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DESCRIPTIONMammalian Nutrition. Miss Tagore. Food Groups. There are 5 main food groups: Carbohydrates Contain the elements carbon, hydrogen and oxygen Used as the main source of energy Can be small, soluble sugars such as glucose and maltose or large insoluble molecules such as starch and cellulose. - PowerPoint PPT Presentation
Mammalian NutritionMiss Tagore
Food GroupsThere are 5 main food groups:
CarbohydratesContain the elements carbon, hydrogen and oxygen
Used as the main source of energy
Can be small, soluble sugars such as glucose and maltose or large insoluble molecules such as starch and cellulose
CarbohydratesThere are three types of carbohydrate that you need to know about:
Monosaccharaides (mono = one)
Disaccharides (di = two)
Polysaccharides (poly = many)Monosaccharaides (mono = one)The simplest form of carbohydrate
Single structured molecules
Disaccharides (di = two)Disaccharides are formed from the combination of two monosaccharaides by a chemical reaction called dehydration synthesis (more on this later).
Examples of disaccharides are sucrose, maltose and lactose.
Polysaccharides (poly = many)Polysaccharides are many monosaccharaides linked together. These are stored form of sugar.Examples of polysaccharides are starch (synthesized by plants), glycogen (synthesized by animals) and cellulose (material that makes the plants cell wall).
Food GroupsFatsContain the elements carbon, hydrogen and oxygen
Used as an energy source but contain twice as much energy as carbohydrates
One fat molecule consists of 3 fatty acids and one glycerol
Organic molecules that are waxy or oily
Fats3 major roles:
Form biological membranes
Chemical messengers (hormones)
3 types of lipids:
Sterols (steroids)Neutral FatsFound on humans in the inner thigh and torso area.
Two types: Saturated fats
Saturated FatsAll carbon atoms have two hydrogen atoms attached
There are no double bonds between carbons The lack of double bonding makes saturated fats a solid at room temperature
Examples of saturated fats are lard, butter, animal fats
Unsaturated FatsNot all carbon atoms have two hydrogen atoms attached
The lack of single bonds makes unsaturated fats a liquid at room temperature
Examples of unsaturated fats are olive oil, corn oil and palm oil.
All neutral fats are made from a glycerol molecule with 3 fatty acid chains attached to it
PhospholipidsHave the same structure as neutral fats, except one fatty acid chain has a polar group that contains phosphorus.
Part of the molecule is attracted to water (hydrophilic = water loving), the other end repels it (hydrophobic = water fearing).
These properties make a phospholipid perfect for forming cell membranes.
SteroidsSteroids are made of 4 interlocking rings. They are an important part of the body involved in building cells and carrying messages.
Examples of steroids are cholesterol and sex hormones.
Food GroupsProteinContain the elements carbon, hydrogen, oxygen and nitrogen
Proteins are essential part of our diet as they help to make muscle, hair and many other structural parts of the body
Proteins are made from sub-units called amino acids
There are about 20 different amino acids
Amino Acid StructureEach amino acid has an amine group (-NH2) and a carboxyl group (-COOH).
It is between these groups that amino acids link together to form chains.
What makes each of the 20 different amino acids different is the R group. This region is different, thus making each amino acid different.
Peptide BondsPeptide bonds are bonds formed between amino acids that result from dehydration synthesis.
Two amino acids bonded together are known as dipeptides (2 amino acids)
Three amino acids bonded together are known as tripeptides (3 amino acids), Polypeptides are a long chain of amino acids.
A complete protein contains one or more polypeptide chains.
The Function of ProteinsCarry out chemical reactions (enzymes)
Pump molecules into and out of cell
Make cells move.
Food Groups4. Vitamins
Do not give energy and they are needed in very small quantities.Vitamins are necessary for normal growth, work with enzymes, and regulate cellular activities.
Vitamins are complex molecules needed in small amounts and cannot be made in the body.
Some of these elements are called Essential elements because they are required by living things to perform essential functions.
Minerals are inorganic substances like Ca, Cl, Mg, K, P, Na, Fe, F, I.
What to do nowComplete task 3 in your booklet.
Make sure that you review your notes on this section and use them to help you answer the questions.
Check the answers with your teacher.
Amend any corrections.how molecules bond together and break apartThe process of forming large compounds (polymers) by joining together smaller compounds (monomers) is known as polymerization.
This process allows living things to form many molecules from the combination of just a few subunits
for example different proteins being formed from only 20 amino acids;
the different types of fats and carbohydrates that are naturally produced.
PolymerizationAll polymers are formed by the process of dehydration synthesis.
As the name suggests, this involves a loss of water.
The OH- group on one monomer combines with the H on another monomer.
Hydrolysis ReactionHydrolysis reactions break up a polymer into its monomers by the addition of water to a bond.
This reaction is the exact opposite reaction of dehydration synthesis since the OH group of water goes to one monomer and the other -H group goes the bond on the second monomer.
Food TestsStarchIodine solution changes from orange to blue/black if starch is present
Benedicts solution changes from blue to brick red/orange when heated to 80oC (tests for other simple sugars also e.g. Maltose)Clinistix also tests for the presence of glucose
Buriets reagent tests for the presence of protein by changing from blue to lilac only if protein is present
Leaves a translucent spot on filter paper if fat is present (think of chips on kitchen roll)
Testing Unknown Food GroupsAIM: to identify three unknown food group using different food tests.MethodIn groups of three, allocate each person to test a single powder.
Each person should collect: 3 Boiling tubesa Large beaker Test tube rackStirring rodSpatulaSafety goggles!!!
Using only your assigned powder, add one spatula full into each boiling tube and half fill the boiling tube with water.
Stir the contents with the glass rod to ensure that all the particles have dissolved as much as possible.
Test each tube with the three different testing solutions; iodine solution, Benedict's solution and biurets reagent.
Feed back to the rest of your group which solution gave a positive test with which particular testing solution.