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 position
Biomolecules = carbohydrates, fats, proteins
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 Carbohydrate
Cell 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
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• Myelin helps transmit messages in nerve cells
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
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 vitamin10
What does the ‘Metabolic Role of
Biomolecules’ mean?
Metabolic = metabolism = all the chemical
reactions in a cell
Role = function/job or position/involvement
Biomolecules = carbohydrates, fats, proteins
Metabolic Role of Biomolecules = the
function / job / involvement of
carbohydrates, fats, proteins in the chemical
reactions in cells making various substances
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for living things
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 metabolism
Glucose & Lipids
2. Name two important metabolic pathways
and state whether they are anabolic or
catabolic
Photosynthesis – anabolic
Respiration – catabolic
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Metabolic Role of Hormones
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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Learning check
What is the metabolic role of protein?
Enzymes are proteins.
Enzymes control the processes of photosynthesis
and respiration
Chlorophyll is a protein that traps the sun’s
energy during photosynthesis
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Metabolic Role of Vitamins
Definition: can you remember it
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
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 D
- Ascorbic acid Calciferol
- Water soluble Fat soluble
- Connective Absorb
tissue
calcium
formation
- One source
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One source
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
Symptoms: softening of the bones of the spinal
column and bowlegs
osteomalacia in adults
Symptoms: the bones lose calcium and become
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weak – common in vegans
END
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