Lecture 5 - Microbial Growth

Genome Replication

The process by which a cell duplicates its DNA before cell division.

DnaA

A protein that binds to oriC and initiates the replication of DNA in bacterial cells.

oriC

The origin of replication in bacterial genomes where DNA replication begins.

SeqA

A protein that prevents reinitiating of genome replication by binding to hemimethylated DnaA boxes.

Z-ring

A structure formed by FtsZ protein that constricts the cell membrane during division.

Replisome

The multi-protein complex responsible for DNA replication.

Dam methylase

An enzyme that methylates DNA, specifically at GATC sites in oriC.

Min proteins

Proteins that regulate cell division by preventing the recruitment of FtsZ to the poles of the cell.

FtsZ

A protein that forms a ring at the future site of cell division and recruits other proteins necessary for cell growth.

Peptidoglycan

A polymer that makes up the cell wall of most bacteria, providing structural support.

Lag Phase

The initial phase of microbial growth where there is no cell division as the cells acclimate.

Exponential Phase

The phase in the growth curve where the population doubles at a consistent rate.

Stationary Phase

A period of microbial growth where the cell population stabilizes and growth ceases.

Death Phase

The phase where the viable cell count decreases due to the depletion of nutrients and accumulation of waste.

Psychrophile

An organism that thrives at low temperatures, typically below 15°C.

Thermophile

An organism that thrives at higher temperatures, often between 45°C and 80°C.

pH

A measure of acidity or basicity of an environment important for microbial growth.

Osmotic Pressure

The pressure required to prevent water from moving across a semipermeable membrane; affects microbial cell stability.

Obligate Aerobes

Organisms that require oxygen for survival.

Facultative Anaerobes

Organisms that can grow with or without oxygen.

Obligate Anaerobes

Organisms that cannot survive in the presence of oxygen.

Catalase

An enzyme that converts hydrogen peroxide into water and oxygen, protecting cells from oxidative damage.