2.3: EUKARYOTIC CELLS

2.3.1, 2.3.2: Liver cell

2.3.3: Electron micrograph of liver cell (rat) Glycogen

2.3.4: Prokaryotic VS Eukaryotic cell FEATURE Prokaryotic cell Eukaryotic cell DNA Naked DNA DNA associated with proteins Ribosomes 70s 80s DNA inside the cytoplasm DNA enclosed by a membrane Mitochondria no yes Internal membranes

2.3.5: State three differences between plant and animal cells Plant cells have large vacuoles and animal cells do not have large vacuoles. Plant cells have a cell wall and animal cells do not have a cell wall. Plant cells (may) have chloroplasts and animals do not have chloroplasts. Plant cells store excess glucose as starch and animal cells store excess glucose as glycogen.

2.3.6: Outline two roles of extra cellular components The plant cell wall maintains cell shape, prevents excessive water uptake, and hold the whole plant up against the force of gravity. Animal cells secrete glycoproteins that form the extracellular matrix. This functions in support, adhesion and movement. Glycoproteins Animal cells secrete glycoproteins, which are composed of a protein and a carbohydrate. Glycoproteins are used in proteins that are located in the extracellular matrix (the space outside the cell). One example of glycoproteins found in the body are mucins, which are secreted in the digestive tracts. The sugars attached to mucins make them resistant to proteolysis by digestive enzymes. Glycoproteins on the surface of lymphocytes allow them to stick to other types of cells and move across their surfaces.

IB Question: Eukaryotic cells have intracellular and extracellular components. State the functions of one named extracellular component. [4]

IB Question: Eukaryotic cells have intracellular and extracellular components. State the functions of one named extracellular component. [4] name of component [1 max] e.g. plant cell wall/cellulose/interstitial matrix/basement membrane/glycoprotein/bone matrix; functions [3 max] EITHER e.g. (plant cell wall) strengthens/supports the cell/plant (against gravity); prevents the entry of pathogens; maintains the shape of plant cells; allows turgor pressure/high pressure to develop inside the cell; prevents excessive entry of water to the cell; OR helps cells to stick together/adhere; needed to hold cells/tissues together / example of cells/tissues holding together; forms interstitial matrix / forms basement membrane to support single layers of cells; e.g. around a blood capillary; forms (part of the) filtration membrane in the glomerulus; [4 max]

IB Question: Compare the structure of prokaryotic and eukaryotic cells