Biology SL chapter 2.4 (Membranes)

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Draw and label diagram to show structure of membranes
1. Phopholipid bilayer 2. Peripheral protein 3. Channel protein 4. Carrier protein 5. Glycoprotein 6. Cholesterol
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Structure of phospholipids
Polar head (hydrophilic) made from glycerol and phosphate. consists of two non-polar fatty acid tails (hydrophobic)
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Phospholipid arrangement in membrane
Phospholipids arrange in a bilayer. Hydrophobic tails face inwards and are shielded from surrounding polar fluid. while the hydrophilic head regions associate with cytoplasm and extracellular environments.
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Structural properties of phospholipid bilayer pt 1
1.Phospholipids are held together in bilayer by hydrophobic interactions (weak associations)2. Hydrophilic/hydrophobic layers restrict entry/exit of substances 3. Phospholipids allow for membrane fluidity / flexibility (important for functionality)
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Structural properties of phospholipid bilayer pt 2
1.Phospholipids with short or unsaturated fatty acids are more fluid 2. Phospholipids can move horizontally or occasionally laterally to increase fluidity 3. Fluidity allows for the breaking / remaking of membranes (exocytosis / endocytosis)
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Functions of inner membrane proteins (TRACIE)
Transports (protein channels/pumps), Receptors(insulin, glucagon), Anchorage, Cell recognition, Intercellular joinings, Enzymatic activity(metabolic pathways)
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Define diffusion and osmosis
DIFFUSION: Movement of particles from area of high concentration to low concentration. OSMOSIS: movement of water across a semi-permeable membrane from low solute concentration to high solute concentration
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Passive transport across membrane in terms of simple diffusion and facilitated diffusion
Plasma membrane is semi-permeable and selective in what can cross. Substances that move across conc gradient don't require atp. Simple diff: small molecules diffuse across membrane. Facilitated Diff: large,polar molecules require channel proteins
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Explain role of protein pumps in active transport
Active transport is the transport of materials against the concentration gradient. This requires protein pumps which use ATP to move molecules.
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Explain how protein pumps work
The hydrolysis of atp causes a change in the shape of the protein pump, resulting in movement of the substance. Protein pumps are specific for a given molecule.
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Explain how vesicles are used to transport materials within a cell. pt1
Polypeptides destined for secretion contain a signal which directs the ribosome to the ER. The polypeptide continues to be synthesis by ribosome into lumen of ER.
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Explain how vesicles are used to transport materials within a cell. pt2
the polypeptide within the Rough ER is then taken to the golgi apparatus in a vesicle. The polypeptide then moves via vesicles from the cis to the trans face of the golgi and may be modified along the way. It is then released thru the plasma membrane
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Explain the fluidity fo cell membranes
The membrane is principally held together by relatively weak hydrophobic associations between phospholipids. This allows the membrane to be fluid and flexible and allows the membranes to break to allow larger substances to move across
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Endocytosis
The process by which large substances enter the cell without travelling across the membrane. The membrane envelops the material and is sealed and forms a vesicle.
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Exocytosis
Vesicles (usually from the golgi apparatus) fuse with the plasma membrane expelling their content in the extracellular environment
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Other cards in this set

Card 2

Front

Structure of phospholipids

Back

Polar head (hydrophilic) made from glycerol and phosphate. consists of two non-polar fatty acid tails (hydrophobic)

Card 3

Front

Phospholipid arrangement in membrane

Back

Preview of the front of card 3

Card 4

Front

Structural properties of phospholipid bilayer pt 1

Back

Preview of the front of card 4

Card 5

Front

Structural properties of phospholipid bilayer pt 2

Back

Preview of the front of card 5
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