Microbial Growth: Cell Division and Population Measurement

Binary Fission

Cell growth continues until it divides into 2 equivalent cells

Cell Elongation

The cell expands to 2 times its usual size.

Parition/Septum

A wall stars to form at the center of the cell and constricts it into 2 separate cells.

Generation Time

Time required for the entire process of binary fission.

Divisome proteins

Proteins that control DNA replication and the separation of dividing cells

MinC

inhibits FtsZ polymerization

MinE

Counters the activity of MinCD division inhibitor at the mid cell division cite.

MinD

Oscillates between the cell poles and interacting with the other Min proteins to make sure the FsTZ ring is in the middle of the cell,

FtsZ

a protein that forms a ring along the mid-cell division plane to initiate cell division and create a septum.

MreB

Protein in a non-coccoid bacteria and some Archea that forms helical filaments on the surface of cytoplasmic membrane.

Non-coccoid

rod shaped

Growth Zone

In coccoid, Gram positive bacteria where peptodiglycan synthesis and cell wall growth, overlap of MreB and cell membrane.

Precursor Units

Monomers of peptodiglycan, chain of amino acids and two polysaccarides NAG and NAM.

Bactoprenol

Carrier molecule that moves precursor unit from the inside of the membrane to the outside.

Autolysin

Enzymes that cut peptodiglycan to create holes that are filled by new precursor units

Transglycosylase

Connects sugars of the precursor units

Transpeptidase

Connects peptides of the precursor units

Bacitracin

Inhibitor of bactoprenol function

Penicillin

Inhibitor of transpeptidase

Pencillin binding protein

Transpeptidase

Direct Slide Count

Count the microorganisms with a microscope

Peter-Hausser counting chamber

special glass slide with an etched grid that holds the cover slip 0.02 mm above the grid.

Viable Cell Count

Provide an accurate estimation of the amount of viable cells in a sample by inoculating multiple plates per serial dilution.

Spread Plate method

a plate count method in which inoculum is spread over the surface of a solid culture medium

Pour plate method

A method of inoculating a solid nutrient medium by mixing bacteria in the melted medium and pouring the medium into a Petri dish to solidify

Molten Agar

Melted nutrient agar that can be added in with a bacteria sample and solidified to determine viable cell count of original bacterial sample.

Turbidity

Bacteria growth makes the culture cloudy which can be measured by a spectrophotometer to find how much bacteria there is.

Spectrophotometer

Device that methods how much or what substance is there by shining a light through and measuring absorbance and the % Transmittance

Optical Density (OD)

A measure of the amount of turbidity. Frequently called absorbance.

Standard Curve

graph or curve generated from a series of samples of known concentration