SB3e - genetic variants and phenotypes

what does the genetic code do?

matches codons to specific amino acids

how is a mutation/variant created?

by a change in the bases of a gene

what can a variant/mutation be caused by?

DNA not being copied properly in cell division

what do dome mutations change?

an organism’s phenotype

what is the organism’s phenotype?

observable characteristics

what are alleles?

genes that exist in different forms

what is the reason why alleles exists?

mutations

what does haemoglobin contain? (to copy: α β)

four polypeptides of two kinds, α and β.

what do the polypeptides of haemoglobin do?

fold and join up to form a globular (spherical) protein, which carries oxygen

what disease can incorrect folding of haemoglobin polypeptide cause?

sickle cell disease

what is sickle cell disease?

red blood cells become sickle shaped and stick together, resulting in episodes of extreme pain

what else does incorrect folded chain of haemoglobin can cause?

red blood cells to break apart and cause shortness of breath

what causes genetic disorders?

mutations

what is the disorder GA-1?

a disorder caused by an enzyme that does not work but which should break down the amino acids lysine and tryptophan.

what do the amino acids lysine and tryptophan do in very lange amounts?

damage tissues and organs

what is the cause of the non-functioning enzyme in GA-1?

change in one amino acid

what does RNA polymerase attach to?

DNA bases in front of a gene

what does a mutation in the non-coding region may result in?

RNA polymerase not binding well to DNA bases in front of a gene, reducing transcription

what can mutation in the non-coding region cause? (to copy: β)

β-thalassaemia

what is β-thalassaemia?

when not enough β-polypeptide is made for haemoglobin

what does β-thalassaemia cause?

tiredness, weakness and shortness of breath

what can other non-coding mutation result in?

RNA polymerase binding better and producing more mRNA