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LESSON 1-3:
Biomacromolecules
LEARNING OUTCOMES
By the end of these lessons, you should be able to:
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Describe the structure and function of lipids.
Describe the structure and function of the nucleic acids;
DNA and RNA.
Describe the structure and functional diversity of
proteins.
Describe the synthesis of the biomacromolecules:
polysaccharides, nucleic acids and proteins.
Water – what do you already
know?
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1
Each water molecule consists of a single oxygen
atom
2
3
covalently
bonded to two hydrogen
atoms.
4
The main component of organisms.
5
It provides the environment needed for metabolic
6
reactions
to take place.
7
A dipolar
molecule – one side is positively charged
and the other is negatively charged.
Water molecules are attracted to each other and
8
form hydrogen
bonds easily (but these also break
easily).
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This allows it to have a low viscosity
and act as a
10
solvent.
Carbohydrates
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1
All carbohydrates contain the elements carbon,
2
3
hydrogen
and oxygen
in varying ratios.
The basic unit of a carbohydrate is a sugar
4
5
molecule – a monosaccharide. Glucose
and
6
fructose
are examples. They have the formula
C6H12O6.
7
A disaccharide
contains two monosaccharides. E.g.
sucrose and lactose. They have the formula
C12H22O11.
A polysaccharide
is a complex carbohydrate and
8
contains many sugar units. E.g. starch, cellulose,
glycogen.
Lipids
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Fats, oils and waxes.
Hydrophobic – no attraction to water; they are
insoluble.
Contain C, H and O, but little water.
Contain a lot more energy than any other
compound found in plants and animals.
Fats are made of fatty acids and glycerol.
A common fat is a tryglyceride – a single glycerol
with three fatty acids attached.
NOW TEST
EACH
OTHER!
Phospholipids

Phospholipids are made
from glycerol, two fatty
acids, and (in place of
the third fatty acid) a
phosphate group.
Phosphate ‘Head’ is
HYDROPHILLIC
Fatty Acid Tails are
HYDROPHOBIC
Phospholipids

Phospholipids will spread out on water into a
single layer (monolayer) because of their
hydrophilic heads and hydrophobic ends.
Hydrophobic tails
(lipid)
Hydrophilic heads
(phosphate)
Water

In the bilayer of the membrane, the non-polar
tails face inwards and the polar heads face
outwards.
Nucleic Acids
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DNA and RNA are examples of molecules in the
group called nucleic acids.
DNA is a polymer of nucleotides.
Each nucleotide is made of a sugar (deoxyribose),
a phosphate and a nitrogenous base.
Nucleotides
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DNA is an
example of a
group of
molecules called
nucleic acids.
It is made of
monomers called
mononucleotides.
A
phosphate
group
A pentose
(5 carbon)
sugar called
deoxyribose
An organic
nitrogenous
base, either
Thymine,
Adenine,
Guanine or
Cytosine
A NUCLEOTIDE
Structure of DNA
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The sugar and the
phosphate join to
form ‘a sugar
phosphate
backbone’.
The bases are
complementary to
each other and are
held together by
hydrogen bonds.
A polynucleotide
chain is formed.
RNA: Ribonucleic acid
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Also a polymer of nucleotides.
Exists as a single chain (rather than double like
DNA).
The sugar is ribose instead of deoxyribose in DNA.
The bases are Adenine, Guanine, Cytosine and Uracil
(instead of Thymine in DNA).
There are three kinds of RNA, all of which have very
specific jobs:
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Messenger RNA (mRNA) – involved in protein synthesis.
Transfer RNA (tRNA) – also involved in protein synthesis.
Ribosomal RNA (rRNA) – part of the ribosomes.
Now complete Page 14
“Organic Molecules”
in your Student
Workbook.
Proteins
Use the plasticine
to make what you
think a protein
molecule might
look like.
What are Proteins?
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Proteins are organic molecules made of carbon,
hydrogen, oxygen and nitrogen. They sometimes also
contain sulphur and may form complexes with other
molecules.
Proteins are made of small units called amino acids.
These link together by peptide bonds to form chains
of polypeptides.
Musical Proteins
Types of Proteins
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Antibodies bind to specific foreign particles, such as
viruses and bacteria, to help protect the body.
Enzymes carry out almost all of the thousands of
chemical reactions that take place in cells. They also
assist with the formation of new molecules by
reading the genetic information stored in DNA.
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Messenger proteins, such as some types of
hormones, transmit signals to coordinate biological
processes between different cells, tissues, and
organs.
Structural proteins provide structure and support
for cells. On a larger scale, they also allow the body
to move.
Transport proteins bind and carry atoms and small
molecules within cells and throughout the body.
Amino Acid Structure

