MOLECULES OF LIFE
More than 96%
of all atoms in
the human
body are
hydrogen,
oxygen, carbon
and nitrogen.
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INORGANIC COMPOUNDS
Composed of elements other than carbon
Most abundant is water (H2O)
called "universal solvent" since it dissolves so many
things.
Carbon dioxide (CO2) is the exception to the "no
carbon" rule it is found in many chemical
compounds of living things.
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ORGANIC COMPOUNDS
ALWAYS CONTAIN CARBON
They usually also contain hydrogen or hydrogen and oxygen.
They may also contain nitrogen phosphorus or sulfur
In 1828 Friedrich Wohler, a German chemist, was the first to
demonstrate that organic compounds could be made from
inorganic compounds
Prior it had been believed that only living organisms could make
organic compounds.
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CARBON
•A carbon atom forms four covalent bonds
–It can join with other carbon atoms to make chains or rings
Structural
formula
Ball-and-stick
model
Space-filling
model
Methane
The 4 single bonds of carbon point to the corners of a tetrahedron.
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CARBON
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POLYMERS
•Most of the large molecules in living
things are macromolecules called
polymers
–Polymers are long chains of smaller
molecular units called monomers
–A huge number of different polymers
can be made from a small number of
monomers
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DEHYDRATION SYNTHESIS
The opposite of Hydrolysis
Cells link monomers to form polymers by dehydration
synthesis
Short polymer
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Unlinked monomer
Removal of
water molecule
Bryan James Longer
Cowley polymer
M.A.
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HYDROLYSIS
The opposite of
dehydration synthesis
During digestion
water is added to a
carbohydrate allowing
the food to be broken
down into smaller
molecules that can
enter cells
Once inside the cell
dehydration synthesis
may again take place
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Addition of
water molecule
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CARBOHYDRATES
•First group of organic compounds
•Chemical formula for all is a multiple of C6H12O6
•Sugars and Starches
•from small sugars to large polysaccharides
•Energy source
•Produced during photosynthesis
•Used during cellular respiration
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MONOSACCHARIDES
(Carbohydrates)
Simple sugars, contain only one sugar
molecule (e.g. Glucose, fructose and
galactose).
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MONOSACCHARIDES
(Carbohydrates)
The monosaccharides
glucose and fructose
are isomers
They contain the same
atoms but in different
arrangements
Glucose
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Fructose
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MONOSACCHARIDES
(Carbohydrates)
Many monosaccharides form rings, as shown
here for glucose
Abbreviated
structure
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DISACCHARIDES
(Carbohydrates)
Double sugars, are two monosaccharides. (e.g.
sucrose, maltose)
Disaccharides are formed by DEHYDRATION
SYNTHESIS where small molecules bond to form
large molecules
When two monosaccharides bond the result is one
disaccharide and one molecule of water.
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DISACCHARIDES
(Carbohydrates)
Monosaccharides can join to form disaccharides, such as sucrose (table
sugar) and maltose (brewing sugar)
Glucose
Glucose
Sucrose
Maltose
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POLYSACCHARIDES
(Carbohydrates)
Polysaccharides are long polymers of monomers
Formed by dehydration synthesis of many
monosaccharides
Examples include cellulose, starch (plant sugar
storage) and Glycogen (animal sugar storage in liver
and muscles).
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POLYSACCHARIDES
(Carbohydrates)
These large molecules are polymers of hundreds
or thousands of monosaccharides linked by
dehydration synthesis
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PROTEINS AND AMINO
ACIDS
Second group of organic compounds
Comprised mainly of carbon, hydrogen, oxygen and
nitrogen
Only small amounts of other elements (e.g.sulfur,
phosphorus iron and zinc)
Greek Proteios meaning "of first importance”
Proteins are used for cell growth, maintaince and
repair.
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PROTEINS
Proteins are made of molecules of up to 20 different kinds of
amino acids strung together like beads
Hundreds of amino acids may bond to form a protein
When more than two amino acids bond a POLYPEPTIDE is
formed
When many Polypeptides bond they form a PROTEIN
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ENZYMES
Special proteins that cells produce enabling
cellular chemical reactions.
Enzymes act as CATALYSTS or chemicals that
speed up reactions without changing themselves.
Enzymes are specific, that is, they each have their
own special job.
For example, the enzyme that hydrolyzes
maltose is maltase
The names of enzymes usually end in-ase.
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ENZYMES
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PROTEINS
A protein’s primary structure is its amino acid sequence
Secondary structure is polypeptide coiling or folding produced
by hydrogen bonding
Primary
structure
Amino acid
Secondary
structure
Hydrogen
bond
Pleated sheet
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Alpha helix
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PROTEINS
Tertiary structure is the overall shape of a polypeptide
Quaternary structure is the relationship among multiple polypeptides of
a protein
Tertiary
structure
Polypeptide
(single subunit
of transthyretin)
Quaternary
structure
Transthyretin, with four
identical polypeptide subunits
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AMINO ACIDS
A molecule of an amino acid is made up of three groups of
atoms
Amino Group (NH2)
Carboxyl Group (COOH)
R Group consist of a hydrogen atom or a group of hydrogen
and carbon atoms. Different amino acids have different R
groups.
