Membranes Flashcards
How is a red blood cell’s membrane adapted to do its function?
Permeable to oxygen, carbon dioxide.
It is a biconcave disc to have a larger surface area for better permeability.
It is very flexible to go into small places.
How is a phagocytes membrane adapted to do its function?
Needs to be able to engulf pathogens.
Flexible to be able to wrap around foreign bodies.
They have receptors to engulf foreign bodies,
How is a muscle cell’s membrane adapted to do its function?
Permeable to oxygen, carbon dioxide, and glucose.
Can transmit electrical impulses to each other using special molecules. have receptors to know when to contract and relax. Have a lot of proteins.
How is a shoot cell’s membrane adapted to do its function?
Has auxin receptors to know when to grow
Flexible so it can grow
How is a neurone cell’s membrane adapted to do its function?
Can transmit electrical impulses to each other using special molecules.
How is chloroplast membrane adapted to do its function?
Permeable to oxygen, carbon dioxide and glucose.
Chlorophyll and many thylakoids to increase surface area
What are the general functions of membranes?
Separates the cells internal parts to its surroundings
Site of chemical reactions
Releases chemicals to signal to other cells
Partially permeable to regulate transport in and out of the cell
-Has antigens to recognise own body and foreign cells
Contains receptors that receive chemical signals, such as hormones and drugs
-Contain enzymes involved in specific metabolic pathways
What makes up different parts of the membrane
Phospholipid bilayer (lipids with a phosphate group)
- Glycolipids (lipid with a carb molecule)
Proteins, glycoproteins (protein with a carb molecule)
Fluid because compartments can move across each other
Channel proteins - to allow substances through
Antigens to allow the cell to be recognised
What is a phospholipid?
A molecule with a phosphate head and 2 fatty acids as tails
What part of the phospholipid is hydrophilic and why?
The phosphate head is polar so it is hydrophilic
What part of the phospholipid is hydrophobic and why?
The fatty acid tail is not polar so it is hydrophobic
What are the 2 structures can phospholipids make in water and why does it become these shapes ?
It can make a complete circle with the hydrophobic tails in the centre and the hydrophilic heads on the outside called a micelle to protect the hydrophobic tails
It can make a double layered membrane with hydrophilic heads on the outside on both sides and the hydrophobic tails in between them.
What is cholesterol’s function?
-It is important in regulating the membranes fluidity, the more cholesterols the less fluid or permeable the membrane because nothing can enter where the cholesterol it.
-It also keeps the cell stable at normal body temperature, without it cell membranes would burst open
What is a carrier protein function?
It transports substances that can’t go through the membrane, such as sugars, ions and amino acids but are still needed in the cell
What is a channel protein function?
It transports ions that can’t go through the membrane but are still needed in the cell
What is an intrinsic protein?
These are proteins that span the entire width of the membrane
What is an extrinsic protein?
Proteins that may be free on the membranes surface of attached to an intrinsic protein
Why is the cell membrane inside of a mitochondria folded?
To increase SA for more chemical reactions
What is a glycoprotein?
A carbohydrate chain attached to a protein in the cell membrane
What is a glycoproteins function?
It is a receptor involved in cell recognition and and cells binding to make tissues
it also can be a receptor for hormones or an enzyme. It also can give off hormones
What is a glycolipid?
A carbohydrate chain attached to a phospholipid in the cell membrane
What is a glycolipids function?
It is a receptor involved in cell recognition and and cells binding to make tissues
What is the function of extrinsic proteins on the inside the cell membrane?
They are used in cell signalling or chemical signalling
What types of molecules can pass through the phospholipids through the bilayer?
Small non-polar molecules can pass though the bilayer easily
Small polar molecules can pass though the bilayer slowly
What types of molecules can’t pass through the phospholipids through the bilayer?
Charged particles like ions are unlikely to pass through the bilayer, even if they are small
What happens to the saturated fatty acids in the cell membrane if the temperature decreases?
Fatty acids become more condensed
What happens to the unsaturated fatty acids in the cell membrane if the temperature decreases?
They compress and the kinks in the tails push the phospholipids away to maintain the cell membranes permeability.
What does cholesterol do when the temperature decreases?
It buffers the effect of the lowered temperature to prevent a reduction in the membrane fluidity by preventing the phospholipids from packing together too closely.
What does cholesterol do when the temperature increases?
They buffer the effect of the increasing heat as it reduces the cell membrane permeability.
What happens to the phospholipids in the cell membrane if the temperature increases?
They have more kinetic energy do they start to move more and in random ways, increasing fluidity and permeability
What happens to the intrinsic proteins in the cell membrane if the temperature increases?
The intrinsic proteins may shift their position, altering the rate of the reaction they catalyse and the active site may change and denature the protein
What affects phagocytosis and how?
An increase in temperature may affect the infolding of the plasma membrane during phagocytosis
What happens to proteins in the cell membrane if the temperature increases?
The high temperatures cause the ionic and hydrogen bonds in the protein to break the bonds holding its structure together, so it unfolds.
What happens to proteins tertiary structure in the cell membrane if the temperature increases?
They can’t change back to their original structure so they are denatured.
What happens to cytoskeleton if the temperature increases?
If both the intrinsic proteins and cytoskeleton threads become denatured then the plasma membrane will start to fall apart and make the cell membrane more permeable.
What happens to the phospholipids in the cell membrane if the there is a solvent?
Organic solvents such as acetone and ethanol will damage the cell membranes because they dissolve lipids.