There are twenty different amino acids, but they
all have the general formula NH2.RCH.COOH
The ‘R’ group differs between
amino acids. It is always
bonded to a C-H
They all
have an
amino group
They all have
a carboxyl
group
(basic)
(acidic)
Identify the amino, carboxyl and ‘R’ groups on
the following amino acids:
Peptide Bonds:
How do amino acids join together?
Two amino acids
link together to
form a dipeptide.
When more amino
acids are linked
together, a
polypeptide is
formed
This reaction produces water? What type of
reaction is it?
Try and
draw out 2
amino acids
linked by a
peptide
bond.
animation
Condensation Reaction
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At least two amino acids join together (with a
polypeptide
peptide bond) to form a larger _____________.
hydrogen
A peptide bond forms between the _________
carboxylic
acid
and __________
_____(hydroxyl)
groups.
Water is released.
_______
Hydrolysis Reaction
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peptide
Breaks the ________bond
holding the amino
acids together.
Water is used to split the bond.
_______
Try and draw the basic
structure of an amino acid
(from memory!) labelling
the different groups.
Amino Acid Structure
The ‘R’ group differs between
amino acids. It is always
bonded to a C-H
They all
have an
amino group
They all have
a carboxyl
group
(basic)
(acidic)
Protein Structure
Find out:
a) what the primary, secondary, tertiary and quaternary structures
of proteins are.
b) For each of the above, what type of bonding is involved in creating
and maintaining the structures.
LEVEL OF
STRUCTURE
DESCRIPTION
BONDING
INVOLVED
Primary
Specific sequence of
amino acids forming a
polypeptide chain
Peptide
bonding
Secondary
Shape the polypeptide
folds into; an alpha
helix or beta pleated
sheet (non-specific)
Hydrogen
bonding
Tertiary
Caused by interactions
between R groups which
leads to bending and
twisting of the
polypeptide helix into a
compact shape
Disulphide (between
sulphurs on R groups)
Hydrogen and ionic bonds
Hydrophillic and
hydrophobic interactions
Quaternary
Combinations of a
number of different
polypeptide chains and
associated non-protein
groups
As above
Structures
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amino
Primary structure – the long chain of _______
acids
______.
oiled and t______
wisted chain
Secondary structure – a c____
of amino acids.
folded
Tertiary structure – when the protein is _______
up tightly. The 3D shape of the tertiary structure is
chemical ______and
bonds
held together by _________
intermolecular forces.
The 3D shape is important in situations like active
sites in enzymes and use in cell membranes.
SECONDARY STRUCTURE
Alpha Helix
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An alpha helix is
formed when
hydrogen bonds
form between the
amino and
carboxylic acid
groups all along
the chain.
This makes the
chain coil up (like a
DNA helix).
Beta-pleated Sheets
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Parallel folded
sections.
They are held in
place by hydrogen
bonds between
the amino and
carboxylic acid
groups along the
parallel chains.
TERTIARY STRUCTURE
Quaternary Structure
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A protein that is made up
of more than one folded
protein unit joined
together have quaternary
structure.
Haemoglobin
____________
is an
example – it has four
joined polypeptide chains.
QUATERNARY STRUCTURE
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The 3D shape depends on the primary structure
because the amino acid side groups respond
differently to water, altering the shape.
Hydrophobic – water repelling. A hydrophobic
side group will turn inwards, away from the water,
towards the centre of the protein molecule.
Hydrophilic – water attracting. A hydrophilic side
group will turn outwards, forming hydrogen bonds
with the surrounding water molecules.
KEY WORDS Anagrams
1. ROTINPE
2. RAYMIRP
3. NODYCRASE
4. RABCOXLYIC
5. LAAPH LEIXH
6. TITYREAR
7. TEBA-DEELPAT
8. GOBLINMEAOH
9. NETRAQUYAR
10. DITYEEPPOLP
11. NOGHYEDR NOBD
12. SORDYYISHL
13. NOOTDENCANSI
14. TIEDEPP NOBD
15. NIMAO CAID
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
Protein
Primary
Secondary
Carboxylic
Alpha helix
Tertiary
Beta-pleated
Haemoglobin
Quaternary
Polypeptide
Hydrogen bond
Hydrolysis
Condensation
Peptide bond
Amino acid
Card sort

Now complete the Proteins Key Terms card sort
Proteins
Carboxylic acid
group
Amino group
Ions
R group
Condensation
Peptide bond
1. Amino acids join together so that the
hydrogen and hydroxyl groups meet.
Water is removed in this reaction.
2. The amino acid group consisting of 2
hydrogen atoms and a nitrogen atom.
3. This type of bond is formed between
the two amino acids.
4. Polymers made up of long chains of 20
different amino acids.
5. The amino acid group consisting of
COOH.
6. This amino acid group varies from a
single hydrogen atom, to a side chain
several carbon atoms long, or containing a
benzene ring.
7. Amino acids are soluble in water so
they form these.
Proteins
Carboxylic acid
group
Amino group
Ions
R group
Condensation
Peptide bond
4. Polymers made up of long chains of 20
different amino acids.
5. The amino acid group consisting of
COOH.
2. The amino acid group consisting of 2
hydrogen atoms and a nitrogen atom.
7. Amino acids are soluble in water so
they form these.
6. This amino acid group varies from a
single hydrogen atom, to a side chain
several carbon atoms long, or containing a
benzene ring.
1. Amino acids join together so that the
hydrogen and hydroxyl groups meet.
Water is removed in this reaction.
3. This type of bond is formed between
the two amino acids.
Dipeptide
1. This structure is formed when the
protein folds up tightly.
Hydrolysis
2. This structure is formed when proteins
are made up of more than one folded
protein unit joined together. E.g.
haemoglobin.
Primary structure
3. This reaction involves water being used
to split the bond between amino acids.
Secondary
structure
Tertiary
4. The name of the product formed
between two amino acids.
5. This structure is a long chain of amino
structure acids.
Quaternary
structure
6. This structure is formed from
interactions between the different side
groups of the amino acids, causing the long
chain to coil and twist.
Dipeptide
4. The name of the product formed
between two amino acids.
Hydrolysis
3. This reaction involves water being used
to split the bond between amino acids.
Primary structure
5. This structure is a long chain of amino
acids.
6. This structure is formed from
interactions between the different side
groups of the amino acids, causing the long
chain to coil and twist.
Secondary
structure
Tertiary structure
Quaternary
structure
1. This structure is formed when the
protein folds up tightly.
2. This structure is formed when proteins
are made up of more than one folded
protein unit joined together. E.g.
haemoglobin.