Download 1.3.2 Chemical Elements

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).
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 elements
C, H, O, N, P, S
• Salts of
Na, Mg, Cl, K, Ca
• Three trace elements (Tiny amount)
Fe, Cu, Zn
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Food
Food 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. H O
2
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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 = y
There 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 together12
Monosaccharides
These are
single sugar molecules
• There are the building blocks of other important
carbohydrates
Monosaccharides are:
simple sugars
soluble in water
sweet to taste
Examples:
Found in:
glucose, fructose
fruit
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Glucose
• This is the most important
monosaccharide sugar
• C6H12O6
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Disaccharides
These are
• two monosaccharide sugar units joined
together –(double sugar)
• soluble in water
• sweet to taste
• May be reducing or
non-reducing sugars
Examples:
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 liquid
containing 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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Polysaccharides
These 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:
Found in:
Glycogen, starch, cellulose
Bread, pasta, cereals
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Learning check
Give examples and sources of:
Examples
Monosaccharides
Glucose
Sources
Fruit
Fructose
Disaccharides
Polysaccharides
Sucrose
Table sugar
Lactose
Milk
Starch
Bread, Pasta,
Cellulose
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, animals
Eqn: …
• 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
This is the smallest lipid
It is made up of
3 fatty acid molecules
and
1 glycerol molecule
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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
Hydrogen
Oxygen
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
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Minerals
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 Animals
Animals 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
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blood.
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
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