Human condition, history and race

Question 1

Phenotype of malaria

Answer 1

HbSHbS Phenotype
- Chronic anaemia
• Defective sickle cells are cleared from the blood by spleen
• fatigue and shortness of breath
• jaundice & iron accumulation
• Sickled cells get trapped in small capillaries cutting off blood flow to tissues • Organ damage – death in childhood -> early adulthood
HbAHbS Phenotype
• Hemoglobin S tends to crystallize at low oxygen pressure -> cells burst
• Exposes Plasmodium to phagocytosis
• Less severe malaria symptoms. Less likely to die

Question 2

The effect of malaria on the alleles frequency

Answer 2

-IN Areas where malaria is prevalent That HbSHbS have ill health and can die early, means that they have less children. This provides a downward pressure on the HbS allele frequency. As individuals of the HbAHbS genotype less likely to suffer the extreme symptoms of malaria than the HbAHbA, this creates an upward pressure on HbS allele frequency.
Incidence of malaria a key factor in setting the HbS allele frequency in a population
-In Areas where malaria is absent That HbSHbS have ill health and can die early means that they have less children. This provides a downward pressure on the HbS allele frequency. As individuals of the HbAHbS genotype have no advantage so there is no upward pressure on HbS allele frequency.
The HbS allele frequency in population will be very low, only maintaining in a population by migration or mutation

Question 3

Darwin proposed

Answer 3

• That a population includes individuals of varying phenotype.
• Some phenotypes are more successful at reproducing (higher relative fitness) than others in a given environment.
• Those phenotypes will increase in frequency while their selective advantage is maintained.

Question 4

History of human

Answer 4

• Early homo sapien arose in Africa
• Migration out of Africa occur 200000 years ago
• Human reach China around 80-120000 years ago and Australia 50000
• Reach Europe around 45000 years ago
• Mitochondrial DNA and Y chromosome can be used to trace human history

Question 5

Overview of Human race

Answer 5

• Arose in Africa
• Our species is very young
• Migration out of Africa 200000 years ago
• limited variation in the African source population
• Most variation seen in human appear recently
• there is a small amount in human genetic variant when compared to other species
• On average, the DNA between two unrelated people is 99.5% in common

Question 6

What’s the difference between the genome of two humans?

Answer 6

• difference in 3-12 million nucleotide(out of 3 billion)
• Most of them occur in outside gene
• Those within the genes do not have a major impact on the protein function
• but all of us are heterozygous for recessive deleterious mutation
• There are also difference in cnv

Question 7

difference human Race

Answer 7

• Race is a social construct
• Skin is just one of our trait
• white skin does not exist but it is a lack of pigment
• Dark skin pigment protects the body from UV ray which is needed for vitamin D synthesis
• Dark skin is best for Africa climate