3. GENES

Question 1

Outline the causes of sickle cell anemia.

Answer 1

• base substitution mutation
• GAG to GTG (on a sense strand)(CTC to CAC on antisense) (GAG to GUG on mRNA)
• glutamic acid to valine in beta hemoglobin chain (sixth aminoacid)
• changes the shape of hemoglobin and consequently red blood cells have sickle shapes
• cannot carry oxygen effectively
• fatigue
• forms clots within capillaries blocking blood supply
• low oxygen concentration seriously affects HbS shape
• homozygous HbS/HbS causes severe anemia at low oxygen concentration
• heterozygous only affected at low levels of oxygen
• otherwise heterozygous state provides protection from malaria

Question 2

Compare chromosome numbers in Homo Sapiens, Oryza Sativa and Canis Familiaris.

Answer 2

24 - Oryza Sativa
46 - Homo sapiens
78 - Canis Familiaris

Question 3

Compare number of genes in E.coli, Homo sapiens and Oryza sativa.

Answer 3

• 4200 E.coli
• 21000 Homo sapiens
• 38000 Oryza sativa

Question 4

Compare genome size in E.coli and Homo sapiens.

Answer 4

• 4.6 million base pairs E. coli
• 3.2 billion base pairs Homo sapiens

Question 5

Outline natural methods of cloning in some eukaryotes

Answer 5

• clones are genetically identical organisms
• identical twins
• binarry fission in amoeba
• budding in hydra and fungi
• fragmentation is starfish
• runners (horizontal stems that grow roots and develop into a plant)
• potato tubers

Question 6

outline somatic nuclear transfer

Answer 6

• somatic cell is taken and nucleus is extracted
• egg cell is taken and its nucleus destroyed
• somatic cell’s nucleus is implanted into the enucleated egg cell
• embryo is genetically identical to nucleus donor
• therapeutic (differentiate into needed tissues) or reproductive (produce a clone with the same traits)