Chromosomes, Genes And DNA

Question 1

DNA / RNA contain

Answer 1

Sugar (ribose or deoxyribose )
Nitrogenous base ( A,G,T,C,U)
Phosphate

Question 2

Phosphodiester bonds form between…..

Answer 2

3’ carbon (free OH group) of one ribose and 5’ carbon (free phosphate ) of next carbon

Question 3

How do RNA bases form H bonds?

Answer 3

RNA single strand loops back on itself forming an anti parallel strand.

Question 4

Features of a DNA double helix?

Answer 4

2 independent polymers
Entirely complementary
One complete turn is 10bp
Space between each BP is 0.34nm
Purine and pyrimidines are planar and unsaturated
Major grooves (expose bases) and minor grooves

Question 5

Which nitrogenous bases BP and bonds formed?

Answer 5

CG 3 h bonds

AT AU 2 bonds

Question 6

Describe the beads on a string structures (decondensed chromosomes= chromatin)

Answer 6

In the nucleus each double strand DNA molecules is wrapped around his tones to form nucleosomes.

Question 7

What do nucleosomes then do?

Answer 7

Nucleosomes are also tightly packed into solenoid structures forming 30 nm fibres. These fibres are packed into several hierarchical loops to create highly condenses structures which are chromosomes (interphase ones) that are visible under a light microscope during cell division

Question 8

What is chromatin ?

Answer 8

DNA/protein complex that forms a chromosome

Question 9

Difference between miotic chromosomes and chromatin (interphase chromosomes)

Answer 9

Chromosomes are highly condensed fibres, genome is unexpressed so cannot replicate as condensed

Chromatin is decondensed, genome is expressed and therefore can replicate.