Prokaryotes

Bacterial Morphology General MicrobiologyStructure & Function

Morphology (in biology) - study of the size, shape, and structure of microorganisms and of the relationships of the parts comprising them.some terms to know Aerobic bacteria:those that need oxygen in order to live and grow. Anaerobic bacteria:those that dont require oxygen in order to live. Pasteurization:A process by which bacteria in food are killed by heating the food to a particular temperature for some given period of time. Decomposers:Bacteria that break down dead organic matter.

Binary Fission is the primary method of a procaryotic organism. It is the separation of the body into two new bodies. In the process, an organism duplicates its genetic material (DNA), and then divides into two parts (cytokinesis), with each new organism receives 1 copy of DNA.some terms to know

INTERESTING FACTS

All of bacteria in our body collectively weighs about 4 lbs.There are more bacteria in mouth than people in the worldThe smell of rain is caused by a bacteria called ACTINOMYCETESSweat itself is odorless. Its the bacteria that mingles with it that causes body odor.Chocolate has anti-bacterial effect on the mouth and protects against tooth decay.Most antibiotics are made from bacteriaTap water has a shelf-life of 6months, after chlorine dissipates, bacteria starts to grow

The strongest creatures on earth are gonorrhea bacteria. They can pull 100,000 time their own body weight.Earwax has antimicrobial properties that reduce the viability of bacteria & fungus in the human ear.Honey is a natural reservoir for Botulism bacteria. Adults can normally process it and infants cant and this is why you shouldnt give babies honey.Unwashed eggs still have their protective coating, the bloom, and are safe to store on the counter. Many modern countries wash eggs before sale so they look cleaner and safer, but this opens the pores of the shell for infection from bacteria during storage time.Human poop, by weight, is mostly bacteria that are both dead and alive.

Human bites are one of the most dangerous animal bites in the world due to the bacteria in our mouthsA group of scientists transcribed the song Its a Small World After All into the DNA of a bacteria that is resistant to radioactivity, so that in the event of a nuclear catastrophe, we could pass a message on to future intelligent lifeA specie calledDeinococcus radiodurans, can survive almost 10,000 x the dose of radiation lethal to humansE. coli an travel 25 times their own length in 1 second, equivalent to a horse running 135 miles per hour.Australian scientists found that a bacterium called Ralstonia metallidurans can turn dissolved gold into solid nuggets.

Prokaryotic Cellmuch smaller and simpler than eukaryotes

they lack a true nucleus and dont have membrane bound organelles.

Its DNA is found in its central part called nucleoid.

Its cell wall acts as an extra layer of protection, helps maintain cell shape, and prevents dehydration.

Cell division by bacteria

Asexual reproduction

Fission- the act of cleaving or splitting into parts.

Binary fission results in two identical daughter cells.

Binary Fission

Binary Fission Step 1

The cell wall prepares for replication. The cell wall starts to rupture.

Step 2

The cell makes a copy of its single, circular chromosome.

Step 3

The cell grows larger and the chromosomes separate and move to opposite poles of the cell. The cell membrane begins to pinch inward, separating the two identical chromosomes.

Step 4

Cytokinesis occurs and two identical bacterium exist.

BacteriaSingular 'bacterium.

Microscopic single-cell (unicellular) life form that exists practically everywhere

The smallest prokaryotic cell

Visible only with the aid of a microscope

It has peptidoglycan cell wall which protects it from environtment with extreme temperatures.

Size of BacteriaBacteria are measured in units of length called micrometers, or microns.1 mm = 1,000 microns

The small size of prokaryotes allows quick entry in an organism.

