Transcript CHEMISTRY OF LIFE

Chapter 2
CHEMISTRY OF LIFE
NATURE OF MATTER
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Matter - anything that
has mass and occupies
space -consists of atoms
Atom – smallest unit of
matter that cannot be
broken down by
chemical means
Atom consists of three
particles: electron(-),
proton(+), and
neutron(0).
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Electrons are negatively
charged and have little
mass.
Protons are positively
charged and have a mass of
one.
Neutrons have no charge,
but have a mass of one.
Electrons and protons are
opposite charges, so they
attract each other.
F igu re 2 .1 0 E lectro n co n figu ratio n s o f th e first 1 8 elem en ts
Electron Configurations of
the First 18 Elements
Active Periodic Table
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http://www.colorado.edu/physics/2000/applet
s/a2.html
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Atoms typically have
one electron for one
proton, so they have no
electrical charge.
ATOMIC MASS – is the
sum of protons &
neutrons
ELEMENTS - a pure
substance made of only
one kind of atom
Elements differ in the
number of protons
referred to as the
ATOMIC NUMBER.
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The number of neutrons
in an atom is often but
not always equal to the
number of protons in the
atom.
Atoms of an element that
contain different numbers
of neutrons, but same #
of protons are called
ISOTOPES.
Isotopes are written with
the symbol and mass.
C-12, C-13, C-14
RADIOACTIVE ISOTOPES
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Atoms that emit radiation
are said to be radioactive.
Many elements have at
least one radioactive
isotope.
Radioactive isotopes are
frequently used as tracers.
Tracers are extremely
valuable in diagnosing
diseases.
Radioactive isotopes are
used to treat certain
diseases. (Co-60 & C-14)
Radioactive isotopes can
be used to kill bacteria
that cause food to spoil.
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Radiation can damage
or kill living things and
must be handled
properly.
Detecting Damaged Heart Muscle
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An isotope called
thallium-201 is used to
detect damaged heart
muscle after a heart
attack.
Will accumulate only in
normal, undamaged
heart muscle
Cost, risk to patient
advantages &
disadvantages
CHEMICAL BONDING
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A force that joins atoms is
called a chemical bond.
Compound – a substance
made of the joined atoms
of two or more different
elements.
Every compound is
represented by a chemical
formula that identifies the
elements in the compound
and their properties.
COVALENT BONDS
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Covalent bonds form when
two or more atoms share
electrons to form a
molecule.
A molecule is a group of
atoms held together by
covalent bonds.
The arrangement of their
electrons determines how
atoms bond together
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Electrons are grouped into
different levels.
Electrons levels can hold a
limited number of electrons.
Hydrogen (H) and Helium
(He) outer level can hold up
to 2.
2nd level can hold 8 electrons
Higher levels can hold even
greater numbers of electrons
Atoms want to achieve a
stable level which is 8
electrons in the outer level
except H & He
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If the outer electron
level is not full, an
atom will react
readily with atoms
that can provide
electrons to fill its
outer level.
HYDROGEN BONDS
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The electrons in a water
molecule are shared by oxygen
(O) and hydrogen (H). The
shared electrons are attracted
more strongly by the oxygen
nucleus than by the hydrogen
nuclei. Molecules with an
unequal distribution of
electrical charge are called
POLAR MOLECULES. This
attraction between 2 water
molecules is an example of
hydrogen bond – weak
chemical attraction between
polar molecules.
Hydrogen Bonds
 Oxygen
is one of the most
electronegative elements
 In a water molecule
electronegative oxygen “hogs”
electrons.
 This “hogging” of electrons
results in which type of bond
between oxygen and hydrogen
within the water molecule?
Polar covalent
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Hydrogen bonds
occur between two
polar molecules, or
between different
polar regions of
one large macromolecule.
One “relatively”
negative region is
attracted to a
second “relatively”
positive region.
F igu re 3 .1 H yd ro gen b o n d s b etw een w ater m o lecu les
IONIC BONDS
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An atom or molecule that
has gained or lost one or
more electrons is called
an ION.
Ions have an electrical
charge because they
contain an unequal
number of electrons and
protons.
An atom that has lost
electrons is positively
charged, while the atom
that has gained electrons
is negatively charged.
