Biological molecules and digestion

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  • Created by: Jan Shah
  • Created on: 20-04-13 09:21
What are the three main types of molecules?
Lipids (fats), carbohydrates and proteins
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What is the function of carbohydrates?
They store energy (respired to release energy)
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What is the function of proteins?
Form structures (e.g muscle fibres), transport molecules around the body, catalyse reactions.
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What is the function of a lipid?
Protect your organs, store energy, insulation (reduce heat and electrical loss)
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Give an example of a molecule of carbohydrate.
Glucose, starch.
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Give an example of a molecule of protein.
Haemoglobin
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What are polysaccharides?
Polysacccharides are long chains of glucose called starch in plants and glycogen in humans.
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What are proteins made of?
They are made of long chains of amino acids.
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What are lipids made of?
Lipids are made of two different structures, one glycerol is joined to three fatty acids.
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What is similar between the structures of proteins and polysaccharides?
They are both made of long chains of molecules.
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What is different between the structure of lipids and proteins?
Proteins are made of long chains of amino acids whereas lipids are made of one glycerol joined to three fatty acids. Lipids are not polymers like proteins they are a completely different molecule.
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What is the test for starch?
Put a few drops of iodine solution on to the sample. The colour should change from orange to blue/black.
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What is the test for glucose?
Add Benedict's reagent to a sugar solution and heat in a boiling water bath for 5 minutes. If the concentration of sugar in the solution is high the colour will be brick red, if medium the colour will be orange and if low the colour will be green.
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What are the reducing sugars?
Maltose, galactose, fractose, lactose and glucose.
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What are enzymes and what is their function?
Enzymes are a type of protein found in all cells. Their function is to catalyse reactions making them happen faster. Each enzyme can only catalyse one specific reaction.
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What does each enzyme contain?
Each enzyme contains an active site which is a uniquely-shaped pocket into which only one specific molecule will fit.
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What molecule fits into the active site of an enzyme?
Substrate
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Describe how enzymes work.
The substrate binds to the active site of the enzyme then the enzyme catalyses the reaction turning the substrate into products. The products are released from the active site making the enzyme free tie then take part in other reactions.
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Explain why each enzyme catalysed reaction within organisms requires a different enzyme?
Each enzyme has an active site which is a uniquely-shaped pocket and each substrate is a unique shape.
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What happens to the enzyme and substrate as the temperature increases in a reaction?
As the temperature increases the substrate molecules gain more kinetic energy. So more collisions between the substrate and substrate and active site so the rate of reaction increases.
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What happens to an enzyme when it reaches optimum temperature in a reaction?
At this point it is working at it's maximum rate.
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What happens to an enzyme above its optimum temperature in a reaction?
The heat energy causes the bonds to break. This then denatures the enzyme, changing the shape of it's active site. This means that the substrate can no longer bind to the active site so no products can be made (rate of reaction decreases).
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What happens to the enzyme if the solution is too acidic or alkaline?
The bonds break denaturing the enzyme and changing the shape of the active site so the substrate molecules can no longer bind to the active site.
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What is the function of the food type proteins?
It helps to build and repair the body tissues, it produces enzymes, hormones and other substances in the body, keeps the body healthy.
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What are good sources of protein?
Meat, fish and seeds/lentils
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What is the function of the food type fat?
It protects the organs (internal), transports the fat soluble vitamins, it supplies essential vitamins and keeps you warm.
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What are good sources of fats?
Nuts, whole milk, jam doughnuts
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What is the function of the food type fibre?
It helps to absorb water into the body.
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What are good sources of fibre?
Bran
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What is the function of the food type carbohydrates?
Provides the body with energy.
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What are good sources of carbohydrates?
Bread, pasta, rice
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What is the function of the food type water?
It regulates body temperature, transports nutrients and waste products.
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What are good sources of water?
Water
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What is the function and effect of deficiency of vitamin A?
It aids night vision by producing a chemical in the retina, protects the surface of the eye. The effect of deficiency is night blindness and damaged cornea of the eye.
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What is the function and effect of deficiency of vitamin C?
It sticks together cell linig surfaces such as the mouth and the effect of deficiency is scurvy.
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What is the function and effect of deficiency of vitamin D?
