Chapter 5 - Microbial Growth and Control. Flashcards
What is growth in Microbiology?
An increase in the number of cells.
What is binary fission?
Cell division by whereby a cell grows by intercalary growth to twice its minimum size and then divides to form two cells. As well as the fact that 2 cells have arisen from 1.
What is the generation time?
The time required for a cell population to double. Also called doubling time.
What are some of the factors that generation time depends on?
Nutritional and Genetic factors as well as temperature; different species have different requirements and generation times.
What are FtsZ proteins
proteins essential for cell division.
What is FtsZ?
A protein that forms a ring along the mid-cell division plane to initiate cell division. Just as Tubulin is an important cell division protein in eukaryotes.
What is a Divisome?
A complex of proteins that direct cell division processes in bacteria.
How does the formation of the divisome occur and what is the outcome of this process?
1) FtsZ molecules polymerize to form the ring, attracting other divisome proteins FtsA and ZipA. 2) ZIpA- an anchor that connects to the FtsZ ring and stabilizes it. 3)FtsA connects the FtsZ ring to the cytoplasmic membrane and recruit more divisome proteins such as FtsL-needed for peptidoglycan synthesis forming the divisome. The divisome orchestrates the synthesis of new cytoplasmic membrane and cell material called the division septum.
DNA replicates before the FtsZ ring forms because the ring forms between the duplicated nucleotide and effectively block the formation of the FtsZ ring. (T/F)
True
How do the Min proteins guide the FtsZ to the midpoint for cell division?
The proteins MinC,MinD, and MinE all interact with FtsZ to guide it to the midpoint. 1) MinD forms a spiral structure in the inner surface of the cytoplasmic membrane to localize MinC. 2) MinD spiral oscillates along the axis preventing FtsZ from forming. 3) MinE oscillates from side to side pushing MinA and MinC aside leaving the center with the least concentration and the most permissive site for the ftsZ to bind. As a result the Min proteins ensure that the divisome forms only at the cells’ center.
How does the 2 daughter cells form?
As elongation continues and septum formation begins. As the cell constricts the FtsZ ring depolymerizes, triggering the inward growth of the wall materials to form the septum and seal off the 2 daughter cells. FtsZ also hydrolyzes GTP to fuel the process of polymerizing and depolymerizing.
How does Genome Replication Keep up with fast growing cells?
Genome replication keeps up with fast growing cells because they are able to contain multiple replication forks where the new round of replication begins before the old one has been completed.
What is the major shape determining factor in bacteria?
MreB-a protein that forms the cytoskeleton of the in bacteria and some archea.
how does MreB define a cells shape?
It is thought that MreB localizes the synthesis of new cell wall to specific locations along the axis of the cell during growth. This allows the cell to wall to form at several points rather from a single location at the FtsZ site outward. By rotating the within the cell cylinder and imitating cell wall synthesis in such a way that a rod shaped cell only elongates along its long axis.
What protein in addition to the MreB is thought to be associated with the curved shape of Calobacter?
The curved morphology is thought to be due in part to the protein crescentin; this protein organizes itself into 10nm wide filaments that localize the concave face of the cell.
