D. Prokaryotic cell walls

Prokaryotic cell walls

Prokaryotic cell walls

• provides structure and shape to the cell and protects it from osmotic forces

Prokaryotic cell walls

• assists some cells in attaching to other cells or in eluding antimicrobial drugs

Prokaryotic cell walls

note that animal cells do not have cell walls

Bacterial cell walls

composed of peptidoglycan,

N-acetylglucosamine (NAG) and N-acetyl muramic acid (NAM)

a complex polysaccharide which is composed of two regularly alternating sugars called___ and ___ which are structurally similar to glucose

chains of NAG and NAM

are attached to other chains by cross-bridges of four amino acids (tetrapeptides)

tetrapeptides

_____)-these cross bridges are the “peptido” portion of peptidoglycan

Gram Positive Cell Walls (Purple), Gram Negative Cell Walls (Pink)

Two Basic Types of Bacterial Cell Walls:

Gram Positive Cell Walls (Purple)

with thick layer of peptidoglycan (20% of the dry weight of the cell) and unique polysaccharides

teichoic acids

unique polysaccharides called ___ which

are covalently linked to lipids forming

lipoteichoic acids that anchor the

peptidoglycan to the cell membrane

Mycobacterium have cell walls up to 60% mycolic acid-a waxy lipid (AFB)

Example of Gram Positive Cell Walls (Purple)

Gram-positive bacteria

In a structure of ___ it has:

• Peptidoglycan layer (cell wall)

• Cell membrane

• Teichoic acid

• Lipoteichoic acid

• Integral protein

Gram-positive cell wall

In a structure of ___ it has:

• Protein

• Plasma membrane

• Cell wall

• Wall teichoic acid

• Peptidoglycan

• Lipoteichoic acid

Gram Negative Cell Walls (Pink)

with thin layer of peptidoglycan (1-2% of the dry weight of the cell);

Gram Negative cell walls (pink)

outside this layer is a bilayer membrane composed of phospholipids, channel proteins (called porins), and lipopolysaccharides (LPS)

Porins

Channel proteins

lipopolysaccharides (LPS)

- is a union of lipid and sugar.

lipid A (endotoxin)

The lipid portion of LPS is known as ____

lipopolysaccharides (LPS)

is released from dead cells when the cell walls disintegrates, and it may trigger fever, inflammation, shock, and blood clotting in humans

Gram-negative bacteria

In a structure of ___ it has:

• Porin

• Outer membrane of cell wall

• Peptidoglycan layer of cell wall

• Cell membrane

• Integral proteins

• Phospholipids layers

• Periplasmic space

• Porin (sectioned)

• Polysaccharide - LPS layer

• Lipid A-LPS layer

Gram-negative cell wall

In a structure of ___ it has:

• Outer membrane-cell wall

• Peptidoglycan-cell wall

• Plasma membrane

• Periplasm

• Protein

• Porin protein

• Lipoprotein

• Phospholipid

• Enzymes and other active substances

• O polysaccharide- Lipopolysaccharide

• Lipid A-Lipopolysaccharide

Periplasmic space

- found between the cell membrane and outer membrane; this contains the peptidoglycan and periplasm

Periplasm

- the gel between membrane of gram negative cells;

Periplasm

contains water, nutrients and substances secreted by the cell (digestive enzymes, and proteins)

Bacteria Without Cell Walls

- e.g. Mycoplasma pneumoniae

Gram(+) archaeal walls, Gram(-) archaeal walls

Under of Archaeal Cell walls

Gram(+) archaeal walls

like gram (_) bacteria, they have thick wall and stains purple

Gram(-) archaeal walls

- have a layer of protein covering the wall, rather than a lipid membrane in gram (_) bacteria, but they stain pink.

Prokaryotic Cytoplasmic Membranes

-beneath the glycocalyx and cell wall

Prokaryotic Cytoplasmic Membranes

-also referred to as cell membrane or plasma membrane

- composed of lipids and associated proteins

Prokaryotic Cytoplasmic Membranes

composed of lipids and associated proteins

Bacterial membranes

- contain phospholipids; some have sterol-like molecules called hopanoids

hopanoids

sterol-like molecules called

Archaeal membranes

- composed of lipids that lack phosphate groups and have branched hydrocarbons linked to glycerol by ETHER linkages instead of ester linkages

Plasma membrane in cell

in a structure of___ it has:

• Phospholipid bilayer of plasma membrane

• Peptidoglycan

• Outer membrane

Phospholipid bilayer of membrane

In a structure of ___ it has:

• Integral protein

• Pore

• Outside cell

• Inside cell

• Peripheral protein

• Phospholipid bilayer

Phospholipid molecules in bilayer

In a structure of __ it has:

Phospholipids contains

polar (hydrophilic), heads (phosphate group and glycerol)

Non polar (hydrophobic) tails (fatty acids)