Section 10: 10.1 - Structural and functional adaptations contribute to prokaryotic success

Question 1

What are methanogens?

Answer 1

Prokaryotes that use organic carbon and release methane.

Are a problem in tailing ponds.

Question 2

What is methangenomics?

Answer 2

Random sequence of DNA from a specific environment.

Used to explore microbiological diversity in tailing ponds.

Question 3

What are tailings?

Answer 3

Oil sands waste. Toxic to most flora and fauna. Energy source for microbes.

Question 4

What are harsh environments that prokaryotes thrive in?

Answer 4

1. Hyper saline environments
2. Cold environments (Eg; Glaciers)
3. Hot environments (Eg; Hot springs)
4. Acidic environments (Eg; volcanic fumeroles, pH = 0.03)

Can also survive 3.2 km below Earth’s surface, and 3 million rads of radiation.

Question 5

What are are the most abundant organisms on earth? Why?

Answer 5

Prokaryotes. Results from numerous adaptations to extreme and “normal” habitats.

Question 6

What are some facts about prokaryotes?

Answer 6

• First organisms on Earth
• Long evolutionary history and adaptations to various environments (Diverse)
• Size: 0.5-5 micrometers (unicellular)

Question 7

What are the shapes of prokaryotes?

Answer 7

1. Cocci - spherical
2. Bacilli - rod shaped
3. Spiral

Question 8

Why is the cell wall a key structure in prokaryotes?

Answer 8

• Maintains cell shape
• Protects
• Prevents lysis in hypotonic environment
• Anchors molecules that extend from cell surface

Question 9

What are the two types of cell walls?

Answer 9

1. Bacterial cell walls - peptidoglycan
2. Archaeal cell walls - polysaccharides and protein (no peptidoglycan)

Question 10

What is peptidoglycan?

Answer 10

Polymer of modified sugars cross-linked by short polypeptides.

VERY durable

Question 11

What are the two major types of bacteria? What distinguishes them?

Answer 11

1. Gram-positive
2. Gram-negative

Cell wall composition.

Question 12

What is the gram stain?

Answer 12

• Staining with crystal violet (iodine)
• Rinse in alcohol
• Stain with red dye

Question 13

What defines gram-positive bacteria?

Answer 13

• Simple structure
• Thick peptidoglycan layer
• Stains purple

Question 14

What defines gram-negative bacteria?

Answer 14

• More complex structure (Lipopolysaccharide outer membrane)
• Thinner peptidoglycan layer
• Stains red

Question 15

What are medical problems resulting from gram-negative bacteria’s outer membrane?

Answer 15

• Protects it, impeding antibiotics
• Lipid component in outer membrane is toxic - causes fever, shock

Question 16

What are medical problems resulting from certain antiobiotics inhibiting cross-linking?

Answer 16

• Penicillin
• More effective in gram-positive bacteria
• Bacteria increases antibiotic resistance over time - develops enzymes capable of destroying them

Question 17

What are medical problems resulting from multi-drug resistant strains of gram-positive species existing?

Answer 17

• Staphylococcus aureas (MRSA)
• Evolved from a normal skin bacteria
• Causes problems when it penetrates skin
• Resists most antibiotics used to treat it
• Has additional genes, conferring resistance to modern antibiotics
• Some bacteria survive a given antibiotic, and multiply with adaptations, repeating this over and over (multi-drug resistance)

Question 18

What is the capsule? How does it aid prokaryote survival?

Answer 18

Dense layer of polysaccharides or proteins surrounding their cell walls.
- Protects against dehydration
- Shields cell from host immune system
- Sticky (Adheres to substrates or other cells)

When layer is less defined, it is a slime layer.

Question 19

What are fimbriae? How do they assist prokaryote survival?

Answer 19

Hairlike appendages.
- Enables sticking to substrate or other cells
- Contains protein
- Shorter and more numerous than pili

Question 20

What are endospores?

Answer 20

Thick-coated resistant cell produced by certain bacteria when exposed to harsh conditions. Very durable.

Question 21

How do bacteria produce endospores?

Answer 21

• Water is removed, halting metabolism
• Original cell lyses, releasing them

Question 22

What is taxis? Some details about it?

Answer 22

Directed movement.
- Toward or away from stimulus
- Half of prokaryotes
- 50 um/s (50 body lengths/s)

Question 23

What is chemotaxis?

Answer 23

Movement in response to chemicals.

Question 24

What are flagella?

Answer 24

The main structure for motility.

Question 25

What are some details about the structure of prokaryotes?

Answer 25

- Lacks compartmentalization - May have specialized membranes ^ (Performs metabolic functions) - May have simple protein compartments to store metabolic by-products | ^ (Infolding of the plasma membrane)

Question 26

What are some details about DNA in prokaryotes?

Answer 26

- Circular genomes/chromosomes (Much less DNA) - Associated wtih fewer proteins - Has a nucleoid region instead of nucleus - Smaller ribosomes with different proteins and rRNAs

Question 27

What are plasmids?

Answer 27

Smaller circular DNA molecules that carry few genes.

Question 28

How do prokaryotes reproduce

Answer 28

Via binary fission. ## Footnote Reproduces quickly in favourable environments.

Question 29

What is the generation time of prokaryotes?

Answer 29

1-3 hours under ideal conditions

Question 30

How many prokaryotes are usually in a population?

Answer 30

Trillions of individuals.

Question 31

What 3 factors allow the successful reproduction of prokaryotes?

Answer 31

1. Small size 2. Simple division process 3. Short generation times