CMB Lecture 6

Question 1

Three types of RNA

Answer 1

Ribosomal, Messenger, Transfer

Question 2

5’ end has the:

Answer 2

Phosphate group

Question 3

3’ end has:

Answer 3

-OH of sugar

Question 4

DNA nucleotide pairs:

Answer 4

A and T, G and C

Question 5

Nitrogenous bases are bonded by:

Answer 5

H-bonds

Question 6

DNA strands run ___ to each other.

Answer 6

Antiparallel.

Question 7

Which forces form between N bases?

Answer 7

VdW forces, as they are hydrophobic. This stabilizes the structure.

Question 8

Name the 3 bonds that help stabilize the 3D structure of DNA.

Answer 8

H-bonds, phosphodiester bonds, VdW bonds.

Question 9

Chromosomes are:

Answer 9

DNA paced together with with proteins.

Question 10

On histones:

Answer 10

8 clustered together, DNA warps twice around 8 histones. These are called nucleosomes.

Question 11

What does the protein scaffold do in chromosomes?

Answer 11

A core for fibre to loop and anchor

Question 12

Which nucleotide is replaced with another in RNA?

Answer 12

T, with U.

Question 13

Where is rRNA synthesised?

Answer 13

In the nucleolus.

Question 14

mRNA conveys information from __ to ___.

Answer 14

from DNA in the nucleus to the ribosome. Synthesized at a fast rate, degraded rapidly and is present in relatively small amounts.

Question 15

tRNA translates what?

Answer 15

Nucleotide sequence in mRNA to amino acids during protein synthesis.

Question 16

Anticodon:

Answer 16

loop binds to codon in mRNA

Question 17

Replication of DNA:

Answer 17

Parent molecule (Two strands) seperates, Daughter DNA molecules consist of one new parentla strand and one new strand.

Question 18

DNA replication is ______

Answer 18

semiconservative.

Question 19

DNA strands in prokaryotes separates from the

Answer 19

replication fork. Circular shape.

Question 20

How many origins of replication are there in prokaryotes?

Answer 20

One.

Question 21

How many origins of replication are in eukaryotes?

Answer 21

Many. Linear DNA molecule.

Question 22

In both prokaryotes and eukaryotes, DNA replication is ___

Answer 22

bidirectional.

Question 23

Helicase enzyme:

Answer 23

Unwinds DNA, breaks H-bonds, and separates the two strands. Also prevents bending and kinking.

Question 24

Topoisomerase:

Answer 24

Prevents overcoiling, releasing pressure from overcoiling, unwinds the overcoiled regions, forms temporary bonds between the DNA molecules.

Question 25

Single strand binding proteins:

Answer 25

Bind to a single strand to ensure they stay apart.

Question 26

Primer:

Answer 26

The first few nucleotides placed in replication are RNA. The RNA primer adds a 3’end for the DNA polymerase to bind to and add the first few DNA nucleotide.

Question 27

Primase adds a RNA molecule in which direction?

Answer 27

3’ to 5’ direction.

Question 28

Leading strand vs lagging strand

Answer 28

Continuous strand, lagging is discontinuous and fragmented. 5’ to 3’ end.

Question 29

Replication process is driven by ___

Answer 29

energy released from hydrolysis of the bonds between the phosphate groups in the nucleotide being added.

Question 30

New strand run from ___ and are ___

Answer 30

5’ to the 3’ end, and are antiparallel.

Question 31

End of chromosomes get progressively ___ each time cell divides.

Answer 31

shorter.

Question 32

Telomeres:

Answer 32

Protect ends of chromosomes. Prevents loss of genes near the ends.