Transcript Chemical reaction

Chemistry
&
Biochemistry
Chapters 2 & 3
Atoms
• Matter - anything that occupies
space and has mass
• Three states
• Solid
• Liquid
• Gas
• Atoms - the smallest units of
matter that have their own
distinct properties
Atomic Structure
• Nucleus
• Protons (+)
• Neutrons (0)
• Electron Shell
• electrons (-)
Chemical Element
• Chemical elements - composed
of atoms that share the same
characteristics, but differ from
the atoms of other elements
• Elements want eight electrons
in the outermost shell
• Except Hydrogen and Helium
Helium
Compounds
• A pure substance made up of
atoms of 2 or more elements
• A molecule is the simplest
part of a substance that
retains all of the properties of
the substance
Water
Elements
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Oxygen - O
Carbon - C
Hydrogen - H
Nitrogen - N
Calcium - Ca
Phosphorus - P
Sulfur - S
Sodium – Na
Potassium - K
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Magnesium - Mg
Chlorine - Cl
Iron - Fe
Iodine - I
Manganese - Mn
Copper - Cu
Zinc - Zn
Cobalt - Co
Fluorine - F
Ionic Bonds
• A positive ion and negative
ions held together
• Electrostatic - forces of attraction
• A gain or loss of electrons
• Cations - positively charged ions
• Anions - negatively charged ions
Covalent Bond
• Sharing electrons with other
atom
• H-H
• O=O
Hydrogen Bonds
• Weak bonds between hydrogen
and a weak negative charge
• In large numbers they provide
strength to molecules
• Important in DNA
Basic Terms
• Chemical reaction:
• Reactant: a compound or
atom involved in a
chemical reaction
• Product: a compound
formed by a chemical
reaction
Reactions
• In a reaction, bonds present
in reactants are broken,
elements are rearranged,
and new compounds are
formed as products.
• Example:
C12H22O11 +H2OC6H12O6 + C6H12O6
Synthesis Reactions
• A + B  AB
• Requires the formation of new
bonds between the combining
units (reactants)
• Important in repairing worn or
damaged parts
Examples
Decomposition
Reactions
• AB  A + B
• Breaking down of molecules
into simpler molecules
• Digestion
Example
Transfer of Energy
Reactions
• Exergonic reactions:
net release of free
energy
• Endergonic reactions:
net absorption of free
energy
Energy Transfer
• Activation Energy - the
amount of energy needed to
start a chemical reaction
• Catalysts - reduce the amount
of energy needed
Enzymes: important
class of catalysts in
living things
• EX.
Oxidation-Reduction
Reactions
• Transfer of
energy by the
transfer of
electrons
• Oxidation
reactions lose
an electron
• Reduction
reactions gain
an electron
Redox Reactions
Memory TIP
•OIL RIG
•“OIL” = oxidation
loses electrons
•“RIG” = reduction
gains electrons
Terms
• Solution – a mixture in which one or
more substances are uniformly
distributed into another
• Solute – the substance dissolved in
the solution (Sugar)
• Solvent – the substance in which the
solute is dissolved (Water)[aqueous]
Concentration
• Concentration: the
amount of solute
dissolved in a fixed
amount of solution
•Saturated solution: no
more solute can
dissolve
Concentration Cont.
• % Concentration solute =
• Mass of solute/ mass of solution X
100%
• % Concentration solvent=
• Mass of solvent/ mass of solution
X 100%
Kool-Aid
• What is the
percent
concentration of
sugar?
• 10 ml water
• 5g Sugar
• 2g Kool-Aid Mix
Acids and Bases
• Neutral= number of hydronium ions
equal the number of hydroxide ions
• Acid =number of hydronium ions in a
solution is greater than the number
of hydroxide ions (H)
• Base= number of hydroxide ions in a
solution is greater than the number
of hydronium ions (OH)
pH Scale
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0 to 14
0 = very acidic
14 = very basic
7 = neutral
Acid Vs. Base
• Release H+
• Sour
• Corrosive
• Red (pH
indicators)
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Release OH –
Bitter
Alkaline
Feels Slippery
Blue (pH
indicators)
Buffers
• Buffers: chemical
substances that neutralize
small amounts of either an
acid or a base when added
to a solution
• Carbonic acid/ bicarbonate
• Keep blood at a pH of 7.4
Water
• Most abundant compound in living
things
• 60-70% of total body mass
• Important transport medium
• High heat capacity - absorbs
and releases heat slowly
• Effective lubricant
Water’s Polarity
• Polar – unevenly
pattern of
charges
• able to dissolve
many
substances
• Positive on one
end and negative
on the other.
