Units 1&2

• Vesicle: A small fluid-filled sac that is used to transport substances from one part of the cell to another
• Cell membrane: A semi-permeable barrier that surrounds the cell and controls what enters and leaves the cell
• Golgi body: A membrane-bound organelle that modifies and packages proteins for transport
• Mitochondria: Site of aerobic respiration, where most of the energy for cellular respiration is produced
• Nucleus: contains genetic material and controls cell activities.
• Nucleolus: a small dense spherical structure in the nucleus of a cell during interphase.
• Lysosomes: Small membrane-bound organelles that contain enzymes that break down large molecules
• Cytoplasm: A gel-like substance that fills the space between the cell membrane and the nucleus.
• Centrioles: microtubules that are involved in cell division and spindle formation
• Endoplasmic reticulum: provides a surface on which chemical reactions can occur
• Ribosomes: Site of protein synthesis in the cell.
• Cytoskeleto: A network of microtubules and microfilaments that provide the structural framework for the cell.
• The human body is comprised of cells, tissues, and organs within complex systems that work together to maintain life
• Cell organelles maintain life processes and require the input of materials and the removal of wastes to support efficient functioning of the cell
• The cell membrane separates the cell from its surroundings with a structure described by the fluid mosaic model, allowing for the movement of materials into and out of the cell by diffusion, facilitated diffusion, osmosis, active transport, and vesicular transport (endocytosis/exocytosis)
• Factors affecting the exchange of materials across the cell membrane include surface area to volume ratio, concentration gradients, and the physical and chemical nature of the materials being exchanged
• The various tissues of the human body perform specific functions and can be categorized into four basic tissue types: epithelial, connective, muscular, and nervous
• The Cell Theory:

  • All living things are made up of one or more cells
  • Cells are the basic unit of life
  • Cells come from other cells
• Cells are made up of:

  • Cell membrane: surrounds and forms the outer boundary
  • Cytoplasm: fluid within and organelles
  • Organelles: structures within the cell that carry out particular functions
  • Cytosol: liquid part of the cell
  • Cytoskeleton: internal scaffolding of protein fibers within the cell
  • Inclusions: chemical substances within the cell (granules or liquid droplets)
• Cell Membrane:

  • Boundary between cells and their environment
  • Selectively permeable and controls what enters and leaves the cell
  • Composed of a phospholipid bilayer
• Cytoplasm:

  • Jelly-like substance that fills the space between the cell membrane and the nucleus
  • Consists of cytosol, organelles, and inclusions
• Cytosol:

  • Liquid part of cytoplasm, consisting of 75 to 95 percent water
  • Contains dissolved salts, suspended substances like proteins, and waste products
  • Site of most metabolic reactions and controls osmotic pressure of the cell
• Organelles:

  • Structures within the cell specialized for particular functions
  • For example, mitochondria is the site of cellular respiration with a highly folded inner membrane to increase surface area for chemical reactions
• Nucleus:

  • Largest organelle within the cell
  • Contains DNA, chromosomes/chromatin, and the nucleolus important in protein production
• Ribosomes:

  • Produced by the nucleolus
  • Synthesize proteins by assembling amino acids
  • Can be bound on the endoplasmic reticulum or free within the cytoplasm
• Endoplasmic Reticulum (ER):

  • Channels formed by membranes for storing and transporting molecules
  • Rough ER lined with ribosomes transports proteins, while smooth ER is involved in lipid manufacture
• Golgi Body:

  • Series of flattened membranes responsible for modifying proteins and packaging them for secretion
  • Processes lipids to form lysosomes
• Lysosomes:

  • Membrane-bound vesicles containing digestive enzymes
  • Can destroy foreign material or redundant cell structures and cause cell self-destruction if damaged
• Mitochondria:

  • Have a double membrane with a folded inner membrane for increased surface area
  • Known as the powerhouse of the cell, site of cellular respiration to convert glucose and glycerol/fatty acids into ATP
• Other organelles:

  • Nucleolus: manufactures and stores ribosomal RNA
  • Cytoskeleton: maintains cell shape and allows cell movement
  • Centriole: involved in spindle formation during nuclear division
  • Inclusions: chemical substances found in the cytoplasm like haemoglobin and melanin
• Cilia and Flagella:

  • Cilia are tiny hair-like projections, while flagella are longer and generally fewer in number
  • Cilia line the trachea, while flagella are found in sperm cells
• Cytoskeleton:

  • Framework of protein fibers giving the cell shape and assisting movement
  • Microtubules keep organelles in place or move them, while microfilaments move materials around the cytoplasm or the whole cell
• Homeostasis:

  • Body systems work together to maintain a constant cellular environment
  • Cells require nutrients, gases, and waste removal from the extracellular fluid surrounding them
• Cell Membrane:

  • Made of phospholipid molecules in a double layer (phospholipid bilayer)
  • Contains cholesterol for regulating fluidity and membrane strength
  • Includes membrane proteins like receptor proteins, channel proteins, carrier proteins, and cell identity markers
• Functions of the Cell Membrane:

  • Physical barrier separating cytoplasm and extracellular fluid
  • Regulation of material passage through a semi-permeable membrane
  • Sensitivity to changes in extracellular fluid and support through attachment to the cytoskeleton
• Transport Across the Cell Membrane:

  • Transport processes are either passive (no energy required) or active (uses energy - ATP)
  • Includes diffusion, facilitated diffusion, and active transport
• Transport processes across the cell membrane can be categorized into passive transport (no energy required) and active transport (uses energy - ATP)
• Passive transport includes diffusion, osmosis, and carrier-mediated transport
• Active transport involves vesicular transport
• Diffusion is the spreading of particles (liquid or gas) until they are evenly distributed over available space