Transcript The Chemistry of Life

The Chemistry of Life
Chapter 2
Atoms
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“Unable to be
cut”
Element-pure substance composed of only one
type of atom
Isotope-atoms of same element containing
different numbers of neutrons
Nucleus
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Protons- +
Mass = 1
The sum of Protons
and Neutrons is the
mass number
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Neutrons- 0 (neutral)
Mass = 1
Electron
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Charge = -1
Mass = 1/1840
Attracted to positively
charged nucleus but
their constant motion
prevents them from
entering the nucleus
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Because atoms have
equal numbers of
electrons and protons
atoms are neutral.
Isotopes
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Atoms of an element that have differing
numbers of neutrons
Because they have the same number of
electrons, all isotopes of an element have
the same chemical properties
Simple
elements
Compound
Chemical compounds
Chemical Compounds
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A substance formed by
the chemical combination
of two or more elements
Hydrogen gas + Hydrogen
gas + Oxygen gas =
H2O
Chemical Compounds
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Physical and chemical properties of a
compound can be very different from the
elements that make it
Sodium-a silver-colored metal that can be
cut with a knife
Chlorine-a poisonous, greenish gas that was
used to kill soldiers in WWI
Chemical Bonds-The Glue
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Ionic Bondstransferring electrons
from one atom to
another
Covalent Bonding
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Covalent Bonds form when electrons are shared
between atoms.
Van der Waals Forces
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Minor attractions
between molecules
Involves opposite
charges
Water
O
+
+
+
+
+
H+
++
+
+
- -
Hydrogen Bonds
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Cohesion-an
attraction between
molecules of the
same substance
Allows water to form
droplets on smooth
surfaces
Hydrogen Bonds
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Water molecules attract each
other because of partial charges
Polar molecule charges are
written in ( )
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The ability of water
to form multiple
bonds gives it
important
characteristics
A single water
molecule may form
up to four H-bonds
Water
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Cohesion-attraction to itself
Adhesion-attraction to other
substances
Capillary action-moves water against
gravity in tiny tubes
Surface Tension
Cohesion
Mixing it Up
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Mixture- two or more
elements or
compounds that are
physically mixed
together but not
chemically joined.
Ex. Sugar and sand
mixed together
Suspension-mixtures
of water and undissolved particles
 Solution: all
components are
evenly distributed
Ex. Salt water
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Solute
Solvent
pH
H2O
Water
H+ + OH-
Hydrogen Ion + Hydroxide Ion
Acids
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Acid- any compound that forms H+ in
solution
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Have higher concentrations of Hydrogen ions
than pure water
7
Have pH values BELOW 7
ACIDS
Bases
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Compounds that produce OH(hydroxide) ions in solution.
Basic solutions contain lower
concentrations of H+ ions
than pure water and have a
pH value greater than 7.
Bases
7
Common Solutions
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Acidic
Tomato Juice
Lemon Juice
Soda
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Basic
Ammonia
Bleach
Soap
Buffer
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pH of Human body is between 6.5 and 7.5
Buffers- weak acids or bases that can
react with strong acids or bases to prevent
sharp, sudden changes in pH
Carbon Compounds
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Organic-contains
carbon
Four groups of
organic compounds
making up living
things are
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Carbohydrates
Lipids
Nucleic Acids
Proteins
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Carbohydratesstarches and sugars
Lipids-fats, oils and
waxes
Nucleic Acids-DNA
and RNA
Proteins- linked amino
acids
Carbohydrates
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Compounds of C, H,
and O
Living things use
carbohydrates as their
main source of energy
Plants and some
animals can use
carbohydrates for
structure
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Living things store
extra sugar as
complex
carbohydrates known
as starch
“carbon hydrate”
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Cx(H2O)x
Formed when a carbon compound (CO2)
reacts with water
Uses
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Energy
Structure
Cell Recognition
Protection
Monosaccharide
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Monomer
Simplest sugar
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Glucose
Galactose
Fructose
Ribose
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MonoSaccharThey consist of one
sugar and are usually
colorless, water
soluble, crystalline
solids
Glucose
Fructose
Disaccharide
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Covalent bond links
two monosaccharides
results in disaccharide
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Lactose-milk
Sucrose-plants
Maltose-grains
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DiSaccharSucrose= glucose + fructose
Lactose= glucose + galactose
Maltose = glucose + glucose
Lactose
Sucrose
Sucrose
Sucrose
Sucrose
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Starches
Glycogen
Cellulose
Chitin
Starch
Starch
Potato
Corn
Oats
Cellulose
Cellulose
Chitin
Carbohydrates
Lipids
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Fats, oils, and waxes
Generally not soluble in water
Many are made of a glycerol molecule with
compounds of fatty acids attached.
