Growth and Division Flashcards
(47 cards)
Types of culture media
-Defined media
-complex media
Defined Media
-also known as minimal media
-made with purified chemicals so that exact composition is know: Glucose, amino acids, salts, buffer, vitamins.
Complex Media
-also known as undefined media
-made with digests of animal or plant products: yeast extract, casein (milk protein), soybeans, and beef extract
Growth Media: Defined Media
-works well for species with high biosynthetic capacity, as they have the ability to produce all of the amino acids, nucleotides, from basic carbon and nitrogen sources
Growth Media: Complex Media
-often required for species with numerous nutritional requirements
-many animal pathogens never grow outside the animal and so are never required to synthesize many required biosynthetic building blocks
Growth Media: Media used for Isolating/Identifying organisms within a mixed population
-common in clinical labs for identifying pathogens
Growth Media: Selective Media
-Contains compounds that inhibit the growth of certain organisms while allowing others to grow
Growth Media: Differential Media
-contains compounds that cause different colony appearance of different organisms. Often dyes that signal the presence of specific biochemical reactions.
Types of Growth Media
-Solid
-Liquid
Liquid medium
-allows for rapid and contrast mixing, so all cells are experiencing identical conditions at all times
-simple recovery and concentration of cells by filtering or centrifugation
Solid medium
-allows for isolation of individual colonies
-counting of individuals
-observation of colony phenotype differences
-isolation of pure culture
Bacterial Cell Division
Binary fission results in symmetric cell division.
Steps in Cell Division
-DNA replication and segregation (begins before start of division)
-Cytokinesis
-Synthesizing the new cell wall
What is Cytokinesis and what happens in this step of Cell Division?
-Splitting the cytoplasm in two septum formations
-choosing the center of the cell
-divisome formation
-invaginating the membrane
What happens in the synthesize step of cell division?
-polymerizing peptidoglycan strands
-cell shape determination
What is Fts?
-Fts protein
-stands for filamentation temperature sensitive
- a homolog of tubulin found in eukaryotic cells
-forms a hoop-shaped filament around the center of the cell
-linked to cytoplasmic membrane by Zip A and Fts A
What is GTP hydrolysis by and what does it do?
-GTP is hydrolysis by Fts Z drives filament shortening and thus membrane invagination
What is Fts I directly involved in?
-peptidoglycan synthesis in the septum
What are used to finding the Cell Center?
Min proteins
What does Min E do?
-oscillates from pole to pole, driving Min C and Min D away from the poles
What do Min C and Min D do?
-Because of Min E they are also constantly oscillating from one pole to the other
-inhibit divisome formation
-forms where Min protein concentration is lowest, at the cell center
What does the name Min come from?
-Minicell formation
What does Min D do?
-oscillates from pole to pole every 20 seconds.
How can you measure population growth?
-Direct Count/total count
-Viable Count
