Microbiology Exam 2 - Cells structure and Function (ppt 6)

Name the different morphologies of bacteria?

• rods/rod

• coccus/ cocci

• Spirillum/Spirilla (shorter)

• Spirochete (longer)

• Filamentous

• Vibrio (looks like a comma)

which protein generates the oscillation needed for bacterial cell division?

MinE

What are the different arrangements of Cocci?

• Diplococci

• Streptococci

• Tetrads

• Sarcinae

• Staphylococci/Micrococci

Diplococci:

remains in pairs, divides in one plane

Streptococci:

forms chains, divides in one plane

tetrads:

forms groups of 4 and divides in two planes

sarcinae:

forms cubes, divide at the right angles in three planes

Staphylococci/Micrococci:

forms irregular “bunches”, divides irregularly in many planes

What are the factors affecting evolution of the cell shape and size?

• surface area and volume

• Motility and attachment

what can surfaces area to volume ratio effect?

• Rate of Nutrient uptake

• Number of cells produced

Why can surface area to volume ratio affect nutrient uptake?

Higher S/V ratio means faster nutrient uptake '

Stalks have high S/V ratio

Small cells have higher S/V ratio

example: your digestive tract has a higher SV ratio

Why can surface area to volume ratio affect Number of cells produced?

• smaller cells can grow faster with fewer nutrient per generation (higher S/V ratio)

Motility:

• Rods have a greater capability for movement in specific direction

• Spirilli and spirochetes seem to have the greatest capability of moving through highly viscous media (this is because of the cork screw effect they have, they can get through more viscous media)

Attachment to surfaces: which structure do they use?

• Stalked bacteria tend to adhere to surfaces via their stalk

attachment to surfaces: What does the attachment do?

Stalk provide a high surface to volume ratio for nutrient exchange

Amphipathic Phospholipid bilayer:

a bilayer that is both hydrophobic and hydrophilic

Characteristics of a cytoplasmic membranes?

• phospholipid bilayer

• amphipathic

• fluidity

• 50% lipids and 50% protein

the proteins that make up 50 % of the cytoplasmic membrane are what kinds of proteins?

• Intergal Proteins

• Transmembrane proteins

• peripheral proteins

• lipoproteins - covenalently attached to a liquid

what do alot of peripheral protein get modified too?

lipoproteins for membrane

Not all intergal proteins are what

transmembrane proteins

All transmembrane proteins are what

intergal proteins

Bacteria and Eukarya use a phosphoglycerol backbone linked to lipids by what type of bond?

ester bond

Archaea use phosphoglycerol backbone and they are linked with what type of bond to phytanyl

ether bonds

what is phytanyl?

Phytanyl is composed of isoprene units

archaea can also have what?

monolayers

what is a monolayer?

A monolayer has 40 carbons. The more carbons, the more stable at higher temperatures.

what does the cytoplasmic membrane serve as?

Permeability barrier

  Energy conservation (AKA PMF, ATP synthesis!)

  Protein anchor.

what types of transports can be used to cross the cytoplasmic membrane

Passive transport and active transport

What type of diffusions are in passive transport?

simple and facilitated

why is a bilayer so much easier to get through verse a monolayer?

because bilayers become liquid at higher temperatures and gets to the point that it loosing its integrity

Permeability barrier

prevents leakage and functions as a gateway for transport of nutrients into and waste out of the cell

Protein anchor

site of proteins that participate in transport, bioenergetics, and chemotaxis

Energy conservation:

Site of generation and dissipation of the proton motive force

what is passive transport

movement down the gradient, no energy required

What is active transport

Movement up the gradient, energy os required

What is simple diffusion

small non polar and uncharged polar molecules

What is facilitated diffusion

• regulated by the cell

• requires channel proteins or carrier proteins

• selective for specific chemicals

• can be regulated by cell and turned on and off

what does active transport use

Antiporter

Symporter

ABC Transporter

Explain Antiporter

it is a simple transport mechanism and moves 2 molecules at the same time, something is coming in the cell while something is also leaving the cell.

Explain Symporter:

it is also a simple transport mechanism that attaches 2 or more of the same or different molecules and moves them simultaneously through the membrane protein across the membrane.

what does ABC Transporter stand for

it stands for ATP-Binding Cassette

Explain ABC transporter

it is where the molecule binds to the binding protein and moves through the gradient. At the end of the gradient that protein is than formed into ATP.

