Microbiology Lecture 2 - Chapter 3-4

Will not give structures and tell you to label them

Should know what 2 sugars that make it up:

Should know the number of proteins that are mentioned in the slides (like membranes are made up of 2 proteins to give an example

Peptidoglycan Structure

• Peptidoglycan is the structure that is responsible for linking the cell wall together

• It becomes a helical polymer made up of:

  • N-Acetylglucosamine (NAG)

  • N-acetylmuramic acid (NAM)

  • And attached by oxygen molecule (basically water since the O is attached to 2 H)

• Rigidity give specific shape while flexibility allows it to adjust to environment

• Not able to withstand osmotic pressure which is what causes cells without cell wall to experience lysis

• Can generate one backbone but they have to be linked together

• These peptides will be used to form peptide bridges and they will vary (don't need to memorize what they look like )

• Enzymes that target the structure vary due to the variations within the structures that link the peptides together

• They have learned to protect their structures tho (the amino acids protect against enzymes)

Gram Positive Cell Wall

Gram positive cell wall is unique bc it has thick peptidoglycan wall

Anchors: that anchor together the various layers of cell wall but allow its attachment to anchor to the plasma membrane itself

• They impart a neg charge on the cell wall

The lipid headgroups tend to be neg charged as well

• This is what causes some stains to stick

• They repel anything that is negatively charged

Periplasmic space is open to the outside. they're being Bacteria will release enzymes and they stay in this area

The cell wall is porous and they are large enough to let bacteria pick up what they need from the periplasmic space

Gram Positive cell walls also contain teichoic acids

• They are negatively charged

• Help maintain cell enveloped because they’re anchors to the plasma membrane

• Protect from environmental substances by acting as a repellent to other negatively charged things

• May bind to host cell in the case of a bacteria or pathogenic microbe

Random notes she mentioned:

- dont have extra compartment where they can select what to keep or what to send out

They can't digestive stuff in this periplasmic space

Gram Negative

Order of cell wall layer from outer to inner most:

1. Outer most wall composed of Lipopolysaccharide (O specific side chains)

   1. Includes porins

      Creates a hard shell around the typical bi-phospholipid layer

2. Bi-phospholipid layer with embedded porins and lipoproteins

   1. Brauns lipoproteins serves as anchor btw layer 2 and 3

3. Small layer of peptidoglycans

4. Final most inner cell wall comprised of phospholipids with embedded integral membrane proteins

LPS - Lipopolysaccharide

• Makes up the outer wall casing

Extensive periplasmic space

Much more complex due to the duel cell wall

Hydrophilic pores open to the external environment and they are large are not selective, this is passive transport

• Transport proteins and enzymes and electron carriers

Porins: water filled channel allows passage of molecules smaller than about 600 dallons

The inner layer of the outer membrane is the same structure of the inner membrane

LPS – Lipopolysaccharide

• Makes permeability barrier

  • restrict entry of bile, antibiotics, etc

• Protects pathogenic bacteria from host defenses by changing O antigen

  • Gram neg attract things that live within our gut and this o antigen will allow the body to recognize this pathogen as a threat so that it can get attacked

  • So basically the bacteria a baller and going incognito into your guts

Lipid A is a potent endotoxin

• May casually cause septic shock

Gram negative infection: If youre whole immune system is notified of a pathogen and it reacts as the whole, this could potentially cause high blood pressure and convulsion

• You would not use antibiotics that target the LPS

Endotoxin is only release when the cell lysis itself

Exotoxin is released as it is being activated

• Prevent this by stopping cell lysis of gram negative cells on a large scale

Glycocalyx

Glycocalyx: Coating of molecules external to the cell wall

• Layer of amino sugars

• Cant be washed off and allows them to adhere to surfaces

• Allows water to be stored around the wall and remain hydrated

Two types:

1. Slime layer: twitching motility

2. Capsule: K antigen

A layer of mucus that protects them

• Kind of a biofilm

• Has them remaining slippery (this is good for viruses)

Negative stains will let you know if the microbe has a capsule

S layers

• Regulatory structured layers of protein or glycoprotein that self-assemble

• This is like some armor

  • Protects from ion and PH fluctuations, osmotic stress, enzymes and predation

• Involved with the growth of the cell wall - helps in cell wall synthesis and maintenance

• Involved in cell division

In gram negative bacteria the S layer adheres to outer membrane

In gram positive bacteria it is associated with the peptidoglycan

^ basically in both it is on the outer most layer

• Maintains the shape and rigidity

External structures

• Fimbriae

  • Hairlike bristles that are used to attach to a surface; e.coli is an example

    • Are a lot more numerous on the body

    • Adheres to other surfaces or microbes

• Pili

  • Diff bacteria are able to synthesis tubes made up of protein that can anchor other microbes towards their body

  • A form of sexual reproduction since the anchoring leads to reproduction

  • Less on the body (looked like 2-4 max)

• Flagella

  • Threadlike locomotor appendages extending outward from plasma membrane and cell wall

  • Functions

    • Mobility and swarming behavior

    • Attachment

    • May be virulence factors

  • Come in different arrangements and with different amounts depending on the goal of the bacteria

