Nucleic Acids

Question 1

Nucleotides structure
What’s it made up of?

Answer 1

Pentose sugar
Phosphate group PO42-
Nitrogenous base

Question 2

Nucleotide (monomer) -> polynucleotide (polymer)
What’s an example of a polynucleotide

Answer 2

Nucleic acids: these are long chains of nucleotides with phosphodiester bonds between them

Question 3

Where does the phosphodiester covalent bond form between in groups of adjacent nucleotides

Answer 3

5’ Phosphate group to 3’ hydroxyl group
Forms sugar phosphate backbone
This is formed by condensation

Question 4

Examples of nucleic acids

Answer 4

DNA & RNA

Question 5

DNA VS RNA
(helical, any extra forms, strands, pentose sugar present, bases present?)

Answer 5

Question 6

Purine vs pyramidine bases - how many rings

Answer 6

Purine - 2 carbon rings (larger bases)
Pyramidine - 1 carbon ring (smaller)

Question 7

Examples of pyramidines

Answer 7

Cytosine & Thymine

Question 8

Purine bases

Answer 8

Adenine & guanine

Question 9

Adenine -> Thymine how many H bonds

Answer 9

2 hydrogen bonds

Question 10

Cytosine -> Guanine how many H bonds

Answer 10

3 Hydrogen bonds

Question 11

Why is complementary base pairing key?

Answer 11

• DNA can be replicated without error
• same sequence of nucleotides produced = accurate
• reduces occurrence of spontaneous, random mutations
• allows formation of H bonds

Question 12

Example of phosphorylated nucleotides

Answer 12

ADP & ATP
Nucleotides with more than one phosphate group

Question 13

ADP & ATP similarity & difference

Answer 13

ADP = 2 phosphate groups
ATP = 3 phosphate groups
-> both contain a pentose sugar (ribose), a nitrogen base (adenine) & inorganic phosphates

Question 14

What is semi-conservative DNA replication

Answer 14

Each strand acting as a template strand, with each new DNA molecule formed has 1 old strand and 1 new one of DNA

Question 15

Steps of DNA replication

Answer 15

1. DNA unwinded by gyrase
2. DNA helicase unzips the DNA molecule, breaking the hydrogen bonds & separating the 2 strands
3. DNA polymerase forms phosphodiester bonds, joining adjacent free nucleotides together
4. C&G bind (3H), A&T bind (2H)
5. The sugar phosphate backbone forms by phosphodiester bonds

Question 16

How does the structure of DNA allow replication

Answer 16

Purines only bind with pyramidine
Complementary base pairings (C&G, A&T)
Double stranded
H bonds between complementary bases
Each strand acts a template

Question 17

The nature of genetic code traits

Answer 17

• universal (all living organisms use the genetic code: the same triplet = same amino acid in all organisms)
• degenerate (several codons / triplets code for the same amino acid; mutation may be silent, not changing the amino acid coded for)
• non overlapping (each base only ready as part of one codon)

Read as a triplet = each codon only codes for an amino acid

Question 18

What does the nature of the genetic code allow to happen

Answer 18

Genetic engineering and transferable info between species

Question 19

Transcription steps

Answer 19

1. DNA is copied into mRNA
2. Free RNA nucleotides line up by complementary base pairing to the template DNA strand, catalysed by RNA polymerase
3. mRNA carries a copy of the gene code out of the nucleus to ribosomes for protein synthesis

Question 20

Steps of translation

Answer 20

1. mRNA moves to the ribosome
2. tRNA anticodon binds to mRNA codon
3. tRNA brings specific amino acid
4. Peptide bond forms between adjacent amino acids

Question 21

Transcription (& translation) VS Dna Replication

Answer 21

Question 22

Transcription (& translation) VS Dna Replication

Answer 22