Bacterial Cell Structures Quiz

Bacterial Cell Structures

• Essential structures: These are necessary for the survival and function of the bacteria.
  • Plasma membrane: A phospholipid bilayer that encloses the cytoplasm and controls what enters and exits the cell.
  • Cytoplasm: The gel-like substance that fills the cell and contains the cell's internal components.
  • Ribosomes: Sites of protein synthesis, crucial for cellular processes.
  • DNA: The genetic material of the bacteria, containing the instructions for all cellular functions.
• Nonessential structures: These structures may be present in some bacteria, but are not required for survival.
  • Cell wall: Provides structural support and protection.
  • Capsule: A sticky layer outside the cell wall that helps bacteria adhere to surfaces and avoid immune system attacks.
  • Flagella: Long, whip-like structures used for movement.
  • Pili (fimbriae): Hair-like structures used for attachment to surfaces

Bacterial Sporulation

• A survival strategy for bacteria during harsh conditions.
• The process forms durable, resistant spores.
• The process begins with DNA replication and formation of a septum.
• A forespore develops within the mother cell, containing the duplicated DNA.
• The forespore is then coated with multiple layers, forming the spore coat.
• The mother cell disintegrates, releasing the mature spore.

Bacterial Cell Division

• Bacteria reproduce asexually through a process called binary fission.
• The process begins with DNA replication, where a single copy of the bacterial chromosome is duplicated.
• The two copies of DNA move to opposite ends of the cell.
• The cell elongates.
• A septum (new cell wall and plasma membrane) forms between the two copies of the DNA.
• The septum grows inward, eventually dividing the cell into two daughter cells, each with a complete copy of the bacterial chromosome.

Growth Phases of Bacteria

• Lag phase: The initial period after inoculation when bacteria adapt to the new environment.
  • Cells are metabolically active but inactive.
  • Low population growth.
• Log (exponential) phase: Rapid growth and division.
  • Bacteria are actively metabolizing and dividing.
  • Exponential population increase.
• Stationary phase: Growth rate plateaus.
  • Nutrient depletion and accumulation of waste product slow down growth.
  • Number of new cells equals the number of dying cells.
• Death phase: Number of viable cells decline rapidly.
  • Nutrient depletion and toxic waste accumulation lead to cell death.
  • Population decreases significantly.