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03 cell structures


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03 cell structures

  2. 2. CELL STRUCTURES Activity: On a sheet of scrap paper, draw an animal cell and its organelles, and label as many organelles as you can. Repeat this for a plant cell.
  3. 3. CELL STRUCTURES Organelles – internal structures performing specialized functions (in eukaryotes) All organelles have a membrane except for ribosomes and centrioles.
  4. 4. CELL STRUCTURES Nucleus: protects and controls access to DNA, makes ribosome subunits 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
  5. 5. 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.
  6. 6. 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
  7. 7. 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
  8. 8. 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:
  9. 9. 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 substances
  10. 10. CELL STRUCTURES Secretory/Transport Vesicle – Can release important molecules in the body (i.e. proteins, hormones, etc.)
  11. 11. CELL STRUCTURES Mitochondrion: Generates ATP and other molecules -The inner membranes contain enzymes & channel proteins for respiration -Have their own RNA
  12. 12. CELL STRUCTURES 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 Chromoplasts –synthesis and storage of pigments other than chlorophyll Amyloplasts – non- pigmented; synthesis and storage of starch granules (abundant in stems & seeds)
  13. 13. CELL STRUCTURES Ribosome: translates messenger RNA (mRNA) to polypeptide chains used to form proteins Made of two subunits which sandwich mRNA in between
  14. 14. CELL STRUCTURES Cytoskeleton: Dynamic system of filaments and microtubules Functions: -Provides cell structure -Helps with cell division -Enables cell and organelles to move around
  15. 15. CELL STRUCTURES Cytoskeleton: Made of 3 different structures
  16. 16. CELL STRUCTURES Microtubule: Made of dimers of two globular proteins (alpha and beta tubulin) forming a hollow tube. -Form dynamic scaffolding for many cellular processes -Rapid assembly when and disassembly when needed
  17. 17. CELL STRUCTURES Actin filaments: Also called microfilaments; made of the protein actin -Forms at the edge of a cell, allowing the cell to drag or extend -Also found in muscle fibres
  18. 18. CELL STRUCTURES -most stable part of cytoskeleton -made of fibrous proteins -Strengthen and maintain cell and tissue structures Intermediate filaments: Toughest of the cytoskeleton filaments.
  19. 19. CELL STRUCTURES Centriole: Organizes the spindle fibres during mitosis and cytokinesis Most centrioles are made of 9 sets of microtubule triplets.
  20. 20. 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
  21. 21. CELL STRUCTURES Cell wall: Tough, flexible, and rigid layer around plant, bacteria, fungi, and algae cells -Prevents overexpansion when water enters cell -Protects cells against mechanical stress -Made primarily of cellulose
  22. 22. CELL STRUCTURES 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 (found in the xylem)
  23. 23. 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 -The primary cell wall is a type of ECM -Bone is mostly ECM (fibrous collagen, hardened by mineral deposits) -Insects’ exoskeletons are also ECM
  24. 24. CELL STRUCTURES Cell junctions: Structures that allow cells to interact with each other and surrounding environment (3 types in animals) Gap junction Desmosome Tight Junction
  25. 25. CELL STRUCTURES Gap junction: Proteins form holes between adjacent animal cells; allows various ions and molecules to pass freely between cells
  26. 26. CELL STRUCTURES Desmosome: Sticks cells together to help reduce shearing forces; no pores; very wide extracellular space in between (Bind muscle cells to one another)
  27. 27. CELL STRUCTURES Tight junction: Light tight “stitching” (made of proteins) which prevent dissolved materials from crossing at junction
  28. 28. CELL STRUCTURES Plasmodesma (plants only): Like gap junctions, they permit transport and communication between cells.