Coccus = 0.5 to 1.0 mBacilli = 0.5 to 1.0 m in breadth; 1.0 to 4.0 m in length.Spiral bacteria - 1.0 m to over 100.0 m in lengthStar-shaped, filamentous, and lobed commonly fall into a size range of 1.0 m

Shape of BacteriaCocci spherical/ oval shaped (major groups) Bacilli rod shapedSpiral rigid curved/coiled forms

Filamentous flexible slender formsAppendages there is a part that is link/adjoinBox-shapedStar-shapedVibrio curved rodlike; motileSpirochete - spiral-shaped, most are serious pathogens for humans

Shapes of Bacteria:

Spherical Rod-shaped Spiral shapedCOCCI are round cells, sometimes slightly flattened when they are adjacent to one another.are curved bacteria which can range from a gently curved shape to a corkscrew-like spiral.BACILLI

Shapes of Bacteria: Filamentous AppendageBox-shaped

This allow bacteria to have more surface area for long-term attachments and can link themselves with porous surfaces.sensing environment, defense against predators, swimming, walking, grasping, transferring sperm, generating water movement, and in gas exchange.

Other shapes of bacteria

VibrioSpirochetes

Star-shaped

Bacterial morphologies (1)

Arrangement of Bacteria: COCCI

StaphylococciStreptococciDiplococciThe cocci are arranged in cluster The cocci are arranged in pairs.The cocci are arranged in chainsMicrococcus are single

Arrangement of Bacteria: COCCI

Sarcinae

Tetradsgroups of fourgroups of eight

Arrangement of Bacteria: BACILLISquare-ends

Diplobacilli

Coccobacilli

Streptobacilli

Club-shaped

Arrangement of Bacteria: BACILLI

Rounded-ends

Fusiform

Anatomy of a Bacterial Cell

Anatomy of a Bacterial CellOuter layer - two components:Rigid cell wallCytoplasmic (Cell/ Plasma) membrane present beneath cell wall

Cytoplasm - gel-like substance enclosed within the cell membrane. It contains cytoplasmic inclusions, ribosomes, mesosomes and nucleoid.

Additional structures - plasmid, slime layer, capsule, flagella, fimbriae (pili), spores

Structure & Function of Bacteria Cell Components

Bacterial Cell StructureAppendages - flagella, pili or fimbriae

Surface layers - capsule, cell wall, cell membraneCytoplasm - nuclear material, ribosome, mesosome, inclusions etc.Special structure - endospore

Bacterial Cell Structure

Essential structures cell wall cell membrane cytoplasm nucleoidParticular structures capsuleflagellapili

Cell walla rigid cell wall composed of peptidoglycan, a protein-sugar (polysaccharide) molecule

Composed of : N-acetyl glucosamine (NAG) & N-acetyl muramic acid (NAM) alternating in chains, held by peptide chains.Chemical nature of the cell wall helps to divide bacteria into two broad groups Gram positive & Gram negativeGram +ve bacteria have simpler chemical nature than Gram ve bacteria.

Functions of Cell WallThe wall gives the cell its shape and surrounds the cytoplasmic membrane, protecting it from the environment.

Countering the effects of osmotic pressureThe strength of the wall is responsible for keeping the cell from bursting when there are large differences in osmotic pressure between the cytoplasm and the environment.

Providing attachment sites for bacteriophages. bacteriophages - a virus that is parasitic (reproduces itself) in bacteria

Providing a rigid platform for surface appendages- flagella, fimbriae, and pili

control permeability

Wall-less forms of Bacteria.When bacteria are treated with antibiotics that interfere with biosynthesis of peptidoglycan, wall-less bacteria are often produced. Usually these treatments generate non-viable organisms. Wall-less bacteria that can not replicate are referred to as spheroplast.

Cytoplasmic (Plasma) membraneThin layer that separates cell wall from cytoplasmActs as a semipermeable membrane: controls the inflow and outflow of metabolitesComposed of lipoproteins with small amounts of carbohydratesMembranes are also dynamic, constantly adapting to different conditions.

