chapter 2

Question 1

what type of bacteria did the Griffith experiment use?

Answer 1

-S strain: smooth infectious, has a polysaccharide coating around the cell
-IIS: type 2 coat
-IIIS: type 3 coat
-R strain: rough, harmless, has a mutation that prevents coat.

Question 2

describe the initial experiment (Griffith)

Answer 2

mice injected with
-S (heat): lived
-IIS living: died
-IIR: lived
conclusion: bacteria had to be alive and have coat to kill mice,

Question 3

describe the key experiment (griffith) and results

Answer 3

mice injected with:
- IIIS (heat): dead
-IIR living: dead
results: IIIS bacteria was found in the blood of mice.
*IIR transformed into smooth IIS by interaction with dead IIS bacteria.

Question 4

what is the transform principle?

Answer 4

Griffith concluded that an unknown agent transferred genetic material from the dead IIIS to the material in the living IIR.

Question 5

describe the controls and variables in the Griffith experiment

Answer 5

-positive control: mice living or dead
-negative control: needle did not kill mice
-independent variables: heat killing bacteria; (manipulated)
-dependent variables: live/dead mice; tested, (measured)
-confounding variable: age of mice, sex, needle (cannot be controlled).

Question 6

what were the potential transforming principles?

Answer 6

-protein
-DNA
-RNA
-Lipid
-CHO

Question 7

studied the transformation of R type bacteria to S type; found transforming variable

Answer 7

Avery Experiment

Question 8

Describe the Avery experiment procedure

Answer 8

broke open S bacteria and injected nuclease and IIR:
-RNASE + IIR= smooth
-Proteinase + IIR= smooth
-Lipase + IIR= smooth
-Carbase + IIR= smooth
-DNASE + IIR= no transformation
results: DNA was the transforming principle, providing IIR with the genetic material.

Question 9

describe the hersey chase experiment

Answer 9

used bacteriophage to determine whether DNA or protein entered the cell.
-infect e. coli with phages of isotope P or S (DNA contains phosphate and protein contains sulfur). = progeny phages
- e.coli were infected with progeny phages
results: most radioactivity of P was found inside. S was found in phage ghosts (outer layer)
*conclusion: DNA enters the cell and contains genetic info for the next generations.

Question 10

what are the monomers that make up DNA and RNA?

Answer 10

nucleotides: pentose sugar, nitrogenous base, and a phosphate group

Question 11

nucleoside

Answer 11

sugar and base

Question 12

what is the pentose sugar of DNA

Answer 12

deoxyribose: has hydrogen

Question 13

ribose: has hydroxyl group

Answer 13

pentose sugar of RNA

Question 14

purines

Answer 14

-adenine and guanine
-nine membered, double ringed

Question 15

pyrimidines

Answer 15

-thymine, cytosine, uracil
-six membered, single ring

Question 16

polynucleotides

Answer 16

5-3 prime, phosphate bonds with 3’ carbon of sugar of another molecule

Question 17

who concluded the 50-50 ratio of purines and pyrimides

Answer 17

Chargaff

Question 18

Rosalind Franklin

Answer 18

used x-ray diffraction: DNA was a helical structure

Question 19

Watson and Crick

Answer 19

-double helical structure, antiparallel, sugar-phosphate backbone, H bonds bases.

Question 20

chromatin

Answer 20

sustainable material in cell nucleus: DNA and proteins

Question 21

histone proteins

Answer 21

4 types: help organize DNA (wraps twice); have a plus charge
-H2A
-H2B
-H3
-H4
-H1: hydrophobic, brings other nucleosomes together, sticks between other histones.

Question 22

scaffold proteins

Answer 22

acid base proteins
- pull loops of DNA; stick to scaffold. makes shorter packaging

Question 23

euchromatin

Answer 23

less packaged. allows DNA to be copied, actively transcribed, genes can be expressed.

Question 24

heterochromatin

Answer 24

more packaged

Question 25

what happens during the G1 phase of the cell cycle:

Answer 25

-typical cell function
-1 chromosome
-1 chromatid

Question 26

S phase

Answer 26

euchromatin opens; DNA is copied

Question 27

G2 phase

Answer 27

-prepares for mitosis
-2 chromatids: double amount of genes

Question 28

mitosis

Answer 28

-chromatids pulled apart
-prophase, metaphase, anaphase, telophase

Question 29

G0 phase

Answer 29

resting

Question 30

specific set of sequences at the end of a linear sequence and is required for replication
-stabilize the chromosome
-short base sequence (2 per chromosome)

Answer 30

telomeres

Question 31

what are the two types of repetitive sequence DNA

Answer 31

LINE: long interspersed nuclear elements
- function: help regulate which genes will and will not get utilized, do not code for proteins. 15% genome
SINE: short interspersed nuclear elements

Question 32

unique sequence DNA

Answer 32

make up genes, single-stranded, proteins 2% genome/DNA
- 20,000 unique genes