They act as molecular pump that use energy from ATP hydrolysis to transport a wide variety of substances across cell membranes against a concentration gradient

Explain Group Translocation:

Chemical modification of the transported substance driven by phosphoenolpyruvate

What is secretion by the sec system an example of?

Active transport

Energy from ATP and PMF (protein Mot. Force)

Cell envelope

refers to all layers surrounding the cell including any membrane and wall materials

cell walls

refers only to the peptidoglycan layer

what is the cell wall made of

peptidoglycan

what does peptidoglycan help with

resist turgor and determines the cell shape

what is murrain

building blocks of the cell wall

structures of repeating unit in peptidoglycan =

murein = cell wall

what is murein made of

Amino acids (tetrepeptide)

sugars

• acetylglucosamine

• acetylmuramic acid

how is peptigoclycan cross linked

by peptide bonds (amino acid to amino acid)and glucosidic bonds (sugar to sugar)

peptidoglycan is synthesized by?

Transglycosylase

Transpeptidase

Autolysins

Bactoprenol

Penicillin-Binding Proteins

Explain Penicillin-Binding Proteins

Transglycosylase and transpeptidase activity by the same proteins

Explain Bactoprenol

carries lipid

Explain Autolysins

cleaves peptidoglycan

you cleave it because it allows for the remodel of the cell wall

Explain Transpeptidase

crosslinks amino acids

• Energy comes from cleaving the terminal Alanine

Explain Transglycosylase

polymerize glycan for the cell wall

Gram Positive cell envelope

• Thick peptidoglycan

• Teichoic and lipoteichoic acid in the cell wall

  • Negatively charged molecule

  • May buffer the PMF so protons don’t escape!

Gram Negative cell envelope

• Thin layer of peptidoglycan

• Outer membrane

  • Bilayer of phospholipid

  • Lipopolysaccharide (facing outside of the cell)

    • Lipid A (endotoxin, conserved)

    • Core polysaccharide (conserved)

    • O-specific polysaccharide (variable)

• Periplasm

Which are converse LPS

Lipid A

Core polysaccharides

Bacterial cell wall degradation

• Lysozyme cleaves sugar bonds, weakening the cell wall

  • Hypotonic solution kills the cell

  • Isotonic solution does not kill the cell

• Penicillin prevents crosslinking of peptide chains.

• Not all prokaryotes have a cell wall!

Archaeal cell walls

• Pseudomurein cell walls (some archaea… they are diverse when it comes to this)

·      N-acetylglucosamine

·      N-acetylosaminuronic acid

·      Lysozyme can break beta 1,4 links, not beta 1,3.

s - layers

• Paracrystalline surface layer

• Protein or glycoprotein

• Common in Archaea (some bacteria have them)

• Resist osmotic pressure (turgor)

Glycocalyx/capsule/slime layer/extracellular polysaccharide

• Chain of sugar secreted by the cells

• Involved in attachment and biofilm formation

• Protects from the immune cells

  • Blocks phagocytosis

Fimbriae (Fixed)

• Abundant (100/cell)

• Short

• Adherence to surface

• Fixed

   Pili (Retractable)

• Longer

• 1-10/cell

• Retractable

• Function:

·      Adherence

·      Exchange of DNA (Conjugation)

·      Involved in twitching motility (Type IV pili)

Flagella (Rotational)

• Allow for swimming motility

  • Polar: at the pole of the cell

    • Lophotrichous= 1 pole

    • Amphitrichous= both poles

    
    

• Peritrichous: all around the cell

Twitching motility in pili

they throw their pili out, attach and pull to move forward

Flagella Basal Body motor:

• Basal body crosses the cytoplasmic membrane

• It is anchored in the cell wall

• Made of over 20 proteins!

  • 4 Rings!

    • C

    • MS

    • P

    • L

• Rotational motor uses PMF as energy

what are the 4 rings in the flagella basal body motor

• c

• ms

• p

• l

Chemotaxis

o   Bacterial swimming is a random walk (sense of environment)

o   Attractants/Repellent biased the random walk

o   Chemotaxis is based on chemicals (nutrients, toxins, etc.)

o   Phototaxis (light)

o   Aerotaxis (air)

o   Osmotaxis (osmotic pressure)

• Peritrichous:

• all around the cell

polar

from pole to pole

Intracellular structures

• Carbon Storage polymers

• Polyphosphate

• Elemental sulfur

• Gas vesicles

what are the carbon storage polymers

• PHB (poly b hydroxybutyric acid)

• PHA (polyhydroyalkanotes)

• glycogen

what do gas vesicles do

• Helps with buoyancy

• Often found in aquatic phototrophs.