2.1 Cell Structure Summary

Created by: thiamoorhouse
Created on: 06-06-21 20:33

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Cell Structure
- Eukaryotic Cells and Organelles
  - Plasma Membrane
    - Membrane found on the surface of cells. It's made of mainly lipids and proteins
    - Regulates movement of substances into and out of the cell.
    - Has receptor molecules on it which allow it to respond to chemicals
  - Cell Wall
    - Rigid structure that surrounds plant cells.
    - Supports plant cells
  - Nucleus
    - Large organelle surrounded by nuclear envelope which contains pores
    - Contains chromatin and the nucleolus
    - Controls cell's activities
    - Pores allow substances to move between the nucleus and cytoplasm
    - Nucleolus makes ribosomes
  - Lysosome
    - Round organelle with no clear internal structure
    - Contains digestive enzymes to digest invading cells or to break down worn out components of cells
  - Ribosome
    - Very small organelle that either floats free in the cytoplasm or is attached to rough endoplasmic reticulum
    - Made of proteins and RNA and not surrounded by a membrane
  - Rough Endoplasmic Reticulum
    - System of membranes enclosing a fluid filled space
    - Surface dotted with ribosomes
    - Folds and processes proteins that have been made at the ribosome
  - Smooth Endoplasmic Reticulum
    - Similar to rough endoplasmic reticulum but with no ribosomes
    - Synthesises and processes lipids
  - Vesicle
    - Small fluid filled sac in cytoplasm surrounded by a membrane
    - Transports substances in and out of the cell and between organelles
    - Some formed by golgi or endoplasmic reticulum others formed at cell surface
  - Golgi Apparatus
    - Group of fluid filled membrane bound flattened sacs
    - Vesicles often seen at edges of sacs
    - Processes and packages new lipids and proteins
    - Makes lysosomes
  - Mitochondria
    - Have a double membrane and the inner one is folded to form cristae
    - Inside is the matrix which contains enzymes involved in respiration
    - Site of aerobic respiration where ATP is produced
  - Chloroplast
    - Small flattened structure found in plant cells
    - Surrounded by a double membrane
    - Has membrane inside called thylakoid membranes which are stacked up to form grana
    - Grana are linked by lamellae which are thin flat pieces of thylakoid membrane
    - Site of photosynthesis. Some happens in gran and some happens in stroma
  - Centriole
    - Small hollow cylinders made of microtubules
    - Involved in separation of chromosomes
  - Cilia
    - Small hair like structures found on the surface of some animal cells
    - Have an outer membrane and a ring of nine pairs of microtubules with two in the middle
    - Microtubules allow cilia to move which moves substances along the surface
  - Flagellum
    - Two microtubules in the middle surrounded by nine pairs
    - Microtubules contract to make flagellum move
    - Flagella used like motors to propel cells forward
    - Stick out from cell surface and surrounded by plasma membrane
- Protein Production
  - Proteins made at the ribosomes
  - Ribosomes on rough ER make proteins that are excreted or attached to cell membrane
  - Free ribosomes in the cytoplasm make proteins that stay in the cytoplasm
  - New proteins produced at rough ER are folded and processed
    - They're then transported from the ER to the golgi in vesicles
      - At the golgi they undergo further processing
        The proteins enter more vesicles to be transported around the cell
        Protein Production
        Proteins made at the ribosomes
        
        Ribosomes on rough ER make proteins that are excreted or attached to cell membrane
        
        Free ribosomes in the cytoplasm make proteins that stay in the cytoplasm
        
        New proteins produced at rough ER are folded and processed
        They're then transported from the ER to the golgi in vesicles
        At the golgi they undergo further processing
        The proteins enter more vesicles to be transported around the cell
- Cytoskeleton
  - Is a network of protein fibres
  - Functions
    - Support organelles to keep them in position
    - Strengthen cell and maintain shape of cell
    - Responsible for movement of substances in the cell
    - Can also make the cell move
- Microscopes
  - Magnification
    - How much bigger the image is than the actual specimen being viewed
    - Magnification = image size/object size
  - Resolution
    - How detailed the image is. The ability to distinguish two objects from each other
  - Light Microscope
    - Uses light beam
    - Have a low resolution - max resolution of 0.2 micrometers
    - Maximum magnification of x1500
    - Used to look at whole cells or tissues
  - Laser Scanning Confocal Microscope
    - Use laser beams to scan a specimen which is tagged with a fluorescent dye
    - Laser causes dye to give off light which is then focused through a pinhole onto a detector
    - Detector is hooked to a computer that generates an image
    - Can be 3D image
    - Used to look at objects at different depths in thick specimens
  - Transmission Electron Microscope
    - Use electromagnets to focus beam of electrons
    - Denser parts absorb more electrons which makes them darker in the image
    - Provide high resolution images
    - Only used on thin specimens
  - Scanning Electron Microscope
    - Scans a beam of electrons across a specimen which knock off electrons from the specimen which are gathered in a cathode ray tube to form an image
    - Can be 3D images
    - Lower resolution than TEMs

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2.1 Cell Structure Summary

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