Microbiology 1 (bacteria structure + morphology)

what are the types of bacterial shapes

- round (cocci)

- rod (spore forming/non spore forming)

- spiral (vibrios - 1 curve/spirilli - 2 curves /spirochates - many curves)

Bacterial roll roll swissroll

what are the different cell arrangements of bacteria

- single (monococci)

- pairs (diplococci/diplobacteria)

- tetrads (div in 3 planes)

- chains (chain in 1 plane)

- clusters (random)

Single Pringles Talk Crap to Chicks

3 sizes of bacteria

- small (0.2 - 0.3um)

- medium (0.5 - 2um)

- large (3 - 10um)

list the organelles in bacterial cells

cell wall *

cell membrane *

cytoplasm

ribosomes *

inclusions

nucleoid *

plasmids

acting cytoskeleton

endospores

flagella

pilli (reproductive/attachment)

capsule

Captain Cell Cytoplasm Rang In Private Nucleoid After Earth Fell Captive to Pilli

what is the cell envelope made of

cell wall

cell membrane

what is cell wall made of

peptidoglycan (peptide part + glycan part)

glucan part (NAM + NAG + ß1,4 glycosidic bond)

describe cell wall of Gram+ bacteria

- thick layer of peptidoglycan

- negatively charged teichnoic acid on surface

describe cell wall of Gram- bacteria

- thin layer of peptidoglycan

- has 2 membranes (inside and outside of cell wall)

- Lipid A lypoprotein on outside of outer membrane

- perplasmic space (between 2 membrane, containing cell wall)

what are teichoic acids

found in Gram+ bacteria

within thick peptidoglycan wall

Lipoteichoic Acids: anchored to cell membrane beneath wall

Wall Teichoic Acids: extend out from cell wall

negatively charged (regulates ion transport)

what are functions of cell wall in bacteria

- controlls permeability: prevents leakage, transport of nutrients in and out

- protein anchor: for transport of substances

- energy conservation: Proton motive force (electrochemical gradient of H+ ions across cell membrane

what 2 things can damage cell wall

- lysozymes: digest disaccharides in peptidoglycan

- penicillin: inhibits peptide bridges in peptidoglycan

main features of cell membrane in bacterial cells

- target for Lipid dissolving agents

- lack inner membraned structures (golgi/SER/RER/ lysosomes/mitochondria)

function of bacterial cell membrane

respiration

permeability

peptidoglycan synthesis

chromosome replication

definition and functions of mesosomes

they are unfolding of the bacterial cell membrane

functions:

- respiration

- coordination of core material (DNA) + cytoplasm division

describe bacterial ribosomes

they are 70S ribosomes made up of a 30S and a 50S subunit.

(remember it's NOT 80S)

what are the essential organelles

cell wall

cell memebrane

nucleoid (DNA loop)

ribosomes

what are the non essential organelles (i.e. not present in all bacteria)

capsule

flagella

pilli

spores

Can Florish Persevere Survive

what are the 3 types of capsules

real

slime

microcapsule

structure of capsule

can be made up of polysaccharides OR polypeptides

staining if capsule

Klett / Neuffeld

function of capsule

- protection from antimicrobial agents/phagocytes/ etc

- adhesion

- antigenic

parts of flagella

filament (main part -made of flagellin)

hook

basal body (anchored to cell wall)

function of flagella

movement

virulence (protection from phagocytes/etc)

antigenic

receptor

types of pilli

- attachment pilli (adhesion to surfaces/other bacteria)

- sex pilli (facilitates transfer of plasmids)

what protein are pilli made of

pillin (also called fimbrillin)

function of pilli

adhesion

conjugation transfer (of DNA)

antigenic

what causes the formation of spores

stressful environmental conditions - very high temperatures or dehydration

types of spores (categorisation)

- location in cell: central/terminal/subterminal

- shape: round/oval

- capacity to deform the cell: deforming/non-deforming

2 ways of studying bacteria

native (not stain, living + unaltered bacteria)

staining (uses dyes, fixed bacteria)

types of staining

simple: Löeffler, Pfeiffer

complex: Gram, Neisser, Zhiel-Neelsen, Möller

what does Löeffler method use

methylene blue dye (blue stain ofc)

what does Pfeiffer method use

Neutral red dye

what colour is Gram+ staining

purple/blue

what colour is Gram- staining

red/pink

what is Neisser staining used for

volutine granules of corynebacterium diphtheriae

what is Ziehl-Neelsen staining used for

for acid fast bacteria

e.g. myobacterium tuberculosis

what are acid fast bacteria

they have a waxy, lipid-rich cell wall containing mycolic acid

don't stain well with Gram staining - used acid fast stain (fuchsine dye)

what is Klett staining used for

used to stain the capsule

what is Möller staining used for

used to stain spores

what is brightfield microscopy

what is Brightfield microscopy

- dark objects against bright background

​

what is Darkfield microscopy

- light objects against dark background

- enhances contrast in unstained samples

what is Flourescence microscopy

- uses UV light

- fluorescent substances absorb UV light and emit visible light

- sample can be stained with fluorescent dyes

what is immunofluorescence

detection of cells using fluorescently labeled antibodies

- antibodies bind to fluorochrome

- antibodies with fluorochrome bind to antigens on surface of bacteria

- makes detection possible

what are electron microscopes

- used electron beams instead of light to magnify objects

- have very high resolution

- smaller wavelength than visible light

- specimens must be stained with heavy metal salts

- 2 types: SEM (detects internal structures), TEM (produces 3D surface images)