dna , genes and chromosomes exam qs

Question 1

Define the term exon.

Answer 1

Base sequence coding for polypeptide

Question 2

Describe how a phosphodiester bond is formed between two nucleotides
within a DNA molecule.

Answer 2

Condensation (reaction)
(Between) phosphate and deoxyribose;

Question 3

Define ‘non-coding base sequences’ and describe where the non-coding
multiple repeats are positioned in the genome.

Answer 3

DNA that does not code for (sequences of) amino acids
(Positioned) between genes

Question 4

Define the term mutagenic agent

Answer 4

(A factor that) increases (the rate of) mutations;

Question 5

Why is the genetic code described as being universal?

Answer 5

the same triplet codes for the same amino acid

Question 6

DNA is a polymer of nucleotides. Each nucleotide contains an organic base.
Explain how the organic bases help to stabilise the structure of DNA

Answer 6

Hydrogen bonds between the base pairs holds two strands together
2. Many hydrogen bonds provides strength

Question 7

Describe how the production of messenger RNA (mRNA) in a eukaryote cell is
different from the production of mRNA in a prokaryote cell.

Answer 7

1. Pre-mRNA (only) produced in eukaryote (cell);
2. Splicing (only) occurs in eukaryote

Question 8

Suggest how PNA affected the transcription of the section of DNA.

Answer 8

PNA is complementary to DNA
Reducing/stopping transcription

Question 9

Suggest one advantage of showing the genetic code as base sequences on mRNA, rather
than triplets on DNA

Answer 9

(Because) ribosomes assemble polypeptides using mRNA code