Transcript The Chemistry of Life

1. Atom
 2. Nucleus
 3. Electron
 4. Element
 5. Compound
 6. Molecule
 7. Covalent Bond
 8. Ionic Bond
 9. Acid
 10.Base
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Chapter 2
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Biochemistry – the study of the chemicals of
living things and their changes
Democritus –2500 yrs.
Ago
Have subatomic
particles: protons (+),
neutrons (no charge),
and electrons (-)
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Particles found in the
nucleus = protons and
neutrons
Particles found outside the
nucleus in energy levels =
electrons
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One type of Atom
A pure substance
Atomic # = the number of protons
Mass # = the number of protons and
neutrons
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Atoms of the same element that have
different #’s of neutrons
These atoms have the same chemical
properties
Radioactive isotopes = useful and
dangerous
The chemical combination of one or more
elements in a fixed ratio
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Example: H2O = 2Hydrogen: 1Oxygen
Physical and chemical properties of these
elements are quite different
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These bonds hold atoms in a chemical
compound together
Valence electrons = the very outside
electrons of an atom that form bonds.
1. Ionic Bonds = One or more electrons are
transferred from one atom to another.
There is a strong attraction between
elements with opposite charged ions.
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Ion – atom that has gained or lost electrons
Loss (+, more protons), gain (-, more electrons).
Example Na (sodium) loses an electron to Cl
(chlorine) = Na+Cl-
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2. Covalent Bonds =
One or more electrons
are shared from one
atom to another.
◦ There are single and
double covalent bonds
◦ These form molecules
Example: H2 , N2
◦The particles that move around the nucleus of an
atom are called
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neutrons.
protons.
electrons.
isotopes.
◦The atomic number of a carbon atom is 6. How
many neutrons does the isotope carbon-14 have?
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6
8
12
14
◦Which of the following statements about the three
isotopes of carbon is true?
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They are all radioactive.
They have different numbers of electrons.
They have the same chemical properties but differ in
atomic mass.
They have the same number of protons and
neutrons.
◦A chemical compound consists of
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Electrons mixed with neutrons.
two or more elements combined in a definite
proportion.
two or more elements combined in any proportion.
at least three elements combined by ionic or
covalent bonds.
◦Van der Waals forces are the result of
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unequal sharing of electrons.
ionic bonds.
the bonding of different isotopes.
the chemical combination of sodium and chlorine.
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Water is a Polar
Molecule – uneven
distribution of
electrons between
Hydrogen and
Oxygen
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Water is very cohesive
= it is highly attracted
to other water
molecules
◦ This is due to Hydrogen
bonding
A mixture is two or more elements or
compounds that are mixed together
2 Types
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1. Solution = Compounds are evenly distributed.
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2. Suspensions = mixtures with undissolved
materials
Contain solutes = substances being dissolved,
and solvents = the substance in which the
solute is dissolved.
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pH Scale = the concentration of H+
(hydrogen) and OH- (hydroxide) ions in
solution.
Acids = Higher concentration of H+ ions
then pure water = pH below 7
Bases = Lower concentration of H+ ions
then pure water = pH above 7
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Water
H2O
H+
+ OH−
Hydrogen ion + hydroxide ion
Lots of H+ = acid
Lots of OH− = base
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Measure of H+ in solution
The higher the H+ the closer to zero on the
pH scale
Scale from 0 – 14
 0 – 6.9 = acid
 7 = neutral
 7.1 – 14 = base
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Each step on the pH scale represents a factor
of 10
◦ An acid with a pH of 4 is ten times stronger than an
acid with a pH of 5
◦ How many times more basic is a pH of 10 than a pH
of 8?
 100 times more basic
 (10) (10) = 100
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Tools used to measure pH
◦ Example: pH paper, litmus paper
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Measures amount of H+ and changes color
based on the concentration
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Weak acid or base that can react with strong
acids or bases to help prevent sharp, sudden
changes in pH
Buffers are very important for maintaining
homeostasis in living things
◦A molecule in which the charges are unevenly
distributed is called a
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polar molecule.
cohesive molecule.
hydrogen molecule.
covalent molecule.
◦A dissolved substance is called a
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solvent.
solution.
solute.
Suspension.
◦A compound that produces hydroxide ions in
solution is called a(an)
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base.
buffer.
acid.
salt.
◦Hydrogen bonds between water molecules result
from
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adhesion between water molecules.
magnetic attractions between water molecules.
uneven electron distribution in each water molecule
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ionic bonds in the water molecule.
◦On a pH scale, a value of 2 means that the solution
has
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equal concentrations of H+ and OH- ions.
the same concentration of H+ ions as pure water.
higher concentration of H+ than in pure water.
lower concentration of H+ than in pure water.
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Organic Chemistry - Study of all compounds
that contain bonds between carbon atoms.
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Why is Carbon so important?
◦ 4 Valence Electrons = strong covalent bonds
between other atoms
◦ Carbon can bond to other carbon atoms = single,
double, triple bonds
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Giant Molecules
Created by
Polymerization =
Chemical process in
which small units of
compounds, called
monomers, join
together to build large
units, called polymers
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4 groups of carbon based compounds found in
living things
◦ 1. Carbohydrates
 Made up of carbon, hydrogen, and
oxygen atoms in a 1:2:1 ratio
 Bodies main source of energy (Animals)
 Used for structural purposes (plants)
 Sugars (immediate energy) and
starches (stored energy). Sugar
monomers make up starches.
