Genetics Ch. 6

Front 1

Something from one strain of bacteria can "transform" another strain
1. Injected virulent S bacteria kills mice
2. Injected R mutant bacteria does not kill mice
3. Injected heat-killed S bacteria doesn't kill mice
4. Death DOES occur when R bacteria is mixed w S bacteria --> transformation
5. Recover living S bacteria

Back 1

Griffith Experiment

Front 2

Bacteriophage

Back 2

virus that infects bacteria

Front 3

Pyrimidine

Back 3

nitrogenous base containing a single ring

T and C

Front 4

Deoxyribose

Back 4

sugar within the nucleotide subunits of DNA

Front 5

Hydrogen Bonds

Back 5

noncovalent bonds that hold 2 strands of the double helix together

Front 6

Complementary Bases

Back 6

2 nitrogenous bases that can pair via hydrogen bonds

Front 7

Origin

Back 7

short sequence of bases where unwinding of the double helix for replication begins

Front 8

Okazaki Fragements

Back 8

short DNA fragments formed by discontinuous replication of the lagging strand

Front 9

Purine

Back 9

nitrogenous base containing a double ring

A and G

Front 10

Topoisomerases

Back 10

enzymes involved in controlling DNA supercoiling

Front 11

Meselson and Stahl Experiment

Back 11

-confirmed semiconservative replication
1. Control: E.coli grown in N14 medium. Produce a band after centrifugation.
2. E. coli grown in N15 medium. Produce a band after centrifugation.
3. N15 cells transferred to N14 medium. Cells replicate once. Centrifuged produce a band between the N14 and N15 band.
4. Cells replicate a 2nd time and centrifuged and produce an N14 band and an N14/N15 band.

Front 12

Lagging Strand

Back 12

strand that is synthesized discontinuously during replication

Front 13

Telomeres

Back 13

structures at ends of eukaryotic chromosomes

Front 14

Avery, MacCleod and McCarty

Back 14

-proved that DNA was the transforming particle
1. Nonvirulent R bacteria mixed with heat killed S bacteria. R bacteria get transformed to S bacteria.
2. Treat R cells with different chemicals.
a. Protease--> transformed S
b. RNase--> transformed S
c. DNase--> R Cells
d. Ultracentrifugation--> S cell
e.

Front 15

Transformational Frequency

Back 15

-2 genes that are closer together on the chromosome will end up on the same fragment after breakage of DNA for transformation.
-a high cotransformation frequency between 2 genes indicates that they're close together.

Front 16

Structures?
1. DNA with broken sugar phosphate bonds
2. DNA with broken sugar-base bond.
3. DNA with broken hydrogen bonds

Back 16

1. pairs of complementary nucleotides held together by hydrogen bonds and attached to a sugar
2. base pairs sugar phosphate chains
3. single stranded DNA

Front 17

Virus with
20% A
35% T
25% G
20% C
why?

Back 17

virus must be single stranded

Front 18

1.Why do A-T regions denature 1st during denaturation?

Back 18

1. A-T base pairs only have 2 hydrogen bonds; requires less energy to break them.

Front 19

Hershey-Chase

Back 19

-best evidence that DNA is the transforming substance, Bacteriophage T4, P-DNA and S-protein
-phage with P-DNA infects cells
-phage with S-protein infects cells
-cells are found to have P-DNA

Front 20

Chargaff's Rules

Back 20

A to T ration = 1

G to C ration = 1

A+G = T+C

Front 21

Nucleoside

Back 21

base+deoxyribose
dG, dA, dT, dC

Front 22

Nucelotide

Back 22

nucleoside+phosphate
dNMP, dGMP, dAMP, dTMP, dCMP

Front 23

B-DNA

Back 23

right handed spiral
-what we see majority of the time

Front 24

Z-DNA

Back 24

Left handed spiral
-found in vitro