Prokaryotic Structure and Function

bacteria shape

mostly round and rods because microscopes can only see them with little resolution so basic shapes

Cell morphology of prokaryotes

coccus, rod/bacillus, spirillum, spirochetes, appendaged bacteria, filamentous bacteria

The term used to describe bacteria with round shape is

coccus

Coccus

spherical or ovoid

Rod/bacillus

cylindrical

spirillum

long, curved or spiral

spirochetes

tightly coiled & long

appendaged bacteria

filamentous bacteria

cyanobacteria

Arrangement in prokaryotes

diploid, tetrads of Sarcina, chains (Streptococcus), grapelike clusters of Staphylococcus

Size range for prokaryote diameter

0.2 μm to > 700μm

cultured rod-shaped bacteria width

0.5 to 4.0 μm

cultured rod-shaped bacteria length

< 15 μm

examples of very large prokaryotes

Epulopiscium fishelsoni & Thiomargarita namibiensis

size range for eukaryotic cell diameter

2 to > 600 μm

advantages to being small

higher surface area / volume ratio, less energy required to multiply, more nutrient and waste product exchange

high surface area to volume ratio

more surface/membrane than volume so more transport membranes on surface for faster transportation of materials with less energetic requirements → multiples faster

ultramicrobacteria

0.2-0.4 μm in diameter; usually in open oceans; genomes highly streamlined & missing functions that must be supplied by other microbes/hosts

cytoplasmic membrane

surrounds cytoplasm, separates inside from environment, composed of lipids & proteins, selective permeability

selective permeability

proteins in the membrane transport nutrients into the cell and waste products out of the cell

Role of Proteins in cytoplasmic membrane

protein anchor, transport proteins, energy conservation and consumption

Protein anchor

holds transport proteins in place

transport proteins

accumulate solutes against the concentration gradient; proteins in the membrane transport nutrients into the cell and waste products out

Roles of proteins in bacterial cell membrane

protein anchor, transport proteins, energy conservation and consumption

Energy conservation and consumption

electron transport chain which generates the proton motive force and ATP through oxidative phosphorylation

mitochondria?

NO! in the membrane of bacteria for energy

Bacteria & fatty acids

they can change the length and saturation of fatty acids

fatty acid lengths change with

temperature

Increasing temperature, fatty acid lengths are

longer

Cholesterol in eukaryotes

stabilize membranes

hopanoids in bacteria

stabilize membranes

Archaea membranes

ether linkages in phospholipids, have isoprenes (no fatty acids), phosphoglycerol diethers with phytanyl C₂₀ side chains to form lipid bilayers; diphosphoglycerol tetraethers with biphytanyl C₄₀ side chains to form lipid monolayers

Bacteria and Eukarya linkages in phospholipids

ester

Archaea linkages in phospholipids

ether

Archaeal lipids have

isoprenes (no fatty acids)

archaeal lipid bilayers

phosphoglycerol diethers with phytanyl C₂₀ side chains

Archaeal lipid monolayers

diphosphoglycerol tetraethers with biphytanyl C40 side chains → lots of stability with rings bc one phospholipid

Bacterial Cell Walls

located outside cytoplasmic membrane & protects it; can be targets for some antibiotics, makes cell shape, contributes to overall charge of the microbe, some components can elicit the production of antibodies (recognized by immune system)

Without the cell wall, bacteria would

all be circles

Gram stain

separates species of bacteria into two groups

Gram-negative cell wall

aka cell envelope; at least two layers: LPS (aka outer membrane) and peptidoglycan; may serve as barrier against antibiotics and other harmful agents

gram-positive cell wall

thicker, primarily one layer of peptidoglycan (90%); simpler; pentaglycine interbridge; teichoic acids bound to peptidoglycan which gives negative charge

Peptidoglycan

alternating modified glucose (N-acetylglucosamine and N-acetylmuramic acid) in β-1,4 glycosidic linkages; sheets are cross-linked differently in gram-positive or negative

Lysozyme

enzymes that cleave beta 1,4-glycosidic bond between sugars in peptidoglycan; major human defense against bacterial infection; cannot destroy Archaeal cell walls but destroys pre-existing peptidoglycan;

