Theme 3 - Prokayotic cell

What are the bacteria cell walls made of

Peptidoglycan

What are the archaea cell walls made of

Pseudomurein cell walls

How do prokaryotic cells reproduce

Binary fission

Shape of bacteria

Most are momomorphic ( single shape) whilst there are a few that are pleomorphic ( many shapes)

Bacillus/ Bacilli

Rod-shaped

Coccus/ cocci

Spherical

Spiral

• Vibrio- curved rod

• Spirillum - helical

• Spirochete- helical and flexible

What is the arrangement called when they are in pairs

Diplobacilli, diplococci

What is the arrangement called when they are in clusters

Staphylococci

What is the arrangement called when they are in chains

Streptobacilli, streptococci

What is the glycocalyx

The sugar coat found outside the cell that is sticky and gelatinous

Capsule

Neatly organised and firmly attached that prevents phagocytosis and plays an NB role in virulence

Slime layer

Unorganised and loose

EPS

Extracellular polysaccharide that allows cells to attach

Flagella

• Made if chains of flagellum

• Attached to a protein hook

How is the flagella an orchid to the wall and the membrane

Basal body

Axial filaments/ endoflagella

Found in spirochetes (symphysis) and is anchored at one end of a cell and has rotation which causes the cell to move

Fimbriae

Hair like appendages that are shorter and thinner than flagella and allow for attachment

Pili ( singular- Pilus )

Longer than fimbriae and only one or two cells that facilitate the transfer of DNA from one cell to another using conjugation

In pili what two kinds of motility do they have ( conjugation)

Gliding and twitching motility

Function of the cell wall

Maintains shape, prevents osmotic lysis, anchor for flagella, contributes to pathogenicity and a target sit for antibiotics

What is the peptidoglycan found in the cell wall composed of

Polymer of disaccharide

• N-acetylglucosamine ( NAG )

• N-acetylmuramic acid ( NAM)

What are the characteristics of a gram-positive cell wall

Thick peptidoglycan and teichoic acids

What are the characteristics of a gram-negative cell wall

Thin peptidoglycan, outer membrane and periplasmic space

Teiochic acid in a gram-positive cell wall

• lipoteichoic acid- plasma membrane

• Wall teichoic acid- peptidoglycan

What is the function of teichoic acid

Regulates movement of cations and antigenic variation

What does the organic material in gram-negative outer membrane consist of

Lipopolysaccharides, lipoproteins, phospholipids

In a gram-negative outer-membrane whee is the peptidoglycan

IN the periplasm between the outer membrane and the plasma membrane

Function of gram-negative outer membrane

Protection from phagocytes, complement and antibiotics

What is Lipid A in the gram-negative outer membrane

Endotoxin

What is the O polysaccharide in the gram-negative outer membrane

Antigen

What is the function of the core polysaccharides in the gram-negative outer membrane

Structural stability

What are porins in the gram-negative outer membrane

Proteins that form channels through membrane so that molecules can pass

What does the alcohol do in a gram-positive stain

Dehydrates the peptidoglycan

What happens to the crystal violet-iodine crystals that form in a gram-positive stains

Do not leave

What happens to the alcohol in a gram-negative stain

Alcohol dissolves outer membrane and leaves holes in peptidoglycan

What happens to the crystal violet-iodine crystals that form in a Gram-negative stain

They are washed out

How does penicillin stop the growth of a bacteria

Inhibits peptide bridges in peptidoglycan

Protoplasm

Wall-less cell

L forms

Wall-less cells that swell into irregular shapes

Spheroplast

Wall-less gram negative

Mycoplasma

No cell wall and contain sterols in plasma membrane to protect the cell from lysis

What do archaea pseudomurein wall lack

NAM and D-amino acids. Also cannot be gram stained, appear gram negative

Cytoplasm

Substance inside the plasma membrane

Nucleoid

Contains the genetic material ( bacterial chromosome)

Plasmid

Small circular double stranded DNA molecules that are not part of chromosomes and not needed for growth

Ribosomes ( 50S+30S=70S)

Site for protein synthesis

In the ribosome where is the antibiotics target site

• Streptomycin, Gentamycin

• Chloramphenicol, Erythromycin

Inclusions

Reserve deposits

Metachromic granules ( volutin) are what kind of reserves

Phosphate reserves

Gas vacuoles are what kind of reserves

Protein-covered cylinders

Magnetosomes are what kind of reserves

Iron oxide ( destroys H2O2 )

Endosperm

Resting cells that are resistance to desiccation, heat and chemicals. E.g Bacillus, Clostridium

Sporulation

Endospore formation

Germination

Return to vegetative state. Triggered by physical or chemical damage