THE MOLECULES OF
This Presentation is a “Mash up” of Five
Presentations From Different Aouthers
The Simplest Hydrocarbon
• Methane = Carbon + Hydrogen
• A cell is mostly water but the rest consists mainly of
carbon based molecules
• Compounds that contain carbon are called organic
• Carbon has the ability to form the large, complex diverse,
molecules necessary for life functions
• Why are carbon atoms so versatile as molecular
Variations in Carbon Skeletons
• Simplest organic compounds are hydrocarbons
• Hydrocarbons consist of carbon and hydrogen
• Each C atom forms 4 bonds; each H atom forms 1 bond
• Main molecules in the gasoline we burn in our cars
• Hydrocarbons of fat molecules provide energy for our
• Each type of organic molecule has a unique 3-dimensional
shape that defines its function in an organism
- the molecules of your body recognize one another based on their shapes
• The unique properties of an organic compound depend not
only on its carbon skeleton but also on the atoms attached to
- these atoms are called functional groups
• Functional groups behave consistently from one organic
molecule to another
4 Important Functional Groups
• Many biological molecules have 2 or more functional groups
• How do cells make large molecules out of smaller organic molecules
Size of Molecules
– Molecules used as subunits to
build larger molecules (polymers)
– Larger molecules that are chains of monomers
– May be split and used for energy
• On a molecular scale, many of life’s molecules are
- biologists call them macromolecules (macro = ‘big’) such as
DNA, carbohydrates, proteins
• Most macromolecules are polymers
- polymers are made by stringing together many smaller molecules
- cells link monomers together through a dehydration reaction
(removes a molecule of water)
• Organisms break down macromolecules (digestion)
- cells do this by a process called hydrolysis (hydro = ‘water’ lyse =
‘break’; to break with water)
Synthesis – a polymer grows in length when an incoming monomer
and the monomer at the end of the existing chain contribute to
the formation of a water molecule, the monomers then replace
their lost covalent bonds with a bond to each other
Breaking a polymer chain – hydrolysis reverses the process by
breaking down the polymer with the addition of water molecules, which
break the bonds between monomers
INPORTANT INORGANIC COMPOUNDS
• and minerals
• Most important biochemical:
• A major component of cells (70-95% of cell mass)
• Provides environment for those organisms that live in water (3/4 of
• Interesting features:
• Exist in liquid form at normal Earth temperatures
• Provides a medium for molecules and ions to mix in and hence a
medium in which life could evolve
• Hydrogen bonds
• More energy needed to break bonds and convert water from liquid
to a gas
Water as a solvent
• Excellent solvent for ions and polar molecules
because water molecules are attracted to them,
collect around and separate them (dissolve)
• Non-polar molecules are pushed together
Water as a transport medium
• Lymphatic system
• Excretory system
• Digestive system
• Vascular tissues of plants
• Hydrogen bonding restricts movement of water
molecules – large amount of energy needed to raise
temperature of water
Oceans and lakes are more stable habitats
Minimise internal (body) changes in temperature
Evaporation transfers a large amount of energy (cooling)
Water will not freeze easily
Density and freezing properties
• Ice is less dense than liquid form
• Acts as insulates
• Changes in density of water with temperature
cause currents which help to maintain the
circulation of nutrients in the oceans
High surface tension and
• Water molecules tend to stick to each other
• Water movement through the vascular tissue in plants
• Important property in cells
• High surface tension (pond skater)
a. elements extracted from the soil; consumed in our diet
b. main minerals are calcium, phosphorus, potassium, sodium,
chloride, magnesium, zinc, copper
c. are crucial for synthesis and maintenance of:
Calcium, sodium, phosphorus
Calcium, sodium, potassium,
Text Reading: Chapter 2 (p35-40),
Chapter 3 (p53-62, 70-75)
You are What You Eat:
Macromolecules of Life & Their Relationship to Diet and Nutrition
• Name the four major classes of biological
macromolecules. Describe the composition and function
of each. Provide examples of each.
• Distinguish between steroids and anabolic steroids,
and explain how the use of anabolic steroids can be
dangerous to a person’s health.
• Apply this information to interpreting a food label and
categorize the food as either healthful or junk food.
• There are four categories of macromolecules in cells:
• Major source of energy
• Carbohydrates include
• Simple sugar molecules (fructose,
glucose, sucrose) – enter system
• Complex carbohydrates contain
branched chains of simple sugars
(starch, glycogen) – digested slowly
• Monosaccharides are simple sugars.
• Examples: glucose, fructose
• Glucose found in sports drinks
• Fructose found in fruit, corn syrup
• Honey contains both glucose and fructose
• Monosaccharides are the main fuel
that cells use for cellular work.
• A disaccharide is a double sugar.
• Constructed from two monosaccharides.
– Examples: maltose, lactose,
• Maltose is used to make
beer, malted milk shakes,
& malted milk ball
• Lactose is another type of disaccharide.
• Found in milk products.
• lactose intolerance: inability to digest lactose
• These people don’t make enough lactase, the enzyme
the breaks down lactose.
