L27 Flashcards
What is a nucleoid?
Single circular chromosome with no nuclear membrane, restricted within region called nucleoid
What are plasmids?
Separate, circular self replicating DNA
What is the cell wall of bacteria made of? and whats its functions?
Peptidoglycan
Rigid macromolecular layer providing strength
protection: from osmotic lysis and supports cell shape
What is transpeptidase?
-enzyme that cross links peptidoglycan to for rigid cell walls
What is the structure of peptidoglycan?
repeating units of NAM NAG (glycan chains)
Glycan chains linked together by cross bridge of amino acids
What is gram stain?
To differentiate between bacteria in bacterial culture
Gram positive is purple
Gram negative is red pink
Structure of gram positive (purple) cell wall
-thick peptidoglycan layer
-underneath is plasma membrane
Gram negative (pink) cell wall
Cell wall has two layers
Outer membrane
thin peptidoglycan layer (between outer membrane and plasma membrane
What is the function of flagella? and how does it work?
Provides bacteria motility in liquid
long flexible tails acts like propeller rotation
What is chemotaxis?
Bacteria move towards attractants (positive) and move away from repellents (negative)
what is the function of fimbriae?
Inherited trait of hair like adhesive properties to stick to surfaces
What is conjugative pili?
attachment to other bacteria to transfer genetic material (conjugation)
Form of horizontal gene transfer
What is glycocalyx?
Gelatinous polysaccharide and/or polypeptide outer covering
Forms a sticky meshwork of fibers to stick to things
What is capsule glycocalyx?
Organised defined structure attached firmly to cell wall
What is slime layer glycocalyx
disorganised without cell shape loosely attached to cell wall
What are the functions of capsule glycocalyx
Virulence factors (protection from phagocytosis)
prevent desiccation (prevent drying)
What are the functions of capsule glycocalyx
Virulence factors (protection from phagocytosis)
prevent desiccation (prevent drying)
What is the function of bacterial endospores
Protect cells from stress
How does bacteria reproduce? and what is the process called?
binary fission, division into 2 identical daughter cells
vegetative cycle
What are the stressors which cause endospor formation?
Nutrient starvation
high cell density
What is asymmetric cell division?
In stressed environment:
Mother cell develops endospore which moves to one pole of the cell
Mother cell dies and gives rise to mature endospore