Helps bones absorb calcium and phosphate and the effect of deficiency is rickets, poor teeth.
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What are good sources of a) vitamin A, b) vitamin C, c) vitamin D?
a) Fish liver, oils, butter, margarine and carrots, b) fresh fruit and vegatables, c) fish liver, oils and sunlight
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What is the function of calcium and what are good sources of it?
Making teeth and bones and good sources are dairy products, fish and vegatables.
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What is the function of iron and what are good sources of it?
It is part of haemoglobin in red blood cells, helps carry oxygen and good sources are red meat, liver, eggs and some vegatables e.g spinach.
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What is the function of the digestive system?
Too break down large molecules in food into smaller molecules that can be taken up by body cells.
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What is ingestion?
Ingestion is taking in food (eating)
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What is digestion?
the break down of large molecules using enzymes to produce smaller molecules.
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What is absorption?
The transport of the products of digestion across cells lining the gut into the bloodstream.;
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What is assimilation?
To become part of an organism i.e used in cellular reactions to make larger molecules.
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What is egestion?
It is the removal of undigested foods (as faeces)
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What is the order in which digestion occurs?
Ingestion, digestion, absorption, assimilation and egestion.
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What is the function of the mouth?
Mechanical digestion and starch digestion.
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What is the function of the oesophagus?
Moves the food into stomach.
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What is the function of the stomach?
Mechanical digestion, protein digestion, acid in the stomach to kill bacteria.
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What is the function of the liver?
Produces bile.
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What is the function of the pancreas?
Secretes enzymes.
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What is the function of the small intestine?
site of digestion and absorption
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What is the function of the large intestine?
absorbs water.
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What is the function of the rectum?
Stores faeces.
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What are the three parts of digestive system?
The salivary glands, stomach and pancreas.
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How are the enzymes released from the salivary glands?
The enzymes are released in the saliva work in the mouth.
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How are the enzymes released from the pancreas?
Enzymes released in pancreatic juice work in the small intestine.
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What are the product molecules in a) starch, b) proteins and c) lipids?
a) Glucose, b) amino acids and c) glycerol and fatty acids.
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What enzymes are used to digest a) starch, b) proteins and c) lipids?
a) amylase and maltase, b) protease (family of enzymes), c) lipase.
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What is the site of action and the pH for it for digestion for a) starch, b) proteins and c) lipids?
a) mouth and small intestine, pH is 7 for both, b) stomach and small intestine, pH is 2 for the stomach and 7 for the small intestine, c) small intestine with hte pH of 7.
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Explain how starch is digested?
The amylase acts in the mouth and small intestine and is released from the salivary glands. The amylase digests the starch into maltose. The enzyme maltase digests the maltose into separate glucose molecules.
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Explain how fats are digested?
The lipids enter the small intestine from the stomach. Bile is released from gall bladder which emulsifies the lipid into smaller droplets with a larger surface area. The lipase is released from pancreas which digests lipid into fatty acids, glycerol
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How is food moved through the digestive system?
Food is moved through the digestive system by peristalsis which is a wave of muscular contraction that pushes a bolus (small portion of food) through the gut.
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What is absorption and where does it occur?
Absorption is the transport of small molecules produced by digestion across the epithelial cells into the blood. It occurs in the small intestine.
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What does the small intestine need to be to create the largest possible surface area?
It needs to fold up and consists of thousands of finger-like projections called villi (villus).
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What is the functions of villi?
Small molecules (e.g glucose, amino acids) diffuse into the epithelial cells and then into the central capillaru to be circulated around the body. Fatty acids diffuse into the central lacteal (part of lymph system) to be circulated around the body.
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What is the structural features of a villus that maximise diffusion?
A large surface area is caused by the finger-like shape of the villus and the microvilli on every epithelial cell. A short diffusion distance is caused by the villus only having one layer of epithelial cells.
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What is the structural features of a villus that maximise diffusion (continued)?
A steep concentration gradient is created by the flow of blood in capillary which takes away absorbed molecules (keeps low concentration of molecules in the blood).
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Other cards in this set

Card 2

Front

What is the function of carbohydrates?

Back

They store energy (respired to release energy)

Card 3

Front

What is the function of proteins?

Back

Preview of the front of card 3

Card 4

Front

What is the function of a lipid?

Back

Preview of the front of card 4

Card 5

Front

Give an example of a molecule of carbohydrate.

Back

Preview of the front of card 5
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