The Chemical Basis of Life

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The Chemical Basis of Life
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BASIC CHEMISTRY

• ATOMIC STRUCTURE
• NUCLEUS
• PROTONS ATOMIC MASS 1
• NEUTRONS ATOMIC MASS 1
• ELECTRONS
• NOT ENOUGH MASS FOR US TO CONSIDER.

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Atomic Structure
(-)
()
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Chemical Elements

• All matter on Earth is composed of combinations
  of chemical elements.
• Elements cannot be broken down by chemical
  processes into simpler substances.
• There are over 90 naturally-occurring chemical
  elements.
• The most common chemical elements in living
  things are
• S, P, O, N, C, H

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Periodic Table
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MOLECULES and COMPOUNDS

• MADE OF MORE THAN ONE KIND OF ATOM HELD TOGETHER
  BY A CHEMICAL BOND.
• FAMILIAR ONES INCLUDE WATER, SUGAR, FAT, PROTEIN,
  CARBOHYDRATE, SALT.

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WHY DO SOME ATOMS COMBINE TO FORM COMPOUNDS AND
MOLECULES?

• An Atoms ability to combine with other atoms
  relies on its number of electrons in its outer
  shell (energy level) the outer shell needs to be
  full for the atom to become stable (stable atoms
  do not combine with other atoms).
• For our purposes, the first shell contains 2
  electrons, and each successive shell contains up
  to 8 electrons.

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Electron Energy Levels
First energy level holds up to 2 electrons
Second energy level holds up to 8 electrons
Third energy level holds up to 8 electrons
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Stable atoms

• Some atoms already have a full outer energy
  level.
• These atoms do not react with other atoms to form
  molecules.
• These include the inert or noble gases helium,
  argon, neon, krypton, xenon, and radon.

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If an atom is not stable

• It will combine with other atoms
• Some will give up or gain electrons.
• These form ionic bonds
• Each member is an ion
• The opposite electrical charges attract each
  other
• Some will share electrons between them.
• The force holding them together is called a
  covalent bond.

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Ionic Bonds
NaCl salt
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POLAR MOLECULES

• BECAUSE OF THE WAY SOME MOLECULES COMBINE, THEY
  CONTAIN DIFFERENT ELECTRICAL CHARGES AT OPPOSITE
  ENDS.
• THIS CREATES ATTRACTION TO OPPOSITE CHARGES ON
  OTHER MOLECULES

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Polar Molecules
Positive end
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HYDROGEN BONDS

• HOLD TOGETHER MOLECULES THAT CONTAIN HYDROGEN.
• IMPORTANT IN WATER MOLECULES AND MANY MOLECULES
  IN LIVING ORGANISMS.
• WEAKER THAN IONIC OR COVALENT BONDS.
• THESE HOLD DNA TOGETHER

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CHEMICAL REACTION

• ONE OR MORE SUBSTANCES IS CHANGED INTO NEW
  SUBSTANCES BY BREAKING OR FORMING CHEMICAL BONDS.
• EX
• 6CO2 6H20 ? C6H12O6 6O2
• WHAT IS THE ABOVE EQUATION AND WHAT DOES IT MEAN?

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ALL CHEMICAL REACTIONS INVOLVE ENERGY

• WHEN BONDS
• FORM,
• ENERGY IS
• STORED
• WHEN BONDS
• BREAK,
• ENERGY IS
• RELEASED

ATP energy carrier of a cell
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ORGANIC COMPOUNDS

• COMPOUNDS THAT CONTAIN CARBON, HYDROGEN AND
  OXYGEN IN DEFINITE PROPORTIONS.
• USUALLY ASSOCIATED WITH LIVING THINGS

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CARBOHYDRATES

• BUILDING BLOCKS SIMPLE SUGARS
  (MONOSACCHARIDES).
• MONOSACCHARIDES INCLUDE
• GLUCOSE
• FRUCTOSE ISOMERS
• GALACTOSE
• ALL THREE HAVE THE SAME MOLECULAR FORMULA, BUT
  DIFFERENT STRUCTURE
• C6H1206
• THESE MOLECULES ARE THE MOST COMMON SOURCE OF
  ENERGY FOR LIVING THINGS.

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Isomers can you tell the difference?

