Anatomy and Physiology Answer Key

This pathway provides control over the entry of

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Unformatted text preview: completely penetrates lipid bilayer. Phospholipid Hydrophilic end Substances passing straight through channel provided by the protein. The Role of Membranes in Cells (page 21) 1. (a) (b) (c) (d) (e) (f) Golgi apparatus Lysosome Mitochondrion 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: – Oxygen – 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.

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