Bacteria

Bacteria onthe tip of apin

ProkaryotesIdentified by their• Shapes• Chemical natureof their cell walls• The ways theymove• The ways theyobtain energy

Basic Structure

Cell wall – protects the cell & gives it shape.

Outer membrane – protects the cell against some anibiotics (only present in gram-negative)

Cell membrane – regulates movement of materials into & out of the cell; containsenzymes 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 shapesBacillusCoccusSpirilla

• Cell Arrangements– Diplo – cells are paired

– Staphylo – cells are in grape-like clusters

– Strepto – cells are in long chains

Cell Wall• Two different types of cell walls

are found in eubacteria• Gram staining helps to tell them apart using two different types of

dye– Violet - primary stain

– Red - counterstain

• Gram positive– Bacteria cells containing peptidoglycan absorb only the violet dye– Appear purple in the microscope

• Gram negative– Bacteria with a second(outer) layer of lipid and carbohydrate molecules– Extra layer absorbs only the red stain– Appear pink in the microscope

Gram Staining Bacteria• Gram Positive – stains purple• Gram Negative – stains pinkhttp://www.uphs.upenn.edu/bugdrug/antibiotic_manual/Gram3.htm

Growth and Reproduction

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

• Is this sexual or asexual reproduction?

Growth & Reproduction- Conjugation

• the process by which two living bacteriabind together and one bacterium transfers genetic information to the other.

Sex pili

Growth and Reproduction…

• Endospore – protects the cell against harsh environmental conditions, such as heat and

drought.• May allow the bacterium to survive for

thousands of years.

Bacillus cereus

– (found in soil)• straight rods, arranged singly or in pairs• cells stain Gram-positive (blue-violet)

Bacillus cereus

Aquaspirillum serpens

Aquaspirillum serpens

– (found in fresh water)• -spiral shaped, arranged singly• -cells stain Gram-negative (red)

E. Coli

Escherichia coli

– (digest food in your intestines)• straight rods, arranged singly or in pairs• cells stain Gram-negative (pink)

Staphylococcus Epidermidis

Staphylococcus Epidermidis

– epidermis (found normally on skin)• spherical shape• cells stain Gram-positive (blue-violet)