 Monosaccharides = “single
sugar” molecules. Ex. Glucose
 Polysaccharides = “many
simple sugar” molecules. Ex.
Glycogen (animals) and
Cellulose (plants).
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2. Lipids
◦ Made up of Carbon and Hydrogen
atoms
◦ Insoluble in water.
◦ Fats, oils, steroids, and waxes
◦ Used to store energy.
◦ Composed of glycerol and fatty
acids
◦ 2 types
 1. Saturated = Fatty acid carbon
chains are joined by a single bond.
These fatty acids contain the max. #
of Hydrogen atoms
 2. Unsaturated = Contains one carboncarbon double bond in the fatty acid
Saturated Fat
Unsaturated Fat
3. Nucleic Acids
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Contain hydrogen, oxygen, nitrogen, carbon, and
phosphorous
Polymers assembled from nucleotides = a 5carbon sugar, a phosphate group, and
nitrogenous base.
Store and transmit hereditary or genetic
information
2 Types
 DNA – Deoxyribonucleic acid
 RNA – Ribonucleic acid
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4. Proteins
◦ Contain Nitrogen, Carbon, Hydrogen, and Oxygen
◦ Polymers of amino acids (a.a.) = one amino group
(NH2) end , one carboxyl group (COOH) end, and a
third group called the R-group. Each amino acid
has a different R-group.
◦ Most diverse macromolecules = Amino acids (20)
have an ability to attach to any other amino acid in
nature. Attach at amino and carboxyl groups
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All proteins have specific roles
Control reaction rates and regulate cell processes
All have 4 levels of organization: Important!!
 Primary = sequence of amino acids.
 Secondary = twisted and folded chain
of amino acids.
 Tertiary = Chain is then twisted itself.
 Quaternary = The entire protein
maintains a folded, twisted shape due
to H-bonds and Van der Waals Forces.
◦Large carbohydrate molecules such as starch are
known as
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lipids.
monosaccharides.
proteins.
polysaccharides.
◦Many lipids are formed from glycerol and
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fatty acids.
monosaccharides.
amino acids.
nucleic acids.
◦Proteins are among the most diverse
macromolecules because
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they contain both amino groups and carboxyl groups.
they can twist and fold into many different and
complex structures.
they contain nitrogen as well as carbon, hydrogen,
and oxygen.
their R groups can be either acidic or basic.
◦Which of the following statements about cellulose
is true?
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Animals make it and use it to store energy.
Plants make it and use it to store energy.
Animals make it and use it as part of the skeleton.
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Plants make it and use it to give structural support
to cells.
◦A major difference between polysaccharides and
proteins is that
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plants make polysaccharides, while animals make
proteins.
proteins are made of monomers, while
polysaccharides are not.
polysaccharides are made of monosaccharides, while
proteins are made of amino acids.
proteins carry genetic information, while
polysaccharides do not.
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Chemical Reaction =
◦ The changing of one set chemicals
into another set of chemicals.
◦ It will always involve breaking of
bonds in reactants and forming new
bonds in the products.
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All chemical reactions have 2 parts:
◦ 1. Reactants = The chemicals that enter a reaction
◦ 2. Products = The elements or compounds that are
formed from the reactants chemical interaction
CO2 + H2O
Reactants
H2CO3 + Energy
Products
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Energy in Chemical Reactions = Energy is
released (spontaneously) or absorbed (need a
source of energy) during a chemical reaction
Living things need sources of energy to
continue chemical reactions, and stay alive
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Activation Energy = The energy needed to
start a chemical reaction
Catalysts = A substance that lowers the
activation energy and speeds up the rate of a
chemical reaction.
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Enzymes = Proteins in living things that act
as catalysts. Cells use catalysts to speed up
chemical reactions that take place there
◦ Lower the activation energy
◦ Very Specific = catalyze only one reaction

Activation Site = an area on the enzyme
where the reactants come in contact and are
able to react
◦ Reduces the energy needed
◦ Enzyme catalyzed reactions = Substrates
 regulating chemical pathways.
 making material that cells need.
 releasing energy.
 transferring information.
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pH changes, temperature changes, cell
regulation, etc.
◦The elements or compounds produced by a
chemical reaction are known as
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reactants.
enzymes.
products.
waste.
◦Chemical reactions always involve
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changes in energy.
enzymes.
catalysts.
changes in the atomic number of the reactants.
◦The factor that prevents many energy-releasing
reactions from occurring at relatively low
temperatures is called
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catalytic energy.
chemical bond energy.
enzyme energy.
activation energy.
◦Which of the following statements is true?
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All
All
All
All
proteins are enzymes.
catalysts are enzymes.
enzymes are catalysts.
catalysts are proteins.
◦What happens to an enzyme after the reaction it
catalyzes has taken place?
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The enzyme is destroyed, and the cell must make
another.
The enzyme holds on to the product until another
enzyme removes it.
The enzyme is unchanged and ready to accept
substrate molecules.
The enzyme changes shape so it can accept a different
kind of substrate.