BIOLOGY 2B Enzymes

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  • Created by: CMR71
  • Created on: 25-10-15 17:34
What are enzymes?
They are biological catalysts that reduce the need for high temperatures. Only used for useful chemical reactions in the body.
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Whst is a catalyst?
It is a substance which increases the speed of a reaction whitout being changed or used up in the reaction.
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What are enzymes made from?
The are proteins, made up of chains of amino acids. These chains are folded into unique shapes, which enzymes need to do their jobs.
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What are the other uses of proteins?
They can act as structual components of tissues e.g. muscles, hormones and antibodies.
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How many reactions can an enzyme catalyse?
One - key and lock
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Why can enzymes only catalyse one reaction?
For the enzyme to work, it has to fit its special shape. If the substances doesnt fit the enzymes shape, then the reaction wont be catalysed.
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What do enzymes need to work?
The correct temperature and pH
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What happens to an enzyme reaction if you increase the temperature?
Initially it will increase the rate, but if it gets too hot, some of the bonds holding the enzyme together break. This destroys the enzymes special shape and it is said to be denatured.
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What is the best temperature for an enzyme to work in the human body?
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What is the best pH for an enzyme to work?
Its often neutral pH7 but not always e.g. pepsin is the enzyme used to break down proteins in the stomach. It works best at pH2, which means it is well suited to the acidic conditions
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What do digestive enzymes do?
Break down bigger molecules into smaller ones
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What are big molecules?
Starch, proteins and fats - these are too big to pass through the walls of the digestive system
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What molecules are small enough to pass easily through the walls of the digective system?
Sugars, amino acids, glycerol, and fatty acids
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What do the digestive enzymes do?
They break down the bigger molecules into smaller ones
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What does Amylase do?
It converts starch into sugars
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Where is Amylase produced?
The salivary glands, the pancreas, the small intestine
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What does Protease do?
It converts proteins into amino acids
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Where is Protease produced?
The stomach (pepsin), the pancreas, the small intestine
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What does Lipase do?
It converts lipids into glycerol and fatty acids
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Where is Lipase made?
The pancreas, the small intestine
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Where is bile made?
Bile is made in the liver and is stored in the gall bladder before being released into the small intestine.
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What does bile do?
The hydrochloric acid in the stomach makes it too acidic for the enzymes in the small intestine to work. Bile is alkaline and it neutralises the acid making the conditions more alkaline for the enzymes to work. It also emulsifies fat.
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What does emulsify mean?
It means the breaking down of fat into smaller droplets, thereby increasing the surface area for lipase to work and making digestion faster.
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What is respiration?
It is the process of releasing energy from glucose which goes on in every cell and is controlled by enzymes
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What is aerobic respiration?
It is respiration using oxygen. It is the most efficient way to release energy from glucose. GLUCOSE + OXYGEN = CARBON DIOXIDE + WATER + ENERGY
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Where does aerobic respiration happen?
In the mitochondria
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What is aerobic respiration used for? 4 examples
1. Build up larger molecules from smaller ones 2. To allow muscles to contract 3. In mammals and birds body temperature steady 4. In plants to build sugars, nitrates etc built upto proteins
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What does exercise do to the heart rate?
It increases the heart rate. Muscle cells use oxygen to release energy from glucose which contracts the muscle. Increase in muscle activity requires more glucose and oxygen and carbon dioxide removed. The blood has to flow faster to do this.
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What happens in pysical activity?
Your breathing rate increases and makes you breathe more deeply to meet the demand for extra oxygen and increases the speed at which the heart pumps.
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How is glycogen used during exercise?
Some glucose from food is stored as glycogen, its mainly stored in the liver but each muscle has its own store. During exercise muscles use glucose rapidly so some stored glycogen is converted back to gluscose to provide more energy.
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What is anaerobic respiration?
When your body cant supply enough oxygen to your muscles. It just means without oxygen, its the incomplete breakdown of glucose which produces lactic acid. GLUCOSE = ENERGY + LACTIC ACID
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Why is anaerobic respiration not the best way to convert glucose into energy?
Because lactic acid builds up in the muscles which gets painful. It also causes muscle fatigue, the muscles get tired and stop contracting effectively.
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Name a disadvantage and an advantage of anaerobic respiration
It does not release as much energy as aerobic (around 5% of the energy released by aerobic) but it does mean you can use your muscles for a bit longer
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What is the difference between respiration and breathing?
Respirtation releases energy, breathing lets air in and out of the lungs.
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What happens after you have resorted to anaerobic respiration?
You are in oxygen debt- you have to repay the oxygen to your muscles. This means you have to keep breathing hard for a while after you stop to get more oxygen into your blood. Blood flows and removes lactic acid by oxidising it to CO2 and H2O
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What does the brain do if it still detects high levels of CO2 and lactic acid?
It will keep your pulse and breathing rate hig to try and rectify the situation.
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Is there a difference between being fit and being healthy?
Yes, healthy means free of disease and infection. It is possible to be fit but unhealthy, or healthy but unfit
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Name some uses of enzymes
Enzymes are used in biological detergents - proteases and lipases (to break down proteins and fats). Used to change foods - proteases used in some baby foods to 'pre digest' proteins so they are easier for the baby to digest.
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What are the advantages of using enzymes in industry?
They are specific, use lower temperatures, lower cost, saves e.nergy. Enzymes work for a long time and biodegradable
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What are the disadvantages of using enzymes in industry?
Allergies, some can be denatured by even a small increase in temperature. Susceptible to poisons and pH. Can be expensive to produce and contamination is a risk
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Whst is a catalyst?


It is a substance which increases the speed of a reaction whitout being changed or used up in the reaction.

Card 3


What are enzymes made from?


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Card 4


What are the other uses of proteins?


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Card 5


How many reactions can an enzyme catalyse?


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These are very useful and easy to understand, thank you!!

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