2.1.1 Structure of eukaryotic cells

• What are the distinguishing features of eukaryotic cells?

  ● Cytoplasm containing membrane-bound organelles

  ● So DNA enclosed in a nucleus
• Describe the general structure of eukaryotic cells

  Picture

  
• Describe the function of the cell-surface membrane

  ● Selectively permeable → enables control of passage of substances in / out of cell

  ● Molecules / receptors / antigens on surface → allow cell recognition / signalling

  
• Describe the function of the nucleus

  ● Holds / stores genetic information which codes for polypeptides (proteins)

  ● Site of DNA replication

  ● Site of transcription (part of protein synthesis), producing mRNA

  ● Nucleolus makes ribosomes / rRNA

  
• Describe the function of a ribosome

  ● Made of ribosomal RNA and protein (two subunits)

  ● Not a membrane-bound organelle

  ● Site of protein synthesis (translation)
• Describe the function of rER and sER

  rER ● Ribosomes on surface synthesise proteins

  ● Proteins processed / folded / transported inside rER

  ● Proteins packaged into vesicles for transport eg. to Golgi apparatus

  sER

  ● Synthesises and processes lipids

  ● Eg. cholesterol and steroid hormones

  
• Describe the function of Golgi apparatus and Golgi vesicles

  Golgi apparatus

  ● Modifies protein, eg. adds carbohydrates to produce glycoproteins

  ● Modifies lipids, eg. adds carbohydrates to make glycolipids

  ● Packages proteins / lipids into Golgi vesicles

  ● Produces lysosomes (a type of Golgi vesicle)

  Golgi vesicles

  ● Transports proteins / lipids to their required destination

  ● Eg. moves to and fuses with cell-surface membrane

  
• Describe the function of lysosomes

  ● Release hydrolytic enzymes (lysozymes)

  ● To break down / hydrolyse pathogens or worn-out cell components

  
• Describe the function of mitochondria

  ● Site of aerobic respiration

  ● To produce ATP for energy release

  ● Eg. for protein synthesis / vesicle movement / active transport

  
• Describe the function of chloroplasts in plants and algae

  ● Absorbs light energy for photosynthesis

  ● To produce organic substances eg. carbohydrates / lipids

  
• Describe the function of the cell wall in plants, algae and fungi

  ● Composed mainly of cellulose (a polysaccharide) in plants / algae

  ● Composed of chitin (a nitrogen-containing polysaccharide) in fungi

  ● Provides mechanical strength to cell

  ● So prevents cell changing shape or bursting under pressure due to osmosis
• Describe the function of the cell vacuole in plants

  ● Maintains turgor pressure in cell (stopping plant wilting)

  ● Contains cell sap → stores sugars, amino acids, pigments and any waste chemicals

  
• Describe how eukaryotic cells are organised in complex multicellular organisms. In complex multicellular organisms, eukaryotic cells become specialised for specific functions

  Tissue - Group of specialised cells with a similar structure working together to perform a specific function, often with the same origin

  Organ - Aggregations of tissues performing specific functions

  Organ System - Group of organs working together to perform specific functions
• Describe how you can apply your knowledge of cell features / organelles to explain adaptations of eukaryotic cells


  ● [Named cell] has many [named organelle, eg. ribosomes]

  ● To [link organelle function to cell function eg. increase rate of protein synthesis, making many antibodies