inheritance

Question 1

monohybrid inheritance

Answer 1

the inheritance of one characteristic controlled by the allele of one gene

Question 2

complete inheritance

Answer 2

when the presence/absence of only one dominant allele decides the appearance/phenotype of an individual

Question 4

haemophilia

Answer 4

x-linked recessive
- makes the blood unable to clot normally

Question 5

autosomal dominant

Answer 5

huntington’s disease
widows peak

Question 6

autosomal recessive

Answer 6

albinism, cystic fibrosis, sickle cell anaemia

Question 7

sickle cell anaemia

Answer 7

autosomal recessive

Question 8

what does sickle cell anaemia affect

Answer 8

the beta globin gene
normal haemoglobin (HbA) is protein found in RBCs that transport oxygen, made up of 4 subunits (2 alpha and 2 beta)

haemoglobin S is formed from sca instead of HbA due to mutations on beta-globin gene
1. base pair substitution of thymine to adenine
2. change in mRNA codon from GAG to GUG
3. non-polar and hydrophobic valine coded for instead of hydrophilic glutamic acid
4. polypeptide folds differently, exposing hydrophobic patch on outside of protein

Question 9

how does sickle cell anaemia affect health

Answer 9

When HbS releases oxygen, hydrophobic patch sticks out and associates with hydrophobic patch of other HbS molecules
1. polymerisation occurs, forming rigid, rod-like fibres
2. distorts biconcave shape of RBCs, forming sickle-shaped rbcs

Question 10

sickle cell RBCs

Answer 10

1. inefficient at transporting oxygen
2. clump and clog small arteries, obstructing other cells from moving through capillaries
3. deprive multiple organs of oxygen (organ failure)
4. shorter lifespan compared to normal rbcs, break down faster -> anaemia
5. accumulate in spleen for destruction -> enlarged spleen