Prokaryotes

• Bacteria were first discovered in the late 1600’s by Anton van Leeuwenhoek, using the microscope he invented.

• bacteria found in the dental plaque of two old men who never cleaned their teeth.

Prokaryote Structure• Prokaryotes are simple cells.

NO NUCLEUS- The DNA is loose in the cytoplasm in the form of a NUCLEOID

- The RIBOSOMES are found in the cytoplasm.- NO ORGANELLES

• Has a CELL MEMBRANE and CELL WALL (peptidoglycan not cellulose)

• Some have an outer CAPSULE which is sometimes called a SLIME LAYER or PILI which are tiny stickers

• Bacteria move using FLAGELLA: may have one or many

Relationship to Oxygen

• For more than half of Earth’s history, oxygen wasn’t present in the atmosphere. Many bacteria evolved under anaerobic conditions.

• Classification:• OBLIGATE AEROBES(need oxygen to survive)• OBLIGATE ANAEROBES (killed by oxygen)• AEROTOLERANT(don’t use oxygen, but survive it).• FACULTATIVE AEROBES(use oxygen when it is

present, but live anaerobically when oxygen is absent).

2 Bacteria Kingdoms

• Kingdom Archaebacteria - are ancient bacteria that live in extreme environments

• Kingdom Eubacteria - are generally referred to as bacteria or germs, and are considered more recent. Most types of bacteria belong in this kingdom.

• First appeared approximately 3.7 BYA

The Archaebacteria:

• do not have peptidoglycan in their cell walls

• have ribosomes similar to eukaryotes

• have unique lipids in their plasma (cell) membranes

The Archaebacteria also:

• have some genes that resemble eukaryotic genes

• usually are not pathogenic (they don’t usually make us sick!)

• live in extreme environments:–high concentrations of salt–extremes of pH and temperature

3 Archaebacterial Groups

• Methanogens- turn H2 and CO2 into methane (CH4)

• Halophiles- organisms that live in environments with extremely high salt concentrations

• Thermoacidophiles = live in extremely hot, acid environments

Methanogens

• anaerobic bacteria that get energy by turning H2 and CO2 into methane (CH4)

• live in mud, swamps, and the guts of cows, humans, termites and other animals

Halophiles• are organisms that live in environments

with extremely high salt concentrations–some extreme halophiles can live in

solutions of 35 % salt. (seawater is only 3% salt!)

• halophile means “salt loving”• most halophiles are aerobic and

heterotrophic; others are anaerobic and photosynthetic, containing the pigment bacteriorhodopsin

HalophileEnvironmentssolar salternsOwens Lake, Great Salt Lake,coastal splash zones,Dead Sea

Thermoacidophiles

• Like temperature and pH extremes– Hot = up to 110ºC– Cold = down to 1ºC– Acid = as low as pH 2– Alkali = as high as pH 9

• they are chemoautotrophs, using H2S• the first Extremophile was found about

30 years ago

ThermophileEnvironments

Hydrothermal Vents in the ocean, and

Obsidian Pool in Yellowstone National Park

EUBACTERIA---

• Germs

• PATHOGENS- an organisms that makes another organism sick by living inside

• Examples- bacteria, viruses, fungi, parasites

CLASSIFIED BY METABOLISM

AUTOTROPHICPHOTOAUTOTROPHICCHEMOAUTOTROPHIC

HETEROTROPHIC

AEROBICANAEROBIC

Bacteria are Named by Shape

• Cocci (ball-shaped)–Streptococcus mutans

• Bacillus (rod-shaped)–Clostridium botulinum

• Spirilli (spiral-shaped)–Treponema palladium

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Bacteria are Named by Arrangement

• Paired: diplo• Grape-like clusters: staphylo• Chains: strepto

Examples

• Streptococcus: chains of spheres• Staphylospirillum: Grapelike clusters

of spirals• Streptobacillus: Chains of rods

CLASSIFIED BASED ON THEIR CELL WALL

The Gram stain, which divides most clinically significant bacteria into two main groups, is the first step in bacterial identification.

BACTERIA WITH THICK CELL WALLS – are called GRAM + and will stain purple

BACTERIA WITH THIN CELL WALLS- are called GRAM – and will stain pink

The Gram stain has four steps:• 1. crystal violet, the primary stain: followed

by

• 2. iodine, which acts as a mordant by forming a crystal violet-iodine complex, then

• 3. alcohol, which decolorizes, followed by•

4. safranin, the counterstain.

