Download biomolecules

Carbohydrates
Proteins
Water
School of
Lipids
Biological
Sciences
Edited by Janet A Renshaw
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EXIT
Introduction
Carbohydrates
Proteins
Lipids
Water
Questions and Answers
The three main organic molecules are carbohydrates, proteins and
lipids.
These molecules are very important in living organisms, they can be
used as building blocks for cells and also for energy
They are all based on the chemical elements carbon, hydrogen and
oxygen.
Proteins can also contain the elements nitrogen, sulphur and
phosphorous
Carbohydrates
Proteins
Lipids
The structures of these molecules are
of key importance to their functions
Water is a very important molecule,
it makes up between 45- 75% of the
body mass of most organisms and
without it life on earth would not have
evolved.
carbon
hydrogen
oxygen
cellulose
sugars
starches
glycogen
Carbohydrate molecules
consist of 3 elements
Carbohydrates have roles in all forms of
life and make up most of the organic
matter on earth.
Monosaccharides are the basic monomer units of which
carbohydrates are composed.
The most common monosaccharide is glucose
Glucose
Glucose can exist in two forms, the  form and the  form.
The two forms of glucose have the same properties.
The only difference between them is the position of one of the OH
groups.
H2COH
O
H
OH
OH
H in the  form the OH is here
H
HO
H
OH
H
in the  form the OH is here
OH
This has a great effect on the property of molecules made when
glucose molecules link together.
Disaccharides
When 2 monosaccharides join together they form a larger disaccharide
molecule.
Two monosaccharides can become linked by a condensation reaction.
share
oxygen
Removal of H20
Monosaccharide
Disaccharide
The linkage is via a glycosidic bond where they share an oxygen
molecule and a water molecule is eliminated.
Condensation Reaction between 2 glucose monomers
Glycosidic Bond
H2O
Examples of Disaccharides
Maltose
Formed from 2 glucose molecules, formed in germinating
seeds from the breakdown of starch, providing energy
Sucrose
Formed from 1 glucose and 1 fructose molecule
and is the form in which carbohydrates are
transported in the phloem in plants
Lactose
Formed from 1 glucose and 1 galactose
molecule, it is an energy source found in the
milk of nearly all mammals
Polysaccharides
Carbohydrates which are made from many linked monosaccharide
monomers form long chain-like molecules
called polymers.
glycogen
starch
polysaccharides
- made from glucose
monomers
cellulose
Starch
Found in two forms, which are both made up of  glucose
One form is amylose which consists of
un-branched chains of  glucose,this
coils into a helical compact structure
The other form is amylopectin which
consists of branched chains of 
glucose, this forms a branched
compact brush.
Starch is the main storage carbohydrate in plants.
Amylase
(enzyme)
Breaks down
Starch
maltose
glucose
sources of
energy
H 2O
Hydrolysis reaction:- A chemical process whereby a compound is cleaved into two
or more simpler compounds along with the uptake of water
Glycogen
A polymer of  glucose monomers.
It is the main storage carbohydrate in
mammals found in liver and muscle cells.
It is more branched in structure than amylopectin.
The more branched the molecule, the quicker it can be made and broken.
Cellulose
Is a polymer of  glucose
monomers.
It is an important component
of plant cell walls.
It does not spiral as with
 glucose
 glucose consists of chains that are straight and long, they lie parallel to
each other bound together by hydrogen bonds.
Proteins have many roles in living organisms and are extremely important.
There are many different types of proteins with different functions, for
example,
Enzymes are proteins which speed up the rate of biological reactions
Biological
Enzyme
molecule
Biological molecule
Biological molecule
Biological molecule
with enzymewith enzyme with enzyme
Antibodies are protective proteins and as part of the immune system they
help fight disease
DISEASE
ANTIBODIES
Haemoglobin is a protein that transports oxygen in the blood.
Proteins are polymers made up of monomers called amino acids.
There are 20 different amino acids, amino acids can join in any order to
produce an infinite number of different proteins.
The only thing that changes
between different amino acids is
the R group
The R group can
contain hydrogen
and/or carbon and
sometimes
oxygen, sulphur
and nitrogen.
This is the basic structure of an amino acid.
A condensation reaction joins two amino acids together forming a dipeptide.
The bond formed between them is called a peptide bond
Peptide
Bond
H2O
A chain of many amino acids linked by peptide bonds is called a
polypeptide. A protein can consist of one or more polypeptides.
Proteins can get broken down by hydrolysis reactions into polypeptides,
dipeptides and amino acids.
Protein Structure
There are four different levels of protein structure.
The primary structure :- this is the sequence of amino acids in the
polypeptide formed from many condensation reactions
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
H2O
The secondary structure :- where the polypeptide chains can fold
into stable 3D regular shapes. One secondary structure is the -helix
where the chains fold into a helical shape. Another structure is the 
strand
-helix structure
The tertiary structure :- this is when further folding occurs and this
is the overall shape of the polypeptide chain.
This 3D shape is maintained by a series of weak interactions which
are mostly hydrogen bonds.
This is the tertiary structure of the alpha chain of the protein, haemoglobin.
The quaternary structure :- polypeptides can associate with other
polypeptides and they way in which they bind together to form the
molecule is the quaternary structure.
Quaternary Structure taken by means of rasmol (www.dkfz-heidelberg.de)
Protein Subgroups
Proteins fit into two subgroups, globular proteins and fibrous proteins.
Globular proteins, for example
enzymes, form roughly a spherical
Substrate
shape and most of them are soluble
in water.
The function of a globular protein is
determined by its shape, so its shape
is vital.