Cytoplasmic membrane

CytoplasmColloidal system of variety of organic & inorganic solutes in viscous watery solutionContains:ribosomes,mesosomes,inclusions vacuolesComposed of lipoproteins with small amounts of carbohydratesMembranes are also dynamic, constantly adapting to different conditions.

Cytoplasm It is where the functions for cell growth, metabolism, and replication are carried out

It is a gel-like matrix composed of water, enzymes, nutrients, wastes, and gases and contains cell structures such as ribosomes, a chromosome, and plasmids.

Cytoplasmic ComponentsRibosomes - are microscopic "factories. It is where protein synthesis occur.

They translate the genetic code from the molecular language of nucleic acid to that of amino acidsthe building blocks of proteins.)

Proteins are the molecules that perform all the functions of cells and living organisms.

Cytoplasmic ComponentsMesosomes Principal sites of respiratory enzymes.The major function is to increase the surface area of the plasma membrane to mainly help the cell to carry out cellular respiration more efficiently.

Cytoplasmic ComponentsIntracytoplasmic inclusionsnormally involved in storing energy reserves or building blocks for the cell.

These are structures surrounding the outside of the cell envelope. They usually consist of polysaccharide; but in certain bacilli they are composed of a polypeptide (polyglutamic acid). For:Attachment Protection from phagocytic engulfment. Resistance to drying. Depot for waste products. Reservoir for certain nutrients.

Capsule

NucleoidThenucleoidis the region in the prokaryotic cell that contains the main DNA material.

PlasmidExtrachromosomal genetic material that also has DNA moleculesThey are capable of self-replication and contain genes that confer some propertiessuch as antibiotic resistance.

Chromatoporesarepigment-containing and light-reflecting cellsOnly in photosynthetic bacteria and blue green algae.

For:LocomotionRapid swimming or movement caused by the rotationFlagella

attach to the cell by hook and basal body which consists of sets of rings and rods

Flagella

Functions:Chemotaxis:movement of bacteria toward or away from chemical stimuliMagnetotaxis: movementalong the Earth's magnetic field. Phototaxis: response to differences in light density.Bacteriaswimto areas of particular light intensities.

FlagellaTypes of distribution:Monotrichous flagella:one flagellum, if it originates from one end of the cell, it is called polar flagellum. Rapid swimming caused by the rotation of flagella.Peritrichous flagella: flagella surround the cell. Bundled peritrichous flagella give rise to slower forward motion than polar flagella.

Flagella movement

Short, thin, straight, hairlike projections form surface of some bacteria. Composed of protein pilin, carbohydrate and phosphate.

They are known to be receptors for certain bacterial viruses.

Take part in adhesion of pathogen to specific host tissues. Sex pili are involved in genetic material exchangebetween mating bacterial cells.

Pili or Fimbrae

Additional OrganellesSpores :

Highly resistant resting stages formed during adverse environment (depletion of nutrients)

Formed inside the parent cell, hence called Endospores

Very resistant to heat, radiation and drying and can remain dormant for hundreds of years.

Kinds of Bacteria

Harmless and harmful bacteria Helpful bacteria. Bacteria make possible the digestion of foods in many kinds of animals.- In humans, bacteria known asEscherichia coli(E. coli) occur everywhere in the digestive system, aiding in the breakdown of many kinds of foods.Bacteria are also responsible for the production of vitamin K and certain B vitamins.Certain kinds of bacteria are also essential in the decay and decomposition of waste materials.Some bacteria are involved in the production of many foods eaten humans.

Harmful bacteria. Pathogenic bacteria cause great diseases to animal and plant life. Examples are: cholera, typhoid, pneumonia, dysentery, tuberculosis, tetanus, etc.,Bacteria also attack organisms by releasing chemicals that are poisonous to plants and animals. Such poisons are known as toxins.Some saprophytic bacteria grow on unprotected foodstuffs and results to food spoilageDenitrifying bacteria affects the fertility of the soil by reducing nitrogen which goes to the atmosphere.Harmless and harmful bacteria