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
DNA inside the
cytoplasm
DNA enclosed by a
membrane
Mitochondria
no
yes
Internal
membranes
no
yes
2.3.5: State three differences between plant and animal cells
1.
2.
3.
4.
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
Glycoproteins
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.
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. [5]