Bacteria Structural

Prokaryotes

obsolete as it’s a catch-all for small organisms that lack an internal membrane system

Cocci Shape and Arrangement

provides morphology for identification; big part of naming but not always

Cocci

spherical-like shape; can be strepto-, staphylo-, and tetrads

Streptococci

cells are in a line

Diplococci

pairs

Staphylococci

cluster/clumped shape

Tetrad

groups of 4

Bacilli

rods; length-to-width ratio differ; ex. coccobacilli are short and wide

Vibrios

comma shaped

Spirilla

rigid spiral-shaped; ex. food poisoning

Spirochetes

flexible spiral-shaped; ex. lyme disease (can burrow through tissues)

Mycelium

network of long filaments (hyphae)

Pleomorphic

organisms that are variable in shape

Legionella

identified as chains of rods (streptobacilli)

Bacterial Cell Size

can range from larger than a RBC to smaller than the largest virus; can’t say that bacteria is smaller than euks

What SA to Vol ratio do you want?

a high ratio because it increases efficiency of nutrient uptake and diffusion of molecules within a cell; essentially want where anywhere you are near the outside, you are near the core (want a high SA and low vol for more exchange w/ the exchange

Common Bacterial Structures

provides a structural separation, open cytoplasmic environment and motility; want direct access to nucleus-like region and other stuff; has a cell envelope and flagella for motility; everything is exposed to everything else (can transcribe and translate at same time)

Plasma Membrane Structure

similiar in composition to other types of cells; has diff. lipids to make it move sturdy; selectively-permeable for nutrients

Selectively Permeable Barrier

acquires nutrients using transport systems; eliminates waste; they don’t have homeostatic things around them so they have to deal w/ the random enivironments; detects and responds to surrounding chemicals (more sensitive to tinier level changes - move from danger and towards food);

Aquiring Nutrients using Transport Systems

have to deal w/ diff. conc. of things so may have to rely more or active transport than passive

Metabolic Processes

respiration and photosynthesis

Bacterial Lipids

properties to adapt to the environment; ex. cholesterol in mems. of euks. and bacteriohopanetetrol in bacterial membranes which creates rigid differences in the phospholipid

What do common nutrients do in bacteria?

form structures; complete cofactors for enzymatic fcn; all of the stuff we need, they need (makes us good food) and need these to replicate?

Uptake of Nutrients Methods

microbes can only take in dissolved particles across a selectively permeable membrane; microorganisms use transport mechanisms

Microorganisms Transport Mechanisms

passive diffusion, facilitated diffusion, primary/secondary active transport, and group translocation; transport dependent on environment

Transport is dependent on what?

the external environment; higher conc. → lower conc.

Passive Diffusion

depends on a gradient and lack of selective permeability w/ membrane like CO₂

Facilitated Diffusion

depends on a gradient and lack of selective permeabability w/ membrane (can be a channel or carrier)

Active Transport

can be utilized to obtain nutrients against the gradient; lower conc. → higher conc.; requires ATP or protom motive force (PMF) and carrier protein

Secondary Active Transport

can use PE of ion gradients to cotransport substances w/o modifying them; ex. uniporter, symporter, or antiporter

Uniporter

type of secondary active transport; just one thing going in/out

Symporter

type of secodary active transport; cotransporter; 2 things going in the same direction

Antiporter

type of secondary active transport; cotransporter; 2 things going in opposite directions

Group Translocation

chemically modifies the molcule as it is brought into the cell; important in salmonella

Phosphoenolpyruvate (PEP)

sugar phosphotransferase system (PTS); donates phosphate group

Siderophores

secreted by bacteria; complex w/ ferric ion for transport into cell; important transfer molecule; used bc microorgnisms need iron too and these iron close to membrane so cell can take it in

Bacterial Cell Walls

maintain shape of the bacterium and protects cell from osmotic lysis and toxic materials

Peptidoglycan

made up of amino acids and NEG/NAM; good for identification (ex. gram staining)

NEG and NAM

connects things together by either a direct connection (more rigid) or a peptide interbridge (more flexible)

Gram-Positive Cell Walls

composed primarily of peptidoglycan; features teichoic acid; has a plasma membrane inside the cell wall

Lipoteichoic Acid

allows cells to interact on outiside of the cell

Gram-Negative Cell Wall Structure

2 phospholipid bilayers with peptidoglycan in between; highly active periplasmic space including metabolic and transport traffic

Periplasmic Space and Peptidoglycan

very active metabolically

Lipopolysaccharide (LPS)

common glycolipid found in gram negative outer membrane; vital to cell stability; can be a pathogenic feature of the cell; one of the most imflammatory thing we can have in our immune system; has 3 parts - lipid A, core polysaccharide, and O side chain (O antigen)

Lipid A

buried in outer membrane

Core Polysaccharide

10 sugar structure joined to lipid A

O Side Chain (O antigen)

polysaccharide that extends outward from the core (can change)

LPS

contributes to negative charge on cell structure; helps stabilize outer membrane structure bc outer membrane is looser compared to peptidoglycan; creates a permeability barrier; host defense protection; acts as an endotoxin

