KINGDOM BACTERIAKINGDOM BACTERIASEC 12.2

Classifying BacteriaClassifying Bacteria

ShapeShape

Structure of cell wallsStructure of cell walls

Source of food and energySource of food and energy

RNARNA

Bacteria are prokaryotes!Bacteria are prokaryotes!

Bacteria and Science - Timeline of Knowledge

ShapeShape Cocci Cocci (round)(round) BacilliBacilli (rod shaped)(rod shaped) SpirilliSpirilli (spiral Shaped) (spiral Shaped)

Different prefixes:Different prefixes:

DiploDiplo - describes cells arranged in pairs - describes cells arranged in pairs StaphyloStaphylo – describes cells arranged in clusters – describes cells arranged in clusters

resembling grapesresembling grapes StreptoStrepto – arranged in a chain – arranged in a chain

3 Types of Bacteria

Cell Wall StructureCell Wall Structure

Gram positive Gram positive bacteriabacteria Have a thick protein Have a thick protein

layer on their cell wall layer on their cell wall and stain purpleand stain purple

Gram negative Gram negative bacteriabacteria Have a thin protein Have a thin protein

layer on their cell walls layer on their cell walls and stain pinkand stain pink

Source of EnergySource of Energy Bacteria are found in almost every environment Bacteria are found in almost every environment

because they can use widely different energy because they can use widely different energy sources.sources.

Based on their energy source bacteria can be Based on their energy source bacteria can be grouped into 4 major types:grouped into 4 major types:

Photosynthetic BacteriaPhotosynthetic Bacteria: (1) Photoautotrophs and : (1) Photoautotrophs and (2) Photoheterotrophs(2) Photoheterotrophs

Chemosynthetic BacteriaChemosynthetic Bacteria: (3) Chemoautotrophs : (3) Chemoautotrophs and (4) Chemoheterotrophs and (4) Chemoheterotrophs

AerobicAerobic requires oxygen for growth and metabolismrequires oxygen for growth and metabolism

Obligate anaerobesObligate anaerobes dies when exposed to oxygendies when exposed to oxygen

Facultative anaerobesFacultative anaerobes can grow with or without oxygencan grow with or without oxygen

SaprotrophsSaprotrophs feed on dead organisms or organic wastesfeed on dead organisms or organic wastes

ParasiteParasite absorb nutrients from the body fluids of living hosts.absorb nutrients from the body fluids of living hosts.

ThermophilesThermophiles grow at temp about 50Cgrow at temp about 50C

PsychrophilesPsychrophiles grow best at temp below 15C and die when exposed to room temp.grow best at temp below 15C and die when exposed to room temp.

Beneficial Bacteria

Harmful Bacteria

Quick FactQuick Fact

Yogurt is live bacteria !Yogurt is live bacteria ! When children are When children are

placed on antibiotics placed on antibiotics their parents are told their parents are told by the doctor to feed by the doctor to feed them yogurt. The them yogurt. The yogurt will replace the yogurt will replace the bacteria that the bacteria that the antibiotic is killing.antibiotic is killing.

Bacterial ReproductionBacterial Reproduction The main method of reproduction is asexual – The main method of reproduction is asexual –

only one parent is needed to reproduceonly one parent is needed to reproduce

BINARY FISSIONBINARY FISSION

Binary Fission Video Clip (1:03) Binary Fission Video Clip (1:03)

Bacterial DNA is replicated.Bacterial DNA is replicated.

The bacteria cell then undergoes cytokinesis The bacteria cell then undergoes cytokinesis and produces TWO daughter cells, that are and produces TWO daughter cells, that are completely identical to the original cell.completely identical to the original cell.

Bacterial Reproduction

Other Forms of ReproductionOther Forms of Reproduction Bacteria do not undergo sexual reproduction Bacteria do not undergo sexual reproduction

in the true meaning of the word, however, they in the true meaning of the word, however, they have 3 means of sharing genetic material with have 3 means of sharing genetic material with each other. each other.