Saturated-has all possible H atoms
attached
Un-saturated- has at least one double
bond occupying an atom’s position
Glycerol Backbone
Saturated
Unsaturated
Saturated Fats
Saturated Fats
Unsaturated Fats
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Tend to be liquid at room temperature
Come from vegetable sources
Has at least one carbon-carbon bond
Polyunsaturated-has more than one
double bond
Corn oil, sesame oil, canola oil, and
peanut oil are polyunsaturated
Unsaturated Fats
Peanut Oil
Corn Oil
Canola Oil
Nucleotides
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Nucleic acids are assembled from
individual monomers known as nucleotides
Nucleotides have a 5-carbon sugar, a
phosphate group, and a nitrogenous base.
Nucleotide
Nucleic Acids
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Store and transmit hereditary or genetic
information.
Ribonucleic acid (RNA)- contains the sugar
ribose
Deoxyribonucleic acid (DNA)- contains the
sugar deoxyribose
Arranged in sequence to form
informational code that
Deoxyribonucleic
Acid
Deoxyribose-monosaccharide
Ribonucleic Acid
Ribose- monosaccharide
Ribonucleic Acid
Proteins
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Macromolecules that contain nitrogen as
well as carbon, hydrogen, and oxygen
Polymers, they are made of monomers
called amino acids.
There are more than 20 amino acids found
in nature.
Some amino acids are acidic or basic.
Some are polar. Some are non-polar.
Proteins
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The instructions for arranging amino acids
into many different proteins are stored in
DNA.
Some proteins control the rate of
reactions, some form muscles, and some
transport substances or fight disease.
Proteins
Protein Transport
Enzymes
Enzymes
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Speed up chemical reactions that take
place in cells
Functioning depends on shape of twisted
protein
Temperature and pH change shape of
proteins and so change functioning of
enzymes
Chemical Reactions
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Process that changes
one set of chemicals
into another set of
chemicals
Reactants- go into the
reaction
Products- come out of
the reaction
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Chemical reactions
always involve the
breaking of bonds in
reactants and the
formation of new
bonds in products
Baking Soda + Vinegar
CH3COOH + NaHCO3
H2CO3
Carbonic
Acid
Salt and Carbonic Acid
CH3COONa + H2CO3
H2O + CO2
Water and Carbon
Dioxide
Energy in Reactions
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Reactions that release energy often occur
spontaneously
Reactions that absorb energy will not
occur without a source of energy.
2H2 + O2
2H2O
Burning releases energy
But . . .what do you have to have to start the fire?
Releasing Energy
Activation Energy
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The energy that is needed to get a
reaction started
Activation Energy
Energy-Absorbing
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EndoTherm-
Endo/Exo
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The reaction that
changes water into
hydrogen and oxygen
gas absorbs so much
energy that it
generally can’t occur
by itself.
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Water can be made
through the burning
reaction of Hydrogen
and Oxygen which
produces lots of
energy and water.
Energy Releasing
ExoTherm-
Catalyst
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Some chemical
reactions that make
life possible are too
slow or have
activation energies
that are too high to
make them practical
for living tissue.
Amylase on cracker
Catalyst
Enzymes
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Proteins that act as
biological catalysts
Speed up chemical
reactions that take
place in cells
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Carbonic anhydrase
speeds up CO2
removal by a factor of
10 million