Digestion and Enzymes

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What are the 3 important groups of biological molecules, what are they made of and what do they do?
1. Carbohydrates. Made of C, H and O. -Simple carbohydrates eg. glucose: -fast acting source of energy -soluble in water -tastes sweet Complex carbohydrates eg. starch or cellulose: -slow release energy/storage -long chains of sugar joined together
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What are the 3 important groups of biological molecules, what are they made of and what do they do? (Cont.)
2. Proteins. Made of C, H, O and N. eg. Enzymes, Haemoglobin -Complex molecules consisting of long chains of amino acids -For growth and repair -Can be used for energy but only when there is no carbohydrate or fat reserves -There are 20 amino acids
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What are the 3 important groups of biological molecules, what are they made of and what do they do? (Cont..)
3. Lipids/Fats. Made of C, H and O. -Made of fatty acids and glycerol -Excellent sources of energy (and storage of energy) -Provide 2x energy per gram as carbohydrates and proteins
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What important links are there between our diet and health?
Obesity: caused by taking in too much energy. Heart disease + stroke: caused by the build up of fatty substances (cholesterol) in the walls of our arteries. Diabetes Type 2: caused by poor diet or obesity leading to body not controlling blood levels
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What are the different food tests?
Benedict's solution: sugar. - turns from blue to brick red precipitate. Iodine: starch. - turns from yellow-brown to blue-black.
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What are the different food tests? (Cont.)
Biuret: protein. - turns from blue to purple. Ethanol: lipids. turns from clear to cloudy white emulsion
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What are enzymes?
Enzymes are proteins and a biological catalyst, meaning they speed up the rate of reactions. THey can break down large insoluble molecules into small soluble ones ( in Digestion) or they can build small molecules into larger ones (in Photosynthesis)
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What is the model called and what does it explain?
The 'Lock and Key' model can be used to explain enzyme specificity. Each enzyme has a specific active site shape which will only work on its substrate eg. Protease will only act on protein, not starch or lipids
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Which subtrate is broken into 2 different products?
Lipids. They break into fatty acids and glycerol.
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What are the enzyme and product of a) Starch b) Carbohydrates c) Proteins d) Lipids ?
a) Amylase and simple sugars/Glucose b) Carbohydrase and Glucose c) Protease and Amino acids d) Lipase and Fatty acids + glycerol
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What is digestion?
The breakdown of large insoluble food molecules into small soluble food molecules which can then me absorbed into the blood stream in the small intestine (ileum)
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What happens in the mouth?
-Food is broken into bite-size chunks -Digestion starts here -Food is broken up by the teeth -Saliva contains amylase which breaks down starch -Mucus aids the movement of food in the throat -Food moves down the oesophagus through peristalsis
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What happens in the stomach?
-Food enters from the oesophagus --It mashes the food into a pulp with the aid of gastric juices (which contain protease) -The stomach contains hydrochloric acid and so the stomach protease has a optimum pH of around pH2
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What happens in the Ileum?
-The small intestine is a 6 metre long tube -All 3 enzymes are present as well as bile -Bile emulsifies the fat (breaking it into small pieces to increase surface area) and also neutralises the HCl -Amino acids and glucose are absorbed
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What happens in the ileum? (Cont.)
-The rest go on to be processed by the liver
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How is the small intestine well adapted for absorption?
1. It has a large surface area 2. It is folded 3. It is long 4. It has villi and microvilli
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What happens in the large intestine?
- Food that can't be digested in the small intestine passes on to the large intestine -It coverts the semi-liquid chyme into solid waste by absorbing water -It soaks up to 1.5l every day -The once watery waste starts to become faeces
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What are the 3 factors enzyme productivity is affected by?
1. pH 2. Temperature 3. Enzyme concentration
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What are inhibitors?
These are molecules that fit loosely or partially into the active site of some enzymes. When they enter the active site, the substrate cannot enter and be broken down which leads to a reduced rate of reaction
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What happens if an enzyme is too hot/cold?
If the enzyme is too cold it will have less kinetic energy and so there is less chance the enzyme and substrate will hit each other. If it is too hot the enzyme becomes denatured as the active site changes shape and the substrate no longer fits
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How does enzyme concentration effect enzyme activity?
-Enzyme activity increases with enzyme concentration until it levels off as it is limited by another factor
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How are enzymes used in industry?
1. Enzymes are used in biological washing powders to make them more thermostable, meaning they can work in a wide range of temperatures. The enzymes digest large insoluble stains into small soluble molecules that dissolve in water.
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Card 2

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What are the 3 important groups of biological molecules, what are they made of and what do they do? (Cont.)

Back

2. Proteins. Made of C, H, O and N. eg. Enzymes, Haemoglobin -Complex molecules consisting of long chains of amino acids -For growth and repair -Can be used for energy but only when there is no carbohydrate or fat reserves -There are 20 amino acids

Card 3

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What are the 3 important groups of biological molecules, what are they made of and what do they do? (Cont..)

Back

Preview of the front of card 3

Card 4

Front

What important links are there between our diet and health?

Back

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Card 5

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What are the different food tests?

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