Mass Transport in Animals Flashcards
Define Digestion
Large biological molecules are hydrolysed by enzymes into molecules that can be absorbed across cell membranes
What happens to polysaccharides in digestion?
Their glycosidic bonds are hydrolysed and they are broken into disaccharides by an enzyme
What happens to disaccharides in digestion?
Their glycosidic bonds are hydrolysed and they are broken into monosaccharides by an enzyme
How is starch digested?
It is hydrolysed into maltose by amylase
How is maltose digested?
It is hydrolysed into alpha glucose by maltase
How is alpha glucose assimilated?
It is absorbed by co-transport with Na+
Where is amylase secreted?
The salivary glands and the pancreas
Where is maltase secreted?
In the small intestine
How is sucrose digested?
It is broken into glucose and fructose by sucrase
How is lactose digested?
It is broken into galactose and glucose by lactase
How are large lipid droplets broken down?
Bile salts are added in the process of emulsification
How are small lipid droplets broken down?
Two ester bonds between fatty acid molecules and glycerol are broken and a monoglyceride and two fatty acids are present as micelles
What are micelles?
Tiny droplets of monoglyceride and fatty acids that release the monoglyceride close to the cell surface membrane so that they can pass across the cell surface membrane and into the epithelial cells of the small intestine (pass across because they are fat soluble)
What are peptidases?
Enzymes that break the peptide bonds within a protein
What are endopeptidases?
Enzymes that break the peptide bonds inside a polypeptide chain
What are exopeptidases?
Enzymes that break the peptide bonds at the end of a polypeptide chain
What are membrane bound dipeptidases?
Enzymes that are attached to a membrane (e.g. the ileum) that hydrolyse the peptide bond in a dipeptide
How are amino acids absorbed?
By co-transport with Na+
What is haemoglobin?
A protein with a quaternary structure
Where is haemoglobin found?
In red blood cells
What does haemoglobin do?
Transports oxygen (haemoglobin + oxygen <=> oxyhaemoglobin)
What happens to the % saturation of O2 in haemoglobin as it travels around respiring cells and the lungs?
- Oxygen loads onto haemoglobin at a high partial pressure of oxygen (at the lungs)- Haemoglobin becomes saturated with oxygen- Oxygen unloads at cells where partial pressure of oxygen is low
What effect does the BohR shift have on the oxyhaemoglobin dissociation curve?
It shifts it to the right
Why does the BohR shift happen?
- When an organism respires a lot there is more carbon dioxide in the blood- An increase in carbon dioxide causes an increase in blood acidity- An increase in blood acidity decreases the haemoglobins affinity of oxygen- Oxygen unloads more easily at respiring cells- Haemoglobin is less saturated with oxygen because it has released more oxygen at respiring cells
What happens to haemoglobin in a higher oxygen environment?
- Haemoglobin has a lower affinity for oxygen- Releases more oxygen at cells- Useful for animals with a high rate of respiration- E.g. small mammals have a higher SA:V so they lose more heat per gram maintaining an internal temperature
What happens to haemoglobin in a lower oxygen environment?
- Lower partial pressure for oxygen in the lungs - Haemoglobin has a higher affinity for oxygen- Able to load oxygen at a lower partial pressure of oxygen