Essential Biology 03.2: Carbohydrates, Lipids and Proteins
1.
Define organic molecule.
Organic molecules are molecules that come from living things. Most have carbon with some
exceptions.
2. What are three carbon-containing groups or molecules that are not organic?
Hydrogen carbonate, carbon dioxide and carbon monoxide.
There are many organic molecules in living things. The same (or very similar) molecules are used in many
different living things for the same purpose.
3. Saccharides are sugars and carbohydrates. Sugars (monosaccharides and disaccharides) are used
to build up carbohydrates (polysaccharides).
a. What happens to the structure of monosaccharides when they are placed in water?
In water monosaccharides go into a ring structure.
b. Draw the simplified (ring) structures of glucose and ribose. Number the carbon atoms
correctly. Which sugar is a pentose? Which is a hexose? How are they named this way?
Hexose
It is named a hexose because it has the shape of a hexagon
C6H2OH
C5
O
H
OH
Pentose
It is named pentose because it has the
Shape of a pentagon.
O
C5H2OH
OH
H
C4
C1
OH
H
C3
C2
HO
H
C4
C1
H
OH
C3
H
H
H
C2
OH
H
OH
c. Draw a generalized hexose and pentose sugar on chemsketch and render it in 3D.
Stick the 3D ball-and-stick model below: (http://www.acdlabs.com/download/)
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Essential Biology 03.2: Carbohydrates, Lipids and Proteins
Condensation of monosaccharides is a polymerization reaction. It can continue to create a longer chain
of saccharides (a carbohydrate). These building reactions are anabolic metabolism.
d. What is a polymer?
It is a structure made up of repeated simple monomers.
e. Use the diagram below to show how two monosaccharides are converted into a
disaccharide through condensation. Complete a word equation. What else is needed to
make the reaction occur?
Condensation
Water is removed
Condensation
Glucose +glucose
f.
maltose(disaccharide) + water
Condensation of sugars produces a glycosidic bond.
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Essential Biology 03.2: Carbohydrates, Lipids and Proteins
Distinguish between 1-6 glycosidic and 1-4 glycosidic bonds in terms of their effect on
the shape of the polysaccharide produced. You might want to draw them to help see.
g. Complete the table below:
-saccharides
examples
Glucose
Mono-
Di-
Plant or animal?
Function/ uses
animal
Quickly absorbed and used in
respiration
Galactose
Fructose
plant
Sucrose
plant
Lactose
animal
Maltose
Glycogen
Poly-
animal
Starch
plant
Cellulose
Soluble but unreactive, can be
transported around plant in Phloem.
Quickly digested into
monosaccharides.
Dimer of glucose, broken down from
starch.
Insoluble storage of glucose in the
liver produced using insulin.
Insoluble plant energy storage
molecule.
Structural unit in plant cell walls
Anabolic reactions are those which build organic molecules (such as condensation of saccharides).
Catabolic reactions break them down (e.g. digestion).
Hydrolysis is the catabolic reaction which breaks down organic molecules.
h. What is the function of hydrolase?
Hydrolase is an enzyme that catalyzes the hydrolysis of a chemical bond.
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Essential Biology 03.2: Carbohydrates, Lipids and Proteins
i.
Outline this reaction using an example of a dimer of two pentose sugars. Explain the
relevance of the name of the reaction.
Remember:
Condensation makes bonds: Hydrolysis breaks bonds.
4. Fatty acids and glycerol are used in the production of triglycerides.
a. In the space below, draw the generalized structures of fatty acids and glycerol.
Glycerol
H
H
H
H
C
C
C
O
OH
OH
OH
H
C
Cn
HO
H
C
H
H
H
H
O
C
(CH2)n
(CH3)
HO
b. Distinguish between saturated and unsaturated fatty acids. (Nutrition revision).
Bonding
Shape of chain (draw)
State at room temp
Saturated
Ester bond
The animal fats are solid
at room temperature.
Unsaturated
Ester bond
The plant oils are liquid
at room temperature.
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Essential Biology 03.2: Carbohydrates, Lipids and Proteins
c. Draw a generalized fatty acid or glycerol molecule on chemsketch and render it in 3D.
Stick the 3D ball-and-stick model below: (http://www.acdlabs.com/download/)
d. What is the relevance of the following properties of lipids?
Energy storage*
More efficient than carbohydrates, oils in plants and fish, fats in animals.
Thermal insulation*
Subcutaneous fat insulates against heat loss.
Protection
Fat acts as a shock absorber.
Buoyancy
It floats because it is less dense than water.
Membranes
Phospholipid bilayer, cholesterol
Hormones
*Essential exam examples
e. Write a word equation for the formation of one triglyceride from fatty acids and
glycerol.
HOCH2CH(OH)CH2OH + RCO2H + R'CO2H + R''CO2H → RCO2CH2CH(O2CR')CR'' + H2O(water)
f.
Outline how condensation reactions produce one triglyceride molecule (including the
name of the bonds produced):
A glycerol molecule bonds with carboxylic acid. Water is then pulled out to cause them to bond to make
triglyceride.
g. Explain why condensation of fatty acids and glycerol to produce a triglyceride is not an
example of polymerization.
Polymerization has a dimer which involves two monomers which are identical. However,
fatty acids and glycerol are not identical, and is therefore not a polymerization.
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Essential Biology 03.2: Carbohydrates, Lipids and Proteins
h.
Compare lipids and carbohydrates in terms of energy storage:
carbohydrates
lipids
Stored as…?
Glucose/fructose
Oils in plants and fish or as fat in
animals.
Long/short term storage?
Short term
Long term
Ease of digestion/ release of
energy?
Quick and easy. It also requires
less oxygen to release the
energy.
Requires more oxygen to release the
stored energy.
Energy per gram?
17KJ g-1
38 KJ g-1
Solubility in water?
(and consequence)
Some vitamins are dissolved.
Use of oxygen in
metabolism?
(and consequence)
Less oxygen use for metabolic
processes
More oxygen use for metabolic
processes
5. Proteins are the tertiary (or quaternary) structure of polypeptides, polymers of amino acids.
a. In the space below, draw the structure of a general amino acid. Include (and label) the
amine group, carboxyl group and ‘R’ group.
H
N
H
b. How many different amino acids are there? What is different about each one?
There are only 20 different amino acids found in proteins.
c. What is a polypeptide?
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Essential Biology 03.2: Carbohydrates, Lipids and Proteins
A peptide contains 10 to more than a 100 amino acids.
d. How does the diversity of amino acids lead to infinite possibilities of polypeptides?
Because the amino acids can be arranged in any order.
i.
Could be any length
Polypeptide length:
ii.
Amino acid sequence:
Can be in any order or combination.
e. Use a diagram to show condensation and hydrolysis of peptides.
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com
Essential Biology 03.2: Carbohydrates, Lipids and Proteins
Stephen Taylor
Bandung International School
http://sciencevideos.wordpress.com