  • Structure

    • Gram neg bac and pos are different but they both have the filament which will help it propel itself; it is embedded into the onvola/membrane itself from the basal body (part of the flagella)

Bacterial Flagellar growth

Have ribosomes that assemble proteins that will associate with the inner phase of the plasma membrane and will transfer RNA that is the blueprint for the flagellar protein. There are no ribosome in the periplasmic space so that means that everything out of the plasma is assembled and pushed through the basal body

• The ribosome has help of cap proteins with one job on the outside of the cell wall (typically know the structure of the flagella

Mechanism of Flagella

The flagella

Basal body is the mechanism that performs the movement

The mechanism of the energy using that allows for movement (it uses the charge/proton gradient)

• The bottom disc of the basal body does the twisting movement (basically the rotor)

Many strains that are antigenically

• O antigen

  • Somatic antigen

• H antigen

  • Flagella antigen

• K antigen

  • Capsular fimbriae antigen

^ this allows you to know what type of microbe it is (goal and mechanism)

Motility

• Flagella move in to different directions (counter and clockwise)

Bacteria and archaea have directed movement

• Chemotaxis: directional movement towards or away from something

Move in response to

Movement

• Tumble (clockwise)- halting movement or change direction

• Run (counter) - pushing forward

• Twitching motility - bacteria with pili do this to move around using the pili (not for sex)

Chemotaxis

• directional movement towards or away from something

• Can have positive or negative chemotaxis

When no gradient of nutrients, they just tumble in a lost fashion, this means they most likely have chemoreceptors

Swarming

It is not understood

Bacteria always form a pattern when you put them under similar conditions

They stay as a little colony and move as a colony

Spirochete motility

Spirochete mobility: The flagella wraps around the body of the bacterium

• They have a corkscrew movement after taking this shape

• They're flexible (which separates them from

Specific to spirochete bacteria

The cytoskeleton

They don't

• have organelles

• Nucleus centered

• Rough endoplasmic reticulum

• Mitochondria membrane

FtsZ protein is what allows microbes to divide and remain together

Intracytoplasmic membranes

A lot of bacteria that perform respiration or photosynthesis or using nitrogen they have additional membranes due to the extra proteins necessary which means they will inc their surface area of the cell wall and membrane

This results in infolded membranes to inc surface area

Inclusions

Mechanisms to store glycogen and overall storage

Granules of organic or inorganic material that are stockpiles by the cell for future use

• Granules, crystals, globules

Some icnlusions are enclosed by single layered membrane (which help put things away)

• Membranes vary in composition

• Storage inclusions

  • Carbon storage

  • Phosphate storage

  • Amino acids

Diff microbes have ability to store different things

Micro-compartments

Micro-compartments: Organelles that help compartmentalize different functions

*not for storage

• Done by proteins

• Gas vacuole that made up of layers and layers of proteins

  • Makes it buoyant

• Magnetosome - align them with the earth's magnetic field

  • Linear arrangement

  • Attached to teh membrane

Ribosomes

Involved in protein synthesis

Can target bacteria ribosomes with antibiotic but spare our owns meaning they're a bit different

• Ribosomal RNA have protein and some are similar but some are different

• #S in font of the protein name is used to show how quickly they settle down and this difference can be used to target them

If they use their shape, they lose the ability to perform tasks

Nucleoid and Plasmids

Haploid:

Diploid: 2 copies of genetic material

Polyploid: Can have multiple copies of their genetic material

Nucleiod refers to the place that has the genetic material and mainly free of enzymatic reaction (its own little area)

• Needs to package it well or could be too long

  • Proteins tightly package it and is found in nucliod region

The main dna that has all the genes will be found in the chromosomal dna

Plasmids used to transform bacteria

Advantagous:

• F factor plasmid carries gene for fertility

• These are not essential for nutrient usage, waste productions

• R Factor plasmid allows to pass genes on

Endospores structure

Sometimes bacteria will make endospore and keep them around or use them

• They are survival structures and store them in a particular space within the cell

Endospores layers

Coat is most important layer; impenetrable layer

Cortex a lot of peptidoglycan

Core is dehydrated (has 70% water and needs a lot of water)

• This makes it stabilized

  • Hydration causes reactions (water needs to be there), if no water than there are no reactions happening

  • No metabolic reactions to happen, and no water changes the shape of the enzymes, therefore nothing happens

  • In a way its just dormant

*bacillus spores is what causes smell of rice after being sat out for a couple of days

Boiling spores will only germinate them

Spores grow and produce gas and thats why you shouldn't use cans that are deformed

Sporulation

Divides unequally (which not normal)

The endospore (free spore at the end) has to remerge >>> look at hte next slide for more info

ARCHAEAL Membranes

Composed of unique lipids

Have a monolayer

They have very stable chemical bonds which allows them to thrive in extreme environments

They have the ability to introduce ring layers

They dont have peptidoglycan but they have cell wall with similar structural integrity and function

Lysosomes dont work against them, their peptides are made up of ….

Ribosomes

Share same proteins with everyone but also have their own

GO OVER THE SLIDES LEFT OVER

Staph - violet positive

Mega - violet positive

Endospore - both, variable?

P aeru - red, neg

E. coli - red, neg

*membranes need a bi layer