Phospholipid Bilayer question

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G O D I V A
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#1
Report Thread starter 13 years ago
#1
Membranes are made up of a phospholipid bilayer. What is the use/function of:
  • cholesterol
  • glycoprotein
  • integral proteins embedded in the phospholipid bilayer


I'm revising for an exam in 2 days so please help
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Hobnobs Galore
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#2
Report 13 years ago
#2
Cholesterol molecule straightens out hydrocarbon chains. Glycoprotein- for communication and transport (i think)

and proteins for transport- eg carrier proteins
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BillyMarsh
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#3
Report 13 years ago
#3
Glycoproteins branch off into the surrounding fluids and stabilise the cell.
They are also used for intracellular messaging (Antigens specifically).

The embedded proteins could be carrier proteins / protein channels which are used in Active Transport in and out of the cell i.e. Na+ or they could be enzymes such as ATPase.

Cholesterol maintains mechanical stability.
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Malsy
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#4
Report 13 years ago
#4
Cholesterol; to stabilise the bilayer as it would be too fluid without it.
Glycoproteins; to act as receptors(I think)
Integral Proteins: ion pores(to transport ions) or transport proteins(to carry glucose and amino acids)
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Hobnobs Galore
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#5
Report 13 years ago
#5
Lol this thread proves how long ago it was since i did biology a-level!
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Malsy
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#6
Report 13 years ago
#6
(Original post by Hobnobs Galore)
Lol this thread proves how long ago it was since i did biology a-level!

Lol. count yourself lucky; it's a nightmare.
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kc-raine
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#7
Report 13 years ago
#7
cholesterol stablises the membrane.
glycoproteins are used as receptors i think.
other proteins are used as carriers or to create channels to help transport ions/molecules across the membrane.

hope it helps a bit!
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BillyLiu
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#8
Report 13 years ago
#8
(Original post by G O D I V A)
Membranes are made up of a phospholipid bilayer. What is the use/function of:
  • cholesterol
  • glycoprotein
  • integral proteins embedded in the phospholipid bilayer


I'm revising for an exam in 2 days so please help
I'll help myself helping you by doing this Interview tomorrow in Cambridge - might come up:

Cholesterol does maintain membrane fluidity - it increases fluidity at lower temperature, and vice versa at higher temperatures. The mechanism is that it acts as a wedge to seperate the phospholipid a little, thereby reducing Van Der Waals bonding and also increasing permeability to molecules.

Glycoprotein acts as cell recognition proteins - "self and non self" really.

Integral proteins -
Carrier proteins - actively transport molecules across the membrane against a concentration gradient (e.g. Na - K pump).

Protein Channels - provides a hydrophilic channel through which water solutes can diffuse through, though the protein is specific [question to others: am I right in saying this is facilitated diffusion?]

Protein Receptors - a ligand attaches to the substrate of the protein on one end, and the other end sends a cascade signal inside the cell, expressing or inhibiting a certain gene from T&T a protein.

Cell Adhesion - certainly some attach to the cytoskeleton inside the cell, and attach to other cell membranes.

lol, wall of text there. Hope this helps!
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FATIMABHATTI
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#9
Report 4 years ago
#9
Thanks hope this comes up in the exam now
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