Crosslink for gram-negative bacteria

L-alanine, D-glutamic acid, L-lysine, D-alanine

Crosslink for gram-negative bacteria

L-alanine, D-glutamic acid, diaminopimelic acid (DAP), D-alanine

Gram-negative link between peptidoglycan sheets

Diaminopimelic acid (DAP) and D-alanine

Gram-positive link between peptidoglycan sheets

L-lysine and glycine (5 of them, then attached to D-alanine)

glycosidic linkages are in

carbohydrates

peptide bonds are in

amino acids (proteins)

L prefix for amino acids

usually used for enzymes

D prefix

usually not used

contains diaminopimelic acid (DAP)

most likely gram-negative cell wall

Which glucose monomer do you see peptide bonds from?

N-acetylmuramic acid (M)

The diether molecule within the membrane structure of the _____ yields a lipid ______

Archaea / bilayer

Negatively charged molecules that are partially responsible for the negative charge of the gram-positive bacterial cell surface are

teichoic acids

Penicillin

cannot destroy Archaeal cell walls; inhibits transpeptidation (cross linkage synthesis); compromises strength of peptidoglycan; destroy peptidoglycan

Pseudomurein amino sugars

N-acetylglycosamine & N-acetyltalosaminuronic acid

Pseudomurein linkage

beta 1,3-glycosidic linkage

What are the peptides that link pseudomurein?

L-lysine and L-glutamic acid

Why are there so many species of prokaryotes small?

higher SA:V ratio which supports more nutrient and waste exchange + less energy requirements → faster to divide

1 in bacterial membranes

glycerophosphates

2 in bacterial membranes

fatty acids

3 in bacterial membranes

integral membrane protein

Is the bacterial membrane a lipid bilayer or monolayer?

bilayer

What is the name of the chemical linkage between the hydrophobic and hydrophilic group in bacterial membrane?

ester linkage

1 in archaeal membrane

glycerophosphates

2 in archaeal membranes

phytanyl

3 in archaeal membranes

membrane protein

Is this archeael membrane a lipid bilayer or monolayer?

bilayer

What is the name of the chemical linkage between the hydrophobic and hydrophilic group in the archaeal membrane?

ether linkage

fill in the blank for thsi archaeal membrane

biphytanyl or crenarchaeol

Is this archaeal membrane a lipid bilayer or monolayer?

monolayer

What is the name of the chemical linkage between the hydrophobic and hydrophilic group in the archaeal membrane?

ether linkage

Peptide order in gram-positive bacteria

L-alanine, D-glutamic acid-NH₂, L-Lysine, D-alanine where L-lysine is bonded to 5 glycines, D-alanine, L-lysine, D-Glutamic acid-NH₂, L-alanine

Peptide order in gram - bacteria

L-alanine, D-glutamic acid, Diaminopimelic acid (DAP), D-alanine with DAP bonded to D-alanine, L-lysine, D-glutamic acid, L-alanine

Full name for NAM

N-acetylmuramic acid

Full name for NAG

N-acetylglucosamine

What is the active site of lysozyme?

β 1,4-glycosidic linkage between NAG & NAM

How does penicillin affect cell walls?

inhibits the transpeptidation (cross linkage synthesis) to lessen the strength and formation of peptidoglycan

1

o-specific polysaccharide

2

core polysaccharide

3

lipid A

4

phospholipid

5

Braun lipoprotein

6

peptidoglycan

7

periplasm

8

cytoplasmic membrane

9

outer membrane

10

cell wall

This figure depicts Gram ____ cell membrane and cell wall.

negative

Considering the structure of gram-negative cells, would you expect lysozyme to work?

yes bc there is a β 1,4-glycosidic linkage in gram - cells

Label the black and orange (one part)

lipid A

blue part

core polysaccharide

red part

o-specific polysaccharide

Which part of the lipopolysaccharide is an endotoxin?

Lipid A

When does lipid A become an endotoxin?

if it is released

Which part of the lipopolysaccharide elicits an antibody response?

o-specific polysaccharide

1

phospholipid