Transcript The Molecules of Life

THE MOLECULES OF LIFE
Biology Fall 2014
IMPORTANCE OF CARBON

Carbon is the main ingredient of organic
molecules.
 a.k.a
biomolecules
 Composed
of a backbone of carbon atoms bonded to
one another
CARBON SKELETONS & FUNCTIONAL GROUPS
Carbon-based molecules are classified as
organic molecules.
 Inorganic molecules do not contain carbon
skeletons
 Hydrocarbons- molecules that contain only
carbon and hydrogen

CARBON SKELETONS & FUNCTIONAL GROUPS
Functional group- group of atoms with a
molecule that interacts in predictable ways with
other molecules.
 Hydrophilic- molecules that attract water
molecules

MONOMERS & POLYMERS


Monomers- small molecular unit that is the building
block of a larger molecule
Polymers- long chain of small molecular units called
monomers


All are built from fewer than 50 kinds of monomers.
Life’s large molecules are classified into 4 main
categories: carbohydrates, lipids, proteins, and nucleic
acids.
BUILDING & BREAKING POLYMERS
Dehydration reaction- a chemical reaction in
which a water molecule is removed
 Hydrolysis reaction- a chemical reaction in
which a water molecule is added

CARBOHYDRATES
Provide fuel & building material.
 Include starches & sugars.
 Used as an energy source.
 Carbohydrate- an organic compound made up
of sugar molecules

SUGARS

Sugars contain the elements carbon, hydrogen,
and oxygen in a ratio of 1 carbon : 2 hydrogen :
1 oxygen
MONOSACCHARIDES
Simple sugars contain just one sugar unit
 Ex: glucose, fructose, and galactose
 Sugar molecules, primarily glucose, are the
main fuel supply for cellular work.
 Cells use the carbon skeletons of these as raw
material for manufacturing other kinds of
organic molecules.

DISACCHARIDES
Cells construct these using a hydrolysis
reaction from two monosaccharides
 Most common is sucrose

POLYSACCHARIDES
Long polymer chains made up of simple sugars
monomers
 Starch- a polysaccharide found in plant cells
composed entirely of glucose monomers
 Glycogen-polysaccharide in animal cells that
consists of many glucose monomers

POLYSACCHARIDES…
Cellulose- polysaccharide consisting of glucose
monomers that reinforces plant-cell walls
 Most animals including people cannot digest
cellulose
 Almost all carbohydrates are hydrophilic

 Water
loving
 Most can be dissolved in water
LIPIDS
A class of water avoiding molecules.
 Hydrophobic- water fearing
 Hydrophobia is important to the function of
lipids

FATS
Consists of a three-carbon backbone called
glycerol attached to three fatty acids.
 Solid at room temperature
 Cushion your organs
 Store energy for later use
 Provide your body with insulation

FATS CONT…
Saturated fat- fat in which all three fatty acid
chains contain the maximum number of
hydrogen atoms
 Unsaturated fat- fat that contains less than the
maximum number of hydrogen atoms in one or
more of its fatty acid chains

STEROIDS
Steroid- a lipid molecule in which the carbon
skeleton forms four fused rings
 Classified as lipids because they are
hydrophobic, but are very different in function
and structure.
 Cholesterol- steroid molecule present in the
plasma membranes of animal cells.

ENZYMES
Proteins that speed up specific reactions in
cells.
 Activation energy- minimum amount of energy
required to trigger a chemical reaction
 Catalysts- compounds that speed up chemical
reactions.

HOW ENZYMES WORK
Substrate- specific reactant acted on by an
enzyme
 Active site- region of an enzyme into which a
particular substrate fits

HOW ENZYMES WORK