enzymes and digestive system

Question 1

what are the 3 main food nutrients

Answer 1

carbohydrates, proteins and lipids

Question 2

why cant the main food nutrients be absorbed into the blood stream

Answer 2

they are large molecules and are too large to be absorbed in the blood stream

Question 3

what happens during digestion

Answer 3

during digestion large food molecules are broken down into smaller molecules by enzymes so that they can be absorbed into the blood stream

Question 4

what happens in the first stage and what enzyme

Answer 4

food is chewed and enzymes in the saliva start to digest starch into smaller sugar molecules
amylase

Question 5

stage 2

Answer 5

the food passes down the oesophagus into the stomach where enzymes begin protein digestion
protease

Question 6

whats in the stomach that aids enzymes in digestion

Answer 6

hydrochloric acid

Question 7

what does the stomach do to the food which is being digested

Answer 7

the churning action of the muscles turns the food into a fluid increasing surface area for enzymes to digest

Question 8

stage 3

Answer 8

the fluid now passes into the small intestine where chemicals are being released from the liver and the pancreas

Question 9

what does the pancreas do

Answer 9

the pancreas releases enzymes continuing the digestion of starch and protein and also start digestion of lipids

Question 10

what does the liver do

Answer 10

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

Question 11

what happens in the small intestine

Answer 11

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

Question 12

stage 4

Answer 12

the fluid makes its way trough the large intestine where water is absorbed by the bloodstream
faeces is released

Question 13

what does the body do with the products of digestion

Answer 13

the body uses it to build new carbohydrates, proteins and lipids
glucose produced used in respiration

Question 14

what do eznymes do

Answer 14

they catalyse chemical reactions

Question 15

what are enzymes

Answer 15

large protein molecules with a groove on their surface called the active site which is where the substrate attaches to

Question 16

what is a substrate

Answer 16

a food molecule which enzymes break down

Question 17

what is the lock and ke theory

Answer 17

enzymes are specific and the substrate must fit into the active site perfectly

Question 18

what is protein broken down by and where is this found

Answer 18

protease found in the stomach, pancreas and small intestine

Question 19

what happens when we digest proteins and what are proteins

Answer 19

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

Question 20

what is starch broken down by and where is this found

Answer 20

amylase found in saliva and pancreatic fluid

Question 21

what is starch and what happens when we digest it

Answer 21

starch is a chain of glucose molecules and when carbs like starch are digested we produce simple sugars

Question 22

what breaks down lipids and where is this found

Answer 22

lipase found in pancreatic fluid and the small intestine

Question 23

what is a lipid and what happens when we digest it

Answer 23

lipid is a molecule of glycerol attached to 3 molecules of fatty acids
lipase produces glycerol and fatty acids

Question 24

where is bile made and where is it stored

Answer 24

bile is made in the liver and is stored in the gall bladder

Question 25

what does bile do how does it speed digestion
3 pts

Answer 25

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

Question 26

what happens as you increase tempurature

Answer 26

enzyme activity increases so reaction gets faster

Question 27

what happens to the enzyme at high tempuratures

Answer 27

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

Question 28

describe enzyme activity when tempurature starts to increase

Answer 28

enzyme and substate are working faster
there are more collisions per second between them

Question 29

what is the optimum tempurature

Answer 29

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

Question 30

what happens to enzymes past optimum temp

Answer 30

enzyme activity rapidly decreases to 0
it stops working since the active site is denatured

Question 31

what is optimum ph

Answer 31

ph where enzyme activity is maximum

Question 32

what happens if you make the ph more acidic or alkaline

Answer 32

enzyme activity drops to 0
in conditions that are too alkaline or acidic the active site denatures

Question 33

which enzyme works best in alkaline conditions

Answer 33

lipase

Question 34

which enzyme works best in acidic conditions

Answer 34

protease