MARKSCHEMES Flashcards
1
Q
Outline the gene transfer of plasmids
A
- plasmid is a small piece of circular DNA from a prokaryotic cell
- Plasmid removed from host cell
- cleaved open with restriction enzyme
- gene/DNA fragment from another organism cleaved by same restriction enzyme
- inserted into plasmid;
- spliced into plasmid by DNA ligase
- inserted into host cell
- host cell replicates, cloning the gene
2
Q
Explain how meiosis and fertilization can give rise to genetic variety
A
- random of bivalents / pairs of chromosomes
- maternal and paternal chromosomes could go to either pole
- eg. over 8 million in humans
- crossing over
- exchanges of material between homologous chromosomes
- segregation of alleles in meiosis
- combination of alleles are of broken up
- fertilization makes new gene combos
- random fertilizations may occur
- eg over 64 mil in humans.
3
Q
Sickle cell anemia is a serious disease caused by a single base substitution. explain
A
- mutation is a change in DNA sequence
- Changes the mRNA during transcriptions
- changes the amino acid sequence
- substitution mutation / changes to one codon
- glutamic acid is changed to valine /GAG to GTG
- changes the shape of the hemoglobin/ hemoglobin becomes less soluble and crystallizes out;
- cannot carry oxygen well
- red blood cells sickle / impairs blood flow
- causes other health problems / anemia
- sickle cell anemia caused by two mutated alleles
