Cell Structure: Prokaryotes

Cell Structure

• Prokaryotes are single-celled microorganisms that lack a true nucleus.
• They have a simple cell structure, consisting of:
  • Cell wall: provides shape and support
  • Plasma membrane: regulates the flow of materials in and out of the cell
  • Cytoplasm: contains genetic material, ribosomes, and various metabolic components
  • Genetic material: single circular chromosome (DNA) found in the cytoplasm
• No membrane-bound organelles, such as mitochondria or chloroplasts, are present.

Evolutionary Adaptations

• Prokaryotes have evolved various adaptations to survive in diverse environments:
  • Extreme temperatures: thermophilic (heat-loving) and psychrophilic (cold-loving) species
  • High salinity: halophilic (salt-loving) species
  • Low oxygen: anaerobic species
  • Radiation: radioresistant species
• These adaptations allow prokaryotes to thrive in environments where other organisms cannot survive.

Metabolic Processes

• Prokaryotes have diverse metabolic processes, including:
  • Photosynthesis: some species, such as cyanobacteria, can convert light energy into chemical energy
  • Respiration: aerobic and anaerobic species use different electron acceptors to generate energy
  • Fermentation: anaerobic species break down organic compounds to generate energy
  • Nitrogen fixation: some species can convert atmospheric nitrogen into a usable form
• Prokaryotes play a crucial role in many ecosystem processes, such as decomposition, nutrient cycling, and primary production.

Reproduction

• Prokaryotes reproduce primarily through:
  • Binary fission: a process of cell division that results in two identical daughter cells
  • Fragmentation: some species can break apart and grow into new individuals
  • Spore formation: some species can form dormant, highly resistant spores that can survive extreme conditions
• Prokaryotes can also exchange genetic material through horizontal gene transfer, which allows for rapid adaptation to changing environments.

Cell Structure

• Prokaryotes lack a true nucleus and have a simple cell structure consisting of a cell wall, plasma membrane, cytoplasm, and genetic material.
• The cell wall provides shape and support, while the plasma membrane regulates the flow of materials.
• The cytoplasm contains genetic material, ribosomes, and various metabolic components.
• Genetic material is composed of a single circular chromosome (DNA) found in the cytoplasm.
• Prokaryotes do not have membrane-bound organelles such as mitochondria or chloroplasts.

Evolutionary Adaptations

• Prokaryotes have evolved adaptations to survive in diverse environments, including:
  • Thermophilic (heat-loving) species that thrive in extreme temperatures.
  • Halophilic (salt-loving) species that can survive in high-salinity environments.
  • Anaerobic species that can survive in low-oxygen environments.
  • Radioresistant species that can resist radiation.
• These adaptations enable prokaryotes to thrive in environments where other organisms cannot survive.

Metabolic Processes

• Prokaryotes have diverse metabolic processes, including:
  • Photosynthesis: converting light energy into chemical energy (found in cyanobacteria).
  • Respiration: using different electron acceptors to generate energy (aerobic and anaerobic species).
  • Fermentation: breaking down organic compounds to generate energy (anaerobic species).
  • Nitrogen fixation: converting atmospheric nitrogen into a usable form (some species).
• Prokaryotes play a crucial role in ecosystem processes, such as decomposition, nutrient cycling, and primary production.

Reproduction

• Prokaryotes reproduce primarily through:
  • Binary fission: resulting in two identical daughter cells.
  • Fragmentation: breaking apart and growing into new individuals (some species).
  • Spore formation: forming dormant, highly resistant spores that can survive extreme conditions.
• Prokaryotes can also exchange genetic material through horizontal gene transfer, allowing for rapid adaptation to changing environments.