Nucleic Acids and Chromosomes

Question 1

List all the purine bases

Answer 1

Guanine Adenine

Question 2

List all the Pyrimidines

Answer 2

Cytosine Thymine Uracil (RNA only)

Question 3

What does a nucleotide consist of

Answer 3

Nitrogenous base Sugar Phosphate Group add pic

Question 4

What is the difference between a deoxyribose and a ribose

Answer 4

Deoxyribose lacks an oxygen atom that is present in the ribose add pic

Question 5

In the image below indicate which carbon is linked to the base and which one is linked to the phosphate? add pic

Answer 5

The 1’ C is linked to the base; the 5’ C is linked to the phosphate.

Question 6

What is the difference between purines and pyrimidines?

Answer 6

Purines have two rings whilst pyrimidines have one ring add pic

Question 7

Define nucleoside

Answer 7

Base + (deoxy)ribose = nucleoside NO PHOSPHATE

Question 8

Name the corresponding Nucleoside for the bases listed below. Adenine Guanine Cytosine Uracil Thymine

Answer 8

(deoxy)adenosine (deoxy)guanosine (deoxy)cytidine (deoxy)uridine (deoxy)thymidine Pyrimidines end with dine Purines end with sine add pic

Question 9

What is a nucleotide?

Answer 9

Base + ribose + phosphate = nucleotide add pic

Question 10

Name the nucleotide which consists of a adenine base bonded to 3 phosphate groups and a ribose

Answer 10

Adenosine triphosphate add pic

Question 11

Name the nucleotide which consists of a cytosine base bonded to 3 phosphates and a deoxyribose sugar.

Answer 11

deoxycytidine triphosphate (dCTP) add pic

Question 12

Explain the structure of DNA?

Answer 12

A long chain of deoxyribonucleotide units linked by phosphodiester links. The bases point inwards and the flat planes are perpendicular to the helix. The 3’-OH of sugar of one nucleotide is linked to phosphate group, which in turn is joined to 5’-OH of adjacent sugar. The chain has two ends, the 5’ end and the 3’ end. It is not symmetrical. The two chains are held togethere by hydrogen bonds between bases A and T C and G The secondary stricture of DNA is a right handed Double Helix, with the negative charges outside Phosphate sugar backbone add pic

Question 13

What bonds link nucleotides togethere

Answer 13

phosphodiester bond

Question 14

What is the primary sequence

Answer 14

linear sequence of the bases. by convention, the nucleotide sequence is specified in the 5’ to 3’ direction

Question 15

What is the secondary structure of DNA

Answer 15

right-handed double helix

Question 16

What does “ the chains are antiparallel” mean?

Answer 16

The chains are antiparallel - they run in opposite directions.

Question 17

Lable in the diagram below the minor and major groves? add pic

Answer 17

add pic

Question 18

Name ways of melting or disassociating the two strands of DNA.

Answer 18

High temperature or low salt concentration

Question 19

Name ways of re-annealing or hybridise two DNA strands?

Answer 19

Cool or high salt concentration

Question 20

Define karyotype

Answer 20

A karyotype is an organised profile of someone’s chromosomes

Question 21

What does chromatin condense into?

Answer 21

Chromosomes

Question 22

What is the lowest level of packing?

Answer 22

nucleosome

Question 23

What does a nucleosome consits of?

Answer 23

consists of DNA wrapped around histone proteins. add pic