bacteria and archea

Question 1

What are prokaryotes

Answer 1

• represents 2 of the 3 domains of life: bacteria and archaea
• any organism that lacks a distinct nucleus and other organelles due to the absence of internal membranes
• archaea share structural simplicity with bacterial but are molecularly closer to eukaryotes

Question 2

How do prokaryotes differ from eukaryotes?

Answer 2

Prokaryotes lack a nucleus and membrane-bound organelles due to the absence of internal membranes.

Question 3

What is the function of a prokaryotic cell wall

Answer 3

provides structural support and defense

Question 4

what molecule is unique to bacterial cell walls

Answer 4

peptidoglycan

Question 5

how do archaeal cell walls differ from bacterial cell walls

Answer 5

unlike bacteria, archaea lack peptidoglycan; they have pseudopeptidogycan instead

Question 6

what are the 3 shapes of prokaryotes

Answer 6

cocci (spherical), bacilli (rods), spirilla (spirals)

Question 7

What is the significance of cyanobacteria in Earth’s history?

Answer 7

Cyanobacteria introduced oxygen to Earth’s atmosphere ~2.5 billion years ago

Question 8

What roles do prokaryotes play in nutrient cycling?

Answer 8

Decomposition, nitrogen fixation, and carbon cycling.

Question 9

What is symbiosis?

Answer 9

Close ecological relationships, including mutualism (e.g., nitrogen-fixing bacteria in plants) and parasitism (e.g., pathogens).

Question 10

whats biofilm

Answer 10

A community of prokaryotes in a protective extracellular matrix.

Question 11

Firmicutes (ferm-e-cutes)

Answer 11

SHAPE: rod or spherical-shaped

STRUCTURE: Gram-positive bacteria with thick peptidoglycan wall that forms endospores

ECOSYSTEM: found in extreme environments like the human gut or soil. important for human health and disease
- chemoheterotrophs (need to consume energy from the environment)

Question 12

Cynobacteria

Answer 12

responsible for oxygen reproduction
- found in extreme environments and aquatic environments like hot springs and desert soils

independent cells, chain

Question 16

what are plasmids, what is their role in prokaryotes, and how do they transfer DNA

Answer 16

• small circular DNA molecules in prokaryotes
• carry genes for antibiotic resistance, toxin production and metabolic advantages.
• they transfer DNA through conjugation

Question 17

What are the four metabolic types of prokaryotes?

Answer 17

Photoautotrophs: Light + CO₂.
Chemoautotrophs: Inorganic molecules + CO₂.
Photoheterotrophs: Light + organic molecules.
Chemoheterotrophs: Organic molecules for energy and carbon.

Question 18

Whats horizontal gene transfer?

Answer 18

movement of genes between organisms

Question 19

how does horizontal gene transfer fuel prokaryotic adaptability & evolution

Answer 19

HGT occurs in three ways:
1. transformation: prokaryotes take DNA from their environment; incorporating it into their genomes.

2. transduction: viruses transfer DNA between prokaryotes
3. conjugation: prokaryotes connect through billus and transfer plasmids (small, circular DNA )

This is important because it creates genetic diversity without reproduction, enables rapid adaptation, like developing antibiotic resistance genes and facilitates metabolic innovations, allowing survival in extreme environments

Question 20

What are the key structural features of prokaryotes?

Answer 20

features:

SHAPES: spiral (spiral-shaped),
cocci (spherical-shaped),
bacilli (rod-shaped)

CELL WALL: bacteria contain peptidoglycan that
provides structural support.

                  archaea do not have that, but 
                  instead, they have 
                  pseudopeptidpglycan 

Adaptations for survival:
endospores: thick-walled dormant
structures form to help bacterial
handle harsh conditions
motility:
flagella: tail of the cell
gliding motility: slime layer movement
axial filaments: found in spirochetes for
corkscrew motion:

Question 21

How do prokaryotes thrive in varied environments?

Answer 21

Prokaryotes can use diverse energy and carbon sources, allowing them to live in nearly any habitat:

Photoautotrophs: Use sunlight and CO₂ for energy (e.g., cyanobacteria).

Chemoautotrophs: Oxidize inorganic molecules like NH₃ for energy and use CO₂ for carbon.

Photoheterotrophs: Use sunlight for energy but require organic carbon.

Chemoheterotrophs: Consume organic molecules for energy and carbon.

Answer 22

BACTERIA:
Firmicutes:
Cyanobacteria:
Actinobacteria:
spirochaetes:
chlamydiae:
Proteobacteria:

ARCHAEA:
Halophiles: Thrive in salty environments, such as salt flats.

Thermophiles: Survive in extreme heat, like hydrothermal vents.

Methanogens (Euryarchaeota): produce methane, which is found in anaerobic habitats like wetlands.

Question 23

What roles do prokaryotes play in global cycles and ecosystems?

Answer 23

Nutrient Cycling:

Decompose organic matter, recycling carbon and nitrogen.
Nitrogen-fixing bacteria make nitrogen available to plants.
Symbiosis:

Mutualism: Gut bacteria aid in digestion and immunity.
Parasitism: Pathogens cause diseases like cholera and tuberculosis.
Biofilms:

Protect communities of bacteria from harsh environments.
Found in dental plaque and pipelines.
Bioremediation:

Break down pollutants like oil spills or heavy metals.
Industrial Applications:

Enzymes from extremophiles (e.g., Taq polymerase for PCR).
Fermentation in food production (e.g., yogurt, cheese).