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Biological Molecules and Digestion
Carbohydrates
- Contain carbon, hydrogen, oxygen (i
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a hydrated carbon)
- Polymer; contain monomers (glucose/maltose) joined in a long chain
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- Maltase (produced in the ileum) then converts maltose into glucose (C6H12O6)
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- Carbohydrates are generally needed as an energy store (for respiration)
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- Polymer; contain monomers (amino acids) in a chain to form polypeptides
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e
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- Proteins are generally needed for growth and repair
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- Examples; keratin, collagen, melanin, antibodies, enzymes etc
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- Contain carbon, hydrogen and oxygen (like carbohydrates); has a higher
hydrogen ratio than carbohydrates and therefore a higher ATP release rate
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- Broken down by lipase and emulsified by bile (produced in the liver and stored
in the gall bladder)
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- Benedict's solution is an irritant
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Iodine solution is an irritant
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- Biuret solution is corrosive
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- Ethanol is flammable
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Saliva
- Produced in the salivary gland
- Contain amylase
2
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Pancreatic juice
- Produced in the pancreas
- Contain protease, amylase and lipase
4
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Carbohydrases
Amylase; starch → maltose
Maltase; maltose → glucose
2
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Lipases
Lipase; lipids → glycerol + fatty acids
- Enzymes are tertiary proteins and are involved in catabolic and anabolic
reactions
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- Enzymes are biological catalysts; they speed up reactions but are not used up
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Temperature
Below the optimum temperature, the enzyme does not have enough kinetic
energy and reaction rate is low
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2
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At alkaline or acidic
extremes the enzyme becomes denatured
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Physical digestion occurs in the mouth and stomach; the mouth chews the food
to form a bolus and the stomach churns the food
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Chemical digestion occurs when enzymes chemically break down (hydrolyse) the
food polymers
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ADAPTATIONS OF THE DIGESTIVE SYSTEM
BILE
- Bile is produced in the liver and stored in the gall bladder before being
released into the ileum
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This allows the
enzymes in the ileum to work as they have a neutral pH optimum (i
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pH 7)
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This increases the SA:V ratio and increases
surface area for lipase hydrolysation, therefore increasing the overall reaction
rate
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This gives the ileum a very large
surface area for absorption of
food molecules
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- The villi have a good supply of capillaries linked directly to veins; this maintains
a concentration gradient and maintains a fast diffusion rate
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B
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)
ESSENTIAL NUTRIENTS
Six essential nutrients are;
1
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Proteins; found in red meats and eggs- needed for growth and repair
3
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Vitamins; found in oranges (vitamin c), kale (vitamin A) and parsley (vitamin
K)- needed for metabolic reactions
Vitamin C is needed to prevent scurvy
Vitamin A helps to improve vision
Vitamin D is needed to calcium absorption
5
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Water; needed as a medium for metabolic reactions and a solvent
[7
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g

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