Bacteria (unfinished)

Morphology

the scientific study of form and structure

What are the morphologies of bacteria (mentioned in this lesson)?

1. Cocci (Spherical)

2. Bacillus (Rod-Shaped)

3. Vibrio

4. Spiral

5. Pleiomorphic

6. Hyphae

7. Mycelia

8. Trichomes

Cocci

spherical

single: coccus

plural: cocci

Bacillus

rod-shaped

single: bacillus

plural: bacilli

Vibrio

comma-shaped

single: vibrio

plural: vibrios

Spiral

single: spirillum

plural: spirilla

Pleiomorphic

(varied shapes)

Hyphae

branching filaments of cells

Mycelia

tufts of hyphae

Trichomes

smooth unbranched chains of cells

Are all bacteria the same size?

No!

What are the benefits of being smaller?

1. Higher surface area to volume ratio

2. greater rate of nutrient+waste exchange/unit volume

3. supports higher metabolic rate

4. supports faster growth rate, faster evolution

What are 2 bacteria that are exceptions to the size rule? What are benefits for being larger?

1. Thiomargarita namibiensis

2. Epulopiscium fishelsoni
   
   

Contents of a Bacteria’s Cytoplasm

1. Nucleoid

2. Chromosome-packing proteins

3. Synthesis-related enzymes

4. Regulatory Factors

5. Ribosomes

6. Plasmid(s)

7. Catabolic Enzymes

8. Inclusion Bodies

9. Gas Vesicles

10. Magnetosomes

11. Cytoskeletal structure

Bacterium Nucleoid

• largest region

• houses chromosome(s) and DNA replication machinery

• no surrounding membrane

• no histone proteins

How does DNA compress within the nucleoid of bacteria?

N.B. DNA is -vely charged therefore are attracted to cations

1. cations shield -ve charges on on sugar-phosphate (PO4-) backbone

2. small, +vely charged proteins bind to chromosome to maintain condensed structure

3. topoisomerases modify structure of DNA to enable “supercoiling”

How does DNA compress within the nucleoid of bacteria?

N.B. DNA is -vely charged therefore are attracted to cations

1. cations shield -ve charges on on sugar-phosphate (PO4-) backbone

2. small, +vely charged proteins bind to chromosome to maintain condensed structure (histone-like)

3. topoisomerases modify structure of DNA to enable “supercoiling”

What are Microcompartments? What are examples in prokaryotes?

protein-enclosed structure

1. carboxysomes

2. gas vesicles

What are Microcompartments? What are examples in prokaryotes?

membrane-enclosed structures

1. magnetosomes

What are Inclusion Bodies for? What are examples?

storage

• polyhydroxybutyrate granules: carbon storage

• sulfur globules: sulfur storage for energy

• glycogen: stored form of glucose

What are Polyhydroxybutyrate Granules for?

Carbon Storage

What are Gas Vesicles for?

Buoyancy Control

Carboxysomes

location of carbon fixation reaction

RUBISCO

Magnetosomes

organelles associated with direction finding

Some ____________ proteins are involved in cell wall synthesis during cell division

cytoskeleton

MreB

Homolog of actin - microfilaments

bacteria’s version of actin

FtsZ

Homolog of actin - microtubules

bacteria’s version of tubulin

• aids in cell division

Bacterial Cytoskeleton Key Features

• series of internal proteins

• assist in:

  • structure - MreB

  • cell wall synthesis during cell division - FtsZ

  • moving internal items - plasmids

What is the Cell Envelope?

any membrane, cell wall, or outer membrane surrounding the cell’s cytoplasm

What are the roles of the Plasma Membrane?

1. capturing energy

2. Holding Sensory Systems

3. Permeability Barrier (but not stuctural)

Plasma Membrane Composition

• usually composed of a phospholipid bilayer w/ embedded proteins

• hydrophobic core

• hydrophillic surfaces interact w either the external environment or cytoplasm

Phospholipids

• 
  

Cytoplasmic Membrane

• all cells have them

• separates interior from exterior