Exam 2 Stuff

Merodiploid

Multiple copeis of genes in bacteria cell (Could be when F’ plasmid brings in new genes to bacteria)

Benefits of transduction

• Efficient

• Can survive harsh conditions

• Can carry large pieces of “foreign” DNA

Transduction steps

1) Phage infection

2) Destruction of host DNA and replication of phages

3) Phage protein components assembled

4) Mature phages are released

5) Infects another cell, bacterial DNA infected by phage

REC proteins

necessary to recombine new, incoming DNA to replace existing chromosomal info

Transformation steps

1) DNA fragment binds to receptor on cell and enters

2) Separates into two single strands

3) One strand degraded, the other recombines with homologous site

• Requires that there be homologous sequence in order for this to happen

• Advantage is usually fixing mutant alleles

4) After one round of cell division, a transformed and nontransformed product are formed

Interference

When regions near where a crossing over event happened are less likely to experience another nearby

Euploidy

The condition of having an integral number of sets (whole set) of chromosomes

Aneuploidy

Condition of NOT having an integral number of sets of sets of chromosomes

• When a chromosome BUT NOT a complete set is lost

• Just one is missing or gained

• 2n + x

Homeologous

Chromosomes in allopolyploid with similar but not identical chromosomes - cannot synapse during meiosis

Endopolyploidy

Condition where only certain cells or tissues are polyploid in a diploid organism

• e.g. liver cels in humans (4n or 8n)

• polytene chromosomes in some insects

Allotetraploid can form

trivalents and univalents during meiosis

Nondisjucnation

Cna occur in Meiosis 1 or 2

• Errors in crossing over

• loss of sister chromatid cohesion

• Defects in spindle assembly/disassembly

Two basic mechanisms of structural abnormalities

• Breakage and reunion

• non homologous recombination