Bacterial Morphology Flashcards
Bacterial Morphology Def
Study of bacterial shape and structure
Colony Morphology Def
Study of bacterial colonies shape and colour. Can be seen by naked eye
Cell Morphology Def
Study of shape and colour of a single bacterial cell
What type of microscope can see viruses
Electron microscopes
Gram Positive Bacteria Outline
thick peptidoglycan wall and low cell envelope lipid, Stains purple
Gram Negative Bacteria Outline
Thin peptidoglycan wall between 2 bilipid membranes and high cell envelope lipid. Stains red/pink
Gram Staining
Crystal violet added (both blue), iodine makes dye less soluble (both blue), alcohol (positive = blue, negative = colourless) and neutral red (positive = blue, negative = red)
Most important stage of gram staining
Alcohol. Gram positive and negative have differnt colours. Gram positives low lipid content gets dehydrated and becomes impermiable. Gram negative has high lipid content gets extracted and get permiabilised
Ziehl Nelson Stain
Used in bacteria that can’t be stained by gram eg mycobacteria (due to high wax content in envelope and no cell wall)
How does alcohol permiabilise gram negative bacteria
Extract lipid from cell envelope
How does alcohol impermeabilise gram positive bacteria
Dehydrating cell
How is yeast gram staining differentiated from bacterial
Yeast cells are significantly bigger
Cocci Meaning
Round shaped
Bacilli Meaning
Rod shaped
Shapes of Bacteria
Coccus, Bacillus, spiral and curved
Cell arrangements
single, pair, chain, tetrads, clusters
Bacterial Cytoplasm Outline
80% water. Contains digestive/respiratory enzymes (catabolic) and cell wall synthesis (anabolic) enzymes. Suspendes ribosomes, a single double strand of DNA and a Plasmid. Site of bacterial glycolysis and TCA cycle
Bacterial Cytoplasmic membrane
Phospholipid bilayer (lipophilic internally, hydrophilic externally). Contains embedded proteins (permeases - transport). Selectively permeable to molecules (only small lipophilic can enter via diffusion). Site of bacteria ETC
Peptidoglycan Function
Main component of bacterial cell wall. Gives cell shape and prevents osmotic lysis. Synthesis prevented by penicillin. Acts as antigenic synthesis
Gram Positive Cell Envelope
Thick layers of peptidoglycan . Phospholipid bilayer with proteins embedded in membrane. Teichoic acid and lepteihoic acid in environment. Function Adherence to cells, antigenic surface and ion passage, cell wall containing LTA stimulates inflammation
Gram Negative Cell Envelope
Thin cell wall in periplasm (space between 2 membranes that contains hydrolytic enzymes). Lipoproteins attach outer membrane to wall. Membrane is phospholipid-LPS-membrane. Antigenic regulation through O antigen LPS. Multiple layers of moving
Gram Negative Sepsis Outline
LPS is an endotoxin binds to protein on monocyte/macrophage cells stimulating inflammation (resulting in fever, hypotension and rapid death)
Chemotaxis Outline
Movement of a bacterium towards chemoattracters and away from chemorepellents using flagella and pili on cell surface
Monotrichous Bacteria
Bacteria with 1 flagellum (in total)
Amphitrochous Bacteria
Bacteria with 1 flagellum on each side
What enable bacteria to turn around
Flagellar rotation. Flips bacteria over
Common Pilli Function
Adherence (attachment) to cells. Some bacteria change pilli to increase receptor
Conjugative Pili Function
Plasmid transfer from 1 bacteria to another
Spores Outline
Hard, dormant structures formed in response to extremes such as dehydration or intense heat. peptidoglycan rich cortex layer and a keratin coat. Only some gram positive bacteria can form spores, gram negative can’t (mainly bacxillus and clostridium)
2 Types of Spore Disinfection
Autoclaving (high temp 121 degrees Celsius, 15 PSI) and vapourised hydrogen peroxide
Capsules and Slime (outline)
Carbohydrate and protein layers. Protects from phagocytosis and promotes adherence. Capsules are more tightly associated then slime
Biofilm Outline
Protective layer and glue like substance that causes bacteria to stick to cells
2 types of bacteria
psuedomonas arguesa and staphyloccocus epidermis
