Enzymes Flashcards
What is differentiation
The process of which cells become specialised for a specific job
What do large multicellular organisms contain
Different organ systems inside of them for exchanging and transporting material
What is a tissue
A group of cells that work together to carry out a particular function
Examples of tissues and what they do
- muscular tissue - contracts to move whatever it’s attached to
- glandular tissue - makes and secretes chemicals like enzymes and hormones
- epithelial tissue - covers some parts of it he body
What is an organ
A group of different tissues that work together to perform a certain function
What tissues is a stomach made up of
- muscular tissue - which moves the stomach wall to churn up the food
- glandular tissue - which makes digestive juices to digest food
- epithelial tissue - which covers the outside and inside if the stomach
What is an organ system
A group of organs working together to perform a particular function
What organs is the digestive system made out of
- glands - which produces digestive juices
- stomach and small intestine- which digest food
- liver- which produces bile
- small intestine- which absorbs soluble food molecules
- large intestine- which absorbs water from undigested food, leaving faeces
Cons of speeding up a reaction by raising the temperature
- would speed up unwanted reactions
- there a limit on how much you can raise the temperature without damaging cells
Advantages of enzymes
- reduces the need for high temperatures
- they only speed up useful chemical reactions in the body
What is a catalyst
A substance which increases the speed of a reaction without being changed or used up in a reaction
What are enzymes
They are proteins that act as a biological catalyst
lock and key model explanation
1) substrate collides with the active site of enzyme and becomes attached
2) the active site has a complementary shape to the substrate and once the substrate binds to the enzyme it forms an enzyme substrate complex
3) the enzyme catalyses the reaction and breaks down the substrate
4) the reaction takes place rapidly and products are released from the surface of the enzyme
5) the enzyme molecule is unchanged an can be used again
What happens if the substrate does not match the enzymes active site
The reaction won’t be catalysed
What is the induced fit model of enzyme action
It’s a more accurate model of the enzyme action as the active site of the enzyme changes shape a little as the substrate binds to it to get a tighter fit
What do chemical reactions involve
Things either being split apart or joined together
How do enzymes speed up reactions
- breaking down larger molecules into smaller ones
- building larger molecules into smaller ones
- changing one molecule to another
What factors effect enzyme action
- temperature
- pH
How does temperature effect enzyme action
- changing temperature changes the rate of an enzyme catalysed reaction
- a high temperature increases the rate at first but after around 40 degrees the binds holding the enzyme together break, this changes the shape of the enzymes active site so the substrate won’t fit anymore so other enzyme is denatured and can no longer act as a catalyst
- all enzymes have an optimum temperature they work best at
How does pH effect enzyme action
- if the pH is too high or low it can affect the binds that hold the enzymes together, this changes the shape of the active site and denatures the enzyme
How to calculate the rate of the reaction
1000/ time OR the amount a substance has changed/ time
Effect in pH on enzyme activity REQUIRED PRACTICAL
1) place one drop of iodine solution into each well of a spotting tile
2) take 3 test tubes in test tube 1 add 2cm3 of starch solution in test tube 2 add 2cm3 of amylase solution in test tube 3 add 2cm3 of a pH 5 buffer solution (this controls the pH)
3) place all the test tubes in a water bath at 30 degrees no leave them for 10min to allow the solutions to reach the correct temperature
4) combine the three solutions into one test tube and mix with a stirring rod and return to the test then test tube to the water bath and start a stopwatch
5) after 30s use the stirring rod to transfer 1 drop of solution to quell in the spotting tile which contains iodine
6) the iodine should turn blue black to show that starch is present
7) we take a sample every 30 seconds and continue until the iodine remains orange, when the iodine remains orange tells us that starch is no longer present and the reaction has completed, and we record the time for this in our results
8) repeat the experiment several times using different pH buffers
Anomalies of REQUIRED PRACTICAL of the effect on pH
- we are only taking samples every 30 seconds, this means that we only have an approximate time for the reaction to complete, we can improve this by taking samples every 10 seconds
- we are looking for the time when iodine does not go blue black and this is not always obvious, as the colour change tends to be gradual as some wells can have a small amount of blue black mixed with orange, you can improve this by getting several people to loot at the toe and decide whether the reaction is completes
Examples of large molecules
- starch
- proteins
- fats
What do digestive enzymes do to big molecules
- they break them down into smaller ones e.g sugars, amino acids, glycerol and fatty acts these smaller, soluble molecules can pass through the walls of the digestive system allowing them to be absorbed into the blood stream
What chemicals are carbohydrates made form
