Recording-2025-03-24T14:42:47.839Z

Mitochondria Structure and Function

• Two Membranes: The mitochondria have an inner membrane and an outer membrane.

• Mitochondrial Matrix: The space enclosed by the inner membrane is called the mitochondrial matrix.

• Intermembrane Space: The space between the inner and outer membranes is known as the intermembrane space.

• Cristae: The folds of the inner membrane, called cristae, increase the surface area for biochemical reactions to occur.

Cytoskeleton Components

• Microtubules and Microfilaments: These structures are vital for cellular movement and shape.

  • Dynein and Kinesin: These are motor proteins that move along microtubules, transporting cellular materials.

  • Cilia and Flagella: Both contain microtubule structures and are involved in movement (e.g., sperm motility, respiratory tract mucous movement).

Photosynthesis in Chloroplasts

• Thylakoid Membrane: The inner membrane system in chloroplasts where the light reactions of photosynthesis occur.

• Stacks of Thylakoids: These stacks are referred to as grana.

• Stroma: The fluid interior of the chloroplast, surrounding the thylakoids.

Cellular Processes

• Vesicle: A small sac filled with fluid, used for transport within cells.

• Endocytosis: The process of taking substances into the cell via vesicles.

• Exocytosis: The release of substances from a cell by vesicles that fuse with the plasma membrane.

Muscular Contraction Mechanism

• Actin and Myosin: Actin filaments and myosin are the primary proteins that interact to cause muscle contraction.

Intermediate Filaments

• Supportive Role: Intermediate filaments provide mechanical support and help maintain cell shape. They are the most resilient protein fibers and persist even after cell death (e.g., found in dust as dead skin cells).

• Relatively Stable: They help keep organelles fixed within cells but also allow for some movement and restructuring within the cytoplasm.

Extracellular Matrix (ECM)

• Definition: The ECM is the non-cellular component in tissues that provides structural and biochemical support.

• Components: Includes proteins like collagen and elastin, which facilitate various tissue functions.

  • Collagen: Provides strength to tissues.

  • Elastin: Gives tissues elasticity, allowing them to return to their original shape after stretching.

• Fluid Connective Tissue Example: Blood has a liquid ECM known as plasma, primarily made of water, with few fibers.

• Bone Matrix: Solid ECM of bone is composed mainly of calcium carbonate and protein fibers, giving strength and rigidity.

Tissue Types and Cellular Components

• Eukaryotic Tissues: Different tissues have unique cellular compositions and ECM structures that define their functions, such as muscle, blood, and connective tissues.

• Hierarchical Organization: Different organisms show varying organization levels from single cells to complex multicellular structures.

Plant Cell Structure

• Cell Walls: Plant cells have cell walls made of cellulose, which provides additional rigidity and is structured in layers:

  • Primary Cell Wall: The outermost layer; thin and flexible.

  • Secondary Cell Wall: Sometimes deposited between the plasma membrane and primary cell wall for added strength.

  • Middle Lamella: A pectin layer between adjacent primary cell walls, aiding in cell adhesion.

Intercellular Communication

• Types of Junctions: Cells communicate through various junctions:

  • Plasmodesmata: Plant cell junctions allowing fluid and nutrient exchange.

  • Tight Junctions: Animal cell junctions that seal cells tightly to prevent leakage, maintaining tissue integrity.

  • Desmosomes: Anchor cells together, providing structural stability under stress.

  • Gap Junctions: Enable direct communication between adjacent cells by allowing small molecules and ions to pass through.

Summary of Cell and Tissue Functionality

• Support and Integrity: ECM and cellular structures ensure the strength, flexibility, and functionality of tissues. They allow cells to communicate and respond to environmental changes effectively.

• Homeostasis: Organisms maintain a stable internal environment via complex intercellular signaling and tissue interactions.