Lecture Six: DNA & RNA Structure

Question 1

What are the several key characteristics genetical material posses?

Answer 1

• Genetic material must contain complex information.
• Genetic material must replicate faithfully.
• Genetic material must encode the phenotype.
• Genetic material must have the capacity to vary.

Question 2

So why was the discovery of the structure of DNA so important for understanding genetics?

Answer 2

Without knowledge of the structure of DNA, an understanding of how genetics information was encoded or expressed was impossible

Question 3

what was Fredrick Meisher intrested in?

Answer 3

The composition of the nucleus

Question 4

True or False: Did Edward Chargraff agree that all four nitrogen bases were equal amounts?

Answer 4

False: He did not believe that they were all equal amounts

Question 5

What were the two strains that Frederick Griffith used?

Answer 5

S-strain: looked smooth and glossy

R-strain: lacked a capsule forming rough and irregular colonies when cultured

Question 6

What characteristics do the DNA helix A form have?

Answer 6

• Right handed helix
• Less H2O presented
• Shorter and wider than B-form

Question 7

What characteristics do the B form DNA helix have?

Answer 7

• Right handed helix
• Lots of H2O present
• Most stable physiologically

Question 8

What characteristics do the Z form DNA helix have?

Answer 8

• Left Handed helix
• Zigzag sugar phosphate backbone
• Stretches of DNA sequences (ie: CGCGCG…)

Question 9

A and T have how many hydrogen bonds?

Answer 9

Two

Question 10

G and C have how many hydrogen bonds?

Answer 10

Three

Question 11

How is Bacterial genomic DNA contained?

Answer 11

it is contained in a single double stranded + closed circular chromosome

Question 12

How are bacterial chromosomes organized?

Answer 12

compacted into loops by specialized proteins within the bacterial cell

Question 13

Genomic DNA in the eukaryotes are associated with what?

Answer 13

Histones to form chromatin

Question 14

What is in the first level of chromatin organization?

Answer 14

Each nucleosome consists of two molecules of each type of core histones [Eight in total]

Question 15

What happens in the second level of chromatin organization

Answer 15

• core histones are small and highly basic proteins

Question 16

What led to Fredrik Griffth to accidently find the function of DNA?

Answer 16

The pneumonia epidemic (at the end of ww2)

Question 17

What did Avery, Mcleod, and Mccarty discover? and how?

Answer 17

that DNA (not proteins) can transform the properties of cells, they did this by studying Streptococcus pneumoniae

Question 18

What does Avery, MacLeod and McCarty identify DNA as?

Answer 18

The transforming principle

Question 19

What did Hersey and Chase want to determine?

Answer 19

Whether proteins or DNA was the genetic material

Question 20

What did Hersey and Chase already know + did not know?

Answer 20

They knew that bacteria can be transformed by virus, they did not know which part of the virus did this

Question 21

What was used to label proteins? and why?

Answer 21

Sulphur b/c proteins contain Sulphur and not DNA

Question 22

What was used to label DNA?

Answer 22

Phosphorus

Question 23

What did Watson and Crick discover?

Answer 23

They discovered the double helix structure of DNA

Question 24

Who gave Watson and Crick the idea of the helical shape of DNA?

Answer 24

Rosalind Franklin- her photo (photo 51) discovered the helical shape of DNA

Question 25

What do Telomeres look like?

Answer 25

Small dots at the end of the chromosomes-they cap the ends of the chromosome

Question 26

Why is capping of the chromosome important?

Answer 26

protects the DNA from losing coding information during replication

Question 27

What several functions do the telomeres have?

Answer 27

• prevents the ends from fusing to other chromosomes
• prevents degradation from nuclease enzymes
• Help DNA repair mechanism to identify DNA breaks from chromosomal ends
• Helps in determining the number of times that a cell can divide
• important in determining the lifespan of an organism

Question 28

Why is the agouti gene silenced/tuned off?

Answer 28

Because it is methylated

Question 29

What happens when the agouti gene is turned on?

Answer 29

• Changes phenotype (color, size)

- higher chance of getting cancer, diabetes, and heart disease

Question 30

what food groups can help prevent the agouti gene to go into offspring?

Answer 30

foods with methyl groups

Question 30

what food groups can help prevent the agouti gene to go into offspring?

Answer 30

foods with methyl groups