Bacteria Discussion September 19, 2018 (Really)

I. Prokaryotes Basic Characteristics Single celled No membrane-bound organelles Nucleoid region Microscopic

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 (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.

II. Shapes & Groupings of bacteria Three basic shapes of bacteria Bacillus = rod shape Coccus = round or spherical shape Spirilla = spiral shape

B. Cell Groupings Diplo – cells are paired Staphylo – cells are in grape- like clusters Strepto – cells are in long chains

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 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.) 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 (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 Bacillus cereus Found in soil Straight rods Arranged singly or in pairs Cause of a lot of food borne illnesses

V. Examples (cont.) Aquaspirillum serpens Found in fresh water Spiral shaped Arranged singly

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 (cont.) Staphylococcus epidermidis Staphylococcus aureus Epidermis = skin Spherical shape In clusters Usually not pathogenic Staphylococcus aureus Most common type of staph infections in humans MRSA: Methicillin-resistant S. aureus Highly resistant to antibiotics