• glucose

C6H12O6
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MORE COMPLEX CARBS

• DISACCHARIDES
• MADE UP OF TWO MONOSACCHARIDES CHEMICALLY
  COMBINED.
• GLUCOSE GLUCOSE MALTOSE
• GLUCOSE GALACTOSE LACTOSE
• THIS IS MILK SUGAR
• GLUCOSE FRUCTOSE SUCROSE
• THIS IS TABLE SUGAR
• These molecules store energy for later use

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THE MOST COMPLEX CARBS

• STARCH MADE UP OF MANY GLUCOSE UNITS COMBINED.
• PLANT LONG-TERM FOOD STORAGE
• GLYCOGEN MADE OF MANY GLUCOSE UNITS COMBINED
• ANIMAL STORAGE IN LIVER AND MUSCLES
• CELLULOSE MADE OF MANY GLUCOSE UNITS COMBINED.
• PLANT CELL WALLS FIBER
• CHITIN PROTECTIVE COVERINGS IN INSECTS AND
  OTHER ARTHROPODS ALSO IN FUNGUS CELL WALLS

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DEHYDRATION SYNTHESIS

• In order for two molecules to join together, each
  molecule must break off atoms to provide a
  bonding place.
• Most organic molecules do this by losing a
  hydrogen atom from one molecule and a hydroxyl
  group from the other.
• These two join to form water, and allow the
  molecules to make a bond.

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Dehydration Synthesis
C6H12O6 C6H12O6 ? C12H22O11 H2O


disaccharide
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Hydrolysis

• In order to break down a large molecule to make
  smaller molecules, a molecule of water has to be
  added.
• This fills in the spots where the bond broke
  one molecule gets a hydrogen atom, the other gets
  the hydroxyl group.

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Hydrolysis

• ADD WATER

TO A
POLYSACCHARIDE
AND FORM MANY
MONOSACCHARIDES
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Dehydration Synthesis and Hydrolysis store and
release energy

• Dehydration synthesis stores energy by forming
  bonds.
• As in the formation of polysaccharides from
  monosacharides
• Hydrolysis releases energy by breaking bonds.

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Lipids fats, oils, waxes, phospholipids,
steroids

• Used for longer-term storage of energy
• Fats in animals
• Oils in plants
• Waxes water repellent (In your ears, beeswax,
  coat plant leaves), waterproof bird feathers.
• Steroids in animal cell membranes and some
  hormones.
• Phospholipids make up parts of cell membranes

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A common fat Triglyceride

• Composed of one glycerol and three fatty acids,
  joined together by dehydration synthesis

3 F A T T Y A C I D S
G L Y C E R O L
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Saturated and unsaturated fats

• Saturated fats have no CC bonds within the fatty
  acids
• These are considered unhealthy they clog up the
  coronary (heart) arteries.
• These are solid at room temperature.
• From animals.
• Unsaturated fats have at least one CC bond in
  one of its fatty acids
• These are considered healthier.
• Plant oils are usually unsaturated.
• Liquid at room temperature.

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PROTEINS

• Important for movement, structure, regulation,
  transport, nutrition, and defense.
• Composed of building blocks called amino acids
• Humans cannot make these from scratch we must
  eat foods with proteins, then use the amino acids
  to make our own proteins.

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Amino Acids

• There are 20 different aas
• They are combined in various numbers and orders
  to produce a great number of different proteins.
• Each aa has an amino group, an acid group
  (carboxyl), and a variable group (there are 20
  different variable groups).
• Amino acids attach to each other by dehydration
  synthesis forming a peptide bond between the
  amino group of one aa and the acid group of the
  other aa.
• Change the number or arrangement of the aas and
  the protein is changed.

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Amino acids
Acid group

• Three different R groups

Amino group
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Dipeptide two aas joined by a peptide bond.
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Polypeptide
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Enzymes Special Proteins

• Change the rate of chemical reactions without
  being used up themselves (biological catalyst).
• Can be used over and over.
• Action is very specific
• each enzyme will only
• work on one particular substance (the substrate).

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HOW DOES AN ENZYME WORK?

• LOCK AND KEY MODEL

• INDUCED FIT MODEL

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Nucleic Acids

• Molecules of heredity.
• DNA deoxyribonucleic acid
• makes up chromosomes (GENES)
• Contains the genetic code
• Determines the organisms traits
• Contains the code for making proteins
• Which control the cells activities
• RNA ribonucleic acid
• Helps DNA make proteins

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Metabolism

• All the chemical reactions that take place in the
  organism
• These reactions need to be balanced to keep the
  organism alive
• The balance is called homeostasis

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Water and Solutions

• H2O
• Forms solutions easily all lifes chemical
  reactions take place in solutions.
• Solution two or more substances are mixed
  together that they cannot be distinguished.
• Ex- sugar water or salt water
• Sugar or salt is the solute
• Water is the solvent

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Salt Water Solution
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Acids and Bases

• Form when an ionic compound is mixed with water
  to form a solution.
• Acid releases H (hydrogen) ions (like HCl
  hydrochloric acid)
• Base releases OH- (hydroxide) ions (like NaOH
  sodium hydroxide)

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pH scale

• Standard measurement of the H ions in a solution
• Ranges from 0 14
• 7 is neutral
• Water has an equal number of H and OH- ions, so
  there is no excess of either ion.

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pH scale

• Acids are less than 7
• Bases are more than 7
• The further away from 7, the stronger the acid or
  base
• Most chemical reactions in humans take place
  between 68
• However, stomach acid is 2-3
• Enzymes are pH specific

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