BACTERIA DISCUSSION

April 22, 2023 (Really)

I. PROKARYOTESA. Basic Characteristics

1. Single celled2. No membrane-bound organelles3. Nucleoid region 4. Microscopic

B. HOW DO WE IDENTIFY DIFFERENT TYPES OF PROKARYOTES?1. Identified by the following:

a. Shapesb. Chemical nature of their cell wallsc. The ways they moved. The ways they obtain energy

C. BASIC STRUCTURE1. Cell wall – protects the

cell & gives it shape.2. Outer membrane –

protects the cell against some antibiotics (only present in some)

C. BASIC STRUCTURE (CONT.)

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

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

5. 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

II. SHAPES & GROUPINGS OF BACTERIAA. Three basic shapes of bacteria

1. Bacillus = rod shape2. Coccus = round or

spherical shape3. Spirilla = spiral shape

B. CELL GROUPINGS1. Diplo – cells are paired2. Staphylo – cells are in

grape-like clusters3. Strepto – cells are in long

chains

III. CELL WALL TYPESA. Two different types of cell walls are

found in eubacteria1. Bacteria cells containing peptidoglycan 2. Bacteria with an outer layer of lipid and

carbohydrate moleculesB. Gram staining helps to tell them apart

using two different types of dye1. Violet - primary stain2. Red - counterstain

IV. GROWTH & REPRODUCTIONA. Binary Fission: bacterium

doubles in size, it replicates its DNA and divides in half

1. Each daughter cell is a clone of the parent

Is this sexual or asexual reproduction?Asexual

IV. GROWTH & REPRODUCTION (CONT.)B. Types of Genetic Recombination

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

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

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

IV. GROWTH & REPRODUCTION (CONT.)C. Endospore: thick-walled, dehydrated

structures inside bacterium1. Protects the cell against harsh

environmental conditions, such as heat and drought

2. May allow the bacterium to survive for thousands of years

3. Not for reproduction, but for survival

V. EXAMPLES OF BACTERIAA. Bacillus cereus

1. Found in soil2. Straight rods3. Arranged singly or in pairs4. Cause of a lot of food borne illnesses

V. EXAMPLES (CONT.)B. Aquaspirillum serpens

1. Found in fresh water2. Spiral shaped3. Arranged singly

V. EXAMPLES (CONT.)C. Escherichia coli (E. Coli)

1. Straight rods2. Arranged singly or in pairs3. Named after pediatrician who discovered

it4. Digest food in your intestines (benefit to

us)5. Some strains are very harmful and can

lead to food borne illnesses

V. EXAMPLES (CONT.)D. Staphylococcus epidermidis

1. Epidermis = skin2. Spherical shape3. In clusters4. Usually not pathogenic

E. Staphylococcus aureus1. Spherical shape2. In clusters3. Most common type of staph

infections in humans4. MRSA: Methicillin-resistant S. aureus

a. Highly resistant to antibiotics