Prokaryotes

Kingdoms Eubacteria & Archaebacteria

Prokaryote “Before nucleus”

Characteristics:• Unicellular• 1-5 μm diameter• Cell walls -Maintains shape -Provides protection -Prevents lysis in a

hypotonic environment

PROKARYOTES

EUKARYOTES

Size 1-10 microns 10-100 microns

Complexity unicellular, rarely small colonies

sometimes unicellular more often multicellular

Membrane bound organelles

none nuclei, mitochondria, chloroplasts, lysosomes, endoplasmic reticulum, golgi, & vacuoles

c) Membrane bound organelles

none nuclei, mitochondria, chloroplasts, lysosomes, endoplasmic reticulum, golgi, & vacuoles

Nucleus no yes

Chromosomes

single & circular usually several & linear

Introns Rarely frequent

Histones no yes

Prokaryotes

Eukaryotes

Histones no yes

Ploidy haploid diploid

Mitosis & Meiosis

absent present

Sexual reproduction

none, or unidirectional from donor to recipient

usually, involves fusion of haploid gametes

Prokaryotes

Eukaryotes

Bacteria

Single-celled prokaryotes

Two kingdoms of bacteria:• Archaebacteria• Eubacteria

Archaebacteria

• Methanogens: Anaerobic bacteria (oxygen is a poison) Produce energy by converting H2 & CO2 into methane gas. Live in swamps & marshes

• Extreme Halophiles: “Salt-loving" bacteria that use

salt to generate ATP for energy.

• Thermoacidophiles: Live in extremely acidic environments (pH less than 2) that have extremely high temperatures (up to 110o C). e.g. geothermal springs at Yellowstone National Park.

Archaebacteria

Eubacteria

• Contains the bacteria commonly referred to as germs.

• This kingdom contains most of the world's bacteria

Eubacteria are classified by:• Shape• Clustering• Respiration

Eubacteria Shape

• Coccus - round• Bacillus - rod-shaped• Spirillum - spiral-shaped

Eubacteria Clustering

• Diplo - a prefix used with the shape name to indicate pairing of cells.

• Strepto - a prefix used with the shape name to indicate chains.

• Staphylo - a prefix used with the shape name to indicate clusters

Streptococcal (Group A) Infections

Susceptibility & Resistance

Eubacteria Respiration• Obligate anaerobes - cannot survive in the

presence of atmospheric oxygen. • Facultative anaerobes - can live with or without

atmospheric oxygen. • Obligate aerobes - cannot survive without

atmospheric oxygen.

MRSA

Staphylococcus aureus

The acronym MRSA stands for methicillin-resistant Staphylococcus aureus

Maggots Rid Patients Of Antibiotic-resistant Infection, MRSA

ScienceDaily (May 5, 2007) — University of Manchester researchers are ridding diabetic patients of the superbug MRSA - by treating their foot ulcers with maggots.

Gangrene

Tetanus

Necrotizing Fasciitis

Leprosy

Helicobacter pylori

Lyme Disease

Gram Staining

Many antibiotics have no effect on gram-negative bacteria

• Gram-positive. Gram-positive bacteria have a cell wall with a large amount of peptidoglycan that traps the violet dye in the cytoplasm. The alcohol rinse does not remove the violet dye, which masks the added red dye.

• Gram-negative.Gram-negative. Gram-negative bacteria have less peptidoglycan, and it is located in a layer between the plasma membrane and an outer membrane. The violet dye is easily rinsed from the cytoplasm, and the cell appears pink or red after the red dye is added.

(a) Gram-positive. Gram-positive bacteria have a cell wall with a large amount of peptidoglycan that traps the violet dye in the cytoplasm. The alcohol rinse does not remove the violet dye,which masks the added red dye.

(b) Gram-negative. Gram-negative bacteria have less peptidoglycan, and it is located in a layer between theplasma membrane and an outer membrane. The violet dye is easily rinsed from the cytoplasm, and the cell appears pink or red after the red dye is added.