Molecular representation of an enzyme
The usual function for this subgroup is a chemical function.
Fibrous proteins do not form a spherical structure they form long chains
and they are insoluble.
Fibrous proteins have structural roles, like giving strength or elasticity to
certain tissues.
Muscle Fibre (www.uoguelph.ca)
Proteins can become denatured causing their shape to change therefore
affecting their function.
A protein can vibrate due to an increase in temperature, which can
cause it to become denatured, causing the weak bonds holding the
tertiary or quaternary structure together to break.
Example shows an enzyme becoming denatured and losing hold on a substrate
waxes
fats
carbon
hydrogen
oxygen
oils
Lipid molecules consist of 3
elements
Lipids are insoluble.
They are important dietary
constituents as they are full of
energy, contain certain vitamins
and have a major role in cell
membranes.
Unlike carbohydrates and proteins, lipids do not form polymers.
Two major types of lipids are triglycerides and phospholipids.
Triglycerides
This group of lipids are the
fats and oils.
They are formed from a glycerol molecule linked by ester bonds to three
fatty acids.
Ester bond:-This is formed from a condensation reaction where the carboxyl group of a fatty
acid and an OH group from the glycerol join and water is lost so they share an oxygen atom.
The formula for fatty acids is R-COOH, where the R, which is the
hydrocarbon chain can be saturated or unsaturated.
Triglyceride Molecule
ester bond
3 saturated fatty acids
Glycerol
3H2O
Phospholipids
Fatty acid
glycerol
Fatty acid
phosphate
The phosphate group is soluble in water, it is water loving, which is termed
hydrophillic.
The fatty acids are insoluble in water, they repel water, which is known as
hydrophobic.
fatty acids
Due to these properties
glycerol
phospholipids form cell
membranes when in water
water
glycerol
glycerol
phosphates
Simplified structure of a
phospholipid molecule used in
diagrams of membranes
H2O
H2O
H2O
Phospholipid
Bilayer formed in
water
H2O
H2O
H2O
H2O
Water is an inorganic substance.
It has many essential properties, it has these properties because of the
way in which the molecules in water bond together.
The biological importance of water is dependent on its
physical properties.
Some Important Properties of Water
Solvent Properties
Water is a polar molecule and it’s polarity makes it an excellent solvent
for other polar molecules.
There is a whole range of other polar molecules, which
include small organic units such as glucose and amino
acids, also ions like calcium,potassium and sodium.
Non-polar substances do not dissolve in water.
Specific Heat Capacity
Water has a high specific heat capacity,
which means it has temperature stability.
It takes a large amount of heat (energy)
to raise the temperature of water
measurably. Due to this water containing
organisms are stable thermally.
Latent Heat of Evaporation
Due to the high specific heat capacity, water resists
evaporation into gas better than other liquids do.
This is significant to humans and other animals as we
rely on the evaporation of water from our body surface as
a cooling device.
This section is to test your knowledge on what has been
covered in this package.
You will need paper and a pen to help you answer some of
the questions
To get the answer click on the answer button
Now go to the next page to start testing your knowledge.
CARBOHYDRATES
Question 1
What is the name of this
carbohydrate monomer ?
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Question 2
Draw a diagram to show how two of these monomers form a
disaccharide and label the bond
Click here to see diagram
Question 3
What is the name of the disaccharide formed ?
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Question 4
What are the two forms of the polysaccharide starch ?
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Question 5
What are the differences between the two forms ?
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PROTEINS
Question 6
What three elements can be found in proteins but not in
carbohydrates and lipids ?
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Question 7
There are two subgroups of proteins, globular proteins and
fibrous proteins.
Which subgroup a) is soluble in water ?
b) has structural roles ?
c) form long chains ?
d) is spherical in shape ?
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Question 8
What type of reaction occurs to join amino acids together?
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Question 9
What is the name of the bond formed between amino acids
in a protein ?
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LIPIDS
Question 10
What are the two major types of lipids?
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Question 11
How is an ester bond formed in a triglyceride?
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Question 12
The phosphate group of a phospholipid is soluble in water,
what is the term used for this type of molecule
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Question 13
Fatty acids are insoluble in water, what is the term used for
this type of molecule?
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WATER
Question 14
Name two important properties of water.
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Question 15
Water is a polar molecule do Non-polar substances
dissolve in water?
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Q1
Answer
This carbohydrate monomer
is glucose
Q2
Glycosidic Bond
Answer
H 20
Q3
Answer
The disaccharide formed
is maltose
Q4
Answer
The two forms of starch are
amylose and amylopectin
Q5
Answer
Amylose consists of unbranched
chains of  glucose and has a helical
compact structure
Amylopectin consists of branched
chains of  glucose and has a branched
compact structure
Q6
Answer
Nitrogen, sulphur
and phosphorous
Q7
Answer
a) soluble in water ?
Globular proteins
b) structural roles ?
Fibrous proteins
c) form long chains ?
Fibrous proteins
d) spherical in shape ?
Globular proteins
Q8
Answer
A condensation reaction
Q9
Answer
A peptide bond
Q10
Answer
Triglycerides and phospholipids
Q11
Answer
An Ester bond is formed from a
condensation reaction where the carboxyl
group of a fatty acid and an OH group
from the glycerol join and water is lost so
they share an oxygen atom.
Q12
Answer
The phosphate is termed
as a hydrophillic molecule
Q13
Answer
Fatty acids are
hydrophobic molecules
Q14
Answer
Two from any of these
- solvent properties
- high specific heat capacity
- high latent heat of evaporation
Q15
Answer
No