Introduction to DNA

Question 1

What is the function of chromatin ?

Answer 1

To efficiently package DNA into a small volume to fit into the nucleus

Question 2

Would heterochromtin be labelled as the darker , dense region on a microscopic slide or the lighter region?

Answer 2

• darker regions

Question 3

Would euchromatin be labelled as the darker or lighter region on the microscopic slide of a nuclear DNA?

Answer 3

Lighter region

Question 4

Which of the two types of. Chromatin is responsible for the expression of genes ?

Answer 4

Euchromatin

Question 5

Is heterochromatin responsible for activation or deactivation of genes ?

Answer 5

• deactivation

Question 6

How do you change active chromatin to inactive chromatin ?

Answer 6

• DNA methylation

- histone deacylation

Question 7

How do you change from inactive chromatin to active chromatin?

Answer 7

• DNA demethylation

- histone acylation

Question 8

How many genes do humans have ?

Answer 8

25,000

Question 9

Define genome

Answer 9

Entire DNA sequence

Eg 24 chromosomes (22 plus chromosomes X and Y)

Question 10

What structural components make up a nucleoside ?

Answer 10

• BASE + SUGAR

Question 11

What structural components make up a nucleotide ?

Answer 11

BASE+ SUGAR + phosphate

Question 12

What is the difference between 2-deoxyribose and ribose sugar ?

Answer 12

• on the second carbon of deoxyribose , there is no OH group only a H. Whereas in ribose sugar ( in RNA) there is an OH group on the second carbon.

Question 13

On what carbon would you find a nitrogenous base on DNA/RNA ?

Answer 13

• 1st carbon

Question 14

On what carbon would you find the phosphate group on DNA/RNA?

Answer 14

-5th carbon

Question 15

What are the two categories nitrogenous bases can be placed in ?

Answer 15

• purines ( adenine , guanine)

- Pyrimidines ( uracil , cytosine , thymine)

Question 16

How many rings does purine have ?

Answer 16

2

Question 17

How many rings does pyrimidine have

Answer 17

1

Question 18

What would the DNA nucleoside be called - the one with an adenine base ?

Answer 18

Deoxyadenosine

Question 19

What would the DNA nucleotide be called - with an adenine base ?

Answer 19

• deoxyadenosine monophosphate (dAMP)

Question 20

What would the DNA nucleoside with Thymine base be called ?

Answer 20

Deoxythymidine

Question 21

What would the DNA nucleotide with a thymine base be called ?

Answer 21

Deoxythymidine monophosphate

Question 22

What would an RNA nucleoside be called - one with a cytosine base ?

Answer 22

Cytodine

Uracil ( uridine)

Adenine ( adenosine)

guanine ( guanosine)

Question 23

What would an RNA nucleotide be called with an uracil base ?

Answer 23

Uridine monophosphate

Question 24

How can you distinguish between a 5’ and 3’ end ?

Answer 24

• 5’ end would have a phosphate on the edge

- whereas a 3’ end would have an OH end

Question 25

How are RNA/DNA nucleotides joined by?

Answer 25

Phosphodiester bonds

Between the -OH group on the 3rd carbon of the pentose sugar and one oxygen from the phosphate group.

Question 26

How do bases join in opposite DNA strands ? And how many bonds between each C-G and A-T ?

Answer 26

Hydrogen bonds

3 hydrogen bonds between C-Gbases

2 hydrogen bonds between A-T.

Question 27

By convention how do you depict a DNA sequence ?

Answer 27

5’ to 3’ prime

Question 28

How do you describe a chromosome ?

Answer 28

• chromosome number , sex complement and any structural changes - separated by commas
• FOR EXAMPLE : 46th chromosome in a female : 46,XX- normal female