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bilayer. Phospholipid Hydrophilic
straight through channel
provided by the protein. The Role of Membranes in Cells (page 21)
(f) Golgi apparatus
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
Peroxisome 3. Compartments within cells allow specific metabolic
pathways in the cell to be localized. This achieves
greater efficiency of cell function and restricts
potentially harmful reactions and substances (e.g.
hydrogen peroxide) to specific areas. 4. (a) Lipid soluble molecules pass easily through the
phospholipid bilayer by dissolving in it. Lipid
insoluble substances cannot pass directly into the
bilayer (they must move through channels).
(b) Lipid soluble substances pass very rapidly
into cells (many drugs are lipid soluble). Lipid
insoluble molecules must pass through protein
channels (either by facilitated diffusion or active
transport). 5. (a)-(c) Any of, in any order:
– Energy source (=food = glucose)
– Mineral and trace elements
– Water 6. (a) Carbon dioxide
(b) Nitrogenous waste Cell Structures and Organelles (page 23)
(b) Name: Mitochondrion
Location: In cytoplasm as discrete organelles
Function: Site of cellular respiration (ATP formation)
Visible under LM: Not with most standard school LM,
but can be seen using high quality, high power LM.
(c) Name: Centrioles
Location: In cytoplasm, usually next to the nucleus.
Function: Involved in cell division (probably in the
organization of the spindle fibers).
Visible under LM: No.
(d) Name: Ribosome
Location: Free in cytoplasm or bound to rough ER
Function: Synthesize polypeptides (=proteins)
Visible under LM: No Hydrophobic
end Some proteins are
embedded in the
lipid bilayer. 2. Membranes are critical to the functioning of cells.
They form the outermost boundary of the cell and
regulate the entry and exit of material into and out
of the cell. They form the basis of membranous
organelles involved in protein synthesis and
packaging (rough ER), lipid and hormone synthes...
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This document was uploaded on 01/28/2014.
- Winter '13