enzymes and digestion Flashcards
properties of enzymes
- proteins made of different amino acids
- enzymes speed up the rate of chemical reaction
- all enzymes are specific amd can only catalyse one type of molecule
-work best at particular temp (optimum temp)
-work best at a particular PH optimum PH
how do enzymes work
work by the lock and key model
a substrate is held in an active site, this increases the probability that a reaction will take place
absorption of food in the small intestine
small soluble food molecules diffuse into the bloodstream in the small intestine
digestion of protein
amino acids
gall bladder function
stores bile produced by liver in the breakdown of fat
testing for starch of digestion
iodine
method- add brown iodine to some food
positive result - blue black colour
what does bile do
increases the PH of the small intestine to the optimum for lipase
what does bile breakdown
bile emulsifies fats, which means breaking down large droplets of fat to smaller droplets, this increases the surface area of the fats for the enzyme lipase to work
how to calculate energy (J)
rise in temp X volume of water X4.2 / mass of food
saturated fat
tends to be from animal fat.
its high in cholestrol and increases the chances of developing heart disease, obesity
what does carbohydrase contain
they contain a lot of energy, foods that contain fat contain alot of energy because 1g of fat has twice as much energy
molecules of digestive system
- the molecules must be small enough and soluble to pass through
- other molecules are too large and insoluble
- before these molecules can be absorbed into the blood, they must be digested into small soluble molecules
stomach
secretes stomach acid PH2
secretes protease
method using visking tubing as a model gut
- visking tube is filled with a mixture of starch, glucose, fats and proteins and left for 30 min
- the water is then tested for them
metabolic reaction
- involve building large molecules from small ones as well as breaking down large molecules into smaller ones
- these reactions are controlled by a special type of molecule called an enzyme
similarities of model gut (visking tubing)
- food molecules are contained in a tube whose walls are permeable only to small molecules
- the food in a tube is a mixture of large and small molecules
- the tube is surrounded by liquid that contains a low concentration of food molecules
enzymes work best at a particular temp the optimum
- if the temp is higher or lower than tis temp the enzymes will catalyse the molecule at a much slower rate
- if the temp gets too high the enzymes active site will change shape and stop working , called denaturation
digestion of starch
Glucose
mouth function
starch digestion begins by carbohydrase in saliva
bile duct function
carries bile to small intestine
digestive enzymes
they speed the process of breaking down large insoluble molecules to small soluble molecules
what are the digestive enzymes
carbohydrase
protease
lipase
carbohydrase
food= starch
product= glucose
used for= provide energy
protease
food= proteins
product= amino acids
used for= making proteins for growth and repair
how and why is fibre excreted from the body
its excreted from the body as faeces as its not possible to digest and absorb it into the blood
stages of digestive system
- ingestion
- digestion
- absorption
- egestion
protein
needed for growth, protein is used to produce new cells and repair the body
carbohydrates
they are needed for energy
high salt diet
- can increase blood pressure
-high blood pressure can lead to increased chance of heart attack, stroke or kidney disease
why does the graph increase
enzyme and substrate have more kinetic energy and collide more often, the rate of reaction increases
minerals
these keep us healthy
the optimum PH
it varies according to where the enzyme is found
eg ph2 in the stomach but ph10 in small intestine
the PH is far below or above the optimum
the enzyme is denatured, no reaction can occur
where is excess energy stored
as fat
what can obesity lead to
- heart disease
- high blood pressure
- type 2 diabetes
- cancer of bowel
what happens when you light food
the energy content can be released
what happens when you hold a burning food under a known volume of water
the temp increase can be measured
hot fat
- can spit
- can burn skin when burning food
- use pot to hold food
sharp needle
- can cut skin
- use tongs to pick food up
hot flame/ boiling tube
- can burn
- you should wait until cool
too much sugar can lead to
-type 2 diabetes
-obesity
-tooth decay
vitamins
keep us healthy
fibre
provides bulk in the digestive system and helps movement of food by peristalsis
a lack of fibre can lead to constipation
fats
provide energy
water
an essential part of many body processes and functions
lipase
foods= fats
product= fatty acids, glycerol
used for= provide energy
breaks down fat
how do you ensure a more accurate experiment when investigating enzyme activiy
use a colourchart or a colourimeter
amylase enzyme could get transferred to the eyes from the hands
10% amylase enzyme solution is irritant
control measure= wear eye protection
amylase enzyme could get on to the skin when pouring into the tube
10% amylase enzyme solution is irritant
control measure= wash has=ns immediately, gloves
enzymes
an enzyme is a biological catalyst it speeds up a reaction, but it does not take part in the reaction
testing for protein of digestion
biuret
method- add blue biuret to some food in a test tube
positive result- lilac colour
how is food moved along digestive system
food is moved by the contraction of muscles in the gut wall. this is called peristalsis
digestion of fat
glycerol = fatty acids
anus
egestion of waste
large intestine
absorption of water
when the graph is at the highest temp but lowest point on graphy
causes the specific shape of the active site to be destroyed, the enzyme can no longer bind with its substrate, no reaction can occur enzyme is denature
pancreas
secretes lipase, protease and carbohydrase into the small intestine
small intestine
continued digestion of carbohydrase by carbohydrase to glucose and proteins by protease to amino acids, lipase digest fats to fatty acids and glycerol
soluble products of digeSTion absorbed into blood
PH 7-8
steps of peristalsis
- muscles in the wall of the gut contract
- food is pushed along the digestive system
liver function
production and secretion of bile
how is the concentration gradient for diffusion maintained
a relatively large surface area produced by the villi
a rich blood supply which carries small soluble molecules away to the rest of body
testing for glucose digestion
benedicts
method= add blue benedicts too some food in a test tube
place the test tube in boiling water bath for 5 min
positive result= turns green, orange then brick red
function of digestive system
digest large insoluble molecules to small soluble ones by using enzymes
absorb small soluble molecules into the blood
example of vitamin C
oranges (citrus fruits)
what mixes with food in the stomach to help break it down
gastric juice
oesophagus function
transport food entering the mouth through the throat and into the stomach.
limitations of using visking tube model gut
Smaller surface area due to lack of villi
why is using distilled water in the model gut (visking) a limitation
Does not flow so concentration gradient is not maintained
how many grams of salt per day should an adult have
6g
how many grams of salt per day should a child have
4g
what is the lock and key structure called
substrate and enzyme complex
glucose
provides energy
