Bacterial growth Flashcards
How do bacterial cells divide?
Binary fission
1) elongation
2) formation of division ring
3) contraction of ring
4) separation of cells
How are bacterial populations measured?
Viable count - counts the living cells. Form serial dilutions and allow to grow, then count the colonies
Turbidity - does not take into account the death phase. Shine a light of a certain wavelength on the colony, the less light that gets through the higher the population.
What is chemotaxis?
Sensing and movement towards food (chemical energy)
Depends on the bacterias ability to sense and its motility - needs a flagella
The structure of flagellum
Rotating helical structure that allows motility by kinetic energy.
Attached to the cell envelope, the direction of movement depend on the position on the cell envelope.
What structures are found in all bacteria?
Peptidoglycan cell wall
Cytoplasmic membrane
Cytoplasm
Ribosomes
What structures are found in some bacteria?
Pili
Flagellum
Capsules
What structures are found only in G-ve bacteria?
Outer membrane
Periplasm
What structures are found only in G+ve bacteria?
Lipoteichoic acid
Describe the bacterial genome?
Haploid cells, reproduce through asexual reproduction. Have a circular genome, with little regulation (no intron), some have extra DNA called plasmids
How is DNA exchanged?
Horizontal gene transfer
Transformation - DNA uptake
Transduction - phage-mediated DNA transfer
Conjugation - Pilus-mediated DNA transfer (needs a sex Pilus)
Why can bacteria exchange DNA?
Plasmids can move more easily than chromosomes
