Cell Biology Lecture 3

Cytoplasm

• Cytoplasm is a thick solution filling each cell, enclosed by the cell membrane.
• Composed mainly of water, salts, and proteins, it houses most cell organelles like ribosomes and the Golgi apparatus.
• Primary functions include:
  • Transport of materials
  • Maintenance of cell shape and structure
  • Protection of organelles
  • Storage of substances
  • Site for metabolic activities
  • Facilitation of cell movement, division, and growth

Cytosol

• Cytosol is the fluid component of the cytoplasm, constituting over 70% water.
• Surrounds organelles and plays a crucial role in signal transduction from the cell membrane to the nucleus.
• Involved in transporting metabolites and is the site for metabolic chemical reactions in prokaryotes.
• Distinction: Cytosol is the fluid, while cytoplasm includes all cell components (excluding the nucleus).

Protoplasm

• Protoplasm refers to the cytoplasm and internal cell components, including the nucleus.
• Composed of proteins, lipids, carbohydrates, phosphates, potassium, sodium, and water.
• Difference from cytoplasm: Protoplasm encompasses all cellular components, including the nucleus.

Cell Membrane

• Also known as the plasma membrane, it is a double layer of lipids and proteins surrounding the cell.
• Separates cytoplasm from the external environment and is present in all cells (prokaryotic and eukaryotic).
• Functions to provide cell structure, regulate material transport, and facilitate cell signaling.
• Made of a phospholipid bilayer: hydrophilic phosphate heads and hydrophobic fatty acid tails.

Mechanisms of Cell Transport

• Cell membranes are selectively permeable, allowing certain molecules to cross.
• Molecules move via diffusion (passive transport) or active transport, with osmosis affecting water movement.
• Diffusion is the movement of substances from high to low concentration.
• Factors affecting diffusion include temperature, area of interaction, particle size, and steepness of the concentration gradient.
• Significance of diffusion:
  • Facilitates gas exchange in respiration (e.g., carbon dioxide diffusion).
  • Allows water uptake in plant roots.
  • Enables ion movement in neurons, generating electrical charges.

Cytoplasm

• Cytoplasm is a thick solution filling each cell, enclosed by the cell membrane.
• Composed mainly of water, salts, and proteins, it houses most cell organelles like ribosomes and the Golgi apparatus.
• Primary functions include:
  • Transport of materials
  • Maintenance of cell shape and structure
  • Protection of organelles
  • Storage of substances
  • Site for metabolic activities
  • Facilitation of cell movement, division, and growth

Cytosol

• Cytosol is the fluid component of the cytoplasm, constituting over 70% water.
• Surrounds organelles and plays a crucial role in signal transduction from the cell membrane to the nucleus.
• Involved in transporting metabolites and is the site for metabolic chemical reactions in prokaryotes.
• Distinction: Cytosol is the fluid, while cytoplasm includes all cell components (excluding the nucleus).

Protoplasm

• Protoplasm refers to the cytoplasm and internal cell components, including the nucleus.
• Composed of proteins, lipids, carbohydrates, phosphates, potassium, sodium, and water.
• Difference from cytoplasm: Protoplasm encompasses all cellular components, including the nucleus.

Cell Membrane

• Also known as the plasma membrane, it is a double layer of lipids and proteins surrounding the cell.
• Separates cytoplasm from the external environment and is present in all cells (prokaryotic and eukaryotic).
• Functions to provide cell structure, regulate material transport, and facilitate cell signaling.
• Made of a phospholipid bilayer: hydrophilic phosphate heads and hydrophobic fatty acid tails.

Mechanisms of Cell Transport

• Cell membranes are selectively permeable, allowing certain molecules to cross.
• Molecules move via diffusion (passive transport) or active transport, with osmosis affecting water movement.
• Diffusion is the movement of substances from high to low concentration.
• Factors affecting diffusion include temperature, area of interaction, particle size, and steepness of the concentration gradient.
• Significance of diffusion:
  • Facilitates gas exchange in respiration (e.g., carbon dioxide diffusion).
  • Allows water uptake in plant roots.
  • Enables ion movement in neurons, generating electrical charges.

Explore the structure and function of cytoplasm and cell membranes in this quiz. Dive into the mechanisms of cell transport through membranes and learn about the various types of intercellular junctions. This material is essential for understanding cellular biology and its applications.