1.3.6 + 7 Structural & Metabolic Roles of Biomolecules

Need to know

• Structural Role of Biomolecules • State carbohydrates role as cellulose in cell

walls • State proteins role as fibrous protein e.g.

keratin or as myosin • State the role of lipids as Phospholipids in

cell membranes

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What does the ‘Structural Role of Biomolecules’ mean?

Structure = the way in which something is built e.g. timber structure, steel structure

Role = function/job or positionBiomolecules = carbohydrates, fats, proteinsStructural Role of Biomolecules = the

function/job of carbohydrates, fats, proteins in making various parts of living things

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Structural role of CarbohydrateCell Structure • Cellulose found in plant cell

walls• Cotton fibres represent the

purest natural form of cellulose, containing more than 90% of this fibre

• Chitin found in fungal cell walls and insect exoskeletons

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Structural role of Proteins

Cell structure• Proteins are fibrous (threadlike) in nature. • They combine with phospholipids to from

cell membranes (lipoproteins)• Keratin is the structural protein in skin, hair

and nails• Myosin is the structural protein in muscle

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Learning check

What does the ‘Structural Role of Biomolecules’ mean?

Structural Role of Biomolecules = the function / job of carbohydrates, fats, proteins in making various parts of living things

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Structural role of Lipids

Cell Structure• Important storage molecules in organisms• Heat insulation – e.g. under the skin• Waterproof the body• Protection around body organs e.g. kidney,

heart• Phospholipids and lipoproteins are major

components in cell membranes• Myelin helps transmit messages in nerve cells 7

Learning check

What is the structural role of proteins?• Proteins are fibrous (threadlike) in nature. • They combine with phospholipids to from

cell membranes (lipoproteins)• Keratin is the structural protein in skin, hair

and nails• Myosin is the structural protein in muscle

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1.3.7 Metabolic Role of Biomolecules

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Need to know• State that carbohydrates & lipids act as a

primary source of energy • State that proteins act as enzymes and are

made of amino acids • State that hormones (protein) act as

regulators of metabolic activity • 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 fat-soluble vitamin

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What does the ‘Metabolic Role of Biomolecules’ mean?

Metabolic = metabolism = all the chemical reactions in a cell

Role = function/job or position/involvementBiomolecules = carbohydrates, fats, proteinsMetabolic Role of Biomolecules = the

function / job / involvement of carbohydrates, fats, proteins in the chemical reactions in cells making various substances for living things

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Metabolic Role of Carbohydrates and Lipids

These are the primary sources of energy for metabolism – e.g.

• glucose (carbohydrate) is an immediate source of energy

• lipids are a long-term energy storage

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Metabolic Role of Carbohydrates and Lipids

They are important in the following processes:

Respiration – energy is released when glucose is broken down to form carbon dioxide and water – catabolism

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

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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. enzymes control the processes of photosynthesis and respiration

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

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Learning check

1. Give examples of the primary sources of energy for metabolismGlucose & Lipids

2. Name two important metabolic pathways and state whether they are anabolic or catabolicPhotosynthesis – anabolic Respiration – catabolic

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Metabolic Role of Hormones

Hormones regulate body functionse.g. the hormone insulin controls the amount

of glucose in the bloodOestrogen, progesterone and testosterone are

other hormones controlling human sexual development

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Learning check

What is the metabolic role of protein?Enzymes are proteins. Enzymes control the processes of photosynthesis

and respirationChlorophyll is a protein that traps the sun’s

energy during photosynthesis

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Metabolic Role of Vitamins

Definition: can you remember itVitamins are essential organic catalysts of

metabolismThey are needed in small amounts for the

correct functioning of the body They cannot be made by the bodyThey must be in the diet

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Vitamin C

Chemical name: ascorbic acid Solubility: water solubleFunction: 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 solubleFunction: needed to absorb calcium from

food. Calcium needed for healthy teeth and bone formation and their maintenance

Source: Dairy products, fish liver oils, egg yolk, made by skin in sunlight

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Learning check

For the vitamins C & D give the following

The chemical name - Solubility - Function -

Source in the diet -

Vit C Vit DAscorbic acidWater solubleConnective tissue formation

One source

CalciferolFat solubleAbsorb calcium

One source

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Vitamin deficiency disordersLack of Vitamin C causes

scurvy Symptoms: soft bleeding gums, bad and loose

teethLack of Vitamin D causes

rickets in young childrenSymptoms: softening of the bones of the spinal

column and bowlegs osteomalacia in adults

Symptoms: the bones lose calcium and become weak – common in vegans

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END