Digestion and Enzymes Flashcards
What is the function of the digestive system?
Your digestive system breaks down the food you eat into smaller soluble molecules so that they can then be absorbed into your bloodstream so your body can use them for energy, growth and repair. Unused materials are discarded as faeces.
Molecules we eat must be broken down becuase they are too large to pass through the wall of the gut
Why does your digestive system need to break down the food you eat?
The digestive system needs to break down the food you eat becuase food is made of large insoluble molecules. They can’t pass through the wall of the intestine. Therefore, they need to be broken down to from smaller soluble molecules that can then be absorbed and used by cells.
What do enzymes do?
The break down of food is catalysed by enzymes. They increase the rate at which the break down of large insoluble food molecules into smaller soluble ones, occurs
Describe the journey food undertakes
mouth → oesophagus → stomach → small intestine → large intestine → rectum → anus
What do glands do?
They release digestive juices containing enzymes to break down food molecules
What are faeces
Faeces are the material left after water and nutrients have been absorbed into the blood
Where is water absorbed into the blood?
large intestine
Function of the salivary glands?
These produce the amylase enzyme in saliva
Function of the stomach? (2)
- Pummels food with it’s muscular walls + chemical digestion
- It produces hydrochloric acid to
a) kill bacteria
b) to give the right PH for the protease enzyme to work
Function of the gall bladder?
Where bile is stored before being released into the small intestine
Function of the liver?
Where bile is produced. Bile neutralises stomach acid and emulsifies lipids.
Function of the pancreas?
Produces protease, amylase and lipase enzymes and releases these into the small intestine
Function of the small intestine? (2)
- Produces protease, amylase and lipase enzymes
2. This is where the digested food is absorbed out of the digestive system into the blood.
Function of the large intestine?
where excess water is absorbed from the food
Function of the rectum?
Where faeces (made up mainly of indigestible foods) are stored before they are excreted through the anus
Food test for sugars
Benedict’s solution - Add Benedict’s to the food and boil in a water bath.
Blue → Orange
Food test for starch
Iodine - Add a few drops of iodine to the food.
Brown → Black
Food test for protein
Biurets solution - add a few drops to food
Blue → Purple
Food test for lipids
Ethanol - Add water to food then add water food solution to ethanol
Colourless → cloudy
What is a catalyst?
a catalyst is a substance which increases the rate of a reaction, without being changed or used up in the reaction
What are enzymes made out of?
Large proteins - and all proteins are made up of a chain of amino acids that are folded into unique shapes
What are enzymes?
They are biological catalysts
What is the lock and key theory?
Every enzyme has an active site (the region where the substrate binds to the enzyme) that only allows a specific substrate (the substance on which the enzyme acts) to fit, similar to how locks and keys work.
Once the substrate binds to the active site, the reaction takes place rapidly and products are released. The enzyme itself remains unchanged
Where is amylase (a carbohydrase) produced? (3)
What does it break starch into?
- Salivary glands
- Pancreas
- Small intestine
Starch →(amylase)→ sugars
Where is protease produced? (3)
What does it break proteins into?
- Stomach
- Pancreas
- Small intestine
Proteins →(protease)→ amino acids
Where is lipase produced? (2)
What does it break lipids into?
- Pancreas
- Small intestine
Lipids →(lipids)→ fatty acids + glycerol
What does Bile do to lipids?
bile emulsified fats, which means that bile breaks down fats into tiny little droplets, increasing the surface area of the fat for the enzyme lipase to work on, which makes its digestion faster.
What causes a protein to change shape?
Heat
Why does heat also speed up chemical reaction?
The molecules get more kinetic energy, which means more frequent collision between particles therefore the rate of the reaction increases
Why does heat also speed up chemical reaction?
The molecules get more kinetic energy, which means more frequent collision between particles therefore the rate of the reaction increases
What happens when an enzyme is heated past the optimum temperature?
The active site changes shape so the substrate can no longer fit = no more reactions = the enzyme is denatured, this happens at what is known as the peak temperature
Describe the graph showing temperature and the rate of enzyme reaction
https://www.evolvingsciences.com/
Temperature%20and%20pH.html
Why do plants work slower in the winter?
The rate of reactions of their enzymes are slower becuase of the temperature
Why do we sweat or shiver?
To try and keep the body’s heat at/as close to optimum temperature as possible
What is another factor apart from temperature, that affects enzymes?
Ph - if the PH is to low or to high it interfears with the bonds holding the enzyme together and changes the shape of the active site, denaturing the enzyme.
Pepsin optimum PH
PH 2
Describe graph showing PH and rate of enzyme reaction
https://www.pathwayz.org/Tree/Plain/ENZYMES+-pH
Calculating rate of reaction
change/time - on a graph draw a tangent
y2-y1) / (x2-x1