In Gram-positive bacteria, the purple crystal violet stain is trapped by the layer of peptidoglycan which forms the outer layer of the cell. In Gram-negative bacteria, the outer membrane of lipopolysaccharides prevents the stain from reaching the peptidoglycan layer. The outer membrane is then permeabilized by acetone treatment, and the pink safranin counterstain is trapped by the peptidoglycan layer.

Is this gram stain positive or negative? Identify the bacteria.

Is this gram stain positive or negative? Is this gram stain positive or negative? Identify the bacteria.Identify the bacteria.

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•Binary Fission- the process of one organism dividing into two organisms

•Fission is a type of asexual reproduction

Reproduction of BacteriaReproduction of Bacteria

How?...The one main (circular) chromosome makes a copy of itselfThen it divides into two

•Asexual reproduction- reproduction of a living thing from only one parent

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BINARY FISSION

Bacteria dividing Completed

Reproduction of BacteriaReproduction of Bacteria

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•The time of reproduction depends on how desirable the conditions are. (example- leaving milk out vs keeping them in the refridgerator)

•Some can reproduce every 20 minutes

(one bacteria could be an ancestor to millions in less than a day)

“EXPONTENTIAL GROWTH”

Reproduction of BacteriaReproduction of Bacteria

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Bacterial Cell & Nucleiod DNA Ring

Step 1

DNA replicates

Step 2

DNA (chromosomes) move to opposite ends and attach to cell

membrane

Step 3-Cell grows in the middle

How do bacteria survive in inclimate environments?

• CAPSULES-(Gram -) prevent bacteria from drying out

• GLYCOCALYX- capsule with a sticky substance that allows the bacteria to stick to a specific environment

• ENDOSPORES- dormant structure that surrounds the DNA in Gram + bacteria

ENDOSPORE

How do Bacteria become drug resistant? (DNA)

• MUTATIONS- • PLASMIDS- tiny rings of DNA that can be transferred

from one bacteria to another • TRANSFORMATION-absorbing DNA from the

environment (example- other bacteria that have died)• TRANSDUCTION- Virus carries DNA from one bacteria

to the next• CONJUGATION- passing of DNA from one bacteria to

the next

TRANSFORMATION

CONJUGATION

STEP 1- Bacteria replicates a PLASMIDSTEP 2- Bacteria creates a CONJUGATION

BRIDGE from one bacteria to the nextSTEP 3- PLASMID crosses the CONJUGATION

BRIDGESTEP 4- PLASMID may or may not become part

of the chromosome of the new bacteria

TRANSDUCTION

CONJUGATION

CONJUGATION

BENEFITS OF BACTERIA

1. DECOMPOSERS—Saprophytes- breakdown dead organisms and place nutrients back into the soil (important in the carbon cycle, nitrogen cycle)

2. NITROGEN FIXATION- extremely important in the nitrogen cycle- bacteria called RHIZOBIUM- are found in the roots of LEGUMES (bean plants). These rhizobium can turn unusable nitrogen into a type of nitrogen that plants can use to make proteins. (examples- crop rotationing)

BENEFITS OF BACTERIA

3. Make foods like- PICKLES, CHEESE, BUTTER, YOGURT (Lactobacilli and bifidobacterium), SAUERKRAUT , SAUSAGES, COCOA and COFFEE BEANS—SOUR DOUGH BREAD

4.Live in our digestive systems (ENTERIC BACTERIA)- help us breakdown hard to digest food and produces VITAMIN K (example- E. coli)

5.Live on our skin– Staphylococcus epidermis protects us from other bacterial invaders

BIOTECHNOLOGY WITH BACTERIA

6. USING BACTERIA to clean up OIL SPILLS- break it down and give off carbon dioxide and water

7.USING BACTERIA to de-thatch you YARD and in PEST CONTROL

8.USING BACTERIA to produce certain PROTEINS and INSULIN used in medicine

PROBLEMS WITH BACTERIA

• EUTROPHICATION“population bloom” of

bacteria (fungi or plants) that use up all the nutrients in a lake, pond- most commonly OXYGEN that will kill off all animals in the area

PROBLEMS WITH BACTERIA

PATHOGENS- give off toxins that cause diseases

EXOTOXINS- toxins released by living bacteria-usually made by Gram + bacteria- (Example- tetanus)

ENDOTOXINS- toxins that are released when the cell dies- from the capsule of Gram – bacteria (Example- E. coli)

ANTIBIOTICS

Defined as drugs that “combat” bacteria that interfere with their cellular functions

ANTI= not or againstBIO= living

Types of ANTIBIOTICS (See list on pg 479)

• PENICILLIN- interferes with the bacteria’s ability to make a cell wall (Gram +)

• TETRACYCLINE- interferes with the bacteria’s ability to make proteins-- BROAD SPECTRUM ANTIBIOTIC