The Chemicals of Life

All things (matter), both living and nonliving things are made up of chemicals. **It was once thought that living things were different

Organisms are made of organ systems

organ systems organs

organs tissues

tissues groups of cells

cells chemicals

Chemical Elements of Living Things

•Over 98% of living things are made up of 6 main chemicals..

…C, H, O, N, P, S which join together in different ratios to form all the molecules of

living things.

Defn: The molecules in organisms are known as biochemicals (or biomolecules).

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The other 2% of is made up of..

• The salts of Cl, Na, K, Mg, and Ca

• And trace elements Fe, Zn, Mn and Cu

• Trace element are only required in tiny amounts

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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

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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 (Tiny amount)Fe, Cu, Zn

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FoodFood is needed for:

1. Energy

2. To provide the raw materials which organisms use build new cells and repair of existing cells, organs, body parts etc.

3. To control the chemical reactions in cells i.e. to control their metabolism

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Food Components• Elements combine in different ratios to form

molecules of food• There are 4 major types of molecules of food

(Organic molecules)– Carbohydrates– Lipids– Proteins– Vitamins

• And water and minerals

*** Organic compounds are complex compounds of Carbon, everything else is inorganic e.g. H2O

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Relative Amounts of the Food Components in the Human Body

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What does the ‘Structural Role of Biomolecules’ mean? ..means

involvement of carbohydrates, fats, proteins in making various parts of living

things

What does the ‘Metabolic Role of Biomolecules’ mean? ..means involvement of carbohydrates, fats, proteins in the chemical reactions in cells making various substances for living things

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Carbohydrates

Carbohydrates contain the elements

Carbon Hydrogen Oxygen

The general formula for a carbohydrate is

Cx(H2O)y

x is approx = yThere are twice as many hydrogen molecules

as oxygen molecules

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Carbohydrates are split into three main groups

1.Single sugar unit: monosaccharide (The basic

sugar unit )

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2.

Disaccharide: 2 sugar units

3.

Polysaccharide: Many sugar units joined together

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MonosaccharidesThese are

single sugar molecules• There are the building blocks of other important

carbohydrates

Monosaccharides are:simple sugarssoluble in watersweet to taste

Examples: glucose, fructoseFound in: fruit

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Glucose

•This is the most important monosaccharide sugar

•C6H12O6

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DisaccharidesThese are

• two monosaccharide sugar units joined together –(double sugar)

• soluble in water

• sweet to taste

• May be reducing or non-reducing sugarsExamples: sucrose, lactose, maltose

Found in: table sugar, milk

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Reducing Sugars•All monosaccharides and some disaccharides are reducing sugars..i.e. capable of reducing benedicts solution (benedicts solution changes from blue to orange/red)

Benedicts solution is used to determine if a food is a reducing sugar

Benedicts solution is a turquoise liquidcontaining copper ions (Cu 2+).

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Reducing Sugar

• Is a simple carbohydrate that turns benedicts soln from blue to red/orange.

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PolysaccharidesThese are• Long chains of monosaccharide sugar molecules joined

together• Not soluble in water (so large) • Do not taste sweet • They are used for energy storage (glycogen

and starch)• They are also structural, cellulose (fibre)

Example: Glycogen, starch, celluloseFound in: Bread, pasta, cereals

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Learning check

Give examples and sources of:

Examples Sources

Monosaccharides

Disaccharides

Polysaccharides

Glucose

FructoseFruit

Sucrose

Lactose

Table sugar

Milk

Starch

Cellulose

Bread, Pasta,

Cereals

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Metabolic Role of Carbohydate

Are the primary sources of energy

• glucose (carbohydrate) is an immediate source of energy

• Animals Catabolic

• Plants Anabolic

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Metabolism Carbs..

• Respiration – energy is released when glucose is broken down – catabolism

Happens in humans, animalsEqn: …• Catabolic Reaction: Big molecules are broken down

into simpler molecules

• Photosynthesis – glucose molecules are made from carbon dioxide and water using the sun’s energy – anabolism

Eqn: …• Anabolic Reaction: Smaller (simple) molecules are

built up into bigger (complex) molecules

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Structural role of Carbohydrate

Cell Structure

• Cellulose (polysaccharide) found in plant cell walls

• Chitin (polysaccharide) found in fungal cell walls.

• LEARN ONE

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Lipids

Lipids are a diverse group of substances which include

• 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.

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Structure of Lipids

They are made up of the elements carbon hydrogen oxygen

But not have the same ratios as carbohydrates.

