Biology

• The nucleus is the control centre of the cell, containing DNA.
• Cell Capsule


  • Helps protect bacteria from being eaten by larger cells and from being infected by viruses
• Endoplasmic Reticulum

  • Interconnected network of thin folded membranes filling a large portion of the cell's cytoplasm
  • Rough ER: covered with ribosomes, production of proteins
  • Smooth ER: not covered with ribosomes, production of lipids, breaking down of drugs and alcohol
• Function of Plasma Membrane

  1. Separates the material outside the cell (extracellular) from the material inside the cell (intracellular)

  2. Controls passage of materials into and out of the cell

  3. Double layer of phospholipid molecules
• Parts of Nucleus

  • Nucleolus
  • Nuclear Pores
  • Nuclear Envelope
  • Nucleoplasm
  • Chromatin
• Cell Wall


  • Surrounds plasma membrane
  • Provides tensile strength and protection against mechanical and osmotic stress
  • Allows cells to develop turgor pressure
• Vacuoles


  • Fluid-filled sac for the storage of materials needed by the cell
• Vesicles

  • Sacs formed from the ER & Golgi apparatus
  • Transport materials within and outside of the cell
• Nucleus

  • Cell's headquarters
  • Contains majority of the cell's DNA
  • Sends out messages to tell the cell to grow, divide, or die
• Parts of fatty acid/lipid that make up the membrane

  • Hydrophilic Head
  • Hydrophobic Tail
• Plasma Membrane / Cell Membrane


  • Made up of a bilayer of phospholipids with embedded proteins, carbohydrates, glycolipids, and glycoproteins, and in animal cells, cholesterol
• Cell Wall composition in different organisms

  • Plants and algae: cellulose
  • Fungal cell: chitin
  • Bacterial Cell: peptidoglycan
• Golgi Apparatus / Complex


  • Proteins from rough ER are processed, sorted, and delivered here
  • Contains enzymes that further modify the proteins
• Types of Vesicles

  • Storage Vesicle
  • Transport Vesicle
  • Secretory Vesicle
• Plasmids


  • Found in bacteria acting as genetic organelles
  • Often contain genes not related to basic life functions like antibiotic resistance genes
  • Replicate independently from host's chromosomal DNA
• Sacs formation

  1. Formed from the ER & golgi apparatus

  2. Transport materials within and outside of the cell
• Vacuoles are fluid-filled sacs for the storage of materials needed by the cell, including water, food molecules, inorganic ions, and enzymes
• Lysosomes contain a powerful enzyme called lysozyme, which can defend the cell from invading bacteria and viruses
• There are more lysosomes in animal cells than in plant cells
• Chloroplasts have their own ribosomes and DNA
• Mitochondria were originally free-living prokaryotes that were taken in by larger cells
• Cilia allow the cell to move like an oar or a whip
• Mitochondria are the powerhouse of the cell
• Mother centriole forms flagella and cilia in non-dividing cells
• Peroxisomes breakdown complex molecules into smaller molecules
• Centrosome is made up of 2 centrioles arranged in an orthogonal manner
• Centriole is a microtubule unit which makes the centrosome
• Cytoskeletons provide sturdy mechanical support and help the cell to organize its contents and direct its movement in response to the changing needs and signals from its external environment
• Most animals contain small vacuoles, while plants have a central vacuole which strengthens the cell and helps support the entire plant by making it erect
• Centrosome forms the spindle apparatus during cell division
• Chloroplasts help plants to convert solar energy to chemical energy through the process of photosynthesis
• Peroxisomes help in breaking down alcohol in the body
• Lysosomes breakdown damaged or worn-out cell parts
• Flagella are lash-like appendages that protrude from the cell body
• Centriole is a cylindrical structure
• Flexible Networks of Protein

  • Microtubules – give the cell shape and serve as anchorage for membrane-bound organelles and other cell parts
  • Intermediate Filaments – give the cell tensile strength / ability to stretch without breaking apart
  • Microfilaments – provide a protective meshwork under the plasma membrane
• Mitochondria have their own ribosomes and DNA
• Centrosome is a small dense region of cytoplasm that serves as the main microtubule organizing center (MTOC)
• Peroxisomes contain digestive enzymes for breaking down toxic materials
• Cilia and flagella are locomotory projections in eukaryotes