3.1.5.1 Structure of DNA and RNA

Question 1

DNA function

Answer 1

holds genetic information in all living cells

Question 2

RNA function

Answer 2

transfers genetic information
from DNA to the ribosomes
in all living cells

Question 3

What are Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)?

Answer 3

Important information-carrying molecules

Question 4

What are ribosomes formed from

Answer 4

RNA and proteins

Question 5

Nucleotide components

Answer 5

Phosphate group
Pentose sugar
Nitrogen containing organic base

Question 6

Nucleotides

Answer 6

Complex chemicals
made up of an organic base, a sugar and a phosphate
They are the basic units of which the nucleic acids DNA and RNA are made.

Question 7

The components of a DNA nucleotide

Answer 7

Phosphate group
Deoxyribose sugar
Nitrogen containing organic base
└adenine, cytosine, guanine, thymine

Question 8

The components of a RNA nucleotide

Answer 8

Phosphate group
Ribose sugar
Organic base
└adenine, cytosine, guanine, uracil

Question 9

RNA

Bases

Answer 9

4 bases 
Specific and complimentary base pairs
└purine to pyrimidine
  └purine= A,G 
  └prymidine= C, U
└A + U, C + G
└purine= larger molecules
   └double ring structure
└prymidine= smaller base
  └single ring structure

Question 10

A condensation reaction between two nucleotides forms..

Answer 10

…a phosphodiester bond

Question 11

DNA molecule structure

Answer 11

Double helix
2 poly nucleotide chains
└sugar phosphate backbones
└antiparralel
  └strands run in opposite rirections parallel to each other 
└5’-3’
└phosphodiester bonds
└hydrogen bonds between specific complementary base pairs

Question 12

DNA molecule

Bonds

Answer 12

Held together by hydrogen bonds
└2 bonds between A + T
└3 bonds between C + G
└specific and complimentary base pairs

Phosphodiester bond
└in sugar phosphate backbone

Question 13

DNA

Complimentary base pairing

Answer 13

4 bases 
Specific and complimentary base pairs
└purine to pyrimidine
  └purine= A,G 
  └prymidine= C, T
└A + T, C + G
└purine= larger molecules
   └double ring structure
└prymidine= smaller base
  └single ring structure

Question 14

Purine

Definition + examples

Answer 14

E.g. Adenine and guanine

nitrogenous bases consisting of a double ring structure

Question 15

Prymidine

Definition + examples

Answer 15

E.g. Thymine, cytosine and uracil

nitrogenous bases consisting of a single ring structure.

Question 16

DNA

Location

Answer 16

Prokaryotic- cytoplasm
Eukaryotic- nucleus
Mitochondria, chloroplasts

Question 17

DNA

Structure to function

Answer 17

Very stable - can pass through generations without change

• weak hydrogen bonds: so double strand separates more easily for replication
• Extremely large molecule and therefore carries and immense amount of genetic information.
• By having base pairs within helical cylinder of deoxyribose-phosphate backbone the genetic information is protectted from chemical and physical forces.
• double standed: so replication can occur semi-conservatively / strands can act as template / complementary base pairings mean accurate replication/identical copies can be made
• sugar-phosphate backbone: provides stability/strength / protects the bases
• large: store a lot of information
• helix: so compact

Question 18

RNA molecule

structure

Answer 18

Relatively short polynucleotide chain

Question 19

RNA

location

Answer 19

Eukaryotes- nucleus +cytoplasm

Question 20

RNA

Types

Answer 20

mRNA (messenger ribonucleic acid)
└codes for chemical blueprint of protein in protein synthesis
└carries the complementary DNA/genetic information out of the nucleus to the ribosome for protein synthesis

tRNA ( transfer ribonucleic acid)
└protein synthesis- transports specific amino acid to the ribosome to be added onto the growing polypeptide chain
└carries amino acids

rRNA (ribosomal ribonucleic acid)
└ribonucleic acid component of the ribosome

Question 21

the relative simplicity of DNA led…

Answer 21

many scientists to doubt that it carried the genetic code

Question 22

DNA vs RNA

Answer 22

DNA= double stranded (double helix held together by H bonds)
RNA= single stranded

DNA= deoxyribose sugar
RNA= ribose sugar

DNA= bases- ATCG
RNA= bases- AUCG

DNA= long 
RNA= relatively short