Structure of bacterial cells Flashcards
What are the two classifications of microbe?
Prokaryotic
Eukaryotic
What microbes class as prokaryotes?
Bacteria
Archaea
What microbes class as eukaryotes?
Yeast
Algae
Protozoa
What do prokaryotic microbes express?
Cell wall
Flagella
Cytoplasmic membrane
Ribosomes
What do eukaryotic microbes express?
Nucleus
Chromosomes
Mitochondria
Chloroplasts
Describe the cell structure of a prokaryote
Cell wall Cytoplasm Nucleoid Ribosomes Cytoplasmic membrane
What is the capsule?
Present in some bacteria species
Polysaccharide gel surrounding the cell wall
Protects against adverse conditions to increase chance of survival
What is the capsule made of?
Polysaccharides
Single sugar polymerised e.g. glucose to glucan
Or
Repeat units of two or more derivatives e.g. glucosamine and glucuronic acid
What is the glycocalyx?
Loose meshwork of fibrils extending outwards from the cell
Helps adherence to surfaces
What is a gram stain?
Bacteria are either gram negative or gram positive
Based on retention of crystal violet/iodine
What will a gram stain look like?
If it is positive, will appear purple
If it is negative, will appear pink
What does coccus mean?
Round in shape
What does bacillus mean?
Rod shaped
What is a gram positive cell wall like?
Thick layer of peptidoglycan outside the cell membrane
What is peptidoglycan?
N-acetyl glucosamine
N-acetylmuramic acid
What is a gram negative cell wall like?
Membrane and outer membrane
In the middle is periplasm
Periplasm contains peptidoglycan
What is the difference in gram negative and gram positive peptidoglycan?
Gram positive has glycine linkages
Gram negative has linkages between different amino acids
What is present in a gram positive cell wall?
Peptidoglycan layer contains:
Lipoteichoic acid
Teichoic acid
Wall-associate protein
What is present in a gram negative cell wall?
Outer membrane contains: Lipoprotein (extending inward into periplasm) Proteins Porins Lipopolysaccharides
What are fimbriae?
Involved in adherence to surfaces
What is a type I fimbriae?
Expressed by gram negative bacteria
Highly inflammatory
Bind to macrophages, neutrophils, mast cells and lymphocytes
What are flagella?
Long thin appendages
Polar, appear at one end
Very thin
Chemotaxis
What is the name given to flagella located all over the cell?
Peritichous
What is the structure of flagella?
Helically shaped Made of flagellin Hook structure for base Mot proteins drive movement Fli proteins act as switch to reverse motor Energy from protonmotive force
What is a spore?
A resting cell
Highly resistant to desiccation, heat and chemical agents
What is the bacterial chromosome?
Found in the nucleotide
Contains a single long continuous circular double stranded DNA molecule
What are plasmids?
Extra chromosomal elements
