Chapter 3

Question 1

What is DNA?

Answer 1

DNA is the molecule by which hereditary information is transmitted from generation to generation.

Question 2

how does protein play a role in genetics?

Answer 2

proteins do play a role in heredity, they do so by supporting replication, error correction, and readout of the information encoded in DNA.

Question 3

Can genetic information be transmitted between two strains of bacteria?

Answer 3

• an experiment was done to prove this
• virulent bacteria and non-virulent bacteria
• He based this conclusion on the observation that one strain of bacteria (nonvirulent) was transformed into another (virulent) by an unknown molecule from the virulent cells.

Question 4

Which molecule carries genetic information?

Answer 4

DNA is the molecule responsible for transforming nonvirulent bacteria into virulent bacteria. This experiment provided a key piece of evidence for the idea that DNA is the genetic material.

Question 5

subunits of DNA

Answer 5

nucleotides

Question 6

what subunits form the backbone of the molecule?

Answer 6

5-carbon sugars and phosphate group

Question 7

Explain the transforming principle?

Answer 7

mice injected with a mixture of living R bacteria + heat killed S bacteria died

Some living R bacteria acquired traits from killed S bacteria => transformed

Question 8

brief transforming principle

Answer 8

substance from killed infective pneumonia bacteria could transform noninfective living pneumonia bacteria to the infective type

Question 9

what is the transforming principle?

Answer 9

In 1944 Avery, MacLeod & McCarty identified nature of Griiith’s transforming principle

Question 10

How did Avery, MacLeod & McCarty identified nature of Griiith’s transforming principle?

Answer 10

Broke down heat killed S bacteria and destroyed one class of molecules either Protein, DNA or RNA

Question 11

What happened when DNA was destroyed?

Answer 11

The transforming principle was lost

Question 12

three components of nucleotides

Answer 12

1. 5 carbon sugar ribose or deoxyribose
2. base containing nitrogen
3. 1/ more phosphate groups

Question 13

nucleotide bases

Answer 13

1. Pyrimidine bases - Cytosine, Thymine, Uracil
2. Purine bases - Guanine, Adenine

Question 14

what is a nucleoside?

Answer 14

nitogenous base + sugar

Question 15

What is Chargaff’s rule?

Answer 15

Abundance of purines = abundance of pyrimidines

A=T

C=G

Question 16

What did watson and crick propose in 1951?

Answer 16

double helix, sugar phosphate centre and bases outside

Question 17

what’s a phosphodiester bonds

Answer 17

bonds that connect adjacent deoxyribose sugars of the 4 subunits of DNA

Question 18

how many hydrogen bonds keep A and T held together?

Answer 18

2

Question 19

how many hydrogen bonds keep C and C held together?

Answer 19

3

Question 20

what contributes to the stability of DNA?

Answer 20

Hydrogen bonding and base stacking

Eg- 5’- GATC-3’

3’-CTAG-5’

Question 21

How many chromosomes does one DNA molecule form in eukaryotes?

Answer 21

1

Question 22

What protein is DNA packed with?

Answer 22

Histone

Question 23

how are chromatin formed?

Answer 23

Histones+ DNA

Question 24

function of chromatin

Answer 24

form of DNA that makes up the chromosomes in our cells

Question 25

what are nucleosome?

Answer 25

Nucleosomes are the basic units of DNA packaging.

Question 26

Key features of DNA

Answer 26

• double stranded helix, uniform diameter
• right handed
• antiparallel
• complementary base pairing A-T 2 hydrogen bonds, C-G by 3 hydrogen bonds
• outer edges of nitrogenous bases are exposed in the major and minor grooves