Microbial Cell structure Flashcards
What is the role of the capsid?
allows protection against adverse conditions including desiccation and the immune system
Contributes to invasiveness
Reduces opsonisation
Protection from phagocytosis
What is the capsid made out of?
Polysaccharide gel - high in water content
Single sugar polymerised
What is the glycocalyx?
loose meshwork of fibrils extending outward from the cell, plays a major role in bacterial adherence to surfaces
What are the two types of bacteria?
Gram positive
Gram Negative
What is the structure of a Gram negative bacterial cell wall?
Out lipopolysaccharide membrane
thinner peptidoglycan cell wall
Cell membrane
What is the structure of a Gram positive bacterial cell wall?
Thick peptidoglycan cell wall followed by the cell membrane
What turns pink in a gram stain reaction?
gram negative bacteria
What turns purple in a gram stain reaction?
gram positive bacteria
Describe the bacterial chromosome
a single long continuous circular double stranded DNA molecule
What is the other way that bacteria store their DNA
plasmids
often code for things such as antibiotic resistance
What is special about plasmids?
they can be lost or gained without causing damage to the bacterial cell
What is the basic structure of a prokaryote?
Capsule Cell wall membrane surface proteins naked DNA ribosomes Flagellum
What shape are Coccus bacteria?
Round
What shape are Bacilus bacteria?
Rod
What are the cell walls of bacteria made up of?
Peptidoglycan
What does peptidoglycan consist of?
Two sugar polymers:
N-acetyl glucosamine
N-acetylmuramic acid
What are the cell wall crosslinks between in a gram negative bacteria?
DAP and D-Ala
What are the cell wall crosslinks between in a gram positive bacteria?
l-Lys to 5x Gly to D-Ala
What are the role of fimbriae?
Involved in adherence to surfaces
No fimbriae = No disease
What is Type 1 fimbriae?
Expressed by Gram negative bacteria
Highly inflammatory
Bind to macrophages, neutrophils, mast cells, T/B lymphocytes
What is P-fimbriae?
Bind to Gal
Functional mimic of normal TNF pathway
What is the structure of flagella?
Helically shaped made of flagellin
Polar at one end
Base has a hook structure that connects to motor
What is the function of flagella?
Energy provided by protonmotive force to use the flagella for chemotaxis
What is the nuclear area of a prokaryote like?
Contains a single long continuous circular dsDNA molecule
