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22 Cards in this Set
- Front
- Back
What does 'amphipathic' mean?
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Contains both hydrophobic and hydrophilic parts (i.e. the cell membrane)
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Which part of the phospholipid bilayer is hydrophilic?
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The head
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What is the ratio of Cholesterol:Phospholipids?
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1:1
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Which molecules stabilise and regulate the fluidity of the phospholipid bilayer?
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Cholesterol
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Cholesterol molecules prevent overly dense packing of the phospholipid fatty acid tails and also fill the gaps between kinks, providing stability.
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.
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What are intrinsic proteins?
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Proteins which are incorporated into the membrane (not all the way through)
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What are extrinsic proteins?
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Proteins that are held on the surface by weak electrostatic forces
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What is the name given to an intrinsic protein that spans the entire membrane?
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A transmembrane protein
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What is a glycoprotein/glycolipid?
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A cell surface protein which is conjugated with short chains of lipid/polysaccharide
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Sometimes, glycoproteins and glycolipids are collectively referred to as...
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...the glycocalyx
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In general, the plasma membrane is IMPERMEABLE to hydrophilic or hydrophobic molecules?
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Hydrophilic (however water, urea, bicarbonate are able to for unknown reasons!)
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What are the four methods of transport in and out of the cell?
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Passive diffusion, facilitated diffusion, active transport and bulk transport (endo/exo cytosis)
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Which molecules can enter via passive diffusion?
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Lipid and lipid soluble molecules
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What method of transport is generally used for larger hydrophilic molecules? What are examples of such molecules? (2)
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Facilitated diffusion.
Glucose and amino acids |
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How does transport take place in facilitated diffusion?
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Through protein carrier molecules (gated pores).
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Facilitated diffusion: This allows molecules to bind specifically but reversibly. When glucose is bound to its carrier protein, the transmembrane protein undergoes a change in _____ which moves the glucose moelcule to the interior of the cell, where it is able to dissociate from the carrier which then returns to its ______ _____
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shape, original shape
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AT is dependent/independent of concentration gradients
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independent
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What is a classic example of AT?
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The sodium pump
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Energy is/is not required for AT
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is
1040081010 |
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Pinocytosis is the uptake of extracellular fluid. Sometimes it is transported across a cell and excreted onto another. What is this called?
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Transcytosis
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What are the three main methods for transporting messages across the plasma membrane?
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Simple diffusion (by lipid soluble molecules) (DISADVANTAGE: Info delivered to ALL cells)
Proteins binding to a specific receptor on the cell surface membrane (second messenger model) Neurotransmitters - Released from a nerve cell that causes ion channels to open which depolarises the membrane |
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What is basement membrane?
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A thin sheet of fibers that underlies the epithelium, which lines the cavities and surfaces of organs including skin, or the endothelium, which lines the interior surface of blood vessels
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