Lecture 21: Methods of Genetic Transfer

what is genetic recombination

exchange of genes between DNA molecules to create new combination

Why is recombination important?

increase in genetic diversity

What is vertical gene transfer?

Transfer of genes from parent to offspring

What is horizontal gene transfer?

Transfer of genes between cells of the same generation

What happens to the recipient cell after horizontal transfer?

It becomes a recombinant

What are plasmids and transposons?

Mobile genetic elements outside chromosomes

Where are they found?

Both prokaryotes and eukaryotes

What are plasmids?

Small, circular, self-replicating DNA molecules

Where are plasmids commonly found?

Bacteria

What can plasmids code for?

Traits like toxin production and antibiotic resistance

What are R factors?

Plasmids that carry antibiotic resistance genes

What are the two parts of R factors?

RTF (transfer/replication genes), R-determinant (resistance genes)

What is a conjugative plasmid?

A plasmid that enables transfer via sex pili

What are dissimilation plasmids?

Plasmids that help break down unusual compounds

What are transposons?

DNA segments that move within the genome

What enzyme helps transposons move?

Transposase

What can happen if a transposon inserts into a gene?

it can inactivate the gene

What are Class 1 transposons?

Move via RNA intermediate (reverse transcription)

What are Class 2 transposons?

Directly insert into DNA

What are complex transposons?

Carry additional genes (e.g., antibiotic resistance)

What is transformation?

Uptake of “naked” DNA from the environment

What is conjugation?

ransfer of DNA via direct cell-to-cell contact

How does conjugation occur in Gram-negative bacteria?

Through sex pili

How does conjugation occur in Gram-positive bacteria?

Cells stick together via surface molecules

What are F+ cells?

Donor cells with the F plasmid

What are F− cells?

Recipient cells lacking the plasmid

What happens after conjugation?

F− cell becomes F+

What is transduction?

Transfer of DNA via bacteriophages (viruses

What is generalized transduction?

Random bacterial DNA is transferred

: What is specialized transduction?

Specific bacterial genes are transferred