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Bacteria Discussion. September 7, 2012 (Really). Basic Characteristics Single celled No membrane-bound organelles Nucleoid region Microscopic. I. Prokaryotes. B. How do we identify different types of prokaryotes?. Identified by the following: Shapes

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Bacteria discussion

Bacteria Discussion

September 7, 2012

(Really)


I prokaryotes

Basic Characteristics

Single celled

No membrane-bound organelles

Nucleoid region

Microscopic

I. Prokaryotes


B how do we identify different types of prokaryotes
B. How do we identify different types of prokaryotes?

  • Identified by the following:

    • Shapes

    • Chemical nature of their cell walls

    • The ways they move

    • The ways they obtain energy


C basic structure

Cell wall – protects the cell & gives it shape.

Outer membrane – protects the cell against some antibiotics (only present in some)

C. Basic Structure


C basic structure cont
C. Basic Structure (cont.)

  • Cell membrane – regulates movement of materials into & out of the cell; contains enzymes important to cellular respiration.

  • Plasmid – circular piece of DNA that contains some genes obtained through genetic recombination.

  • Capsule & Slime layer – protect the cell & assist in attaching the cell to other surfaces.


3 basic shapes

Bacillus

Coccus

Spirilla

3 basic shapes


• Cell Arrangements

– Diplo – cells are paired

– Staphylo – cells are in

grape-like clusters

– Strepto – cells are in

long chains


Ii shapes groupings of bacteria
II. Shapes & Groupings of bacteria

Three basic shapes of bacteria

Bacillus = rod shape

Coccus = round or spherical shape

Spirilla = spiral shape


B cell groupings
B. Cell Groupings

  • Diplo – cells are paired

  • Staphylo – cells are in grape-like clusters

  • Strepto – cells are in long chains


Iii cell wall types
III. Cell wall types

  • Two different types of cell walls are found in eubacteria

    • Bacteria cells containing peptidoglycan

    • Bacteria with an outer layer of lipid and carbohydrate molecules

  • Gram staining helps to tell them apart using two different types of dye

    • Violet - primary stain

    • Red - counterstain


Iv growth reproduction
IV. Growth & Reproduction

  • Binary Fission: bacterium doubles in size, it replicates its DNA and divides in half

    • Each daughter cell is a clone of the parent

  • Is this sexual or asexual reproduction?

    • Asexual


Iv growth reproduction cont
IV. Growth & Reproduction (cont.)

  • Types of Genetic Recombination

    • Conjugation: process by which two living bacteria bind together and one bacterium transfers genetic information to the other

    • Transformation: occurs when bacterium binds to and then takes up DNA released by dead bacteria

    • Transduction: viruses carry portions of DNA from one bacterium to another


Iv growth reproduction cont1
IV. Growth & Reproduction (cont.)

  • Endospore: thick-walled, dehydrated structures inside bacterium

    • Protects the cell against harsh environmental conditions, such as heat and drought

    • May allow the bacterium to survive for thousands of years

    • Not for reproduction, but for survival


V examples of bacteria
V. Examples of Bacteria

  • Bacillus cereus

    • Found in soil

    • Straight rods

    • Arranged singly or in pairs

    • Cause of a lot of food borne illnesses


V examples cont
V. Examples (cont.)

  • Aquaspirillumserpens

    • Found in fresh water

    • Spiral shaped

    • Arranged singly


V examples cont1
V. Examples (cont.)

  • Escherichia coli (E. Coli)

    • Straight rods

    • Arranged singly or in pairs

    • Named after pediatrician who discovered it

    • Digest food in your intestines (benefit to us)

    • Some strains are very harmful and can lead to food borne illnesses


V examples cont2
V. Examples (cont.)

  • Staphylococcus epidermidis

    • Epidermis = skin

    • Spherical shape

    • In clusters

    • Usually not pathogenic

  • Staphylococcus aureus

    • Spherical shape

    • In clusters

    • Most common type of staph infections in humans

    • MRSA: Methicillin-resistant S. aureus

      • Highly resistant to antibiotics


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