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Ionic Compounds
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Hard
Brittle
High melting & boiling
point
Transfer electrons
Conduct electricity
when dissolved in water
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Covalent Compounds
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Not hard
Not brittle
Low melting and
boiling point
Shared electrons
Doesn’t conduct
electricity when
dissolved in water
Homework
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State the question into a complete sentence
form
P. 30 section review questions 1-6
P. 44 &45 chapter review 1, 2, 6, 19
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Section 2
WATER AND
SOLUTIONS
Water absorbs heat more
slowly and retains this
energy longer than many
other substances do.
Water helps cells maintain
homeostasis.
The hydrogen bonds
between water molecules
cause the cohesion of
liquid water.
COHESION
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An attraction between
substances of the same
kind.
Molecules at the surface
of water are linked
together by hydrogen
bonds, which causes a
condition known as
surface tension.
Surface tension prevents
the surface of water from
stretching or breaking
easily.
ADHESION
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An attraction between
different polar substances.
Adhesion powers a
process, called capillary
action, which water
molecules move upward
through a narrow tube or
climb up paper.
Mixtures
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A substance composed of
two or more elements that
are mixed together but not
chemically combined.
Unlike chemical
compounds, the
substances that make up a
mixture can be added in
varying amounts.
Mixtures that are made
with water can be of two
important types
AQUEOUS SOLUTIONS
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Solutions is a mixture in which
one or more substances are
evenly distributed in an other
substance.
Solvent does the dissolving.
Solute is being dissolved.
Ionic compounds and polar
molecules dissolve best in
water.
Water is the greatest solvent
because of its polarity.
SUSPENSIONS
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A mixture
containing
nondissolved
particles
distributed within
a solid, liquid, or
gas.
Acids and Bases
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Hydrogen ions (H+) and
hydroxide ions (OH-)
form when water
molecules break.
Acid has an increased
number of hydrogen ions
lowering the pH level.
Bases are compounds that
lower the concentration of
hydrogen ions.
All solutions have a pH
values between 0-14.
Below 7 is an acid.
pH scale
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Each whole number represents a factor of 10 on
the scale
pH value of 5 has 100 times as many hydrogen
ions as one with a pH value of 7
Homework
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State question in a complete sentence form
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Section review p. 33 questions 1-5
Chapt review p. 44 & 45 3, 7, 12
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T ab le 2 .1 N atu rally O ccu rrin g E lem en ts in th e H u m an B o d y
Section 3
CHEMISTRY OF CELLS
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Body is composed
of mostly water and
organic
compounds.
Organic
compounds contain
carbon , hydrogen,
and oxygen.
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Four classes of
organic
compounds:
lipids, proteins,
carbohydrates,
and nucleic acids.
95% of all known
compounds contain
carbon
CARBOHYDRATES
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are a key source of energy for
the cell (4 calories per gram)
Building blocks are
monosaccharide's (single
sugar) ex. Glucose, fructose,
& galactose (ose) C6H12O6
Disaccharides - 2 sugars table sugar - sucrose
(1 glucose & 1 fructose)
Lactose Milk sugar– 1
glucose & 1 galactose
C12H22O11
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Carbon has four
valence electrons
and makes covalent
bonds, it can form
molecules that are
long chains. There
are several different
kinds of these we
will be discussing:
hydrocarbons,
carbohydrates,
lipids, proteins,
and DNA.
A functional group is a
group of atoms of a
particular arrangement
that gives the entire
molecule certain
characteristics.
Functional groups are
named according to the
composition of the
group. For example,
COOH is a carboxyl
group.
Structural Formula vs Chemical
Formula
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Structural Formula –
shows not only kinds &
numbers of atoms, but
arrangement
Chemical Formula–
show kinds and numbers
of atoms
Isomers - having same
chemical formula, but
different structural
formulas
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Polysaccharides is a
macromolecule
function as
storehouses of the
energy contained in
sugars. Starch made
by plants and glycogen
made by animals are
examples.
Cellulose is a
polysaccharide that
provides structural
support for plants and
humans can not digest
it. It is considered fiber
Macromolecule
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A very large molecule,
such as a polymer or
protein, consisting of
many smaller structural
units linked together.