They are made up of two main types of molecules

Fatty acids and Glycerol

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Types of Lipid

Two of the main types of lipids are

Triglycerides

Phospholipids

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Triglyceride

It is made up of

3 fatty acid molecules

and

1 glycerol molecule

This is the smallest lipid

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Phospholipids

If one fatty acid of a lipid molecule is replaced by a phosphate group then a phospholipid is formed

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Sources of Lipids

• Fat – in and on meat

• Butter (80% fat)

• Cooking oils

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Structural role of Lipids

Cell Structure

• Heat insulation – e.g. under the skin

• Waterproof the body

• Protection around body organs e.g. kidney, heart

• Phospholipids are major components in cell membranes

• Myelin helps transmit messages in nerve cells

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Metabolic Role of and Lipids

• Long term source of Energy

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Proteins

Proteins contain the elements Carbon HydrogenOxygen Nitrogen

Some may also contain sulphur, phosphorous or iron

Proteins are found in lean meat, fish, pulses i.e. beans, soya and eggs

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Structure of Proteins

Proteins are made up of long chains of

amino acids =sub units (alphabet)

There are 20 common and several rare amino acids found in proteins

Amino acids are joined together by

peptide bonds

This results in the formation of polypeptide chains (diagram)

Shapes of chain (diagram)

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Examples of proteins

• Enzymes (folded), hormones (folded), pigments (twisted), myosin and protein in muscles.

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Structural role of Proteins

Cell structure

• They combine with phospholipids to from cell membranes

• Keratin is the structural protein in skin, hair and nails

• Myosin is the structural protein in muscle

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Metabolic Role of Proteins

All enzymes are proteins and have a folded shape. Enzymes control the chemical reactions in cells. e.g.. amylase

Hormones are protein that regulate body functions

e.g. hormone insulin controls amount of glucose in the bloodstream

In plants..

Chlorophyll is a protein that traps the sun’s energy during photosynthesis

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Metabolic Role of Hormones (Protein)

Hormones regulate body functions

e.g. the hormone insulin controls the amount of glucose in the blood

Oestrogen, progesterone and testosterone are other hormones controlling human sexual development

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Vitamins

• Needed in small amounts, cannot be produced in the body

• Must be supplied continuously and in sufficient quantities

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Vitamins

Vitamins A, B, C, D, E and K

Vitamins can be water soluble or fat soluble

Vitamins B and C are water soluble

Vitamins A, D, E and K are fat soluble

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Sources of Vitamins

Vitamin Source

A Green leafy vegetables, Eggs, Cheese, Carrots

B Lean Meat, Cereals, Nuts

C Citrus Fruits, Green vegetables, Turnips

D Milk and Milk products, Sunlight

E Vegetable oils, fish, nuts

K Green leafy vegetables

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Metabolic Role of Vitamins

Definition:

Vitamins are essential organic catalysts of metabolism

They are needed in small amounts for the correct functioning of the body

They cannot be made by the body

They must be in the diet

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Vitamin C

Chemical name: ascorbic acid

Solubility: water soluble

Function:

• for building connective tissue i.e. tissue used for attaching organs together or for protection, e.g. skin, blood vessels, bone, tendons, cartilage, ligaments

Source: Citrus Fruits, Green vegetables

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Vitamin D

Chemical name: calciferol

Solubility: fat soluble

Function: needed to absorb calcium from food. Calcium needed for healthy teeth and bone formation and their maintenance

Deficiency = Rickets, weak bones

Source: Dairy products, cod liver oil, egg yolk, made by skin in sunlight

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Vitamin deficiency disorders

Lack of Vitamin C causes

scurvy

Symptoms: soft bleeding gums, bad and loose teeth

Lack of Vitamin D causes

rickets in young children and osteomalacia in adults

Symptoms: Weak bones and bow-legs

Minerals

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Minerals

What are minerals?• They are salts formed from the earth’s

rocks. • These mineral salts then dissolve in water

and are absorbed by plants.

• NB Minerals are required by organisms in very small amounts.

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Minerals and Plants

Plants absorb minerals through their roots.They use: • Calcium (Ca) to make cell walls• Magnesium (Mg) to make the pigment

chlorophyll • Nitrates (N) to make proteins • Phosphates (P) to make DNA

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Minerals and AnimalsAnimals get their minerals in the food they eat.

They use • Calcium (Ca) to make bones and teeth..

osteoporosis • Iron (Fe) to make the pigment haemoglobin (which

helps red blood cell carry oxygen).. Anemia • Sodium (Na) for the regulation of the osmotic

balance (water content) of cells and the blood.

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Water

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Water

Cells and body fluids are made up of 70% to 95% Water

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Physical properties of water• water is slow to heat up and cool down –

helps to keep our bodies at constant temp.

• Water good absorber of energy. It absorbs a lot of heat as it evaporates, so sweating and transpiration cools animals and plants. This helps to keep temperature steady.

• Participates in the movement of material in and out of cells.

• Water controls cell shape.

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Chemical properties of water

• It is a universal solvent for transporting substances in blood (e.g. food and oxygen) or in plants (e.g. minerals)

• The medium for metabolism i.e. chemical reactions take place in it.

• It is a reactant/product photosynthesis and respiration