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AMINO ACIDS
an amino group
a carboxyl group
an R group, which distinguishes each of the 20
different amino acids
Amino
group
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Carboxyl (acid)
group
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AMINO ACIDS
Each amino acid has specific properties
Leucine (Leu)
HYDROPHOBIC
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Serine (Ser)
Cysteine (Cys)
HYDROPHILIC
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AMINO ACIDS
Like carbohydrates, amino acids bond by the
process of dehydration synthesis
When the amino group of one amino acid bonds
with the carboxyl group of another a DIPEPTIDE
is formed
This PEPTIDE BOND joins a carbon atom with a
nitrogen atom.
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AMINO ACIDS
Cells link amino acids together by dehydration synthesis
The bonds between amino acid monomers are called peptide
bonds
Carboxyl
group
Amino
group
Amino acid
Amino acid
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Dehydration
synthesis
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PEPTIDE
BOND
Dipeptide
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LIPIDS
Third group of organic compounds
Compounds that are oily, greasy, waxy or fatty
Lipids form part of the cell membrane
In animals lipids provide protection, insulation and
energy
A Lipid forms by the dehydration synthesis of 3
molecules of fatty acid and 1 molecule of glycerol
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LIPIDS
These compounds are composed largely
of carbon and hydrogen
They are not true polymers
They are grouped together because they do not mix
with water
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LIPIDS
Fats are lipids whose main function is energy storage
They are also called triglycerides
A triglyceride molecule consists of one glycerol molecule
linked to three fatty acids
Fatty acid
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LIPIDS
The fatty acids of unsaturated fats contain double bonds
These prevent them from solidifying at room temperature
Saturated fats lack double bonds
They are solid at room temperature
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LIPIDS
Phospholipids are a major component of
cell membranes
Waxes form waterproof coatings
Steroids
are often
hormones
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FATTY ACIDS & GLYCEROL
Fatty acids are long chains of carbon and hydrogen
that contain a carboxyl group
Glycerol is an alcohol. Alcohols contain a
HYDROXYL GROUP (oxygen atom bonded to
hydrogen atom, chemical formula -OH).
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NUCLEIC ACIDS
Fourth group of organic compounds
Store genetic information, control cellular
activity, and direct the making of proteins.
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NUCLEIC ACIDS
There are two types of NUCLEIC ACID
Deoxyribonucleic acid (DNA) contains
material that caries the "genetic message".
Ribonucleic acid (RNA) reads the message
encoded in the DNA. and assembles amino
acids in the proper order.
• There are _ different kinds of RNA.
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NUCLEIC ACIDS
The monomers of nucleic acids are nucleotides
Each nucleotide is composed of a sugar, phosphate, and
nitrogenous base
Nitrogenous
base (A)
Phosphate
group
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M.A.
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DNA has four kinds of bases, A, T, C, and G
Thymine (T)
Cytosine (C)
Adenine (A)
Pyrimidines
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Guanine (G)
Purines
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NUCLEIC ACIDS
The sugar and
phosphate form the
backbone for the
nucleic acid
Nucleotide
Sugar-phosphate
backbone
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DNA
DNA consists of two
polynucleotides
twisted around each
other in a double helix
The sequence of the
four kinds
(adenine,guanine,cyto
cine and Thymin) of
nitrogenous bases in
DNA carries genetic
information
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Base
pair
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DNA
Stretches of a DNA molecule called genes
program the amino acid sequences of
proteins
DNA information is transcribed into RNA, a
single-stranded nucleic acid
RNA is then translated into the primary
structure of proteins
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DNA
DNA is made of chemical units called nucleotides
Each species has its own nucleotide sequence
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DNA
The genetic information in DNA underlies all of the features
that distinguish life from nonlife
–Order and regulation
–Growth and development
–Use of energy from the environment
–Response to environmental stimuli
–Ability to reproduce
–Evolutionary change
DNA as their genetic blueprint
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CHEMICALS AND LIFE
•Chemical
nutrients cycle
within an
ecosystem’s web
•Energy flows in
and out
constantly
Inflow
of
light
energy
Air
Loss
of
heat
energy
Chemical
energy
Organisms
Cycling
of
chemical
nutrients
Soil
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OPARIN'S HYPOTHESIS
It is now accepted that organic molecules developed
chemically from non-living matter about 3.5 billion years ago.
In 1938 Russian biochemist Alexander Ivanovicly Oparin
proposed that Earth’s atmosphere was once ammonia,
methane hydrogen ad water vapor.
This primitive atmosphere was bombarded with heat, ultra-violet
light and lightning which caused the breaking and joining of
chemical bonds.
This led to simple organic compounds (i.e. Amino acids formed)
leading to more and more complex molecules
Eventually self-reproducing molecules like nucleic acids formed.
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MOLECULES OF LIFE
In 1953, Stanley Miller, recreated this
atmosphere in a lab and when the
gasses were repeatedly struck with
electricity amino acids eventually formed.
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REVIEW
Lipids
Proteins
Carbohydrates
Nucleic Acids
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