Biology Unit 1

• Cell


  The building blocks of living things, the simplest parts of an organism
• Levels of biological organisation

  1. Cells

  2. Tissues

  3. Organs

  4. Systems

  5. Organism
• Animal cell structure


  • Plasma membrane
  • Cytoplasm
  • Nucleus
  • Nucleolus
  • Ribosomes
  • Rough endoplasmic reticulum
  • Smooth endoplasmic reticulum
  • Vesicles
  • Golgi apparatus
  • Lysosomes
  • Centrioles
  • Mitochondria
• Plasma membrane


  Protects the cell, allows substances in and out
• Cytoplasm


  Liquid jelly with dissolved substances and chemical reactions
• Nucleus


  Control centre of the cell, surrounded by double membrane with pores
• Nucleolus


  Region in nucleus where ribosomes are made
• Ribosomes


  Make proteins, given instructions from DNA
• Rough endoplasmic reticulum


  Flattened sacs covered in ribosomes, making lots of protein
• Smooth endoplasmic reticulum


  Tube-like structures where lipids are made
• Vesicles


  Small membrane-bound sacs for storing and transporting substances
• Golgi apparatus


  Modifies proteins and packages them in vesicles for transport
• Lysosomes


  Contain digestive enzymes to destroy old organelles and pathogens
• Centrioles


  Involved in cell division, make the spindle
• Mitochondria


  Where respiration happens, produce ATP, have their own ribosomes and DNA
• Electron micrographs


  • Showing different cell organelles
• Prokaryotic cells


  Single cell organisms with no membrane-bound organelles, e.g. bacteria
• Eukaryotic cells


  Plant and animal cells
• Prokaryotic cells don't have a nucleus, whereas eukaryotic cells do
• Parts of a prokaryotic cell

  • Nucleoid
  • Ribosomes
  • Slime capsule
  • Cell wall
  • Plasmids
• Nucleoid


  Single circular length of DNA folded up inside the cell, not bound by a membrane
• Ribosomes


  Floating around in the cytoplasm, 70S ribosomes which are smaller and less active than 80S
• Slime capsule


  Outer layer outside the cell wall, prevents cell from drying out and helps stick to surfaces
• Cell wall


  Made of long-chained molecules of sugar and amino acids called peptidoglycan, supports and protects the cell
• Plasmids


  Double-stranded circular DNA structures, contain additional genes that aid survival e.g. antibiotic resistance
• Peptidoglycan


  What bacterial cell walls are made of, long chain molecules of sugars and amino acids
• Gram-positive bacteria


  • Have a thick peptidoglycan cell wall, absorb stain in Gram test
  • Don't have an outer membrane
• Gram-negative bacteria


  • Have a thin peptidoglycan cell wall and an outer membrane, don't absorb stain in Gram test
  • More resistant to antibiotics as harder for them to get in
• Gram-positive and gram-negative bacteria have structural differences in their cell walls, which is useful for doctors to know as it affects antibiotic resistance
• Components of a plant cell that are also found in animal cells

  • Everything that animal cells have, except for centrioles
• Additional components found in plant cells

  • Chloroplasts
  • Vacuole
  • Tonoplast membrane
  • Cell wall
  • Amyloplasts
  • Middle lamella
  • Plasmodesmata and pits
• Chloroplasts


  Where photosynthesis happens, contain chlorophyll
• Vacuole


  Sack of liquid that stores water and dissolved substances
• Tonoplast membrane


  Membrane of the vacuole that controls movement of molecules in and out
• Cell wall


  Provides support and protection for plant cells, as they don't have a skeleton like animals
• Amyloplasts


  Where starch is stored
• Middle lamella


  Glue that holds plant cells together
• Plasmodesmata and pits


  Allow plant cells to communicate with each other using plant hormones
• Photosynthesis produces glucose, which is converted into starch and stored in amyloplasts
• Plant cells can communicate with each other through plasmodesmata and pits using plant hormones