1.3 Cell membrane and transport Flashcards
Function of cell membrane
-Structural support
-Secretes chemicals
-Cell recgonition
-Collects nutriens
Name the 8 parts of the cell membrane
- Gloycoprotein
- Glycolypid (carbohydrate chain)
- Phosphate head (hydrophilic head)
- Fatty acid tail (hydrophoic tail)
- Intrinsic protein (carrier or channel)
- Extrinsic protein
- Cholestrol (rigididy)
- Phospholypid bilayer
When looking at a cell membrane using a light microscope, how many lines does it apear as?
1
When looking at a cell membrane using a electron microscope, how many lines does it apear as?
2
Function of intrinsic protein
(accross both layers both layers)
Act as a carrier/channel proteins, enzymes + transprot -facilitated diffusion and active transport
Function of extrinsic protein
Act as a receptor, antigen and recognition centers spam through
-stuctural suppot
-recognition site
-Receptor sites for homone attatchment
Function of cholestrol
Rigididy - stabalize the cell and increases melting point
Function of Glycoprotein
Help to recognise and atatch cells
Function of Glycolypid
maintain stability and facilitate cell to cell intreaction
(outer layer)
Glycocalyx
Provent the entery of pathogen into the cell outer layer of membrane glycolypids and glycoproteins are found
Name the bond, reaction and the hydrophilic and hydrophobic part of a phospholipid
Ester bond
Condensation reaction
Hydrophobic - fatty acid tail
Hydrophilic - phosphate head
Phospholipids
They can form layers
Hydrophilic heads
Hydrophobic tail - repel water
Allows lipid-solube molecules across, not water
Whats the name of the model for the cell membrane?
Fluid mosaic model
What part of the cell membrane represents the fluid in the fluid mosaic model?
Phosphholipids are free to move in the membrane
What part of the cell membrane represents the mosaic in the fluid mosaic model?
Proteins move on the surface of the membrane
3 factors that affect the permeability of a cell membrane
- Heat
- Ethanol
- pH
How does heat affect the cell membrane?
denatures the membrane
(makes membrane more permeable - more holes in it)
How does pH affect the cell membrane?
denatures the membrane
(makes membrane more permeable - more holes in it)
How does ethanol affect the cell membrane?
Ethanol disolves the lipid components of the membrane
(makes membrane more permeable - more holes in it)
Name the 6 modes of transoprt
- Diffusion
- Facilitated diffusion
- Active transport
- Co transport
- Osmosis
- Endo/Exocytosis
Definition of diffusion
The passive movement of mlecules from a** high concentration to a low concentration** untill they are equally distributed
Meaning of passive
Does not require energy
6 factors that affect the rate of diffusion
1. Concentration gradient
2. Distance of travel
3. Surface area of a membrane
4. Thickness of exchange surface
5. Size of moecules
6. Temperature - Kenetic energy
Examples of molecules that pass through the membrane by diffusion
CO2, O2
Small
Uncharged
Lipid solubles
Definition of facilitated diffusion
The passive transfer of molecules/ ions down a concentration gradient
-high to low
-by carrier proteins in the membrane
Examples of molecules that pass through the membrane by facilitated diffusion
Na+ K+, glucose, amino acids
Large
Charged
Water solubles
Active transport defintition
Movement of ions/molecules accross the membrane from a low to high concentration against the concentartion gradient
Requires energy
Factors that affect the rate of uptake - active transport
- Respiritory inhibitor - Cyanide
- Number of carrier proteins
- Oxygen availability
Co transport
Type of facilitated diffusion that brings molecules and ions into the cell together on the same transport protein
e.g Sodium and glucose co transport into cell together
What does hydrophobic and hydrophilic mean ?
Hydrophobic - water hating
Hydrophilic - water loving
What does hydrophobic and hydrophilic mean ?
Hydrophobic - water hating
Hydrophilic - water loving
What is the 2 types of proteins in cell membranes
Intrinsic and extrinsic
What is the 2 types of proteins in cell membranes
Intrinsic and extrinsic
Intrinsic proteins
Across both layers of the membrane
Carriers/channels
Extrinsic proteins
On surface if the bilayer
Structural support
Recognition sites
Receptor sites for hormone attachment
Define osmosis
Movement of water from a high to a low water potential through a selectively permanent membrane
Negative to more negative
What is water potential
- Water water potential is the pressure exerted by water molecules. The tendency of water to leave a system
- Measured in kilopascale (kPa)
- Pure water has a water pitential of 0kpa
- A solution with a high water potential has a large number of water molecules that are free to move
I why is the equation to find out water potential
Water potential = solute + pressure
What is pressure potential
The pressure exerted by the small cell wall and membrane on the cell contents
What is the solute potential
The concentration of dissolved substance in the cell vacuole
Define hypertonic
Water potential of external solution is lower than solution inside the cell wall. Water flows out the cell
Define hypertonic
Water potential of external solution is higher than solution inside the cell. Water flows into cell
Define isotonic
Water potential of cell the same as water potential surrounding the cell
What is incipient plasmolysis
-cell membrane begins to pull away from the cell wall
- 50% of cells viewed under microscope are plasmolysed
-
What Is fully turgid
- h20 moved in by osmosis
- placed in hypertonic solution
What is plasmalised
- cell members and pulled away from cell wall (h20 moved out)
- placed in hypertonic solution
