TMC 1

Question 1

How big is the human genome, how many base pairs in the human genome?

Answer 1

3,000,000,000 base pairs of DNA

Question 2

How many copies of the human genome in a somatic cell?

Answer 2

2 copies

Question 3

How many chromosomes in a human somatic cell?

Answer 3

46

Question 4

How many chromosomes in a single human genome?

Answer 4

23

Question 5

How many genes in the human genome

Answer 5

Over 80,000

Question 6

How many protein coding genes in the human genome?

Answer 6

21000

Question 7

How many non-coding genes in the human genome?

Answer 7

60000

Question 8

What is the difference between a protein coding gene and a non-coding RNA gene?

Answer 8

Coding genes encode proteins - mRNAs
Non-coding genes encode rRNAs, tRNAs, microRNAs and long non-coding RNAs

Question 9

Name the bases in DNA

Answer 9

Adenine, Thymine, Guanine, Cytosine

Question 10

Name the bases in RNA

Answer 10

Adenine, Uracil, Guanine, Cytosine

Question 11

What are the DNA base pairing rules?

Answer 11

Adenine pairs with thymine held by 2 hydrogen bonds
Guanine pairs with cytosine held by 3 hydrogen bonds

Question 12

What is the difference between dATP and ATP?

Answer 12

There is a hydroxyl group connected to carbon 2 of ATP but only a hydrogen atom to carbon 2 in dATP

Question 13

Which sugar is present in DNA and which sugar is present in RNA?

Answer 13

DNA - dATP
RNA - ATP

Question 14

What is the N-glycosyl bond?

Answer 14

Joins the bases to the ribose molecule in RNA and to the deoxyribose in DNA
Involves a N on the base and carbon 1 on the sugar

Question 15

Describe cytosine’s structure

Answer 15

Pyrimidine with oxygen attached to C2, and amino group attached to C4

Question 16

Describe thymine’s structure.

Answer 16

Pyrimidine with oxygen attached to C2 and C4, and methyl group attached to C5

Question 17

Describe uracil’s structure.

Answer 17

Pyrimidine with oxygen attached to C2 and C4

Question 18

Describe adenine’s structure.

Answer 18

Purine with amino group attached to C4

Question 19

Describe guanine’s structure.

Answer 19

Purine with oxygen attached to C4 and amino group attached to C2

Question 20

What is the difference between a purine and a pyrimidine?

Answer 20

A pyrimidine is a heterocyclic aromatic molecule (like benzene)
with a nitrogen (N) atom at positions 1 and 3
A purine is a pyrimidine fused to an imidazole ring

Question 21

Which bases are pyrimidines, and which are purines?

Answer 21

Pyrimidines - uracil, thymine, cytosine
Purines - adenine, guanine

Question 22

What is the sugar molecule in DNA and RNA respectively?

Answer 22

Deoxyribose, Ribose

Question 23

List the precursors of DNA

Answer 23

dATP
dGTP
dCTP
dTTP

Question 23

List the precursors of DNA

Answer 23

dATP
dGTP
dCTP
dTTP

Question 24

List the precursors of RNA

Answer 24

ATP CTP UTP GTP

Question 25

What is meant by 5’, 5’ phosphate, 3’ and 3’OH in DNA and RNA?

Answer 25

A strand of DNA or RNA has direction The strand goes from the phosphate at the carbon 5 on the sugar to the hydroxyl group on the carbon 3 of the sugar. Thus, the direction of a strand is from the 5' phosphate to the 3' -OH. Typically, this is written as 5' to 3'

Question 26

List the 12 key aspects of the structure of DNA?

Answer 26

2 strands Anti-parallel Base pairing rules Hydrogen bonds Double helix Base project into the middle of the helix Phosphates on the outside like a backbone Minor groove and major groove One turn is approx. 10.5 base pairs Complementary strands Able to tell the sequence of one strand if you know the sequence of the other Right-handed helix

Question 27

Explain what is meant by anti-parallel strands

Answer 27

One strand goes in a 5' to 3' direction Its complementary strand goes in a 3' to 5' direction

Question 28

Describe the B form of DNA.

Answer 28

Right-handed helix Pitch of 3.4 microns 10bps in one full DNA turn 0.34 nm distance between each base pair Major groove is 2.2nm wide Minor groove is 1.2nm wide

Question 29

What is RNA secondary structure and how can it form?

Answer 29

Complementary regions within RNA molecules can base pair with each other and form different types of secondary structure - intra-strand base pairing Common structures include hairpins, stem loops and pseudoknots