Cells

• Eukaryotic cells


  Complex and include animals and plant cell walls
• Structure of Eukaryotic cell

  - Plasma

  - RER

  - SER

  - Lysosome

  - Ribosome

  - Nucleus

  - Nucleolus

  - Mitochondrion

  - Golgi apparatus

  - Cytoplasm

  - Nuclear envelope
• Plant cells have extra

  - Chloroplasts

  - Plasmodesmata

  - Cell wall

  - Vacuole
• Fungal cells


  Like plant cells, 2 differences:

  1. Cell wall made of chitin

  2. NO chloroplastsc
• Cell surface membrane function

  Controls the movement of substances into and out of the cell
• Cell surface membrane structure

  A phospholipid bilayer with intrinsic and extrinsic protein molecules
• Nucleus structure


  Largest organelle. Surrounded by the nuclear envelope; contains fluid nucleoplasm, nucleoli, and chromatin.
• Nucleus function


  Control center of the cell
• Mitochondrion structure


  Double membrane structure, inner membrane highly folded into internal cristae
• Mitochondrion function


  Site of aerobic respiration where ATP is produced
• Small, flattened

  Double membrane, also has thylakoid membranes, stacked up=grana

  Grana linked by lamellae= thin, flat pieces of thylakoid membrane
• Chloroplast function


  Site of photosynthesis
• Golgi apparatus function


  Modifies and packages proteins
• Golgi apparatus structure


  Fluid filled membrane bound flattened sacs
• Golgi vesicle structure


  A small fluid-filled sac in the cytoplasm, surrounded by a membrane and produced by the golgi apparatus
• Golgi vesicle function


  Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell.
• Lysosome structure


  Round organelles surrounded by a membrane, no clear internal structure
• Lysosome function


  Contains digestive enzymes called lysozymes, digest invading cells and break down worn out components out of the cell
• Ribosome structure


  small organelle made of ribosomal RNA (rRNA) and protein; they are either attached to the ER or free floating in the cell
• Ribosome function


  protein synthesis
• RER structure


  System of membranes enclosing a fluid-filled space, surface covered with ribosomes
• RER function


  Folds and processes proteins that have been made at the ribosomes
• SER structure


  similar to RER but no ribosomes
• SER function


  Synthesises and processes lipids
• Cell wall structure


  Rigid structure that surrounds plants, algae and fungi. Made mainly of cellulose (fungi=chitin)
• Cell wall function


  Supports cell wall and prevents them from changing shape
• Cell vacuole structure


  a membrane-bound organelle found in the cytoplasm of plant cells. contains cell sap - weak solution of sugars & salts. the surrounding membrane is called the tonoplast
• Cell vacuole function


  helps to maintain pressure inside the cell & keep the cell rigid. this stops the plant wilting. also involved in the isolation of unwanted chemicals inside the cell
• Prokaryotic cells


  Smaller and simpler than eukaryotic

  E.g. bacteria
• Prokaryotic cells structure


  - flagella

  - capsule

  - chromosome

  - ribosome
• Virus structure


  Contains genetic material either DNA or RNA, protein coat and attachment proteins
• Binary Fission


  Cell replicated it's genetic material, splitting into two daughter cells

  1. Circular DNA and plasmid replicates

  2. Cell gets bigger, DNA loops move opposite poles

  3. Cytoplasm divides

  4. 2 daughter cells produced
• How do viruses replicate themselves?

  1. Use attachment proteins to bind to the complementary receptor proteins on surface of host cells

  2. Inject their DNA or RNA into host cell and use that cell's organelles to replicate the viral particles for it.
• Plasmid


  A small ring of DNA that carries accessory genes separate from those of the bacterial chromosome
• Flagellum


  A long, hairlike structure that grows out of a cell and enables the cell to move.
• How do bacteria and viruses differ

  Viruses: have no plasma membrane, cytoplasm or ribosomes
• Structure of a virus

  - core genetic material- DNA/RNA

  - protein coat= capsid

  - attachment proteins
• Binary fission


  1. Circular DNA and plasmids replicate

  2. Cell gets bigger and DNA loops move to opposite poles

  3. Cytoplasm divides

  4. 2 daughter cells produced= 1 with copy of circular DNA and other with variable number of copies of plasmids
• How do viruses replicate?

  1. Viruses attachment proteins bind to complementary receptor proteins on the surface of host cells

  2. Different viruses have different attachment proteins and require different receptor proteins on host cells

  3. DONT replicate- inject their DNA or RNA into host cell- enzymes replicate the viral particles
• Magnification


  How much bigger an image appears compared to the original object.