Cell Biology: Modern Cell Theory and Types

The Modern Cell Theory

• The cell is the smallest living unit in all organisms.
• All living things are made of cells. This can be one or more cells.
• All cells come from other, pre-existing cells.

Cell Types

• Cells are divided into two major groups: prokaryotes and eukaryotes.
• Prokaryotes include bacteria and archaea.
• Eukaryotes consist of plants, animals, fungi, and protists.

Shared Features of Prokaryotes and Eukaryotes

• Both contain genetic material, cytoplasm, ribosomes, and a cell membrane.

Differences Between Prokaryotes and Eukaryotes

• Prokaryotes:
  • Lack a nucleus; genetic material is not contained in a membrane-bound structure.
  • Do not have membrane-bound organelles.
• Eukaryotes:
  • Have a nucleus, containing their genetic material and controlling cell activities.
  • Possess membrane-bound organelles.

Organelle Functions

• Cell membrane (plasma membrane):
  • A selectively permeable structure that controls what enters and exits the cell.
  • Maintains the cell's internal environment, known as homeostasis.
• Cytoplasm:
  • A jelly-like substance that surrounds and supports the cell's internal structures.
• Cytoskeleton:
  • A network of fibers providing structure and support to the cell and its organelles.
  • Plays a key role in cell movement.
• Ribosomes:
  • Non-membrane-bound organelles found in both prokaryotes and eukaryotes.
  • Responsible for protein synthesis, essential for various cellular functions.
• Nucleus:
  • Only found in eukaryotes.
  • Houses the cell's genetic material (DNA) and controls cell activities.
  • Contains a nucleolus, the site of ribosome production.
• Endoplasmic Reticulum (ER):
  • A network of interconnected membranes involved in processing and transporting molecules.
  • Rough ER: Contains ribosomes, involved in protein production and transport.
  • Smooth ER: Lacks ribosomes, involved in detoxification and lipid synthesis.
• Golgi Apparatus:
  • The cell's packaging center, receiving molecules from the ER.
  • Modifies and sorts molecules.
• Mitochondria:
  • The powerhouses of the cell, generating ATP energy through cellular respiration.
  • Utilize glucose and oxygen to produce energy efficiently.
• Chloroplasts:
  • Present only in plant cells.
  • Contain chlorophyll, capturing light energy for photosynthesis.
  • Site of glucose production through photosynthesis.
• Vacuoles:
  • Storage compartments for various materials within the cell.
  • Plant cells have a large central vacuole; animal cells have smaller vacuoles.
• Cell Wall:
  • Present only in plant cells.
  • A rigid outer layer providing structural support and protection.

Explore the fundamental concepts of cell biology through this quiz. Learn about the modern cell theory, the differences between prokaryotes and eukaryotes, and the functions of various organelles. Test your understanding of how cells are the building blocks of life!