Figure 27.3a, b

PeptidoglycanlayerCell wall

Plasma membrane

Protein

Gram-positivebacteria

20 m

Outermembrane

Peptidoglycanlayer

Plasma membrane

Cell wall

Lipopolysaccharide

Protein

Gram-negativebacteria

•Using a technique called the Gram stain

–Scientists can classify many bacterial species into two groups based on cell wall composition, Gram-positive and Gram-negative

Bad bacteria - toxic

Toxins

Substances that disrupts the metabolism of other organisms.

• Endotoxin - made up of lipids and carbohydrates associated with the outer membrane of gram-negative bacteria. These toxins are some of the strongest poisons known to man and cause violent reactions in host organisms.

• Exotoxin - proteins produced inside gram-positive bacteria cells and secreted into the environment. These toxins usually produce fever, weakness, and capillary damage.

Parts of a bacteria cell • Cell wall - some rigid and others flexible.

• Cell membrane - same as other cells.

• Cytoplasm - same as other cells.

• DNA - a single, circular chromosome (Plasmid) located in the cytoplasm. Bacteria do not have a nucleus.

• Capsule - a thick, gel-like, protective coating on some bacteria cells.

• Pili - short, hairlike protein structures on the surface of some bacteria that help them stick to host cells.

• Flagella - long protein structures that turn to propel some bacteria cells.

200 nm

Capsule

Figure 27.4

•The cell wall of many prokaryotes

–Is covered by a capsule, a sticky layer of polysaccharide or protein

200 nm

Fimbriae

Figure 27.5

Fimbriae and pili

–allow bacteria to stick to their substrate or other individuals in a colony

Taxis – movement toward or away from a stimulus

+ chemotaxis = movement toward chemical

- chemotaxis = movement away from chemical

Flagellum

Filament

HookCell wall

Plasmamembrane

Basal apparatus

50 nm

Reproduction

• Asexual, by binary fission - the DNA replicates and then the cell pinches inward and splits in two.

• Conjugation - two cells exchange a portion of their DNA across a bridge formed between the cells. New material replaces old material in the cell. While this increases the genetic variability in the organisms, it is not true sexual reproduction.

• Endospores - during adverse conditions, the DNA is encased in a protective envelope. This endospore can lie dormant for years or until favorable conditions return.

Binary Fission

Conjugation

Endospores

Endospore

0.3 mFigure 27.9

Can remain viable in harsh conditions for centuries

Prokaryotic Metabolism

AntibioticsDrugs that fight bacteria by interfering with their cellular

functions.

• PENICILLIN interferes with cell wall synthesis.

• TETRACYCLINE interferes with protein synthesis.

• Many antibiotics are derived from chemicals that bacteria or fungi produce.

• • SULFA DRUGS - antibiotics that are synthesized in laboratories

• Many Antibiotics are able to affect a wide variety of organisms; they are called BROAD SPECTRUM ANTIBIOTICS.

Antibiotic ResistanceWhen a population of bacteria is exposed to an Antibiotic, the

most susceptible DIE. 

A Few Mutant bacteria that are resistant to the Antibiotic may continue to grow.

A Resistant Population then grows from these Mutant Bacteria

through reproduction and genetic recombination.

These new Population are Antibiotic-Resistant.  This has resulted from the Over Use of Antibiotics.  Many diseases that were once easy to treat are becoming more difficult to treat.

http://bp1.blogger.com/_cYSo06Zxvv8/RsUcfFCeK3I/AAAAAAAAACI/cRDjlxr8hdk/s1600-h/NYC+EMSnecrotizingfasciitis.jpg

USEFUL BACTERIA • Used in Sewage Treatment, and as Decomposers, breaking

down the remains of organic matter in dead plant and animal waste.  Recyclers, returning nutrients back to the environment.

• Food production.  Bacteria help us make buttermilk, sour cream, yogurt, cottage cheese, sauerkraut and pickles.

• Used in industrial chemical production.  They produce organic chemicals and fuels. They’re used in the mining of minerals and their products are used as insecticides.

• Used to help clean up environmental disasters caused by humans, such as chemical and oil spills.

•Prokaryotes are the principal agents in bioremediation

–The use of organisms to remove pollutants from the environment