1. 1. ConjugationConjugation

2. 2. TransductionTransduction

3. 3. TransformationTransformation

1. Conjugation1. Conjugation This is the direct transfer of genetic material This is the direct transfer of genetic material

between two bacterial cells that are temporarily between two bacterial cells that are temporarily joined by a sex joined by a sex pilispilis (bridge). (bridge).

DNA (called DNA (called plasmidsplasmids) is transferred one-way; ) is transferred one-way; one cell donates DNA and the mate receives one cell donates DNA and the mate receives the DNA.the DNA.

It is generally the “male” bacteria that is able to It is generally the “male” bacteria that is able to produce a pili and send over information to the produce a pili and send over information to the “female” bacteria.“female” bacteria.

http://fig.cox.miami.edu/~cmallery/150/gene/sf14x1box.jpg

• The F+ cell is considered MALE

• The F- cell is considered FEMALE

PlasmidsPlasmids They are small loops of They are small loops of

DNA that are separate from DNA that are separate from the main chromosomethe main chromosome

A method of genetic A method of genetic recombination in bacteriarecombination in bacteria Combining genes so that the Combining genes so that the

cells that are produced have cells that are produced have different genes from the different genes from the “parent” cells“parent” cells

They can only be They can only be transferred from one transferred from one bacteria to another bacteria to another during during conjugationconjugation

• The green is the bacterial DNA

• The red are the plasmids

2. 2. Transduction Transduction

Bacterial phages carry Bacterial phages carry bacterial genes from bacterial genes from one host cell to one host cell to another.another.

3. 3. TransformationTransformation This is the alteration of a bacterial cell’s This is the alteration of a bacterial cell’s

genotype by the uptake of naked foreign DNA genotype by the uptake of naked foreign DNA from the surrounding environment.from the surrounding environment.

Many bacterial species posses on their Many bacterial species posses on their surfaces proteins that are specialized for the surfaces proteins that are specialized for the uptake of naked DNA from the surrounding uptake of naked DNA from the surrounding solution. solution. These proteins specifically recognize and transport These proteins specifically recognize and transport

only DNA from closely related species of bacteria.only DNA from closely related species of bacteria.

Bacterial ResistanceBacterial Resistance

Over time bacteria that are exposed to antibiotics will Over time bacteria that are exposed to antibiotics will evolve new resistant strainsevolve new resistant strains

For example: they can reduce the amount of For example: they can reduce the amount of antibiotic that enters the cell.antibiotic that enters the cell.

This can be accomplished via mutations or the This can be accomplished via mutations or the transmission of genes between bacterial cells via transmission of genes between bacterial cells via “sexual reproduction”, specifically plasmids.“sexual reproduction”, specifically plasmids.

• Plasmids are circular double stranded DNA molecules that Plasmids are circular double stranded DNA molecules that are separate from the chromosomal DNAare separate from the chromosomal DNA

Antibiotics Movie Clip

The effectiveness of antibiotics is being The effectiveness of antibiotics is being greatly reduced.greatly reduced.

• Why is this phenomenon occurring?Why is this phenomenon occurring?

Scientists have to start to develop new Scientists have to start to develop new antibiotics to combat antibiotic resistance.antibiotics to combat antibiotic resistance.

Understanding Bacteria - Resistance (15:29) Understanding Bacteria - Resistance (15:29)

Life CycleLife Cycle We have seen how they replicate We have seen how they replicate BUTBUT

Some bacteria can have a Some bacteria can have a dormantdormant phase phase where they are able to survive in unfavourable where they are able to survive in unfavourable environments. environments.

They develop a tough outer covering that They develop a tough outer covering that surrounds their DNA and a small amount of surrounds their DNA and a small amount of cytoplasm, they are called cytoplasm, they are called endosporesendospores..

Economic Importance And Uses for Economic Importance And Uses for HumansHumans

Industrial Uses of BacteriaIndustrial Uses of Bacteria

Bacteria Research

Snow Bacteria

How Dirty Our Toilets? How Dirty Our Toilets?

Nuke Your SpongeNuke Your Sponge