enzymes and digestive system Flashcards
what are the 3 main food nutrients
carbohydrates, proteins and lipids
why cant the main food nutrients be absorbed into the blood stream
they are large molecules and are too large to be absorbed in the blood stream
what happens during digestion
during digestion large food molecules are broken down into smaller molecules by enzymes so that they can be absorbed into the blood stream
what happens in the first stage and what enzyme
food is chewed and enzymes in the saliva start to digest starch into smaller sugar molecules
amylase
stage 2
the food passes down the oesophagus into the stomach where enzymes begin protein digestion
protease
whats in the stomach that aids enzymes in digestion
hydrochloric acid
what does the stomach do to the food which is being digested
the churning action of the muscles turns the food into a fluid increasing surface area for enzymes to digest
stage 3
the fluid now passes into the small intestine where chemicals are being released from the liver and the pancreas
what does the pancreas do
the pancreas releases enzymes continuing the digestion of starch and protein and also start digestion of lipids
what does the liver do
the liver releases bile which helps speed up the digestion of lipids and also neutralises stomach acid
it emulsifies fats and turns large lipid droplets into smaller lipid droplets
what happens in the small intestine
the walls of the small intestine release enzymes to continue digestion of protein and lipids, small food molecules produced by digestion are absorbed into the bloodstream by diffusion or active transport
stage 4
the fluid makes its way trough the large intestine where water is absorbed by the bloodstream
faeces is released
what does the body do with the products of digestion
the body uses it to build new carbohydrates, proteins and lipids
glucose produced used in respiration
what do eznymes do
they catalyse chemical reactions
what are enzymes
large protein molecules with a groove on their surface called the active site which is where the substrate attaches to
what is a substrate
a food molecule which enzymes break down
what is the lock and ke theory
enzymes are specific and the substrate must fit into the active site perfectly
what is protein broken down by and where is this found
protease found in the stomach, pancreas and small intestine
what happens when we digest proteins and what are proteins
proteins are long chains of chemicals called amino acids
when we digest protein protease converts them back to amino acids and they are absorbed into the blood stream
when our body absorbs this they join in a different order to make human proteins
what is starch broken down by and where is this found
amylase found in saliva and pancreatic fluid
what is starch and what happens when we digest it
starch is a chain of glucose molecules and when carbs like starch are digested we produce simple sugars
what breaks down lipids and where is this found
lipase found in pancreatic fluid and the small intestine
what is a lipid and what happens when we digest it
lipid is a molecule of glycerol attached to 3 molecules of fatty acids
lipase produces glycerol and fatty acids
where is bile made and where is it stored
bile is made in the liver and is stored in the gall bladder
what does bile do how does it speed digestion
3 pts
bile emulsifies lipids and greatly increases the surfaace area increasing rate of lipid breakdown by lipase
bile is alkaline and creates alkaline conditions in the stomach
bile converts large lipid droplets to smaller droplets
what happens as you increase tempurature
enzyme activity increases so reaction gets faster
what happens to the enzyme at high tempuratures
enzyme molecule vibrates and the active site shape changes.
the substrate no longer fits into the enzyme so the active site is denatured
the enzyme cannot catalyse the reaction
describe enzyme activity when tempurature starts to increase
enzyme and substate are working faster
there are more collisions per second between them
what is the optimum tempurature
at a certain temp, the eznymes are working at the fastest possible rate - optimum temp
this is the maximum rate of successful collisions between the substrate and enzyme
what happens to enzymes past optimum temp
enzyme activity rapidly decreases to 0
it stops working since the active site is denatured
what is optimum ph
ph where enzyme activity is maximum
what happens if you make the ph more acidic or alkaline
enzyme activity drops to 0
in conditions that are too alkaline or acidic the active site denatures
which enzyme works best in alkaline conditions
lipase
which enzyme works best in acidic conditions
protease
