cell structure

• Nucleus structure

  • Nuclear envelope(semi-permeable double membrane)
  • Nuclear pore (substances enter/exit )
  • Nucleolus
  • Contains chromatids( made of DNA and Proteins)
• Nucleus function

  • Nucleolus makes ribosomes
  • Controls the cell's activities (transcription)
• Rough Endoplasmic Reticulum (RER) structure 


  • covered in ribosomes
• Rough Endoplasmic Reticulum (RER) function 


  • Folds and processes proteins (made in ribosome)
• Smooth Endoplasmic Reticulum (SER) structure 


  • No ribosomes
• Smooth Endoplasmic Reticulum (SER) function

  • synthesises and processes lipids
• Golgi apparatus structure

  • flattened sacs
  • vesicles bud off via exocytosis
• Golgi apparatus

  • Modifies and packages lipids and proteins
  • Makes lysosomes
• Ribosome structure

  • Large subunit which joins amino acids
  • Small subunit with mRNA binding site
• Ribosome function

  • site where proteins are made
• Mitochondrion structure

  • Double membrane
  • Inner membrane is folded to form a cristae - inside is matrix which contains enzymes involved in respiration
• Mitochondrion function

  • Site of aerobic respiration
  • ATP produced
• Chloroplast structure

  • Double membrane
  • Inner membrane called thylakoid membrane (flattened discs)
  • Staked up to form a grana - linked together by lamellae
• Chloroplast function

  • Site of photosynthesis
• Centriole Structure

  • Hollow tubes made of microtubules
• Centriole Function

  • Separation of chromosomes (cell division)
• Cilia structure

  • 9 pairs of proteins microtubules outside , two microtubles inside
  • 9 + 2 formation
• Flagellum structure

  • 9 + 2 formation
• Flagellum function

  • microtubules contract to make flagellum move
• Cell Wall

  Bacteria : Peptidoglycan

  Fungi: Chitin

  Plant: Cellulose (have plasmodesmata)
• Role of cytoskeleton

  • Cell support
  • Movement of cilia/flagellum
  • Changing shapes of cell (e.g cytokinesis /phagocytosis )
  • Movement of chromosomes
  • Microtubules/filaments support/keep organelles in position
• Protein Production

  • Proteins made at ribosome
  • Ribosomes on the RER makes proteins that are excreted/attached to cell membrane
  • New proteins at RER are folded and processed in ER
  • Transported form ER to Golgi apparatus in vesicles
  • Golgi apparatus proteins undergo further processing
  • Protein enter vesicles and transport them and fuse to cell surface
• Prokaryotes

  • 70S ribosomes
  • Unicellular
  • No membrane-bound organelles / No nucleus
  • Circular DNA
  • Binary fission
• Eukaryotes

  • 80S ribosomes
  • Often multicellular
  • Nucleus
  • Linear DNA associated with histones
  • Mitosis and Meiosis