Biology
Food
Objectives for food• State the Function of Food• Name three reasons for requiring food• Name six common chemical elements in food: C, H, N, O, P, S• Name five elements present in dissolved salts: Na, Mg, Cl, K, Ca• Name 3 trace elements required: Fe, Cu, Zn• Define Biomolecular Structures• State that simple biomolecular units are composed of a combination of elements in different ratios. Eg carbohydrates
Cx(H2O)y• Name the element components, biomolecular components and sources of: carbohydrates, fats & oil and proteins.• State that carbohydrates are composed of indivisible units and give examples of these. Eg. Monosaccharide –
glucose; Disaccharides – maltose; and Polysaccharides - starch/cellulose.• State that carbohydrates & lipids act as a primary source of energy.• State carbohydrates role as cellulose in cell walls• State that proteins act as enzymes and are made of amino acids• State proteins role as fibrous protein e.g. keratin or as myosin• State that hormones (protein) act as regulators of metabolic activity.• State the role of lipids as Phospholipids in cell membranes• State the requirements & use of any 2 minerals in plants.• State the requirements & use of any 2 minerals in animals.• Explain what a vitamin is.• Name one water-soluble vitamin. Name one water in-soluble (fat-soluble) vitamin.• List the sources of these vitamins• State that vitamin C & D are used for tissue growth, cell production and health maintenance.• Name disorders associated with deficiency of a water-soluble and a water in-soluble vitamin.• State 5 good reasons why water is important for organisms.• Define of the terms: Anabolic and Catabolic. • Give an example of each
Food is needed for:
1.Energy
2.Growth of new cells and
Repair of existing cells, tissues, organs, etc.
3. Provides materials needed for metabolism
What is Food made up of?
Food is made up of:
• Six chemical elementsC, H, O, N, P, S
• Salts of Na, Mg, Cl, K, Ca
• Three trace elements Fe, Cu, Zn
Chemical Elements and their Symbols
Calcium Ca Nitrogen N
Carbon C Oxygen O
Chlorine Cl Phosphorus P
Copper Cu Potassium K
Hydrogen H Sodium Na
Iron Fe Sulphur S
Magnesium Mg Zinc Zn
Test yourself…
• What are three functions of food?
• There are six elements present in food. Can you name them?
• What elements are present in salts found in our bodies?
• Name 3 trace elements.
By the end of today’s class you should be able to…
• Define Biomolecular Structures• State that simple biomolecular units are
composed of a combination of elements in different ratios. Eg carbohydrates Cx(H2O)y
• Name the element components, biomolecular components and sources of: carbohydrates,
• State that carbohydrates are composed of indivisible units and give examples of these.
• Do a test for the presence of reducing sugar in food.
Types of Food
Food is made up of six different food groups
Water Proteins
Lipids Carbohydrates
Vitamins Minerals
Humans need to consume a balanced diet which contains all of the nutrients in different amounts for the needs of the body
The main nutrients the body needs are:
carbohydrates for energy;
proteins for growth and repair;
fats to store energy;
vitamins and minerals to keep the body healthy.
Which food type does the body need the most of?
What is a balanced diet?
Nutrients in food
Learning check
What are the six different food components?
Water Proteins
Lipids Carbohydrates
Vitamins Minerals
Carbohydrates
Carbohydrates contain the elements
Carbon Hydrogen Oxygen
The general formula for a carbohydrate is
Cx(H2O)y
There are twice as many hydrogen molecules as oxygen molecules
A common carbohydrate
General formula = Cx(H2O)y
When x = y = 6
We get the formula C6H12O6
What is the name of this monosaccharide carbohydrate?
Glucose
Another common carbohydrate
General formula = Cx(H2O)y
When x = 12 and y = 11
We fet the formula C12H22O11
What is the name of this disaccharide carbohydrate?
Sucrose
Learning check
Name the three elements that make up carbohydrates
Carbon Hydrogen Oxygen
What is the general formula for a carbohydrate?
Cx(H2O)y
Carbohydrates which are made of long chains of identical small sugar molecules.
carbohydratemolecule one sugar
molecule
The long chains of carbohydrates are broken down into the smaller sugar molecules
These are used by the body to release energy
3 Types of Carbohydrate
Monosaccharides
Disaccharides
Polysaccharides
Monosaccharides
These are single sugar molecules
smallest carbohydrate unit
Examples: glucose, fructoseFound in: fruit
Disaccharides
These are
• two monosaccharide sugar units joined together – known as double sugar molecules
Examples: sucrose, lactose, maltose
Found in: table sugar, milk
Polysaccharides
These are
• Many sugar molecules joined together
Example: starch, cellulose
Found in: bread, pasta, cereals
Learning check
Name the three types of carbohydrate
• Monosaccharides
• Disaccharides
• Polysaccharides
To test for the presence of a reducing sugar
• Stand the two test tubes in boiling water for about 3 minutes.
• If sugar is present in a food it will turn Benedict's solution from blue to red
How can you test different foods for the presence of a simple sugar..
• It has to be a fair test
• There has to be a control experiment – a standard to compare the other experiments against.
Can you..
• Name the elements present in carbohydrates?• Know the ratio which describes carbohydrates?• Know the ratio of oxygen to hydrogen in
carbohydrates?• Know the three types of carbohydrates and give
examples of them?• Describe how to do a test for the presence of
reducing sugar in food.
