Prokaryotic (Bacteria) Cell Structure & Function | Cell Biology

Main ideas / lessons

• Prokaryotic cells are simple cells that lack a nucleus and lack internal membrane-bound organelles (no compartmentalization).
• Prokaryotes include two domains: Archaea and Bacteria.
• E. coli is given as an example of a prokaryotic cell.
• Prokaryotes have distinct external structures (capsule, cell wall, membrane, flagella, pili) and internal components (cytoplasm, DNA/nucleoid, plasmids, ribosomes) that support survival, protection, movement, communication, and gene expression.

Concepts and functions by cell part

Capsule / slime capsule (outer layer)

• Composition: thick layer of polysaccharides
• Functions:
  • Protects the cell from drying out
  • Helps the cell attach to surfaces

Cell wall (rigid layer, when present)

• Composition: peptidoglycan
• Functions:
  • Provides structural support and helps maintain cell shape
  • Prevents the cell from bursting due to turgor pressure

Cell membrane

• Property: semi-permeable
• Function:
  • Regulates movement of materials in and out of the cell

Flagellum (long external extension)

• Function: locomotion (movement)

Pili (small hair-like extensions)

• Two types and functions:
  • Attachment pili
    • Help bacteria adhere to surfaces
  • Sex pili
    • Support bacterial conjugation
    • Enable transfer/swap of DNA between bacteria

Cytoplasm

• Components/contents described:
  • Nucleoid region (DNA location)
  • Cytosol (gel-like liquid)
  • Ribosomes
• Cytosol function: site of most metabolism in prokaryotic cells

Genetic material

Nucleoid

• Region where the DNA is located in prokaryotes
• Includes the genophore: described as the circular DNA strand

Plasmids

• Small, autonomous circular DNA pieces
• Can be transferred between bacteria via horizontal gene transfer

Ribosomes

• Size: 70S in prokaryotes (compared to 80S in eukaryotes)
• Function: protein synthesis during translation

Speaker / sources featured

• No specific named person or external source is identified in the subtitles.
• The only direct “source” is the narrator/instructor speaking to the audience (“In this video…”, “Thank you for watching…”).