3.1.5.1 Structure of DNA and RNA

Question 1

Nucleotide definition

Answer 1

The monomers that make up polynucleotides (e.g. DNA, RNA)

Question 2

Nucleotide components

Answer 2

Phosphate group
Pentose sugar
Nitrogen containing organic base

Question 3

The components of a DNA nucleotide

Answer 3

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

Question 4

The components of a RNA nucleotide

Answer 4

Phosphate group
Pentose sugar
└ribose
Nitrogen containing organic base
└adenine, cytosine, guanine, uracil

Question 5

Phosphodiester bond

Answer 5

-condensation reaction between 2 nuclotides

└involving the elimination of water

Question 6

DNA molecule

structure

Answer 6

-double helix
-2 poly nucleotide chains
-sugar phosphate backbones
└phosphodiester bonds
-antiparralel
-hydrogen bonds between specific complementary base pairs

Question 7

Complimentary base pairing

Answer 7

-purine= double ring structure
└A,G
-prymidine= single ring structure
└T,G,U

DNA
└A+T, C+G
RNA
└A+U, C+G

Question 8

DNA

Structure to function

Answer 8

• 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 9

RNA molecule structure

Answer 9

Relatively short polynucleotide chain

Question 10

RNA

Types

Answer 10

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 11

DNA vs RNA

Answer 11

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