Question 8

Avery, MacLeod, McCarty Experiment

Answer 8

• transforming principle was not reduced by removal of protein
• concluded heredity material was DNA

Question 9

Hershey-Chase Experiments

Answer 9

“nail in the coffin”

studied viruses that infect bacteria

Question 10

Bacteriophage

Answer 10

host bacteria cell that virus invades

Question 11

Virus Structure

Answer 11

look up image

Question 12

Lytic Cycle

Answer 12

1. virus lands on bacteriophage
2. virus injects DNA
3. viral DNA takes over and replicates
4. new viruses form
5. cell bursts to infect other cells
   * look up image

Question 13

Key to Hershey-Chase Experiment

Answer 13

• radioactive isotopes “tagges” DNA and protein
• DNA tagged with 32P
• protein tagged with 35S

Question 14

Hershey-Chase Results

Answer 14

• found 32P inside the infected bacteria

HAD to be DNA

Question 15

DNA is made of _______.

Answer 15

nucleotides

Question 16

Large Bases

Answer 16

• purines
• double ring structure
• Adenine (A) and Guanine (G)

Question 17

Small Bases

Answer 17

• pyrimidines
• single rings
• Cytosine (C) and Thymine (T)

Question 18

Chargaff’s Rule

Answer 18

• Edwin Chargaff
• DNA molecules always have equal purines to pyrimidines
• A=T
• C=G

Question 19

Rosalind Franklin

Answer 19

• xray defraction

- DNA has regular structure shaped like a corkscrew

Question 20

Francis Crick and James Watson

Answer 20

elaborated on Franklin and Chargaff that DNA is a double helix

Question 21

Base Pair

Answer 21

because purine of one strand binds to pyrimidine of other strand, DNA keeps constant thickness

Question 22

Complimentary Mirror Image

Answer 22

• each DNA strand is a complimentary mirror image

- makes is possible for DNA to copy itself

Question 23

3 DNA Replications

Answer 23

• conservative
• semiconservative
• dispersive

Question 24

Conservative Replication

Answer 24

• 2 strands completely separate and act as template
• original strands rejoin
• look up image

Question 25

Semiconservative Replication

Answer 25

- DNA unzips for template - one half of original strand stays in both new strand * look up image

Question 26

Dispersive Replication

Answer 26

original and new strand are dispersed among both new | *look up image

Question 27

Meselson and Stahl

Answer 27

- tested 3 alternatives - used radioactive N isotopes to label DNA - DNA replication is semiconservative

Question 28

DNA Replication Enzymes

Answer 28

- DNA polymerase - helicase - DNA ligase

Question 29

DNA Polymerase

Answer 29

- builds DNA - adds correct complimentary nucleotide to growing daughter strand - can only add to existing and end

Question 30

Helicase

Answer 30

- unzipper | - created replication fork

Question 31

DNA Ligase

Answer 31

- superglue | - seals DNA fragments together

Question 32

Steps of DNA Replication

Answer 32

1. direction (3 prime end, 5 prime end) 2. phosphate backbone 3. deoxyribose sugar 4. nitrogenous bases w/ Chargoff's rule 5. hydrogen bonds 6. 3 phosphates attach free floating nucleotide

Question 33

Replication Fork

Answer 33

a primer must first be added to give a place for DNA polymerase to start

Question 34

Leading Strand

Answer 34

from 3 prime lead, builds in a continuous fashion

Question 35

DNA only builds in _____ direction.

Answer 35

one | *builds 5 o 3 lead

Question 36

Lagging Strand

Answer 36

- directionality is a problem - assembled in segments that are joined together - before segment come together, must get rid of primers - DNA ligase joins everything

Question 37

Lagging Strand Primer

Answer 37

okazagi fragment

Question 38

DNA Repair

Answer 38

- comparing daughter strand to parent DNA to check for mistakes - proofreading is not perfect because mutations are possible