Nucleic Acids

Question 1

What does DNA stand for?

Answer 1

Deoxyribonucleic acid

Question 2

What does RNA stand for?

Answer 2

Ribonucleic acid

Question 3

Monomer of nucleic acids is…

Answer 3

… nucleotides

Question 4

What makes up a nucleotide?

Answer 4

Phosphate, pentose sugar and nitrogenous base

Question 5

What types of pentose sugar are there?

Answer 5

Deoxyribose (in DNA) and ribose (in RNA)

Question 6

What are the types of nitrogenous bases?

Answer 6

Adenine, thymine (DNA only), cytosine, guanine and uracil (RNA only)

Question 7

What are pyramidines?

Answer 7

Single ring structures eg. Cytosine, thymine and uracil

Question 8

What are purines?

Answer 8

Double ring structures eg. Adenine and guanine

Question 9

Describe the structure of RNA

Answer 9

Single stranded polynucleotide chain that is relatively short. Pentose sugar is always ribose and nitrogenous bases either A, G, C or U

Question 10

What are the types of RNA?

Answer 10

mRNA (messenger), rRNA (ribosomal) and tRNA (transfer)

Question 11

Describe structure of DNA

Answer 11

Double helix structure made of 2 polynucleotides, extremely long molecules. Pentose sugar always deoxyribose. Nitrogenous bases either A, T, C, or G

Question 12

How are the 2 polypeptide chains in DNA held together?

Answer 12

Hydrogen bonding between nitrogenous bases

Question 13

How are the nucleotides held together?

Answer 13

3,5 phosphodiester bonds, forming the sugar-phosphate backbone

Question 14

Describe the complimentary base pairings

Answer 14

T/U with A (2 hydrogen bonds) and C with G (3 hydrogen bonds)

Question 15

How is DNA adapted for its function?

Answer 15

Very stable structure so can pass through generations with rare mutations. 2 strands are held together by H bonds (weak individually) allowing strands to be separated in DNA replication. Extremely large molecule so carries a huge amount of genetic information. Function of gene depends on base sequence. Complimentary base pairs means DNA is replicated accurately.

Question 16

Why is DNA stable?

Answer 16

Phosphodiester backbone protects the bases inside double helix. Many H bonds are strong together

Question 17

Describe semi-conservative replication

Answer 17

DNA helix add (enzyme) unwinds molecule and breaks H bonds between complimentary base pairs.

Bases are exposed when strands separate allowing each strand to act as a template.

Free activated nucleotides found in nucleoplasm form H bonds to complimentary bases.

DNA polymerase joins adjacent nucleotides by forming phosphodiester bonds and rewinds molecule.

This forms 2 identical DNA molecules each with 1 original strand and 1 new strand

Question 18

What does ATP stand for?

Answer 18

Adenosine triphosphate

Question 19

What is ATP made of?

Answer 19

3 phosphate groups, ribose and adenine

Question 20

How is ATP a source of energy?

Answer 20

Energy stored in ATP is released by breaking off the third phosphate

Question 21

What does ADP stand for?

Answer 21

Adenosine diphosphate (one phosphate broken off)

Question 22

What does ATP hydrolase do?

Answer 22

Hydrolyses ATP into ADP and Pi (inorganic phosphate)

Question 23

What does ATP synthase do?

Answer 23

Condenses ADP and Pi into ATP

Question 24

What are the processes that synthesise ATP?

Answer 24

Oxidative phosphorylation, photophosphorylation and substrate-level phosphorylation

Question 25

Describe the properties of ATP

Answer 25

Releases energy is small amounts rapidly. One single bond broken so energy source not store. Always readily available. Very water soluble (therefore transportable) but cannot cross plasma membranes as it is polar, so requires protein carries to cross membrane.

Question 26

Describe the roles of ATP

Answer 26

Metabolic processes, movement, active transport, secretion of products from cells and activation of molecules