dna genes and chromosomes past paper

Question 1

Name the fixed position occupied by a gene on a DNA molecule.

Answer 1

loci

Question 2

describe how a gene is coded for by a polypeptide

Answer 2

base nucleotide structure
in triplet
codes for specific sequence of amino acids for primary structure

Question 3

define exon

Answer 3

a base sequence coding for a primary strcuture

Question 4

give three differences between the DNA in plant cells and prokaryotic cells

Answer 4

plant cell has no plasmid
dna contained within a nucleus
dna is longer

prokaryotic cell
free floating dna
dna is shorter
no plasmids

Question 5

give three differances between the structure of dna in the chloroplast compared to in the nucelus

Answer 5

dna is smaller compared to the nucleus
it has fewer genes compared to the nucleus
it is not associated with histones

Question 6

give two reasons why genetic mutations in the nucletoide do not cuase a change in the DNA structure

Answer 6

because it occurs in introns - the non-coding part of the gene
some DNA is degenerate

Question 7

what does a homologous pair of chromosomes mean

Answer 7

two chromosomes that carry the same gene