Flashcards in 2.5- Biological membranes Deck (52)
What is the role of membranes? (name 3)
-To act as a partially a partially and sometimes selectively permeable membrane between cells and their environments
- Site of Chemical reactions
- Sites of cell communication and signalling
What is the function of phospholipids in a cell membrane
Phospholipids form the bilayer and are the main component of the surface area
What Is the function of Cholesterol in a cell mambrane?
It regulates membrane fluidity and flexibility
What is the function of proteins in cell membranes?
carrying out chemical reactions or regulating cross membrane transport
What are the 2 types of proteins in cell membranes?
Integral- span the entire membrane
Peripheral- embedded in half of a membrane
What is the function of glycoproteins and glycolipids in cell membranes?
can be antigens or receptor molecules
can bind with extracellular signalling molecules such as hormones
An increased temperature leads to the membrane increasing its.................
Fluidity and permeability
Why does an increased temperature increase fluidity and permeability? (Phospholipids)
Phospholipids aquire more energy so they move around more
Why does an increased temperature increase fluidity and permeability? (Fatty acids)
fatty acids become less compressed
Why does an increased temperature increase fluidity and permeability? (Proteins)
proteins can denature at high temperatures reducing their ability to control transport across membranes
Which 3 factors can affect membrane permebility?
Changes in PH - affect the function of proteins in the membrane
Organic solvents such as ethanol can damage a membrane by dissolving lipids held through it
Can you draw the fluid Mosic model?
What is the definition of diffusion?
The movement of molecules from a region of high concentration to a region of low concentration until the concentrations of the 2 regions are equal.
What 3 factors does the rate of diffusion depend on?
Surface area of cell
thickness of membrane
i am a small non polar molecule. can i diffuse through a membrane?
yes, i can diffuse quickly
I am a small polar molecule. can i diffuse across a membrane?
yes, although it will be slower
I am an ion. Can i diffuse across a cell membrane?
Noooo, i have to be transported by other methods
I am a large polar molecule. Can i diffuse across a cell membrane??
nope, i have to be transported by other methods
Give 3 examples of molecules which can diffuse through a membrane.
Fat soluble vitamins
What is the definition of osmosis?
the diffusion of water molecules from a region of high concentration to low concentration across a partially permeable membrane
Is osmosis a form of active transport
No, osmosis is a specialised form of diffusion.
What molecules can facilitated diffusion transport that normal diffusion cant?
large and polar molecuses
Give 4 examples of molecules that are transported by facilitated diffusion.
is facilitated diffusion an active process?
No, it is passive
What is needed for facilitated diffusion to occur?
Carrier proteins or Channel proteins
What are the 3 steps for facilitated diffusion through a carrier protein?
-Molecule binds with carrier proteins molecules on cell surface
-Protein changes shape and transports molecule through
-Molecule detaches and protein reverts to its original shape
What does the rate of facilitated diffusion depend on?
-Number of channels or transporter proteins that are available
What are 3 passive processes which move molecules across membranes?
What are 3 active processes that are used to transport molecules across membranes?