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Cell Membranes
Structure & Transport Mechanisms
Question | Answer |
---|---|
What is the cell membrane composed of? | 50% Protein - 45% Lipid - 5% Carbohydrate (Monosaccharide chains) |
What is the architecture of the cell membrane? | 2 sided Lipid sheet with embedded Proteins |
What is an impotant feature of Cell Membranes? | Self Assembly and Resealing capabilities |
What feature of Cell Membranes assists with Membrane Transport? | Lipid Bi-layer is very permeable to NON-Polar molecules & selectively permeable to Polar Molecules and Ions |
What is the function of Protein Channels? | permit PASSIVE DIFFUSION of SPECIFIC Ions from a HIGH --> LOW concentration |
Where are Protein Channels located? | they span the Lipid Bilayer |
What is the function of Carrier Mediated Transport? | to transport Large Polar Molecules in/out of cell |
T/F Protein Channels are one of the Carrier Mediated transport systems. | F. Protein Cahnnels are sperate from the CMT |
What is Facilitated Diffusion? | CMT moves Molecules from a HIGH --> LOW concentration through the bilayer |
What is a benifit to Facilitated Diffusion? | uses NO ATP |
Give 2 examples of Facilitated Diffusion. | Glucose uptake, Nucleotide uptake |
What is Active Transport? | CMT moves Molecules from an area of LOW --> HIGH concentration |
How do Active Transport systems move Molecules? | from LOW --> HIGH - referred to as "PUMPS" |
What is a disadvantage of using Active Transport over Facilitated Diffusion? | AT uses ATP to break attachment w/ carrier - FD no ATP |
What are some examples of Active Transport? | Amino Acid transport IN; Potassium Ions IN; Sodium Ions OUT |
What do Active Transport and Facilitated Diffusion have in common? | both carriers exhibit Carrier Specificity and Carrier Saturation |
What is Carrier Specificity? | carrier will only transport 1 Specific Molecule |
What is Carrier Saturation? | all carriers for a specific Molecule within a cell are busy (working w/ others of the same Molecule) |
What is Endocytosis and give 2 examples? | External Membrane FOLDS INTO the cell - Phagocytosis, Pinocytosis (flluid intake) |
What is Exocytosis? | Internal Vesicles FUSE with Cell Membrane |
What is the function of Exocytosis? | provide means to EXPELL Molecules made in the cell |
What do Endocytosis and Exocytosis have in common? | both REQUIRE Passive Stretching and Active Contraction of the Membrane |