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22 Cards in this Set

  • Front
  • Back
What does 'amphipathic' mean?
Contains both hydrophobic and hydrophilic parts (i.e. the cell membrane)
Which part of the phospholipid bilayer is hydrophilic?
The head
What is the ratio of Cholesterol:Phospholipids?
1:1
Which molecules stabilise and regulate the fluidity of the phospholipid bilayer?
Cholesterol
Cholesterol molecules prevent overly dense packing of the phospholipid fatty acid tails and also fill the gaps between kinks, providing stability.
.
What are intrinsic proteins?
Proteins which are incorporated into the membrane (not all the way through)
What are extrinsic proteins?
Proteins that are held on the surface by weak electrostatic forces
What is the name given to an intrinsic protein that spans the entire membrane?
A transmembrane protein
What is a glycoprotein/glycolipid?
A cell surface protein which is conjugated with short chains of lipid/polysaccharide
Sometimes, glycoproteins and glycolipids are collectively referred to as...
...the glycocalyx
In general, the plasma membrane is IMPERMEABLE to hydrophilic or hydrophobic molecules?
Hydrophilic (however water, urea, bicarbonate are able to for unknown reasons!)
What are the four methods of transport in and out of the cell?
Passive diffusion, facilitated diffusion, active transport and bulk transport (endo/exo cytosis)
Which molecules can enter via passive diffusion?
Lipid and lipid soluble molecules
What method of transport is generally used for larger hydrophilic molecules? What are examples of such molecules? (2)
Facilitated diffusion.

Glucose and amino acids
How does transport take place in facilitated diffusion?
Through protein carrier molecules (gated pores).
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 ______ _____
shape, original shape
AT is dependent/independent of concentration gradients
independent
What is a classic example of AT?
The sodium pump
Energy is/is not required for AT
is

1040081010
Pinocytosis is the uptake of extracellular fluid. Sometimes it is transported across a cell and excreted onto another. What is this called?
Transcytosis
What are the three main methods for transporting messages across the plasma membrane?
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
What is basement membrane?
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