dynamic genomes

Question 1

eukaryotic homologous recombination

Answer 1

1. DNA souble strand break
2. exonuclease resects 5’ –> 3’ with RAD 50
3. 3’ overhangs and invades homologous sequence with RAD51
4. DNA synthesis fills gap - cross strand exchange
5. gymnastics to cross, cut and ligate

Question 2

bacterial homologous recombination

Answer 2

catalyze by rec enzymes

-both strands break and piece exchanged. cross outside strands and do gymnastics to actually exchange

Question 3

meisos and sexual reproduction

Answer 3

• law of independent assortment: alleles and chromosomes separate independently
• you get one of each chromosomal pair per gamete but could be from mom or dad (2^N possible gametes)
• many alleles for 1 gene and most people heterozygous–> unique individuals

Question 4

Transposable elements in genetic diversity

Answer 4

• LINE (have reverse transcriptase and can do transposition), SINE (use LINE reverse transcriptase), Alu sequences (cannot do transposition)
• small mobile DNA sequences
• retrotransposons move via RNA intermediate: then make DNA to insert
• create diversity by disrupting gene function, change gene expression, and unequal cross over

Question 5

how transposons create unequal cross over

Answer 5

transposons insert into a gene and cause misalignment

1. gene familes: misalignment causes duplications and deletions. duplications create similar set of genes, diff genes expressed at dif times
2. exon deletion/duplication: one chromosomes has double exons and other has a deleted exon
3. exon shuffling - an entire exon inserts itself into new gene

Question 6

retroviruses causing genetic instability

Answer 6

• single strand RNA made into dsDNA by reverse transcriptase
• integrate into host DNA:
  1. interupt gene function
  2. turn on neighboring genes
  3. incorporate neighboring genes into viral genome and pass it on to new host (often pick up unregulated growth factors and become tumors)