cell structure

• structure of nucleus in EC

  -nuclear envelope: double membrane

  -nuclear pores

  -nucleoplasm

  -chromosomes (proteins bound linear DNA)

  -nucleolus (site of rRNA production, makes ribosomes)
• function of nucleus in EC


  -site of DNA replication & transcription (makes mRNA)

  -containes genetic code for each cell
• structure of endoplasmic reticulum

  -both RER and SER have folded membranes calls cisternae

  -RER has ribosomes on the cisternae
• function of Endoplasmic Reticulum in EC

  -RER: protein synthesis

  -SER: synthesis of lipids, lipids & carbs can be stored here
• structure of Golgi apparatus

  -folded membranes making cisternae

  -secretary vesicles pinch off from the cisternae
• function of Golgi apparatus 


  -add carbs to proteins: glycoproteins-add carbs to proteins: glycoproteins

  -produce secretory enzymes

  -secrete carbohydrates

  -transport, modify, store lipids

  -form lysosomes

  -molecules labelled with their destination

  -finished products are transported to the cell surface through the Golgi vesicles where they fuse with the contents released
• structure of lysosomes 


  -bags of digestive enzymes, each can contain up to 50
• function of lysosomes 


  -hydrolyse phagocytic cells

  -autolysis: break down dead cells

  -exocytis: release enzymes to outer cell to destroy material

  -digest worn out organelles for reuse of materials
• structure of mitochondria

  -double membrane

  -inner membrane called the cristae

  -fluid centre: mitochondrial matrix
• function of mitochondria


  -site of aerobic respiration

  -site of ATP production

  -DNA to code for enzymes needed in respiration
• structure of ribosomes 


  -small, made up of sub-units of protein and rRNA

  -80s: larger, 25nm, eukaryotes

  -70s:smaller, prokaryotes, chloroplasts, mitochondria
• function of ribosomes 


  -site of protein synthesis
• structure of vacuole


  -filled with fluid

  -surrounded by a single membrane: tonoplast
• function of vacuole


  -makes cells turgid to provide support

  -temporary store of sugars & amino acids

  -pigments can colour petals to attract pollinators
• structure of chloroplasts


  -surrounded by a double membrane

  -contains thylakoids (folded membranes containing pigments)

  -fluid filled with stomata (containing enzymes for photosynthesis)
• function of chloroplasts


  -site of photosynthesis
• structure of cell wall

  -plants & fungi cells

  -in plants: made of microfibrils of cellulose polymer

  -fungi: made of chitin (nitrogen containing polysaccharide)
• function of cell wall


  -provides structural strength to cell
• structure of cell membrane


  -all cells

  -phospholipid bilayer: molecules embed within and attached on outside