Structure of eukaryotic cells

• Structure of the nucleus

  Nuclear envelope ; double plasma membrane

  Nuclear pores

  nucleoplasm ; granula, jelly - like material

  chromosomes ; protein bound linear DNA

  Nucleous ; smaller sphere inside the nucleus where rRNA is produced to make ribosomes
• Function of Nucleus

  Site of DNA replication

  site of transcription ; first stage of protein synthesis, makes mRNA

  contains the genetic code for each cell

  Nuclear pores allow movement of mRNA

  controls all cell activities by controlling transcription
• Structure of rough endoplasmic reticulum

  cristernae; folded membrane

  ribosomes on cristernae making it rough
• Function of rough endoplasmic reticulum (RER)

  Protein synthesis
• Structure of smooth endoplasmic reticulum

  cristernae ; folded membrane

  smooth has it has NO ribosomes on cristernae
• Function of smooth endoplasmic reticulum (SER)

  synthesis and storage of lipids and carbohydrates
• Structure of Golgi apparatus and vesicles

  Folded membranes making cisternae

  secretary vesicles which pinch off from cisternae to carry a finished product produced

  made of polysaccharide
• Function of Golgi apparatus and vesicles

  Add carbohydrates to proteins to form glycoproteins ( proteins passed into the Golgi apparatus via the ribosomes on RER )

  produces secretory enzymes

  secretes carbohydrates

  transport, modify and stores lipids

  production of lysosomes ; vesicles which contain secretory enzymes

  molecules are ‘labelled’ for their destination ; e.g adding a receptor to molecule

  Finished products transported to the cell surface membrane to be released to destination via the Golgi vesicles
• Structure of lysosomes

  Bags of digestive enzymes
• Function of lysosomes (the digestive enzymes)

  Hydrolyse phagocytic cells

  completely break down dead cells ( wether body or phagocytic cells ) ; autolysis

  exocytosis ; release of enzymes outside the cell to destroy material

  digest worn out organelles for reuse of material
• structure of mitochondria

  Double membrane

  inner membrane folded to make cristae

  fluid centre called the mitochondrial matrix

  Contains loops of mitochondrial DNA (codes the enzymes for respiration )
• Function of mitochondria

  Site of aerobic respiration

  site of ATP production

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

  Made of two sub-units ; one smaller one larger made of - protien and rRNA

  80s - larger ribosomes found in eukaryotic cells (25nm)

  70s - smaller ribosomes found in prokaryotic cells, mitochodira and chloroplast
• Function of ribosomes

  The site of protein synthesis
• Structure of vacuole (plant cell only)

  Filled with fluid surrounded by a single membrane called a tonoplast
• Function of vacuole (plant cell only)

  makes cell turgid ; providing support

  temporary store of sugars and amino acids

  The pigments may colour petals to attract pollinators
• structure of chloroplast ( plant cell only )

  Surrounded by a double membrane

  contains thylakoid membrane ; additional folded membranes embedded with pigment )

  Thylakoid membranes stack up to form granum ; site of light independent reactions in photosynthesis
• function of chloroplast (plant cell only)

  Site of photosynthesis
• Why is chloroplast green?

  Chloropyll pigment is imbedded within the membrane of the thlyakoids
• Structure of cell wall in plant

  cellulose polymers bond with hydrogen bonds to form microfibrils
• structure of cell wall in fungi

  Made of chitin ; a polysaccharide containing nitrogen
• Function of cell wall - universally

  Provides structural strength to cell
• Function of Plasma membrane

  Controls what molecules enter and exit the cell

  also controlls the entering and exiting of membrane bound organelles
• Structure of plasma membrane

  found in all cells that have a phospholipid bilayer ; within pb there are proteins embedded and receptors ( e.g glycoproteins, glycolypids etc) carbohydrates and cholesterol