To test for the presence of starch
• Iodine turns from yellow/brown to blue/black if starch is present
Learning check
Give examples and sources of:
Examples Sources
Monosaccharides
Disaccharides
Polysaccharides
Glucose
Fructosefruit
Sucrose
Lactose
Table sugar
Milk
Starch
Cellulose
Bread, Pasta,
Cereals
The‘Structural Role of Carbohydrates
The function/job of carbohydrates in making parts of living things
Cellulose (polysaccharide) found in plant cell walls
• Chitin (polysaccharide) found in insect exoskeletons
The Metabolic Role of Carbohydrates
the function of carbohydrates in the chemical reactions in cells
These are the primary sources of energy for metabolism – e.g.
• glucose (carbohydrate) is an immediate source of energy
• What a lipid is
• The structure of triglycerides and phospholipids
• How to test for fats
• Some sources of fat in our diet.
Lipids
Are:
• fats (solid at room temp.)
• oils (liquid at room temp.)
• steroids which include cholesterol and some of the sex hormones
• waxes which cover insect bodies and plant leaves.
Structure of Lipids
They are made up of the elements
carbon
hydrogen
oxygen
But dont have the same ratios as carbohydrates.
Lipids are made up of fatty acids and glycerols
What are fats?
fat molecule
glycerol
fatty acids
Triglyceride
It is made up of
3 fatty acid molecules
and
1 glycerol molecule
This is the smallest lipid
Phospholipids
If one fatty acid of a lipid molecule is replaced by a phosphate group then a phospholipid is formed
A special test for the presence of lipids
Lipids make brown paper go translucent
(light passes through it very easily)
• Sources of Lipids
• Fat – in and on meat
• Butter (80% fat)
• Cooking oils
Structural role of Lipids• Heat insulation – e.g. under the skin• Protection around body organs e.g. kidney,
heart• Phospholipids and lipoproteins are major
parts in cell membranes
Metabolic Role of Lipids
These are the primary sources of energy for metabolism – e.g.
• lipids are a long-term energy storage
• What a lipid is• The structure of triglycerides and
phospholipids• How to test for fats• Some sources of fat in our diet.• The role of fats in our diet
• What a protein is
• How to test for proteins
• Some sources of protein in our diet.
ProteinsProteins contain the elements
Carbon Hydrogen
Oxygen Nitrogen
Some may also contain sulphur, phosphorous or iron
What are proteins?
protein molecule
one amino acid
Proteins are made up of chains of small molecules called amino acids. There are over 20 different kinds of amino acid.
•Amino acids are joined together by peptide bonds•This results in the formation of polypeptide chains
Learning check
Proteins contain the elements
Carbon Hydrogen
Oxygen Nitrogen
Sometimes they contain
sulphur, phosphorous or iron
Proteins are made up of long chains of
amino acids
To test for the presence of protein in food:
Dissolve the food in some water.
Add 2cm3 of BIURET SOLUTION
If protein is present the solution will turn from a blue to a purple colour!
Sources of proteinMilk
Eggs
CheeseMeat
Nuts
Structural role of Proteins
• Proteins combine with phospholipids to from cell membranes
• Keratin is the structural protein in skin, hair and nails
• Myosin is the structural protein in muscle
Metabolic Role of Proteins
• Enzymes ( made of protein) control the rate of chemical reactions in cells.
• Chlorophyll is a protein that traps the sun’s energy during photosynthesis
Metabolism(all of the chemical reactions in a living thing)
Anabolic reactions Catabolic reactions
Small molecules are combined to make larger molecules. Energy is needed
Large molecules are broken down into smaller molecules. Energy is given out.
• Respiration
Glucose is burnt with oxygen in the body to make energy.
Carbon dioxide and water are also made.
• Photosynthesis
Carbon dioxide and water taken in by a plant. Light is needed. The plant makes glucose.
Metabolic Role of Hormones
Hormones are made of lipids or protein
Hormones regulate body functions
e.g. the hormone insulin controls the amount of glucose in the blood
Metabolic Role of Vitamins
Definition: Vitamins are organic substances needed in small amounts for the metabolism to function normally
Class activity
• Make up your own fact sheet on Vitamin C and Vitamin D
• Do these on PowerPoint slides. One for each Vitamin. Then save the file with your name and send it on.
You should have:• Sources, functions, is it water soluble, and one
deficiency disease. Use pictures if you can when finished!!!
Vitamin C
Solubility: water soluble
Function: for building connective tissue i.e. tissue used for attaching organs together
Source:Fruit
Scurvy – not enough vitamin C
Loose teeth, bleeding gums
Vitamin D – Fat soluble
Needed to absorb calcium from the blood which builds strong bones and teeth
Source:Milk, cheese, yogurt,sunlight
Rickets in children – not enough vitamin D
Softened bones or bow legs
Need to know• Describe what an anabolic and a catabolic reactions
are and give examples• State the metabolic role of fats• State the metabolic role of carbohydrates• State the metabolic role of proteins• State the metabolic role of hormones• Define vitamin• State the functions and sources of vitamin C & D• Name disorders associated with deficiency of a water
soluble and a fat-soluble vitamin
Water (H20)
1. It is a solvent for transporting substances in blood or in plants
2. It is where chemical reactions take place in cells
3. It is a reactant/product in chemical reactions4. Controls cell shape.• It is slow to heat up and cool down – kept at a
fairly steady temperature – helps to keep a constant rate of metabolism.
Minerals
Minerals are salts formed from the earth’s rocks.
The salts then dissolve in water and are absorbed by plants.
Animals then eat the plants.
Minerals and Plants
They use: • Calcium (Ca) to make cell walls• Magnesium (Mg) to make the pigment
chlorophyll
Minerals and Animals
They use
• Calcium (Ca) to make bones and teeth
• Iron (Fe) to make the pigment haemoglobin