Digestion and enzymes Flashcards
Define digestion
The breakdown of large insoluble food molecules into small soluble food molecules by chemical and physical means
State an enzyme found in saliva
Amylase
State two examples of physical digestion
Teeth and churning of food in the stomach
Describe how food moves down the oesophagus
Peristalsis occurs. This means that there is muscular contraction behind the bolus of food (and relaxation in front) pushing the food down
State the enzyme found in the stomach
Pepsin (a protease which breaks down protein)
State the enzyme found in the first part of the small intestine
Amylase (secreted from the pancreas)
Trypsin (secreted from the pancreas)
State the role of the small intestine
Digestion of food (in the first part) and then absorption of nutrients into the blood
State the role of the liver in digestion.
Produce bile. This is stored in the gall bladder before being secreted into the small intestine to neutralise stomach acid and emulsify fats.
State the role of the large intestine
Absorb water by osmosis
Define enzyme
Protein biological catalayst that speeds up chemical reactions by lowering the activation energy.
Describe the active site of an enzyme
Specific and complementary in terms of shape and charge to the substrate. This means that the substrate can attach and enzyme-substrate complexes can form.
Explain why the rate of reaction is low for an enzyme at 5 degrees (very below optimum).
Because the enzyme is inactive.
Then there will be less kinetic energy and successful collisions leading to less enzyme-substrate complexes forming.
Therefore less product produced and a slower rate of reaction.
Explain why the rate of reaction is highest for an enzyme at it’s peak.
Because the enzyme is at it’s optimum.
Then there will be the most successful collisions and the most enzyme-substrate complexes forming
Therefore the most products produced and the fastest rate of reaction.
Explain why the rate of reaction is lowest for an enzyme way above it’s optimum.
Because the enzyme is denatured.
Then the 3D structure of the active site of the enzyme has changed is no longer specific and complementary in terms of shape and charge to the susbtrate and less enzyme-susbtrate complexes form.
Therefore the least products produced and the lowest rate of reaction.
Define absorption
the movement of digested food molecules into the blood or lymph.
Define assimilation
the movement of digested food molecules into the cells of the body where they are used or become part of the cell.
Define excretion
the process of eliminating or expelling waste matter
State the organs of the excretory system
X2 Kidneys
Ureter
Bladder
Urethra
Describe the function of the bowman’s capsule
Filters the blood. This means that water and small molecules can pass into the proximal convoluted tubule. Large proteins and blood cells stay behind.
Describe the function of the proximal convoluted tubule
Reabsorption of ions. This means that glucose, specific ions, and amino acids are reabsorbed into
capillaries by active transport.
Describe the function of the Loop of Henle
Reabsorption of water. This means that the ascending limb actively pumps ions out of the tubule.
This makes the tissue around the descending limb highly concentrated, so water exits.
Describe the function of the Distal convoluted tubule
Selective reabsorption. This means that more active transport of ions out, so that water follows based on requirements and water needs.
Outline how urine leaves the body from the kidney
The urine goes through the ureter (TO)
which takes the urine TO the bladder.
The urine then leaves the body through the urethra.
State the function of bile
Emulsify fats
State what the liver produces that is stored in the gall bladder
Bile