Carbon, hydrogen and oxygen
What do carbohydrates do
They provide fuel for all chemical reactions that are needed to make life possible
What are carbohydrates made from
Simple units of sugar
What enzyme breaks up carbohydrates
Carbohydrase
Example of carbohydrase
Amylase
What does amylase do
It breaks down starch
Where is amylase made
- pancreas
- salivary glands
- small intestine
What chemicals are proteins made form
Carbon oxygen hydrogen and nitrogen
What are proteins made from
Amino acids
What do proteins do
They are the basic building blocks for your cells, tissues and enzymes
How are proteins made
When long chains of amino acids are twisted, folded and coiled to make specific 3D shapes called proteins
What enzymes breaks down proteins into amino acids
Protease
What does protease do
Break down protein into amino acids
What does carbohydrase do
Breaks down carbohydrates into simple sugars
Where are proteins made
- the stomach
- pancreases
- small intestine
Where is pepsin made
Stomach
What do proteins act as
- a structural component for cells and tissues
- hormones
- enzymes
- antibodies
What are lipids
Fats and oils
What do lipids do
They are an efficient store of energy in your body and an important energy source in your diet
Example of protease
Pepsin
What chemicals make up lipids
Hydrogen, oxygen and carbon
What are lipids made out of
Fatty acids connected to a molecule of glycerol
What enzyme breaks down lipids into fatty acids and glycerol
Lipase
What do Lipase do
Break down lipids into fatty acids and glycerol
Where are lipase made
- Pancreas
- small intestine
Where is bile made and stored
- bile is produced in the liver and is stored in the gall bladder before being release into the small intestine
What does bile do
- neutralises the stomach acid as the hydrochloric acid in the stomach is too acidic for enzymes in the small intestine to work properly, so as the bile is alkaline it neutralises the acid and make’s conditions alkaline, and so the enzymes can work best in these conditions
- it emulsifies fat to give it a bugger surface area of fat for the lipase to work on and this makes digestion much faster
How does the digestive system work
1) in the mouth the salivary glands produce amylase in the salvia to break down the starch in the food molecules
2) the food is then passed down the oesophagus into the stomach where it pummels the food with the muscular walls and produces the enzyme pepsin to break down the protein
3) the food then passes to the small intestine where it produces amylase, protease and lipase to complete digestion and is also where food is a sprout of the digestive system I to the bloods
4) the undigested food then passes to the large intestine excess water is absorbed
5) all of the indigestible food is passed to the rectum where it is stored as faeces before it leaves the anus
Why does the stomach produces e hydrochloric acid
- to kill bacteria
- to give the right pH for the protease enzyme to work
How is the small intestine adapted for digestion
The surface of the small intestine wall is folded and has projections called villi , this increases the surface area over which digested food is absorbed
What should we do to the food before testing it with the food tests
1) take the food sample and grind it will distilled water using a mortar and pestle to make a paste
2) transfer the paste to a beaker and add more distilled water and stir so the chemicals in the food dissolve in the water
3) filter the solution to remove suspended food particles
What food test is used to test for starch
Iodine solution test
How to carry out the iodine solution test
1) place 2cm3 of food solution into a test tube , we the add a few drops of iodine solution which is a orange colour
2) if starch is present then the iodine solution turns blue black, if there is no starch then the iodine solution will stay orange
What food test is used to test for sugars
Benedict’s test
How to carry out the Benedict’s test
1) place 2cm3 of food solution into a test tube then add 10 drops of Benedict’s solution, which is a blue colour
2) place the tea tube into a beaker and half fill the beaker with hot water from a kettle and leave it for 5 mins
3) if sugar is present then the solution will change colour, a green coil or tells us there is a small amount of sugar, a yellow colour tells us there is more sugar present and a brick red colour tells us that there is a lot of sugar present, this only works for certain sugars known as reducing sugars
What food test is used to test for proteins
Biuret reagent test
How to carry out the biuret test
1) place 2cm3 of food solution in a test tube and then add 2cm3 of biuret, which is a blue colour
3) if protein is present then the biuret solution will change colour from blue to a purple or lilac colour
What food test is used to test for lipids
Ethanol test
How to carry out the ethanol test
1) unlike the other tests we do not filter the solution as lipid molecules can stick to filter paper
2) transfer 2cm3 of the food solution to a test tube then add a few drops of distilled water and a freeware drops of ethanol
3) gently shake the solution, if lips are present a white cloudy emulsion forms
Explain how amylase breaks down starch.
Answer in terms of the ‘lock and key theory’.
starch / substrate binds to active
site (of enzyme)
(because) shape of active site
and substrate are
complementary
a chemical reaction occurs to
produce smaller molecules
what happens to enzyme activity in low temperatures
its very slow as the enzymes have low kinetic energy so there are few collisions
