Bacterial cell growth dynamics Flashcards
1
Q
Outline cell division in bacteria
A
- Viable progeny must be achieved
- Bacterial genome = ‘simple’ chromosome
- Bacterial cell structure is not complex (no membrane bound organelles)
- As a result, cellular division is straightforward
- It is asexual reproduction
- No mitosis OR meiosis (that’s only in eukaryotes)
- Transfer of genes between bacteria is independent of division - plays no role in reproduction
- It is called binary fission
2
Q
Outline the basic steps of binary fission
A
- Replication of circular chromosome begins at the origin of replication (continues in both directions at once)
- Cell begins to elongate, FtsZ proteins go towards cell midpoint
- Duplicated chromosomes separate and move further away towards opposite cell ends, FtsZ proteins form a ring around periphery of the midpoint (between chromosomes)
- The FtsZ ring directs the formation of a septum (which divides the cell), the plasma membrane and cell wall materials accumulate
- Once septum is complete, cell pinches in two, forming two daughter cells - FtsZ is dispersed throughout the cytoplasm of the new cells
3
Q
What are Fts proteins?
A
- Filamentous temperature-sensitive proteins
- Essential for cell division in ALL prokaryotes
- DNA replicates BEFORE the FtsZ ring forms
4
Q
State some examples of proteins which interact to form the divisome (cell division apparatus)
A
- FtsZ = forms a ring around centre of the cell (related to tubulin)
- ZipA = anchor that connects the FtsZ ring to cytoplasmic membrane
- FtsA = helps to connect the FtsZ ring to the membrane and also recruits over divisome proteins (related to actin)
5
Q
State some examples of min proteins
A
- MinC = stops cell dividing too early
- MinD = recruits MinC to membrane
- MinE = stops CD acting in mid cell, to allow formation of z-ring in proper location
- MinCDE system ensures cell division occurs in the middle of the cell, but overexpression of MinC can stop cell division
