Nucleic Acids and their functions

Question 1

Structure of a nucleotide

Answer 1

Phosphate group, pentose sugar, nitrogenous base

Question 2

Group of organic bases Adenine and Guanine are from

Answer 2

Purine

Question 3

Group of organic bases Thymine, Uracil and Cytosine are from

Answer 3

Pyrimidine

Question 4

Scientist who analysed DNA bases and what he realised

Answer 4

Erwin Chargraf
In DNA, A&T and G&C will have similar percentages
(Ratio of A:T is 1:1, G:C is 1:1)

Question 5

What is the function of DNA?

Answer 5

It is for replication and it stores the genetic code which controls sequences of amino acids in a polypeptide chain, controlled by a sequence of bases

Question 6

3 types of RNA

Answer 6

mRNA = messenger
tRNA = transfer
rRNA = ribosomal

Question 7

RNA polynucleotide structure

Answer 7

Phosphate group, ribose (a pentose sugar), nitrogenous base REPEATED (POLYnucleotide)

Question 8

What is the function of RNA?

Answer 8

Protein synthesis

Question 9

ATP structure (nucleotide)

Answer 9

3 phosphates, ribose, adenine

Question 10

ATP break down equation

Answer 10

ATP + water –> ADP + Pi (inorganic Phosphate) + energy

Reverse equation to show formation

Question 11

Enzyme that breaks down ATP

Answer 11

ATPase (made from ATP synthetase by mitochondria)

Question 12

Functions of DNA

Answer 12

Replication (makes copies for cell division)
Genetic code (instructions for synthesis of proteins)

Question 13

DNA replication

Answer 13

DNA double helix splits apart
Enzyme helicase unwinds and unzips leaving unpaired exposed bases
Free nucleotides (triphosphates) pair to exposed bases using energy from ATP, one phosphate left over is used to form phosphate backbone
New strand is made using old as a template
Winds back up - DNA polymerase (enzyme) zips back up

Question 14

How does DNA polymerase zip DNA back up?

Answer 14

The 2 strands of DNA are anti parallel however DNA polymerase only works in one direction. It works on the first strand. The second strand loops resulting in short strips which are joined together by DNA ligase. This allows DNA polymerase to work on the second strand

Question 15

How is DNA replication described?

Answer 15

Semi-conservative replication

Question 16

Why is DNA replication described as semi-conservative replication?

Answer 16

It uses one strand as a template for the new stand

Semi-conservative replication means half-the same copied

Question 17

Definition of genetic code

Answer 17

The set of rules by which information encoded in genetic material (DNA/RNA sequences) is translated into proteins (amino acid sequences) by living cells