Biology Food. Objectives for food State the Function of Food Name three reasons for requiring food...

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