1: Membrane Structure Flashcards
What does the fluid mosaic model show?
cell membrane structure
of animal cell because it includes cholesterol, more on that later
In the fluid mosaic model diagram, how are phospholipids shown?
phospholipids:
- oval (phosphate head)
- two parallel lines attached (fatty acid tails)
Give the names of types of proteins based on their position in the membrane.
- integral protein
- peripheral protein
Where are integral proteins positioned in relation to the phospholipid bilayer in the membrane?
integral proteins = embedded in the phospholipid bilayer
Where are peripheral proteins in relation to the phospholipid bilayer in the membrane?
peripheral proteins = attached to an outer surface of the membrane
What do glycoproteins have attached to them? Where are they attached? What is the function of a glycoprotein?
- sugar units
- attached to to glycoprotein (duh) on the outer surface of the membrane
- cell-to-cell communication
Draw a diagram of the fluid mosaic model. (p9)
- hydrophilic phosphate head
- hydrophobic hydrocarbon tail
- integral proteins embedded in phospholipid bilayer
- peripheral protein on surface of membrane
- glycoprotein (with sugar units)
- pump or channel protein
- cholesterol
What is the basic component of all biological membranes?
phospholipids
Which part of a phospholipid is attracted to water? Which part is not attracted to water?
- head
- tail
What is the biological term for ‘not attracted to water’? What is the biological term for ‘attracted to water’?
- hydrophobic
- hydrophilic
What is the term that describes a molecule which has one part attracted to water, and one part not attracted to water?
amphipathic
What happens when phospholipids are mixed with water?
they naturally become arranged into bilayers
When in contact with water, which part of the phospholipids will face out? Which part will face in?
- head will face out making contact with the water
- hydrocarbon tail will face away from water
Why is the phospholipid bilayer so stable in water?
attraction between:
- hydrophobic tails in centre of bilayer
- and between hydrophilic heads and surrounding water
= stable membrane
Other than phospholipids and proteins, what is also a component of animal cell membranes?
cholesterol
Is the cholesterol molecule mostly hydrophobic or hydrophilic?
mostly hydrophobic
How is cholesterol structurally similar to a phospholipid? Hence, how is cholesterol positioned in the phospholipid bilayer?
- cholesterol has one hydrophilic end (like phospholipid), but is mostly hydrophobic
- cholesterol fits between phospholipids in the membrane
What is the effect of cholesterol in the membrane? What is the significance of this effect?
- restricts the movement of phospholipid molecules
- therefore reduces the fluidity of the membrane
Cholesterol reduces the fluidity of the membrane. What other effect does cholesterol have on the membrane? Why is this important?
- also reduces the permeability of the membrane to hydrophilic particles such as sodium ions and hydrogen ions
- diffusion across membrane must be restricted because animal cells need to maintain concentration differences of these ions across their membranes
“Membrane proteins are diverse in … , … and … in the membrane.” Fill the gaps.
- structure
- function
- position
Give 6 examples of membrane proteins (other than glycoprotein).
- insulin receptor
- cadherin
- cytochrome c
- cytochrome oxidase
- nicotinic acetylcholine receptor
- calcium pump
Outline the position and function of an insulin receptor in the cell membrane.
- integral protein
- is a hormone receptor
Outline the position and function of cadherin in the cell membrane.
- integral protein
- used for cell-to-cell adhesion
Outline the position and function of cytochrome c and cytochrome oxidase in the cell membrane.
cytochrome c:
- peripheral protein
- used for electron transport
cytochrome oxidase:
- integral protein
- immobilized enzyme
Outline the position and function of a nicotinic acetylcholine receptor in the cell membrane.
- integral protein
- is both a receptor for a neurotransmitter AND a channel for facilitate diffusion of sodium ions
Outline the position and function of a calcium pump in the cell membrane.
- integral protein
- active transport of calcium ions
Draw and label 6 different membrane proteins (not glycoprotein) in the phospholipid bilayer*. (p9)
*phospholipid bilayer can be represented by two parallel lines.
these are the proteins:
- insulin receptor
- cadherin
- cytochrome c
- cytochrome oxidase
- nicotinic acetylcholine receptor
- calcium pump
