2.1

• Structure and function – cell-surface membrane

  Phospholipid bilayer with embedded proteins etc.

  Selectively permeable – enables control of passage of substances in and out of cell

  • Barrier between internal and external environment of cell
• Structure and function – nucleus

  Nuclear envelope, nuclear pores, nucleolus, DNA / chromatin

  Controls the cells activity though transcription on mRNA

  Nuclear pores allow substances e.g. mRNA to move between the nucleus and cytoplasm

  • Nucleolus makes ribosomes which are made up of proteins and ribosomal RNA
• Structure and function – nucleus

  Nuclear envelope, nuclear pores, nucleolus, DNA / chromatin

  Controls the cells activity though transcription on mRNA

  Nuclear pores allow substances e.g. mRNA to move between the nucleus and cytoplasm

  • Nucleolus makes ribosomes which are made up of proteins and ribosomal RNA

  
• Structure and function – mitochondria

  Double membrane – inner membrane folded to form cristae. Matrix containing small 70S ribosomes, small circular DNA and enzymes involved in aerobic respiration (glycolysis).

  • Site of aerobic respiration producing ATP for energy release

  
• Structure and function of Golgi apparatus

  - 3 or more fluid filled membrane bound sacs with vesicles at edge

  • Receives protein from rough endoplasmic reticulum
  • Modifies/processes protein e.g. add carbohydrates/sugars
  • Packages into vesicles e.g. for transport to cell surface membrane for exocytosis
  • Also makes lysosomes

  
• Structure and function – lysosomes

  Type of Golgi vesicle containing lysozymes – hydrolytic enzymes

  • Release of lysozymes to break down / hydrolyse pathogens or worn out cell components
• Structure and function – ribosomes

  Float free in cytoplasm or bound to rER. Not membrane bound. Made from 1 large and 1 small subunit.

  • Site of protein synthesis, specifically, translation

  
• Structure and function – rough endoplasmic reticulum

  Ribosomes bound by a system of membranes

  Folds polypeptides to secondary / tertiary structure

  Packages to vesicles, transport to the Golgi apparatus etc.

  Structure and function – smooth endoplasmic reticulum

  Similar to rER but without ribosomes – system of membranes

  • Synthesises and processes lipids

  
• Structure and function – chloroplasts (plants and algae) - Thylakoid membranes are stacked up in some parts to form grana, which are linked by lamellae. These sit in the stroma (fluid) and are surrounded by a double membrane. Also contains starch granules and circular DNA.

  • (Chlorophyll) absorbs light for photosynthesis to produce organic substances
• Structure and function – cell wall (plants, algae and fungi)

  Made mainly of cellulose in plants and algae, and of chitin in fungi

  • Rigid structure surrounding cells in plants, algae and fungi. Prevents the cell changing shape and bursting (lysis)
• Structure and function – cell vacuole (plants)

  Contains cell sap – a weak solution of sugars and salts. Surrounding membrane is called the tonoplast.

  Maintains pressure in the cell (stop wilting)

  • Stores/isolates unwanted chemicals in the cell
• Organisation of specialised cells in complex multicellular organisms

  Specialised cell – the most basic structural/functional subunit in all living organisms; specialised for a particular function

  Tissue – Group of organised specialised cells; joined and working together to perform a particular function; often with the same origin

  Organ – Group of organised different tissues; joined and working together to perform a particular function

  • Organ system – Group of organised organs; working together to perform a particular function
• You should be able to apply your knowledge to explain adaptations of eukaryotic cells with particular functions - Example: epithelial cells in the small intestine are specialised for efficient absorption. Villi and microvilli increase surface area. Lots of mitochondria to provide energy e.g. for active transport
• Prokaryotic cell cytoplasm contains no membrane bound organelles such as mitochondria.
• Eukaryotic cell contains membrane bound organelles such as mitochondria.
• Prokaryotic cell has no nucleus and its DNA is free floating.
• Eukaryotic cell has a nucleus containing DNA.
• Prokaryotic DNA is circular and isn’t associated with proteins.
• Eukaryotic DNA is linear and is associated with proteins.
• Prokaryotic cell wall contains murein and peptidoglycan.
• Eukaryotic cell wall is made of cellulose.
• Prokaryotic cells have smaller 70s ribosomes.
• Eukaryotic cells have larger ribosomes.
• Prokaryotic cells may have one or more plasmid, a capsule, and/or one or more flagella.
• Acellular → not made of or able to be divided into cells

  • Non-living → unable to exist/reproduce without a host ce

  
• Preparing a ‘temporary mount’ of a specimen on a slide

  Use tweezers to place a thin section of specimen e.g. tissue on a water drop on a microscope slide

  Add a drop of a stain e.g. iodine in potassium iodide solution used to stain starch grains in plant cells

  • Add a cover slip by carefully tilting and lowering it, trying not to get any air bubbles