Download The Chemistry of Living Things

Biochemistry
The Chemistry of
Living Things
Introduction
• Biochemistry is the chemistry of the living
world.
• Plants, animals, and single-celled organisms
all use the same basic chemical compounds
to live in the biosphere.
• Biochemistry is about the smallest parts of
those organisms, the molecules.
• It's also about the cycles that happen to make
those compounds.
• It could be the constant process of
photosynthesis in plants or the building of
complex proteins in the cells of your body.
Introduction
• Living organisms require a supply of
available energy.
• They also require an adequate
supply of water.
• Water is unique.
Introduction
• Biochemical molecules are large.
• They are built from smaller, more
readily available molecules.
• Their synthesis requires energy.
• Energy must be obtained from plant
photosynthesis.
• Living organisms are highly
organized.
Introduction
• Most biopolymers essential for life
belong to four main groups.
– Proteins
– Polysaccharides(carbohydrates)
– Lipids
– Nucleic acids
Proteins
•
•
•
•
•
Polymers of amino acids
Hydrophilic colloids
Do not pass through membranes
Least soluble at the isoelectric point
Can be denatured
Proteins
• Four types of structures within a
protein
– Primary
– Secondary
– Tertiary
– Quaternary
Proteins
• Importance
– Enzymatic catalysts
– Oxygen carriers
– Structural materials
– Hormone regulation
Proteins
• Tests
– biuret – violet – indicates peptides with
at least 2 linkages
– zanthoproteic – yellow – indicates
amino acids containing a benzene ring
– Millon – red – indicates the presence of
tyrosine in the protein
– ninhydrin – blue – indicates the
presence of at least one free amino and
one free carboxy group in the protein
Proteins
• Amino acids are the building blocks of
proteins.
– There are over twenty amino acids.
– Ten are synthesized in the body.
– The others are considered “essential
amino acids” and must be ingested.
Proteins
• Amino acids have a
carboxylic acid part
and a basic part called
an amine. One amino
acid links to another to
form a protein
because of the
attraction of opposite
The amino acid is
charges. This linkage
doubly charged at pH =
is a peptide bond,
7. It is called a
which is an amide
zwitterion.
formation.
Biochemical Compounds
• Carbohydrates give you energy. They
may be simple or complex.
– Starch is a carbohydrate which is
composed of units of the simple sugar
glucose.
– Glucose is a carbohydrate and is the
simplest sugar.
Carbohydrates
• Carbohydrate is a fancy way of saying
"sugar." Sugars end with the suffix -ose.
• They contain carbon, hydrogen and oxygen.
• The hydrogen and oxygen are always in a
ratio of 2 to 1.
• Sugars provide living things with energy and
act as substances used for structure. Some
examples of structures might be the shell of
a crab or the stem of a plant.
• Scientists also use the word saccharide to
describe sugars. If there is only one sugar
molecule, it is called a monosaccharide. If
there are two, it is a disaccharide. If there
are three, it is a trisaccharide.
Carbohydrates
• A sugar called glucose is the most important
monosaccharide on Earth. It is also the simplest
sugar. Glucose is used in cellular respiration and
created by photosynthesis. When you think of table
sugar, like the kind in candy, it is actually a
disaccharide. The sugar on your dinner table is
made of glucose and another monosaccharide
called fructose. Table sugar is sucrose.
• When several carbohydrates combine, it is called a
POLYsaccharide ("poly" means many). Hundreds of
sugars can be combined in a chain. These chains
are also known as starches which are found in foods
such as pasta and potatoes. They are very good
sources of energy for your body.
Structures of sugars
glucose
fructose
sucrose
DNA
• DNA stands for Deoxyribonucleic Acid. It is
special because it holds the code for every
cell in your body. Every cell in your body
uses DNA for an instruction manual. DNA is
a long spiral chain of nucleotides.
• So you get all of those nucleotides in two
long chains that twist around each other.
That twisting shape is called a double-helix.
The spiral ladder has the ability to wind and
unwind so that the nucleic acid chain can
duplicate itself. That duplication process
happens every time a cell divides.
DNA
• DNA is the instruction manual for an
organism. Even though all organisms use
the same five base pairs to build DNA, it
is the order that makes us who we are.
Our DNA has cytosine paired with
guanine and adenine paired with
thymine. Every organism on Earth has a
different number and order of base pairs.
That order determines your physiology.