31 Microbiology and Biotechnology Lecture Notes

Flashcards covering bacterial genetics (conjugation, Hfr cells, plasmids), biotechnology (genetic engineering, molecular cloning, electrophoresis), and methods of microbial control.

Transformation

One of the three methods of genetic diversity in prokaryotes alongside transduction and conjugation.

Conjugation

A form of horizontal gene transfer requiring direct contact between cells via a structure called a sex pilus, discovered by Joshua Lederberg in 1946.

Horizontal gene transfer

The movement of DNA between cells of the same generation rather than from parent to offspring.

F+ cell

A donor bacterial cell that contains the F plasmid and can form a pilus to connect to a recipient.

F- recipient cell

A bacterial cell that receives DNA during conjugation and can become an F+ cell after the transfer.

Hfr (High-frequency recombination) cell

A bacterial cell in which the F plasmid is integrated into the bacterial chromosome, allowing the transfer of chromosomal genes.

Plasmid

Extrachromosomal, circular, double-stranded DNA that exists independently of the chromosome and is self-replicating.

R plasmid

A type of plasmid that carries genes for antimicrobial resistance.

Col plasmid

A type of plasmid carrying genes for toxin production used to combat neighboring bacteria.

Vector

Carrier DNA, commonly a plasmid, used in genetic engineering to move a gene of interest into a host cell.

Restriction Enzymes (restriction endonuclease)

Enzymes that cut DNA at specific sequences, often palindromes, to isolate genes and open vectors.

DNA Ligase

An enzyme that joins a gene of interest with vector DNA by reattaching the DNA backbones.

Palindrome

A restriction sequence in which the sequence of base pairs reads the same forward and back.

EcoR1

A specific restriction enzyme sourced from the organism Escherichia coli.

Sticky ends

Complementary DNA ends left by restriction enzymes that allow foreign DNA fragments to anneal with target plasmids.

lacZ gene

A gene used in molecular cloning that leads to the production of the enzyme $\beta ext{-galactosidase}$; its disruption indicates successful insertion of foreign DNA.

DNA Electrophoresis

A method using an agarose gel and electric current to separate DNA fragments based on size.

Ethidium bromide

A staining agent used in DNA electrophoresis to make DNA visible under ultraviolet light.

Sterilization

The process by which ALL living cells, spores, and viruses are destroyed on an object.

Sanitation

The process of reducing the microbial population to safe levels, involving cleaning and disinfection.

Disinfection

The killing or removal of disease-producing organisms from inanimate surfaces, such as using Lysol.

Antisepsis

The removal of pathogens from the surface of living tissues, such as skin, using agents like Alcohol or Iodine.

Degerming

A microbial control measure achieved through hand washing.

-cidal agents

A broad class of antimicrobials that kill microbes, such as bactericidal or fungicidal agents.

-static agents

A broad class of antimicrobials that inhibit or control growth without necessarily killing, such as bacteriostatic agents.

Decimal Reduction Time (DRT)

Also known as the D-value, it is the time required for the death of $90\%$ of a microbial population; a lower value indicates a more effective disinfectant.