2.1 - Prokaryotes

Question 1

Characteristics of Prokaryotes

Answer 1

Single-celled & lack membrane-bound organelles

Question 2

Roles of bacteria in organisms & ecosystems

Answer 2

• Many are decomposers & producers. Ex. Photosynthetic bacteria are major producers of atmospheric oxygen in marine ecosystems
• They play a role in Mutualism - Relationship between 2 species that benefit from each other. Ex. Bacteria produces vitamins K and B12 in human intestine
• They also produce antibiotics and have commercial uses for kimchi & yogurt

Question 3

Characteristics of Eubacteria - Structure

Answer 3

• Has a single loop of DNA, called a Plasmid: Small loop of DNA carrying a small amount of genes.
• Complex cell walls made of peptidoglycan
• Small, hair-like pili
• Some are also covered by a Capsule: Outer layer, provides some protection

Question 4

Characteristics of Eubacteria - Shape & Metabolism

Answer 4

Shape: Spirillum (spiral shape), bacillus (oval shape), or coccus (circle/sphere shape)

Metabolism:
1. Obligate aerobes - cannot survive WITHOUT oxygen.

2. Facultative aerobes - can survive with or without oxygen
3. Obligate anaerobes - cannot survive WITH oxygen

Question 5

Characteristics of Eubacteria - Reproduction & genetic variation as well as endospore

Answer 5

Reproduction: Normally done asexually through…

Binary fission - division of one parent cell into 2 identical daughter cells

Also can happen through…

Conjugation - two cells joining together to exchange genetic information. One bacterial cell passes a copy of Plasmid to a nearby cell through a hollow pilus

Transformation - Bacterial cell takes in genetic information from its environment (from where the cells died).

Eubacteria can form…

Endospore: Highly resistant structure that forms around chromosome when the cell is under stress

Question 6

Bacterial diseases

Answer 6

Cholera - Vibrio cholerae

Diphtheria - Corynebacterium diphtheriae

Lyme disease - Borrelia burgdorferi

Pertussis - Bordetella pertussis

Rocky mountain spotted fever - Rickettsia Rickettsii

Scarlet fever - Streptococcus pyogenes

Tetanus - Clostridium tetani

Question 7

How does genetic diversity in bacteria lead to antibiotic resistance?

Answer 7

Genetic diversity allows the chance of bacteria with antibiotic resistance to survive exposure to antibiotics and create a population resistant to antibiotics, making them ineffective.

Question 8

Archaea subgroups

Answer 8

1. Methanogens - live in low oxygen environments, metabolism produces CH4
2. Halophiles - live in extremely salty environments. Ex. Dead Sea
3. Extreme thermophiles - live in extremely hot environments (ideal 70 C to 95 C)
4. Psychrophiles - live in very cold environments (ideal -10 C to -20C)