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01 cell structures
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01 cell structures






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01 cell structures 01 cell structures Presentation Transcript

  • CELL STRUCTURES Cell theory: 1) All living things are made of one or more cells 2) The cell is the basic organizational unit of life 3) All cells come from pre-existing cells
  • CELL STRUCTURES Organelles – internal structures performing specialized functions (not in bacteria) All organelles have a membrane except for ribosomes and centrioles.
  • CELL STRUCTURES Nucleus: protects and controls access to DNA, makes ribosomes Nuclear envelope/ membrane – double membrane; selectively permeable; continuous with ER Nucleolus – where subunits of ribosomes are made from proteins and RNA Nuclear pores – protein channels that allow certain substances in and out of the nucleus
  • CELL STRUCTURES Nucleus: protects and controls access to DNA, makes ribosome subunits Chromatin – combination of DNA and protein in nucleus Chromosomes – single piece of condensed (coiled) DNA with protein and RNA Note: Some of the chromosomes look condensed in this diagram, while others don’t.
  • CELL STRUCTURES Endoplasmic reticulum (ER): routes and modifies new proteins, & metabolizes lipids and carbohydrates Rough ER (RER)– studded with ribosomes for protein synthesis - Predominately found in liver cells where protein synthesis occurs actively Smooth ER (SER)– no ribosomes; performs lipid metabolism, carbohydrate metabolism, and detoxification
  • CELL STRUCTURES Golgi apparatus/body: packages proteins and lipids before they are sent to their destination; creates lysosomes Cis face – where vesicles enter the Golgi body Trans face – where vesicles exit the Golgi body Cisternae – the central stacks of the Golgi body
  • CELL STRUCTURES 1. Nuclear membrane 2. Nuclear pore 3. Rough endoplasmic reticulum 4. Smooth endoplasmic reticulum 5. Ribosome attached to RER 6. Macromolecules 7. Transport vesicles 8. Golgi apparatus 9.Cis face of Golgi apparatus 10. Trans face of Golgi apparatus 11. Cisternae of the Golgi Apparatus Summary:
  • CELL STRUCTURES Vesicles: Membrane-bound containers inside a cell (4 kinds) 1) Transport/secretory vesicles – transports substances within a cell, or releases them from the cell 2) Peroxisomes – contain enzymes to break down lipids and amino acids; inactivates toxins 3) Lysosomes – contains digestive enzymes; digest excess or worn- out organelles, food particles, and engulf viruses and bacteria 4) Vacuole – contain waste products (“garbage cans”), water, enzymes and/or other small molecules, export unwanted
  • CELL STRUCTURES Secretory/Transport Vesicle – Can release important molecules in the body (i.e. proteins, hormones, etc.)
  • CELL STRUCTURES Mitochondrion: Generates ATP and other molecules -The inner membranes contain enzymes & channel proteins for respiration -Have their own RNA
  • CELL STRUCTURES Ribosome: translates messenger RNA (mRNA) to polypeptide chains used to form proteins Made of two subunits which sandwich mRNA in between
  • CELL STRUCTURES Cytoskeleton: Dynamic system of filaments and microtubules Functions: -Provides cell structure -Helps with cell division -Enables cell and organelles to move around
  • CELL STRUCTURES Cytoskeleton: Made of 3 different structures
  • CELL STRUCTURES Centriole: Organizes the spindle fibres during mitosis and cytokinesis Most centrioles are made of 9 sets of microtubule triplets.
  • CELL STRUCTURES Cilia & Flagella: Used for locomotion; rotates around in a whip-like fashion. Made of microtubules. Cilia – smaller, more numerous, and can move fluids around stationary cells Flagella – larger, less abundant
  • CELL STRUCTURES Cytoplasm: Includes the cytosol, organelles, and chemicals (i.e. sugar and water); all contained by the cell membrane Cytosol: the fluid between the cell membrane and nucleus
  • CELL STRUCTURES Outside cell Inside cell Hence the cell membrane is called the phospholipid bilayer. Cell membrane: A bilayer of phospholipids which contains the contents of the cell
  • CELL STRUCTURES This bilayer is not static; it is dynamic. There is fluidity in the membrane.
  • CELL STRUCTURES Extracellular matrix (ECM): Supports and anchors cells; mixture of fibrous proteins and polysaccharides secreted by the cell. -Provides structural support for tissues -Separates tissues -Functions in cell signalling -Bone is mostly ECM (fibrous collagen, hardened by mineral deposits) -Insects’ exoskeletons are also ECM
  • PLANT CELLS Plant cells have additional organelles and features that are not found in animal cells.
  • PLANT CELLS Cell wall: Tough, flexible, and rigid layer around plant, bacteria, fungi, and algae cells. Surrounds cell membrane. -Prevents overexpansion when water enters cell -Protects cells against mechanical stress -Made primarily of cellulose
  • PLANT CELLS Cell wall: Made of 3 layers -Pectin layer (also called middle lamella) glues adjacent plant cells together -Primary cell wall is thin and flexible, and forms when cell is growing; like a cellulose “coating” -Secondary cell wall is thick and more rigid, but not found in all cell walls
  • PLANT CELLS Plastids: Organelle found in plants and algae; site of manufacture and storage of important chemicals (3 kinds) Chloroplasts – Make sugars using light energy, CO2, and H2O; contain the pigment chlorophyll for photosynthesis Chromoplasts –synthesis and storage of pigments other than chlorophyll Amyloplasts – non-pigmented; synthesis and storage of starch granules (abundant in stems & seeds)