Bacteria

Two Kingdoms

Archaebacteria and Eubacteria

(Prokaryotes, unicellular)

Prokaryotic Cell Structure bac vid

Bacteria -Prokaryotes

-unicellular

-can be aerobic or anaerobic

-Two Kingdoms:

Archaebacteria and Bacteria

Identifying Bacteria-Gram staining- a dye that causes the cell wall of

a bacterium to turn a certain color

-gram positive – turns purple

-gram negative- turns pink

-this also helps you determine what antibiotic to use

Gram Positive (cell wall)• Gram positive bacteria contain a layer of sugar

polymers with polypeptides woven through them called Peptidoglycans. They protect and anchor other surface molecules.

• Gram stain turns them purple (crystal violet).

• May release exotoxins that make you sick (strep throat).

• Gram negative bacteria contain a layer of lipopolysaccharides (carbs. protruding from a lipid based membrane, LPS) on top of a thin layer of peptidoglycans.

• Gram stain turns them pink (safranin).• Once they die endotoxins are released that make you

sick (salmonella)

Gram Negative (cell wall)

Gram Stain Benefits anti vid

• Antibiotics, like penicillin break down peptidoglycans so they are affective against gram positive bacteria.

• Gram negative bacteria are extremely harmful because their LPS layer is toxic. They cause fever and even shock. Strong antibiotics and alternative medicines are needed to kill them.

Attaching to host• Capsule- sticky outside layer of polysaccharide

or protein used to help the bacteria stick to a host or other colony members.

• Fimbriae- hair like protrusions used to attach itself to a host.

Movement (Motility)• Some bacteria move by using a flagellum.

• Taxis- bacteria will move toward or away from a stimuli, like nutrient.

Bacteria Shape and Growth-shape provided by the cell wall-3 shapes

-rod – bacilli--sphere – cocci--spiral – spirilla-

-Growth arrangements-paired colonies- diplo--chains- strepto--clumps- staphylo-

Bacteria Reproduction bac vid

-Binary Fission (asexual)- the DNA replicates and the cell divides in half.

Bacteria Reproduction-Conjugation - protein bridge is formed between 2

bacteria, a plasmid is donated.

Transformation• A plasmid from a dead bacteria cell is taken up

by another. Can change the geno- or phenotype.

Transduction• A bacteriaphage may accidentally

• transfer bacteria DNA from one

• bacteria to another.

Endospores-endospores- a tough covering containing bacteria DNA.

-produced in unfavorable environments

-bacteria will lie dormant until conditions are right (years)

-extreme heat and acidic cleaners must be used to sterilize surfaces containing endospores

-can cause- botulism in unsterilized canned foods, or tetanus in wounds

Archaebacteria (Kingdom)

- Bacteria that live in extreme environments called extremophiles

Heat Loving Bacteria, Thermophiles

-lives in hot springs and thermal vents in the ocean (100ºC)

Methane Producing Bacteria, Methanogens

- Live in marshes and cow stomachs - Used in sewage treatment plants - Breakdown CO2 and H2

Salt Loving Bacteria, Halophiles- Live in the dead sea and salt lakes, pump in

potassium to achieve isotonic status

Bacteria (Kingdom) p. 568-commonly found everywhere

- We will look at them based on how they produce their energy

Heterotrophic

-most common

-often parasites

Photosynthetic Autotrophs -do photosynthesis to produce energy

-contain chlorophyll

-found in water (rivers, lakes, swamps, etc)

Chemosynthetic autotrophs-use inorganic compounds to make energy (nitrogen,

sulfur)

-nitrogen fixing bacteria

Bacteria Pros tasty vid -fix nitrogen

-help digest food in our intestines

-decomposers

-used to make food (cheese, yogurt)

Bacteria Cons-Cause Diseases

-Over use of antibiotics has created more resistant bacteria.*