Also called supermolecule
or polymer.
Upper right - tailpin
bacterial virus T7
punctures E. coli cell
wall
Reactions of Biological Compounds
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Condensation
Reactions also called
dehydration synthesis
or anabolism– when
smaller molecules are
bonded together to
make large molecules,
water is given off
Hydrolysis or
Catabolism – breaking
down large molecules to
smaller molecules by
adding water
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http://nhscience.lonestar.edu/biol/dehydrat/de
hydrat.html
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Dehydration synthesis
Hydrolysis
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Lipids
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Lipids are nonpolar
molecules.
Fats, steroids, waxes, and
phospholipids (Found in
cell membrane)
Fats store energy.(9
calories per gram)
Saturated fatty acids are
generally solid at room
temperature – mostly
animal
Unsaturated fatty acids
are generally liquid at
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Fatty acid is the basic
building block of lipids
Glycerol is a trihydric
alcohol (containing three
-OH hydroxyl groups)
that can combine with up
to three fatty acids to
form monoglycerides,
diglycerides, and
triglycerides
Protein
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is usually a large molecule
formed by linked smaller
molecules called amino
acids. (4 calories per gram)
Amino acids are the building
blocks of proteins.
There are 20 different amino
acids found in proteins.
Proteins can be enzymes
which promote chemical
reactions.
Collagen found in skin,
ligaments, tendons, & bones.
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Humans can produce 10
of the 20 amino acids
do not have all the
enzymes required for the
biosynthesis of all of the
amino acids.
Bonds between amino
acids are called peptide
bonds
NUCLEIC ACIDS
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A nucleic acid is a long chain of
smaller molecules called
nucleotide.
A nucleotide has three parts:
sugar, a base, and a phosphate
group.
Two types of nucleic acids: DNAdeoxyribonucleic acid consists of
two strands of nucleotides spiral
around each other
Chromosomes contain long
strands of DNA, which stores
heredity information.
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RNA ribonucleic acid,
single strand of
nucleotides.
RNA plays many key
roles in the manufacture
of proteins.
ATP – adenosine
triphosphate – food
energy is temporarily
stored in ATP
Cells need a steady supply
of ATP to function.
HOMEWORK
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Restate the question in complete sentence form
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SECTION 3 PAGE 37
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Chapter review p. 44 & 45 quest. 8,9, 13, 17
STP 1-3
Bonus quest. 18
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quest 1-5
Section4
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Energy and Chemical Reactions
Energy is the ability to move
or change matter. (many
forms)
Energy can be stored or
released by chemical
reactions.
Chemical reaction is a
process during which
chemical bonds between
atoms are broken.
Starting materials called
reactants.
Newly formed substance is
called products.
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Energy is either released
or absorbed during a
chemical reaction.
Metabolism is the term
used to describe all of
the chemical reactions
that occur within an
organism.
Types of chemical reactions
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An exothermic
reaction is a chemical
reaction that releases
energy in the form of
heat..
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An endothermic reaction is
any chemical reaction that
absorbs heat from its
environment.
These examples could be
written as chemical
reactions, but are more
generally considered to be
endothermic or heatabsorbing processes:
melting ice cubes
melting solid salts
evaporating liquid water
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converting frost to water
vapor (melting, boiling,
and evaporation in
general are endothermic
processes)
splitting a gas molecule
cooking an egg
Activation Energy
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The energy needed to start
a chemical reaction is
called Activation Energy.
Enzymes are substances
that increase the speed of
chemical reactions.
Act as catalysts which
reduces activation energy.
Most enzyme-assisted
reactions are reversible.
Enzyme Specificity
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Substrate is a substance
on which an enzyme acts
during a chemical
reaction.
An enzyme’s shape
determines its activity.
Active sites is one or more
deep folds on an enzyme’s
surface
Factors in Enzyme Activity
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Any factor that
changes the shape of
an enzyme can affect
the enzyme’s activity
Temperature and pH
level are some factors
that affect enzyme
activity.
Another limiting factor
is amount of available
enzyme
Homework
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Restate questions in complete sentence form
P. 42 q. 1-6
P. 44 & 45 q. 4, 10, 11, 16