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Biological macromolecules

A biological macromolecule is one that is found in living organisms. Biological macromolecules include molecules such as carbohydrates, proteins and nucleic acids. Lipids are also biological macromolecules. They are essential for all known forms of life to survive.

Biological macromolecule

A biological macromolecule is a polymer that occurs naturally in living organisms. These molecules are essential to the survival of life.


Carbohydrates include the sugars and their polymers. One key characteristic of the carbohydrates is that they contain only the elements carbon, hydrogen and oxygen. In the carbohydrate monomers, every carbon except one has a hydroxyl group attached to it, and the remaining carbon atom is double bonded to an oxygen atom to form a carbonyl group. One of the most important monomers in the carbohydrates is glucose ( [link] ). The glucose molecule can exist in an open-chain (acyclic) and ring (cyclic) form.

The open chain (a) and cyclic (b) structure of a glucose molecule

Glucose is produced during photosynthesis , which takes place in plants. During photosynthesis, sunlight (solar energy), water and carbon dioxide are involved in a chemical reaction that produces glucose and oxygen. This glucose is stored in various ways in the plant.

The photosynthesis reaction is as follows:

6 CO 2 + 6 H 2 O + sunlight C 6 H 12 O 6 + 6 O 2

Glucose is an important source of energy for both the plant itself, and also for the other animals and organisms that may feed on it. Glucose plays a critical role in cellular respiration , which is a chemical reaction that occurs in the cells of all living organisms. During this reaction, glucose and oxygen react to produce carbon dioxide, water and Adenosine Triphosphate (ATP). ATP is a molecule that cells use for energy so that the body's cells can function normally. The purpose of eating then, is to obtain glucose which the body can then convert into the ATP it needs to be able to survive.

The reaction for cellular respiration is as follows:

6 C 6 H 12 O 6 + 60 2 6 CO 2 + 6 H 2 O + ATP

We don't often eat glucose in its simple form. More often, we eat complex carbohydrates that our bodies have to break down into individual glucose molecules before they can be used in cellular respiration. These complex carbohydrates are polymers, which form through condensation polymerisation reactions ( [link] ). Starch and cellulose are two example of carbohydrates that are polymers composed of glucose monomers.

Two glucose monomers (a) undergo a condensation reaction to produce a section of a carbohydrate polymer (b). One molecule of water is produced for every two monomers that react.
  • Starch Starch is used by plants to store excess glucose, and consists of long chains of glucose monomers. Potatoes are made up almost entirely of starch. This is why potatoes are such a good source of energy. Animals are also able to store glucose, but in this case it is stored as a compound called glycogen , rather than as starch.
  • Cellulose Cellulose is also made up of chains of glucose molecules, but the bonding between the polymers is slightly different from that in starch. Cellulose is found in the cell walls of plants and is used by plants as a building material.

    Interesting fact

    It is very difficult for animals to digest the cellulose in plants that they may have been feeding on. However, fungi and some protozoa are able to break down cellulose. Many animals, including termites and cows, use these organisms to break cellulose down into glucose, which they can then use more easily.

Questions & Answers

What is impulse and how does it = to momentum
Robin Reply
what is physics
Jhon Reply
what is a catanation ?
Rithabele Reply
The ability of a few elements, most especially carbon, to yield chains and rings by forming covalent bonds with atoms of the same element.
different structural formula
Lucas Reply
different type of structural formula
primary,secondary and tertiary
how does the earth revolute
Kevin Reply
What is the momentum
Given Reply
The product of the object's mass and it's velocity
electric field def
what is secondary alcohol?
is when Carbon that is bonded with OH is also bonded to 2 carbons of the chain.
how is ester formed
Aubrey Reply
how is n ester formed
Alcohol reacts with a carboxylic acid
and the reaction is catalysed by sulphuric acid
An ester is form when an alcohol reacts a carboxylic acid and sulphuric acid is used as a catalyst which therefore eliminates water.
an athlete with a mass of 70kg runs at a velocity of 45km . determine the athlete's momentum
Lesedi Reply
Is that a velocity or something else
45km/h i guess
Change to m/s
45km/h = 12.5 m/s p=mv =70×12.5 =875 kg.m/s
what are the measures of the rates of reaction
Lesego Reply
Volume Concentration Temperature Pressure Surface Area
the principle of superposition of waves
Sfundo Reply
what is work
Kool Reply
is this a group chat
Nobuhle Reply
Hey can y'all define newton's 2nd law
If a resultant force act on an object...the object will accelerate in the direction of a resultant force,the acceleration of the object is directly proportional to the net force and inversely proportional to the mass of the object
how do you calculate tension force
use the formula Fnet=ma if there is tension connecting two objects
to calculate Tension, usually calculate acceleration first Draw separate free body diagrams for each body. Apply Fnet = ma to calculate Tension
Hi people
when a resultant force acting on an object the object will accelerate in the direction of a force at an acceleration directly proportional to the force and invesly proportional to the mass of the object.
Hey people
how does temperature affect the equilibrium position
Blessing Reply
an increased temperature increases the average kinetic energy thus in turn increases the number of effective collisions........
so...which reaction is favored between endothermic and exothermic .when temperature is increased..?
exothermic reaction because energy is realised to the surroundings as heat and light energy ....graphical so much energy is realised as reactants to form product and because temperature is high rate of reaction is fast which means there is a successful collision
an object will continue in a state of rest unless it is acted upon an unbalanced force
Junior Reply
Newton's Law 1
First Newton's Law
Newton's first law
newton first law
Newton's first law
when pressure is increased what happen to volume
Siphelo Reply
care to explain?
if pressure is applied to a pistol , the volume will decrease and particles will collide more frequently with the wall of a container .Each time they collide with the wall they exert a force on them .More collision means more force and the pressure will increase , that Boyle's Law
Because the volume has decreased , the particle will collide more frequently with the wall of a container and each time they collide with the wall of a container they exert a force on them.More collision means more force so the pressure will increase , that Boyle's Law

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Source:  OpenStax, Siyavula textbooks: grade 12 physical science. OpenStax CNX. Aug 03, 2011 Download for free at http://cnx.org/content/col11244/1.2
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