Organsisms Exchange Substances With Their Environment Flashcards
(18 cards)
Describe molecules that undergo simple diffusion across a membrane.
Small, lipid soluble
Describe the molecules that undergo facilitated diffusion.
Large, water soluble molecules
What do molecules undergoing facilitated diffusion require?
A channel protein
Describe the type of molecule that can move via active transport
Any molecule!
What does a molecule going through active transport require?
A carrier protein
What is co transport?
Molecules travelling across a membrane together
What does co transport require?
A carrier protein
Describe the action of bile salts on lipids.
Bile salts emulsify fats into micelles (tiny droplets)
Describe the action of pancreatic lipases.
They break down triglycerides into a monoglyceride and two fatty acids
What is the role of endopeptidases?
They hydrolyse internal peptide bonds in the middle of proteins.
This forms a shorter polypeptide chain, so there are more ends for proteases to work on
Describe the role of exopeptidases.
They hydrolyse peptide bonds at the end of polypeptide chains to remove terminal amino acids or dipeptides
What is the role of cholesterol in the cell surface membrane
It reduces fluidity of the membrane, therefore stabilising it.
Describe the role of intrinsic proteins in the cell surface membrane (channel and carrier proteins)
They bring large molecules and ions across the membrane
What is the role of glycoproteins and glycolipids?
They are involved in cell signaling, cell adhesion and cell recognition
Describe how cells surface membrane may be adapted for rapid transport of molecules
Increased surface area, more channel and carrier proteins.
What is the structure of the gills?
- located behind the head of the fish
- gill filaments which are stacked in a pile which have gill lamellae which are at right angles to the filaments
- the gills are inside of the eperculum, which are the flaps which we can see
What are the adaptations of gills for gas exchange?
High concentration gradient from a constant flow of blood
Lamellae are thin and flat so there is a short diffusion distance
High surface area from stacked lamellae and there are many of them
What is the counter current principle?
Blood that is already well loaded with oxygen meets water that has its maximum concentration of oxygen
Oxygen diffuses from the water to the blood
Blood with little oxygen meets water that has less oxygen in it, but still more than the blood
Oxygen diffuses from the water to the blood
Around 80% of the oxygen available in the water is absorbed into the blood
