Biology: enzymes and digestion Flashcards
The hierachy of organisms
Cell: basic building block of life e.g nerve cell Remember CT triple O Tissue: e.g nerve cell tissue Organ e.g skin Organ system e.g nervous system Organism e.g human body
Describe the journey food would take ( from 👄 to 🍑)
Mouth: mechanical digestion in teeth and chemical by enzymes in saliva e,g amylase
Oesophagus: food is brought to the stomach via wave- like muscular contractions called peristalsis
Stomach: muscular sac limed with mucous. Food is mixed with hydrochloric acid and stomach enzymes and churned
Food then gets the hydrochloric acid neutralised by bile which is made in the liver, stored in the gall bladder and exited through the bile duct
The food then gets broken down by enzymes produced by the pancreas. The food then passes through the small intestine which produces more enzymes to break the food down. This is where the food is absorbed into the bloodstream. The water is removed from the food by the large intestine and put back into the bloodstream. The undigested food ( faeces ) is then stored in the rectum and exits through the anus
What are the 6 major food nutrients
Proteins Fats ( lipids ) Carbohydrates ( sugar, starch fibre ) Vitamins Minerals Water
What is fat made up of and what enzyme breaks it down
Fats are made up of 3 fatty acids and 1 glycerol
It gets broken down by lipase
What is protein made up of and what enzyme breaks it down
Made up of amino acids
Protease breaks it down
What are carbohydrates made up of and what enzyme breaks them down
Made up of simple sugars ( e.g glucose )
Amylase breaks it down
Describe the process of enzymes breaking down substrates
The enzyme’s active site and the substrate fit into one another, the bonds in the substrate are broken and the products are released. Enzyme is unchanged and can be reused.
How do enzymes get denatured and what happens after that
The active site of the enzyme can change shape due to high temperatures ( i.e above 40 degrees C ) or change from normal pH range.
Damage is irreversible and enzyme will no longer break down the substrate molecules
Give information on bile e.g what it is, does and where it comes from
Bile is not an enzyme
It is a green liquid made in the liver and stored in the gall bladder
It is an alkaline liquid so it neutralises hydrochloric acid leaving the stomach
It also emulsifies lipids to smaller droplets, this increases the surface area for lipase enzymes to work on
What is an independent variable
E.g temperature
It goes on the X axis
It is the one that changes in the experiment
What is the dependent variable
E.g the rate of enzyme action
It goes on the Y axis
The one you measure in the experiment
What formula do you use to calculate the rate ( give all types and why )
Rate = 1/time Rate = 1000/time ( you may need a bigger number that is easier to plot on a graph Rate = change/ time ( how much something has changed over time )
At pH2, kt takes 40 seconds for the enzyme pepsin to break down a protein. Calculate the rate of reaction
R=1/t
1/40 = 0.025 s-1 ( -1 is an indice ) ( s-1 means per second )
The enzyme catalase catalyses the reaction where hydrogen peroxide is broken down into water and oxygen. 40cm cubed was released in 1 minute. Calculate the rate of the reaction ( choose what formula to use )
R = change/time
40/60 seconds = 0.67s-1 ( s-1 is an indice and means per second )
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What elements make up carbohydrates
Carbon, hydrogen, oxygen
What elements make up protein
Carbon, hydrogen, oxygen, nitrogen, sulphur
What elements make up lipids ( fats )
Carbon, hydrogen and oxygen
Where is the production site of protease
Pancreas, stomach, small intestine ( ileum, duodenum)
Where is the production site of lipase
Pancreas, small intestine
Where is the production site of carbohydrase
Pancreas, small intestines, salivary glands
Describe the rate of enzyme action when the temperature is increasing
The rate of reaction starts to rapidly increase as the temperature increases because their is more kinetic energy and therefore more collisions between the enzyme and substrate molecule. Now the enzymes are gradually becoming more efficient
Describe the rate of reaction of enzymes at optimum temperature
Optimum temperature ( 35 - 41 degrees ) this is where there is the most kinetic energy and collisions between the enzyme and the substrate and rate of reaction is fastest. The enzymes are the most efficient at this temperature.
Describe the rate of enzyme action when the temperature is increasing past optimum
As temperature goes past optimum, rate of reaction is slowing as the active site of the enzymes starts to denature. This is because the enzymes have less kinetic energy and there is less frequent collisions
Describe the rate of enzyme action when the temperature is at around 54 degrees ( when enzymes have completely denatured )
The active site of the enzymes have completely denatured and cannot catalyse with the substrate there is no more reactions so rate of reaction is at 0
How do you find the rate of reaction when reading a graph on a steadily increasing line ( straight line )
You find where the number lines up to the y axis on the graph or find the gradient of the line
How do you find the rate of reaction on a graph that the line is curving
You draw a tangent
Describe the method to the enzymes practical procedure
- 3 test tubes: pHx, amylase, starch
- One drop of iodine solution into each depression of spotting tile
- 2cm cubed of each solution into a test tube and then a water bath and wait until all have reached 30C
- Use syringe to place 2cm cubed of of starch into the buffered pH solution
- Then use another syringe to put 2cm cubed amylase into the starch + pH test tube
- Immediately start the clock and leave it on throughout the test
- After every 20 seconds add one drop of the solution to one of the depressions in the spotting tile, the iodine should turn a blue black colour
- Do this every 20 seconds until the iodine has no change in colour ( this is when the amylase has broken down all the starch )
- repeat the test for other pHs
- Record your results on a table
What is the purpose of the enzymes required practical
To see how long an enzyme takes to break down a substrate with different levels of pH
How do you test for starch
Add a few drops of iodine solution
Positive result: brick red - blue black colour
How do you test for sugars ( e.g glucose )
Add a few drops of Benedicts’s solution
Heat gently for approx for 10 mins
Positive result: blue colour - brick red
How do you test for protein
Add a few drops of biuret A and biuret B
Shake the test tube gently
Positive result: blue colour - violet colour
How do you test for fats/ lipids
Add a few drops of water and ethanol
Positive result: white precipitate layer forms
OR
Solid lipids ( e.g not lemonade )
Brown paper, if it turns translucent then there is fats
