module 6: prokaryotes p.2

What is peptidoglycan?

Cell wall polymer in bacteria; target of antibiotics.

What is a stromatolite?

Fossilized microbial mat; earliest evidence of life (3.5 bya).

What is a biofilm?

Surface-coating colonies of prokaryotes with a polysaccharide matrix.

What are cyanobacteria?

Photosynthetic prokaryotes (blue-green algae) that produced Earth's oxygen.

What is the endosymbiotic theory?

Mitochondria from engulfed α-proteobacteria; chloroplasts from engulfed cyanobacteria.

What is the difference between Gram-positive and Gram-negative bacteria?

• Gram-positive: Thick peptidoglycan (purple)

• Gram-negative: Thin peptidoglycan + outer membrane with lipopolysaccharides (pink)

What are hyperthermophiles?

Organisms that grow at 80–122°C; most likely Archaea.

What is the difference between autotroph and heterotroph?

• Autotroph: Makes own food using CO₂

• Heterotroph: Obtains carbon from organic compounds

What are the three types of horizontal gene transfer?

1. Transformation (take in DNA)

2. Transduction (phage transfers DNA)

3. Conjugation (direct contact via pilus)

What is a superbug?

Bacteria resistant to multiple antibiotics (e.g., MRSA).

What is bioremediation?

Using prokaryotes to remove pollutants.