Bacteria Structure and Function Flashcards
(61 cards)
Range of size of Bacteria
1-10micro meter
The envelope of bacteria consists of
Capsule: outer
Outer membrane.
Cell wall
Inner membrane
Function of the envelope
1) protect the cell against chemical and biologic threat
2) perform metabolic functions analogous to organelles of eukaryotes
Shapes of bacteria and example
Spherical -Cocci: > streptococci(chain cocci) staphylococcus( clustered cocci)
Rod shape : Baccilli > bacillus anthracis(straight rods), Vibrio cholera (curved rods).
Pleomorphic cocci: coccobacillus.
Spiral Shape
Is the chemical composition of bacteria similar with eukaryotes?
Yes, they have DNA, RNA, carbohydrates, proteins e.t.c
Features of capsule are;
It’s hydrophilic.
It’s transparent.
It’s not readily stained.
It’s a thick gel layer.
It’s layer is discrete
Polysaccharide are arranged
What’s the feature of a slime layer
It is amorphous
It’s polysaccharide are not arranged
Has other features of the capsule
Function of capsule or slime
Protects the bacteria against the immune system of the host
Example of bacteria without cell wall
Chlamydia and mycoplasm
Function of the cell wall
1) Protect the against mechanical disruption.
Protects the cell from bursting due to tugor pressure from hypertonicity of the inside.
Protects the cell from toxic chemical and biological effects.
It allows passage of nutrients and metabolic byproduct
How are bacteria classified in respect to staining
They are classified using gram stains.
Gram positive bacteria: stains fairly using gram stains e.g mycobacterium tuberculosis
Gram negative bacteria: stains poorly e.g Treponema pallidum(syphilis)
Components of cell wall of gram positive bacteria
Peptidoglycan cell wall , teichoic acid, lipoteichoic acid.
Composition of peptidoglycan cell wall
N-acteyl glutamic acid.
N-acteyl muramic acid.
This two are linked by peptide chains.
N/B: peptide chains crosslink to give the cell wall a 3D rigid matrix
Composition of teichoic acid
It’s either made of glycerol phosphate or ribitol phosphate.
Name two body enzyme that can digest peptidoglycan cell wall
Lysozyme and
Hydrolase from tears
Bacteria in isotonic fluid gives?
A round shaped structure called PROTOPLAST
What envelope does gram positive bacteria lack?
Outer membrane
What are the function of teichoic and lipoteichoic acids
✺✺ Teichoic and lipoteichoic acids
promote adhesion and anchor
wall to membrane
Envelope Features of gram- bacteria that differentiste it from Gram +
- It has outer membrane
- It’s peptidoglycan layer it’s smaller in size due to it’s reduction to form;
- Periplasmic gel.
- It has a well defined periplasmic layer.
How many leaflets does the outer membrane have and the composition
It has two leaflet;
Inner leaflet:, composed of phospholipid layer
Outer leaflet; composed of lipopolysaccharide.
Another name for Endotoxin is
Lipopolysaccharide
Components of an endotoxin
From inner to outer:
Lipid A..(made up of phospholipid and glucoseamine)
Core polysaccharide.
O’ antigen; binds to antibody of host and destroy it
What’s the structure protein seen in the outer cell membrane
Porin
What’s a periplasmic space?
It’s the space between the outer membrane and inner membrane, seen in gram - bacteria
