Bacteria Structure and Function Flashcards
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
What’s contained in periplasmic space
Periplasmic gel.
Composition of periplasmic gel?
It contains,
1: hydrolytic enzymes.
2: Antibiotic resistant enzyme.
3; Transport proteins
4: Chemotactic proteins
What’s the toxic moeity of lipopolysaccharide (Endotoxin)
Lipid A
Which cellular structure is functionally analogous to Mitochondria
The inner cell membrane;
It’s in charge of ETC , serving as the cell powerhouse.
What differentiates the cell membrane of a bacteria to that of eukaryotes.
What’s the exceptional Bacteria
It lacks steroids.
Exception: mycoplasm
List the function of inner cell membrane
1) It replaces fxn of mitotic spindle: segregating daughter chromosomes.
2)It serves as a site of DNA synthesis, cell wall and membrane lipids.
3) it contains ETC for ATP production.
4)it contains receptor proteins responsible in chemotaxis.
5) selectively allows permeation.
6) involves in secretion of proteins to the exterior, especially Exotoxins
What’s the functional equivalence of eurkayotic cell organelle.
Cell membrane
List the appendages of the cell walll
Flagella.
Pili
Fimbria.
Name the parts of the flagella
The basal body
The hook
And rings on central rod.
Function of flagella
Motility
What’s the significance of presence or absence of flagella
It helps in taxonomy classification.
Bacteria with one flagella is called
Monotrichous
Bacteria with many flagella on the cell
Peritrichous
Bacteria with many flagella on one end
Lophotrichous
Bacteria with a single flagellum on both ends
Amphitrichous
What are pili?
Hairlike projections on cell.
What’s the protein component of pili called
Pilin
Name to two type of pili and function
Common pili(fimbriae); adhesion
Sex pili: exchange of genetic material btw gram- bacteria cells.
Which bacteria has common pili and sex pili
Common pili: both
Sex pili: gram negative.
Core of the cell is divided into what regions
Granular region; cytoplasm.
Fibrous region; nucleiod
What’s the significance of the smallness and simplicity of Bacteria design
It facilitates rapid metabolic activities hence growth
Granular appearance of cytoplasm is due to;
The ribosomes
The target of certain antimicrobial in the core of the cell is?
The 70S ribosomes
What’s the functional of the cytoskeleton
It helps in localising proteins.
It participates in cell division.
It also confers strength to the cell wall.
The homologous of microfilament
Cytoskeleton
Microfilament of bacteria is made from
Actin
Microtubules of bacteria is made from
Tubulin
What forms the cytoskeleton
Actin, tubulin and intermediate filament
What’s the major mechanism of bacteria virulence
Modification of the cytoplasm
What does Genome mean?
Complete genetic information
Additional to the design of bacteria what other features aids it’s rapid growth
The absence of nuclear membrane.
Facilitates cell division
How many genes does bacteria antigens contain
600-6000genes
What’s the shape and type of strand of bacteria chromosomes
It’s circular and double stranded
Are mRNA transporters required in bacteria core
No they’re not, due to lack of nuclear membrane
What are plasmids?
Plasmids are small, circular, covalently closed
double-stranded DNA molecules different from chromosomes in the nucleoid
Functions of plasmids ?
The confer antibiotic resistance and
promotes bacteria virulence.
What genes are present in plasmids
Virulence and resistant genes