Gram-Negative Membrane Transport

2 stage process; first solute crosses outer membrane into periplasm and then crosses plasma membrane; porins are essential to this

Lysozyme

breaks beta (1-4) bond between NAG and NAM; destabilizes wall on outside

What happens when a cell loses its cell wall?

in may survive in isotonic environments; for gram negative, the peptidoglycan helps cells resist in hypertonic environments

Extracellular Vesicles

not cells; can transfer genetic info between cells and transfer toxin molecules; can’t survive on their own (like bacteria satellites)

Glycocalyx

on outside of cell wall and important for protection, attachment, and interaction with other cells; ex. capsules, S-layer, and slime layer

Capsules

tightly wound phospholipid layer

Slime Layer

disorganized glycoproteins (cause of cavities)

S-layer

crystal/tile-like layer around a cell

Cell

a boundary between an enxtracellular environment and an internal environment

Protoplast

includes the plasma membrane and everything inside of it; essentially what is left after the cell wall is gone

Cytoplasm

contains ribosomes, inclusions, chromosome, and plasmids

Bacterial Cytoskeleton

made up of protein filaments that polymerize to form functional filaments that extend to full inner dimensions of the cell; made up of monomers (actin, microtubules, and intermediate filaments)

Actin Example

MreB

Microtubules Example

FtsZ

Intermediate Filament Example

CreS which plays a big part in the shape of a structure

How do some bacteria maintain their shape?

some type of tight rod-like things to pull it into the shape (CreS); can use KO experiments to show that w/o it it was filamentus/bacillus instead of vibrio

What can even be found in bacteria?

membrane structures for specialized purposes

Inclusions

segregate cellular components so they don’t diffuse freely in the cytoplasm

Microcompartments

not bound by membranes but compartments for specific functions; ex. carboxysomes

Carboxysomes

CO₂ fixing bacteria

Gas Vacoules

provide bouyancy to aquatic bacteria; allows it to change position; ex. CO₂

Magnetosomes

magnetite particles for orientation in Earth’s magnetic field; act like a compass

Bacterial Ribosomes

diff. size components and diff. structure than euk. ones

Nucleoid

location of chromosome and associated proteins; the chromosome bunches and and as it starts to collaspe, get interacting domains

Plasmids

extrachromosomal DNA; usually small, closed circular DNA molecules; genetic info passed through horizontal gene transfer; this is outside of larger chromosomal material

Pili and Fimbriae Functions

protection, attachment to surfaces, horizontal gene transfer, and cell movement

Fimbriae

stickiness to things/attachment; short and usually a lot of them

Pili

horizontal gene transfer using plasmids and other methods; long flagella-looking things

Flagellar Arrangement

helpful for identification; ex. monotrichous, lophotrichous, and pertrichous

Monotrichous

one singular flagella

Lophotrichous

tufts of multiple flagella at 1 or both sides

Peritrichous

swarming-like motion; a lot of them

Bacterial Flagella Parts

filament, basal body, and a hook; diff. in gram + vs gram -; motor-like part uses PMF which causes conformational changes of the ring so controlable, metabolic process

Flagella Filament

self-assemble w/ help of filament cap at tip, not the base; makes cap and pushes it out

Flagellar-based Bacterial Motility

swimming, swarming, and gliding; also chemotaxis and twitching

Swimming Motility

flagellum rotates like a propeller

ccw - forward run

cw - tumble

Swarming Motility

occurs when cells move in unison across a moist surface; usually uses peritchous flagella (highly controlled); ex. moving away from toxin

Spirochete Motility

axial fibril winds around the cell which allows it to burrow through tissues like a corkscrew

Twitching and Glidling Motility

short, intermittent, jerky motions; moves together by opening/closing the pili together

Chemotaxis

chemical attractants/repellents bind chemoreceptors that transmit signals throughout the chemosensing system; ex. tumbles (turns) more frequent when less food but slowly runs become longer and longer

Bacterial Endospore

complex, dormant structure; formed in response to lack of nutrients; not for reproduction but out of the need for survival; awaits detection of good nutrients

Endospore Structure

layered for a protective structure against adverse conditions

Sporulation

normally starts when growth slows due to lack of nutrients

Why are endospores bad for food safety?

since they are so resistant, they can survive through heat and other cooking porcesses that would kill other bacteria and then eventually they can come back

Endospore Formation

growth slows bc of lack of nutrients and continues through multiple stages

Endospore Formation Steps

activation → germination → outgrowth; cell divides → creates a septum → engulfs forespore (smaller “cell”) → cortex forms → coat and endospore maturation → original cell (big one) lysis

What happens to an endospore when conditions are favorable?

formation of vegetative cell the spore will activate, germinate, and complete outgrowth phase

From reading:

certain antibodies target cytoskeleton or inhibits protein synthesis (important bc bacteria’s ribosomes are different than euks.); murein ex of how to describes peptidoglycan (like glucose is a sugar)

MreB

bacterial actin; loops in bacteria

CreS

protein filament inside membrane