Kingdom Monera – Bacteria Characteristics and Diversity .

Kingdom Monera – Bacteria Kingdom Monera – Bacteria Characteristics and DiversityCharacteristics and Diversity

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Bacteria were first identified in 1677 by Antonie van Leeuwenhook after he developed a primitive version of the compound microscope.

He originally called all single celled organisms he had discovered “animalcules” and they were later separated into groups, one of which included bacteria.

A few bacteria that cause human disease

Salmonella bacteria (red) : causes Salmonella poisoning E.Coli bacteria

Helicobacter pylori: can cause ulcers, stomach cancer… Tetanus bacteria

Bacterial Shapes

Bacterial shape influence the ability of the bacteria

-to attach to surfaces

-acquire nutrients

-move through liquids

-escape predators

Rod shaped : Bacilli

Bacteria are found in three distinct shapes

ex. Anthrax (Bacillus anthraxis) & Tetanus (Clostridium tetani)

2. Spherical shaped Can be found as single cocci, pairs (diploid),

chains, or clumps

Single cocci

2. Spherical shaped Can be found as single cocci, chains, or clumps

Diploids – pairs of spherical shaped bacteria ex. Neisseria (can cause gonorrhea, bacterial meningitis & septicemia)

Bacterial meningitis Neisseria : gonorrhea

2. Spherical shaped

Chains of spherical shaped bacteria ex. Streptococcus ( cause a variety of human disease including meningitis, flesh eating disease, and bacterial pneumonia)

2. Spherical shaped

Chains of spherical shaped bacteria ex. Streptococcus ( cause a variety of human disease including meningitis, flesh eating disease, and bacterial pneumonia)

2. Spherical shaped

Clusters of spherical shaped bacteria ex. Staphylococcus aureous (can cause a variety of human infections including skin infections, Toxic Shock Syndrome, meningitis….)

3. Spiral shapedActually are a form of rod shaped bacteria

Leptospirillum

Bacterial StructureExample: bacillus structure

Internal cell structures

Surrounded by a cell membrane • Acts as a barrier and holds in proteins and other

parts of the cytoplasm• Allows for transport of energy and materials across

it via a concentration gradient

Single ring of genetic material (chromosome) encased in a nucleoid

External cell structuresCell Wall

• Composed of peptidoglycan (as opposed to cellulose in plant cells)• Two types

• Gram positive – have a thick cell wall• Gram negative – have a thin cell wall and most bacteria fall into this

category• Important in antibiotic use as antibiotics affect the ability to produce a cell

wallFlagella

• Used for motility and are driven by energy• Can be found alone, at each end, in clusters at the poles or all over the cell

Pili (sing. Pilus)• Used for transferring genetic material between cells

Fimbriae• Fine filaments of protein that aid in the attachment to other cells

Specialized External Structure:

Endospore: -adaptation to survival during unfavorable conditions -form dormant or resting cells -resistant to severe physical and chemical stresses-simply constructed of a central core of DNA that is surrounded by an impenetrable layer- can remain viable for millions of years -are capable of causing some serious diseases:

ex. Anthrax (Bacillus anthraxis) & Tetanus (Clostridium tetani)

Bacteria have recently been classified by the environment that they live in

1. Archaebacteria – live in an environment

without oxygen

2. Eubacteria – live in an environment with

oxygen

(archae= old)

(eu= true)

Bacteria can also be grouped according to their type of respiration

• Obligate aerobes – must have oxygen to survive• Obligate anaerobes – can only grow in the

absence of oxygen• Facultative anaerobes – prefer environments with

oxygen but can live in environments without oxygen

Nutrition: How do bacteria get the food (carbon) and energy they need to survive?

Some are autotrophs (collect their own energy)Photosynthetic - use of light for energyChemosynthetic – use of chemical substances for

energy

Some are heterotrophs (obtain food from other sources)Saprophytic (obtain raw materials from dead and

decomposing matter)ParasiticSymbiotic / mutualistic (ex. Bacteria in the human colon)

Some are chemotrophs (perform fermentation)

Modes of Bacterial disease transmission

• Direct contact• Airborne droplets• Bacterial toxins in

food (ingestion)• Fecal contamination

of food• Water• Vector bites (ex.

Mosquito)