Microbiology

definition prokaryotes

Pro = primitive
karyote = nucleas
nucleas do not have membrane

Definition Eukaryotes

eu = true
karyotes = nucleas

nucleas surrounding by membrane

Mycobacteria

too much lipid in cell wall so dye cant penetrate
Waxy layer make the stain cant penetrate

used special stain ( ziehl neelsen stain, acid fast staining )

it help penetrate the waxy layer.

Spirochetes

too thin to be seen

Mycoplasma

No cell wall

Chlamydia

Intracellular

cocci

round shape

bacilli

rods

spirochetes

spiral

gram stain positive

violet under em

gram negetive

red under em

peptidoglycan layer

• polymer of N-acetyl muramic acid & N-acetyl glucoseamine

• Gram + = 50 % thick

• Gram - = 5-10% thick

• present in bacteria but not human cell

• good target for antibacterial drugs

Teichoic acid layer

• only at gram +

• polymer of glycerol or ribitol ( joined byb phosphate )

Funtion

1. Maintaining

2. Major cell surface antigen

3. induction of septic shock ( caused by certain gram + bacteria )

Lipoprotien

attach to the peptidoglycan and the outer membrane.

Outer membrane

1. Porins, special channels for passive diffusion of low molecular weight ( sugar, amino acid, certain ions )

2. Lipopolysacchari ( LPS ), antigenic ( somatic O antigen) can be used to identify ( strains and specieas). Lipid A imbedded in membrane, toxic tu human, endotoxin ( when bacteria die it realese the toxin )

3. periplasmic space, contain gel like solution, many virulence factor, B-lactamase.

Funtion bacteria cell wall

1. determies the shape

2. protection to high osmotic pressure and pouter surrouding

3. differentiate between gram + and -

4. Antigenicity, gram + ( teichoic acid , AG ), gram - ( O ntigen )

Differentiation of Gram + & -

Protoplast

a defective cell wall, that completly loses cell wall ( gram + )

Spheroplast

Partially loses all cell wall ( gram - )

L-forms

cell that can be grow and devide ( Can be converted to normal from removal cell wall inhibitor ).

Clinical impact L-forms

1. Antibiotic resistance ( penicilin target cell wall but l from does not have cell wall)

2. persistance of infections

3. diffuculty in diagnosis

4. revert to normal bacteria

Mesosomes

irregular convulated invagination of the cytoplasmic membrane into the cytoplasm.

Type of mesosomes.

1. septal mesosomes ( coordinate division during binary fission )

2. Lateral mesosomes ( function similar to mitochondria )

Function of plasma membrane

1. selective permeability

2. active transport Ions ( K, Na and nutrient )

3. respiration and energy production

4. playing a role in cell division

5. excretion of hydrolytic enzyme ( degrade nutrients to smaller subunits )

why human and bacteria ribosomes differ make it good.

because it allow us to use antibacterial agent ( streptomycin interferes with bacteria metabolism ) without upsetting the human riosomal function

svedberg unit of prokaryotes and eukaryotes

prokaryotes is 80S ( 40S + 60S )

eukaryotes is 70S ( 30S + 50S )

what capsule compose of

polysaccharides or polypeptide

function of capsule

1. virulence factor ( enable to invade human immune system )

2. Adherence

3. Antigenic

4. identification and typing of somes bacteria

5. vaccination