• Most common disaccharide is sucrose (table sugar)
• Consists of a glucose linked to a fructose.
• Extracted from sugar cane and roots of sugar beets.
– USA is one of the world’s leading markets for
• Average American consumes ~64 kg
(>140 lbs!!!) of sugar/year
• Complex carbohydrates are called polysaccharides.
• Long chains of sugar units.
• Polymers of monosaccharides.
– Examples: starch, glycogen, cellulose
– Fiber is an indigestible complex carbohydrate
• Proteins perform most of the tasks the body needs to function.
The Monomers: Amino Acids
• Proteins are polymers of amino acids.
• All proteins are constructed from a common set of 20 kinds of amino acids.
– Each amino acid consists of
• A central carbon atom bonded to four
• Side group is variable among all 20.
• The side group gives each amino acid
Proteins as Polymers
• Cells link amino acids together to form proteins.
• The resulting bond between them is called a peptide bond.
• String of amino acids sometimes called polypeptide.
– Your body has tens of thousands of different kinds of
– Different combinations of amino acids give proteins
– Most proteins are at least 100 amino acids in length.
– Many different sequences possible with 20 amino acids.
– Analogy: 26 letters can make many different words
• Primary structure
• Sequence of amino acids in a protein
– A slight change in the primary structure of a
protein affects its ability to function.
• The substitution of one amino acid in
hemoglobin causes sickle-cell disease.
• Proteins have four levels of structure.
Sequence of amino acids
Local folding patterns
Examples: alpha helix, beta pleated
Overall three-dimensional shape
Overall shape when two or more
polypeptides bind each other
What Determines Protein Structure?
• A protein’s amino acid sequence dictates its structure.
• A protein’s shape is also sensitive to the surrounding environment.
• Unfavorable temperature and pH changes can
cause a protein to unravel and lose its shape.
• This is called denaturation.
Proteins as Nutrients
• Our bodies can make several amino acids.
• Essential amino acids: amino acids our bodies cannot make, must
obtain from food.
• Complete proteins: contain all essential amino acids.
• Animal proteins (meat) more likely to be complete than plant proteins.
Plant proteins can be combined to make complete.
(a) Lentils are high in lysine and low in valine.
(b) Rice is low in lysine and high in valine.
The side groups of
lysine and valine
• Lipids are hydrophobic (water-fearing).
• They do not mix with water.
• Oil and vinegar salad dressing separates into layers.
• Dietary fat consists largely of the molecule triglyceride.
• Triglyceride is a combination of glycerol and three fatty acids.
• Fats perform essential functions in the human body:
• Energy storage
Saturated vs Unsaturated Fats
• Unsaturated fatty acids
• Have less than the maximum number of hydrogens bonded to the carbons (ie
they have double bonds). Greatest called polyunsaturated.
• Saturated fatty acids
• Have the maximum number of hydrogens bonded to the carbons.
• If all three fatty acids in a fat are saturated, it is a saturated fat.
If any are unsaturated, it is an unsaturated fat.
Saturated vs Unsaturated Fats (cont’d)
• Most animal fats have a high proportion of saturated fatty acids, which can
• Examples: butter, lard
• Usually solid at room temperature
• Contribute to atherosclerosis and cardiovascular disease
• Most plant and fish oils tend to be low in saturated fatty acids.
• Example: corn oil, canola oil, cod liver oil
• Usually liquid at room temperature
Hydrogenation and Trans Fats
• Hydrogenation: Conversion
of unsaturated fats to
saturated fats by adding
• Production of margarine and
Fats created by hydrogenation are unhealthy because trans fats are produced.
– Trans fats: type of unsaturated fat (shortening, margarine)
– Found in many fast food products, although now banned
– No nutritional value
– Increase risk of cardiovascular disease
– Even more unhealthy than saturated fats.
• Another type of lipid.
• Different from fats in structure and function.
• Carbon skeleton is bent to form four fused rings.
• Cholesterol is the “base steroid”
from which your body produces
• Example: sex hormones
• Synthetic anabolic steroids are controversial.
• They are variants of testosterone.
– Some athletes use anabolic steroids to build up their muscles quickly.
• However, these substances can pose serious health risks.
• Mood swings
• Liver damage
• High cholesterol
• Shrunken testicles, reduced sex drive, infertility
LIST OF REFERENCES
Slides copied from the following
sources on SlideShare:
• 2- Chemistry of Life I by tchubb on Sep 08, 2011.
08/03/2014. Slide no:18
• Molecules of life introby eruder on Sep 25, 2011. http
08/03/2014. Slide no: 1-13
• 1 molecules of life by Justina, H on Sep 10, 2011.
08/03/2014. Slide: 9, 10, and 22-29.
• Lecture 4 molecules of life by holmeskm on May 27, 2011.
Accessed: 08/03/2014. Slide no: 1, and 9-32
• Water by Jaya Kumar, Lecturer at KDU College Sdn Bhd on Mar 08, 2012.
http://www.slideshare.net/jayak1/water-11916115?qid=77969b92-9647-492c95e1-b85acafadc30&v=default&b=&from_search=8. Accessed: 08/03/2014