Intracellular Stuctures of Prokaryotes

  1. Plasma Membrane

Destruction of the plasma membrane

Uptake of nutrients

Functions

The movement of materials across membranes

Structure

Phospholipid bilayer with proteins embedded in and attached to the inner(intacellular) and outer(extracellular) surface

Synthesizes cell wall components

Assists in DNA replication

Carries on respiration

captures energy as ATP

Selectively permeable barrier

Fluid Mosaic

Lipid Bilayer with floating proteins

amphipathic lipids

membrane proteins

Disinfectants

alcohols and quaternary ammonium compunds

Getting Through the Barrier

Micronutrients

Some unique substances may be required

Macroelements

-K,Ca,Mg and Fe

-required in relatively large amounts

-C,O,N,H,S,P

often supplied in water or in media components

ubiquitous in nature

required in trace amounts

serve as enzymes and cofactors

Mn,,Zn,Co,Mo,Ni,Cu

Passive process

Active process

Facillitated Diffusion

Osmosis

Simple diffusion

polar ends

non-polar tails

Plasmolysis : cell shrink

lysis : cell burst

cause leakage of intacellular contents

Active transport

Group Translocation

  1. Cytoplasm

substances of the cell inside the plasma membrane

Thick , aqueous,semitransparent and elastic

also contains proteins(enzymes), carbohydrates, lipids, inorganic ions and many low molecular weight compounds

The major stuctures in the prokaryotic cytoplasm are DNA, ribosomes and inclusions

About 80% water

  1. Plasmid
  1. Intracytoplasmic Membranes

Plasma membrane infoldings

Anammoxosome in Planctomycetes

-observed in many photosynthetic bacteria

-observed in many bacteria with high respiratory activity

organelle

-site of anaerobic ammonia oxidation

  1. The Nucleur Area

Bacterial chromosome do not include histones and are not surrounded by nuclear envelope

Bacterial chromosome, bacteria often contain small circular , double-stranded DNA molecules called plasmid

Single long circular molecule of double-stranded DNA (bacterial chromosome)

Contain features that enhance survivability

Do not contain genetic material essential for growth(limited)

Small circular, double stranded DNA

Extrachromosomal genetics elements

not connected to bacterial chromosomes

replicate independently of chromosomal DNA

example : gene for drug resistance

Transferable from one bacterial to another

  1. Ribosomes

Each subunit consists of protein and RNA called ribosomal RNA or rRNA

can be inhibits by certain antibiotics

Two subunit

cells that have high rates of protein synthesis, have a large number of ribosomes

70S ribososmes (S-Svedberg unit)

several antibiotics work by inhibiting protein synthesis on procaryotic ribosoms

Function : as the sites of protein synthesis

Streptomysin and gentamicin attach to the 30S subunit

Erythromycin and chloromphenicol attach to the 50S subunit

  1. Inclusions

Can serve as a basis of identification

Types of inclusions

reserve deposits

g. Gas vesicles

e. Carboxysomes

a. Metachromatic granules

b. Polysaccharide granules

f. Magnetosomes

c. Lipid Inclusions

d. Sulfur granules

-collectively known as volutin

-Corynebacterium diphtheriae

-Stain red with certain blue dyes such as methylene blue

-also found in algae, fungi, protozoa

-large inclusion

consist of glycogen and startch

differentiated by using iodine

-reddish brown indicates glycogen granules

-blue indicates starch granules

-storage material -polymer polt-B-hydroxybutyric acid

-revealed by Sudan dyes (fat-soluble)

-Mycobacterium, Bacillus, Azotobacter, Spirillum

Thiobacillus- sulfur bacteria

-Derive energy by oxidising sulfur and sulfur-containining compounds

-serve as an energy reserve

used for CO2 fixation during photosynthesis

Nitrifying bacteria, cynobacteria, and thiobacilli- i=used CO2 as sole source of carbon

Contain the enzyme ribulose 1,5-diphosphate carboxylase

For downward movement until reaching suitable attachment site

Function : to protect the cell against hydrogen peroxide accumulation

Iron oxide (Fe3O4) that act like magnets

Aquaspirillum magnetotacticum (gram -ve bacteria)

collectively called

Appeared bright, refractile areas with an irregular outline in the phase microscope

membrane bounded

consists of thin membrane surrounding a hollow space

found in photosynthetic group

function : provide buoyancy for aquatic procaryotes- to receive sufficient amounts of Oxygen , lights and nutrients

hallow cylinders covered by protein

cynobacteria

proteobacteria

green sulfur bacteria

heterotropic bacteria

archea

  1. Endospores

resting structures formed by some bacteria for survival during adverse environmental conditions

germination results in leaving the dormant stage and once again becoming a typical , multyplying cell(vegetable cell)

click to edit

Characteristics

Endospore structure

Endospores and Infectious Disease

click to edit

click to edit

cannot be destroyed easily, even by harsh chemicals

are formed internal to the bacterial cell membrane

highly resistant differentiated bacterial cell

Enable the organism to endure extreme environmental conditions

Endospore formation leads to a highly dehydrated structure thick walls and additional layers

contain essential macromolecules and a variety of substances absent from vegetative cells

spores are very impermeable to dye. however, they can be stained with special dye, Malachite green

small acid-soluble proteins

Endospore (so called because the spore is formed within the cell)

can remain dormant indefinitely but germinate quickly when the appropriate trigger is applied

Protect DNA from UV radiation, desiccation, and dry heat

serve as a carbon and energy source during germination

involved in the tranmission of some diseases to humans.Infections transmitted to human by endospores include :

Bacillus anthracis

Clostridium perfringens

Clostridium tetani

Clostridium botulinum

small subunit-30S

large subunit-50S

-methanogen

-halophiles

click to edit