Bacteria

Important Facts to know about Bacteria:

Bacteria Facts

The term for parasitic bacteria is PATHOGEN

GENETIC ENGINEERING is a mechanism used by E. coli to produce insulin and growth hormone.
The relationship between bacteria and the roots of legumes is known as MUTUALISM
Cocci describes the spherical shape of a bacterial organism.
The method of sexual reproduction in which viruses carry bacterial DNA fragments between moneran cells is TRANSDUCTION.
ANAEROBES are bacteria that can live without oxygen
ANTIBIOTIC is a substance that prevents bacteria from forming new cell walls.
The oxygen-rich atmosphere of earth may have been developed from a group of bacteria called CYANOBACTERIA.
Bacteria get their food by means of ABSORPTION.
CONJUGATION is the type of reproduction in which genetic material is transferred from one bacterium to another.
NITROGEN is the substance that some bacteria take in from the air and convert to compounds that living things can use. For ex. In the case of plant growth.
ENDOSPORE is the resistant resting cell of a bacterium
FISSION is the asexual reproduction in monerans.
DECOMPOSERS are bacteria that can break down complex molecules into simple, inorganic materials.
The grainy appearance on bacterial cytoplasm is caused by RIBOSOMES.
CHEMOSYNTHESIS is the process by which bacteria make food using only simple inorganic compounds for energy and raw materials.

Bacteria Structure

Bacteria Capsule

The capsule is the main structure of the bacterium that allows for pathogenesis. It is the outermost part of the bacterium and is composed of polysaccharide sugars and proteins. The capsule protects the bacteria from phagocytosis from macrophages.

Bacteria Flagella

Flagella in bacteria are required for motility. The flagella may be located at one end of the bacterium, termed polar flagulla or around the entire bacterium, termed peritrichous.

Pili

Pili, also known as fimbriae, are protein filaments which allow bacteria to attach and stick to things as well as to one another. The pili most importantly allow for the process of conjugation which is “bacterial mating.” Conjugation is the process of DNA transfer from one cell to another. Conjugation allows one bacterium to give genetic information to another bacterium, as in antibiotic resistance.

Endospore

The endospore of bacteria allows bacteria to live in soil and surround themselves with a hard outer coat. The bacterium at this stage is not growing and also does not need respiration. The endospore is formed by a small fraction of gram-positive bacteria, mainly Clostridium and Bacillus species, such as Clostridium tetani. The enospore allows resistance to heat and drying and contains nuclear material and protein allowing germination and bacteria to divide under optimal conditions.

Nucleoid

The bacteria nucleoid is a nuclear region containing a single circular DNA molecule without a nuclear membrane. Plasmids may often also be present within the nucleoid region of bacteria.

Ribosomes

Ribosomes in bacteria transcribe mRNA, messenger RNA, into proteins, which is similar to other cells.

Cell Membrane

Bacterial cell membranes enclose the bacterium and allow fro selective permeability and transport of soultes, such as sodium and potassium into and out of the cell. The cell membrane contains enzymes that produce the energy for the bacterium cell, through electron transport and oxidative phosphorylation. Bacteria do not have mitochondria that preform energy production as in eukaryotes, such as human cells.

Cell Wall

The cell wall of bacteria is a rigid enclosure that surrounds the cell membrane and creats the shape of the bacterium. The cell wall most importantly protects the bacterium against osmotic lysis. The cell wall is a mixed polymer called peptidoglycan. Peptidoglycan is a mix of sugar and protein, polymers of N-acetylglucosamine and N-acetylmuramic acid.

Cell Wall and Gram Stain

The thickness and inner structure of the cell wall determines the characteristics of the Gram stain. Bacteria that stain positive with a Gram stin have thick, dense, rigid layers of peptidoglycan and teichoic acid. Teichoic acid is not present within gram negative bacteria.

Gram negative bacteria have a much thinner peptidoglycan layer. Gram negative bacteria have an outer membrane layer that is much thicker than the layer of peptidoglycan. This outer membrane layer is composed of lipopolysaccharides and lipoproteins, such as LPS and endotoxin.

LPS Lipopolysaccharides

LPS, lipopolysaccharides, is a toxin. When bacteria die, the LPS is released from their membrane into the circulation and can lead to outcomes, such as sepsis and vascular collapse and the body reacts to the antigen.

Bacteria Classification

Bacteria may be classified according to many of their different properties.

Most common:

Gram stain properties

Gram positive bacteria stain blue.

Gram negative bacteria stain pink.

The gram stain is very important as it can divide most bacteri, allows for direction in further testing as to what bacteria is causing the disease and also gives direction to management and treatment of the disease.

Morphology

Cocci which are round bacteria.

Bacilli which are rod shaped bacteria.

Growth Conditions

Bacteria have different preferred growth conditions.

Strict aerobic

Aerobic bacteria, strict, have an absolute requirement for oxygen gas within air and cannot grow without oxygen. There are very few strict aerobic bacteria.

Strict obligate anaerobes

Obligate anaerobes, strict, can grow only in complete or nearly complete absence of oxygen. Oxygen will halt these bacteria’s growth or kill them. Clostridium is an obligate anaerobe.

Facultative anaerobes

Faultative anaerobes are bacteria that can flip between the two above mentioned states. Facultative anaerobes can use oxygen if it is present and can grow also if it is not present. Most bacteria are of the facultative anaerobe type.

Bacteria Structure and Growth Conditions