Neucleic Acids.

Question 0

What are the two main category’s of nucleic acid?

Answer 0

Deoxyribonucleic acid. (D.N.A)

And Ribonucleic acid (R.N.A)

Question 1

What are nucleic acids?

Answer 1

These are very long polymers made out of subunits called nucleotides and as such is a polynucleotide.

Question 2

What are the three types of R.N.A?

Answer 2

mR.N.A (messenger R.N.A)
tR.N.A (transfer R.N.A)
rR.N.A (ribosomal R.N.A)

Question 3

What three parts are nucleotides made out of?

Answer 3

Ribose/Deoxyribose (pentose sugar).
Phosphoric acid.
Organic, nitrogenous base.

Question 4

What is missing on a ribose sugar to form deoxyribose?

Answer 4

The oxygen on the hydroxyl group at the C2 carbon is missing.

Question 5

What is the formula for phosphoric acid?

Answer 5

PH(OH)₃

Question 6

What are the two types of bases?

Answer 6

Purines and pyrimidines.

Question 7

What are the five bases?

Answer 7

Adenine
Guanine
Cytosine
Thymine
Uracil.

Question 8

What bases are purines?

Answer 8

Adenine and guanine.

Question 9

What bases are pyrimidines?

Answer 9

Cytosine
Thymine
Uracil

Question 10

Compare the sizes of purines and pyrimidines and explain how this is causes by the structure.

Answer 10

Purines are approximately twice the size of pyrimidines as they consist of two cyclical molecules joined together whilst pyrimidine bases are a single cyclical molecule.

Question 11

How does a nucleotide form?

Answer 11

The phosphoric acid bonds to the hydroxyl on the C5 carbon via a phospho-ester link.

The base bonds to the hydroxyl on the C1 carbon.

Question 12

What type of reaction occurs to join up the separate elements of a nucleotide and what byproduct is formed?

Answer 12

Two condensation reactions occur each giving off a water molecule so 2 molecules of metabolic water are given off for each nucleotide formed.

Question 13

How do two nucleotides bond to one another and what does this release?

Answer 13

Through a condensation reaction between the hydroxyl on the C3 carbon of one nucleotide and a hydroxyl on the phosphoric acid group on another releasing a molecule of metabolic water.

Question 14

What can be said about the spacing between bases in a nucleic acid.

Answer 14

As the method of bonding for all nucleic acids is the same the interval between their attached bases is fixed and they protrude in a single line.

Question 15

Describe the structure of D.N.A.

Answer 15

This is formed from two parallel polynucleotide chains whose bases are aligned so that they face each-other and are bonded together by hydrogen bonds between bases. These two antiparallel strands then coil around each-other to form a double helix. There are 10 base pairs to every coil of the helix. In addition due to the pyrimidine to purine base pairing the width of the molecule is fixed at a constant 2nm.

Question 16

What do you find when the number of A, C, T and G bases are analysed?

Answer 16

That the ratio of A/T=1 and the ratio of C/G=1. Therefore D.N.A must be a two stranded molecule in which A always bonds to T and C always bonds to G producing a molecule which is symmetrical around its axis.

Question 17

What is the function of D.N.A?

Answer 17

The molecule stores information for making proteins and is the hereditary molecule.

Question 18

What are the two strands in D.N.A called?

Answer 18

The coding and non-coding strands.

Question 19

What is he purpose of the non-coding strand?

Answer 19

This switches off the gene when it is not in use (I.e being copied)

Question 20

What is the purpose of the coding strand?

Answer 20

To hold the triplet code.

Question 21

What does each coding strand consist of?

Answer 21

A sequence of bases which form a gene.

Question 22

What do all genes begin with?

Answer 22

A start codon. Usually TTT.

Question 23

What does a gene end with?

Answer 23

A stop codon.

Question 24

Define a gene.

Answer 24

A sequence of nucleotide bases between a start and a stop codon.

Question 25

When is D.N.A replicated?

Answer 25

It is placated at the very end of interphase.

Question 26

What are the differences between D.N.A and R.N.A?

Answer 26

1 - D.N.A is two stranded, R.N.A is a single strand.
2 - The penthouse sugar in R.N.A is ribose while in D.N.A it’s deoxyribose.
3 - The base thymine in D.N.A is replaced by Uracil in R.N.A.
4 - R.N.A comes in three forms while D.N.A comes in only one.