The activity of enzymes is affected by changes in temperature and pH | |
Enzymes activity has an optimum temperature | Enzyme activity has an optimum pH |
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liver
oesophagus
stomach
large intestines
small intestines
gall bladder
pancreas
mouth
anus
B03) ORGANISATION AND THE DIGESTIVE SYSTEM
Cells, tissues, organs and systems
Principles of organisation
Cells | | e.g. muscle cells | The basic building blocks of all living organisms. |
Tissues | | e.g. muscle tissue | A group of cells with a similar structure and function. |
Organs | | e.g. the heart | Aggregations (working together) of tissues performing a specific function. |
Organ systems | | e.g. the circulatory system | Organs working together to form organ systems, which work together to form an organism. |
The human digestive system
Carbohydrases (e.g. amylase) | | Made in salivary glands, pancreas, small intestine | Break down carbohydrates to simple sugar (e.g. amylase breaks down starch to glucose). |
Proteases | Made in stomach, pancreas | Break down protein to amino acids. | |
Lipases | Made in pancreas (works in small intestine) | Break down lipids (fats) to glycerol and fatty acids). | |
Bile (not an enzyme) | Made in liver, stored in gall bladder. | Emulsifies lipids to increase surface area to increase the rate of lipid break down by lipase. Changes pH to neutral for lipase to work |
Digestive enzymes speed up the conversion of large insoluble molecules (food) into small soluble molecules that can be absorbed into the bloodstream
The products of digestion are used to build new carbohydrates, lipids and proteins. Some glucose is used for respiration.
The ‘lock and key theory’ is a simplified model to explain enzyme action |
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Enzymes catalyse specific reactions in living organisms due to the shape of their active site |
Enzymes catalyse (increase the rate of) specific reactions in living organisms
An organ system in which organs work together to digest and absorb food.
Enzymes in digestion
Sugars (glucose) | Benedicts’ test | Orange to brick red precipitate. |
Starch | Iodine test | Turns black. |
Biuret | Biuret reagent | Mauve or purple solution. |
Food tests
Non-communicable diseases
More energy consumed in food and drink than used |
obesity |
Linked to increased rates of cardiovascular disease and development of diabetes type 2. |
Large changes in temperature or pH can stop the enzyme from working (denature) | |
Temperature too high | pH too high or too low |
Enzyme changes shape (denatures) the substrate no longer fits the active site. | |