Cell structure + function

• Organelles seen in both plant and animal cells

  • Cell membrane
  • Cytoplasm
  • Nucleus
  • Chromatin
  • Mitochondrion
  • Endoplasmic reticulum
  • Ribosomes
  • Golgi body
  • Vacuoles
• Organelles only seen in animal cells

  • Lysosomes
• Organelles only seen in plant cells


  • Cell walls
  • Chloroplasts
• Cytoplasm


  • Organelles are suspended in the cytoplasm
  • Made mostly of water
  • Many chemical reactions take place in the cytoplasm, allowing organelles to move around
  • Can change from/be "jelly-like" or liquid
• Cell membrane


  • Flexible double-layered
  • Supports the cell, allows some substances to enter while keeping others out
  • For example water and oxygen can pass through but larger molecules like protein cannot
• Nucleus


  • Roughly spherical structure
  • Contains genetic information stored on chromosomes
  • Controls all cell activity in the cell
  • Chromosomes contain DNA, which carry coded instructions for all cell activity
  • When a cell divides, the DNA is copied so that each new cell has a complete set of chromosomes
• Chromatin


  • A mass of very thin, tangled fibres containing DNA
  • Found in the nucleus
  • Genetic information of the cell which coordinates the cell's activities
• Mitochondrion


  • Sometimes called the "power plants" of the cell because they make energy available to the cell
  • Reddish, oval structure
  • Cells in which cellular respiration has to happen very fast have many mitochondria
  • Cells that are fairly inactive tend to have very few mitochondria
• Endoplasmic reticulum


  • Three-dimensional network of branching tubes and pockets
  • Rough ER have ribosomes attached
  • Fluid-filled tubes transport materials, such as proteins, throughout the cell
  • In the brain, the ER assists with the production of hormones
  • In muscles, the ER is involved with muscle contraction
• Ribosomes


  Make protein
• Golgi bodies


  • Closely stacked and flattened
  • Located near ER
  • Collect and process materials to be removed from the cell
  • They make and secrete mucus
• Vacuoles


  • A single layer of membrane enclosing fluid in a sac
  • Animal cells have many small vacuoles that are often not visible
  • Plant cells have one central vacuole that is visible under a microscope
  • Contain some substances
  • Remove unwanted substances from cell
  • Maintaining internal fluid pressure (turgor) within the cell
  • When bacteria are "engulfed," a portion of the cell membrane turns inside out and forms a vacuole inside the cell until the engulfed object is digested
• Lysosomes (animal)


  Contain enzymes (proteins) that can break down molecules (food, bacteria, wastes, the cell itself)
• Cell wall (plant)


  • Found just outside the cell membrane of a plant cell
  • Rigid but porous, made of cellulose
  • Provides support
  • Protects from physical injury
• Chloroplasts (plant)


  • Contain chlorophyll and gives leaves their green color
  • Absorb light energy
  • Photosynthesis takes place – the process of converting carbon dioxide and water into glucose and oxygen
• Movement across a membrane

  • Diffusion
  • Osmosis
• Diffusion


  The movement of a substance from an area of high concentration to an area of low concentration
• Osmosis


  The movement of water from an area of high to low concentration of water
• Types of osmosis


  • Hypotonic (cell will swell or burst, plant cells become TURGID)
  • Isotonic (perfectly balanced water and solute concentration)
  • Hypertonic (cell will deflate and plant cells become FLACCID)