Polar Molecules
Dissociation of Water
• The breaking apart of water
molecules into two ions of opposite
charge
H2O  H+ + OHH+ + H2O  H3O+
OH- = hydroxide ion
H3O+ = hydronium ion
Cohesion
• Cohesion: attractive force between
particles of the same kind
 Example: surface tension of
water
• Polar nature of water causes water
molecules to be attracted to each
other.
• This attraction: hydrogen bond.
Adhesion
• Adhesion: attractive forces
between unlike substances
Basic Info.
• Very large organic molecules
composed of many smaller
molecules
• All organisms composed of 4 major
classes of macromolecules:
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Carbohydrates
Proteins
Lipids
Nucleic acids
Carbon
• Primary component of all
macromolecules
• Atom has 4 electrons in the outer
energy level.
• Readily forms 4 covalent bonds
with other elements
 Forms straight chains, branched
chains, or rings
Organic (Carbon)
Compounds
• Contain carbon atoms that are
covalently bonded to other
carbon atoms and to other
elements :
 Typically hydrogen (H),
nitrogen (N) and oxygen (O)
Macro( Large) Molecules
• Macromolecules are built from
smaller simpler molecules
called monomers.
• Monomers bond to one another
to form complex molecules
called polymers
Monomers to Polymers
Carbohydrates
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sugars & starches
energy source
Monosaccharide - simple sugar (glucose)
`(“Mono-” means “one”)
Disaccharide - table sugar
(“Di-” means “two”)
• Polysaccharide - lack sweetness
(“Poly-” means “many”)
Monosaccharide
Isomers
• Isomers- have the same chemical
formula, but have different
properties because of their
structure.
Dissacharides
• Formed when 2
monosaccharides combine by a
condensation reaction or
dehydration synthesis.
• Double sugars
• Example:
glucose + fructose  sucrose
+ water
Example
Polysaccharides
• Complex molecules composed
of 3 or more monosaccharides.
• Insoluble in water.
• Examples
• Glycogen -synthesized by animals
• Cellulose -found in the cell walls of
plants
• Starch
Examples
Lipids
• Major roles in living organisms
are:
 Store energy
 Form biological membranes
 Chemical messengers
 Insulation
Lipids
• Do not dissolve in water
Examples
• Steroids
• Testosterone and Cholesterol
• Waxes
• Plants and animals
Fatty Acids
• Most lipids are made of fatty
acids.
• Unbranched carbon chains
Fatty Acids Cont.
• Two ends of
fatty acid:
 Carboxyl (COOH) group
 Hydrocarbon
(long chains
of hydrogen
and carbon
atoms)
Saturated Vs
Unsaturated Fats
• Each carbon is
covalently bonded
to 4 atoms.
• Contains the
maximum number
of hydrogen
atoms.
• The atom is full or
“saturated”.
• Each carbon atom
is not bonded to 4
atoms.
• Does not contain
the maximum
number of
hydrogen atoms.
• One or more
carbon atoms are
double bonded to
each other.
Complex Lipids
• Divided according to structure.
• Three classes of lipids
important to living things
contain fatty acids:
 Triglycerides
 Phospholipids
 Wax
Triglycerides
• 3 molecules of fatty acids
joined to one molecule of
glycerol.
Saturated Vs Unsaturated
Triglycerides
 High melting
point.
 Solid at room
temp.
 Examples:
shortening
and animal
fats.
 Usually liquid
at room temp.
 Found
primarily in
plant seeds
and fruits.
Phospholipids
• Have 2 rather than 3 fatty
acids joined to a molecule of
glycerol.
• Cell membranes composed of 2
layers of phospholipids: lipid
bilayer.
 Produces a stable barrier for
a cell.
Phospholipids cont.
Wax
• Type of structural lipid.
• Highly waterproof.
 In plants, form protective
outer coating.
 Also forms protective layers
in animals.
Cholesterol
Plant Wax
Little Ear Wax
Lots of Wax
Steroids
 Not composed
of fatty acids.
 Sex hormones
 Cholesterol
 Chlorophyll
(pigment in
plants)
 Retinol (vision
pigment in eyes)
Proteins
• Composed of long chains of
subunits (monomers) called
amino acids.
• Covalent bond between 2 amino
acids form peptide bonds
• More than 50 = protein
Amino Acid Structure
• Each contain a central carbon
atom covalently bonded to 4
other atoms or functional
groups:
 A single H atom at one site.
 A carboxyl group (-COOH)
bonds at a second site.
Cont.
 An amino group (-NH2) bonds
at a third site.
 A functional group (“R”)
bonds at the fourth site.
R (functional group)
NH2
C
(amino
group) H
COOH
(carboxyl
group)
20 Different Kinds of
Amino Acids
• Main difference among amino acids
is found in their “R” (functional)
group.
Dipeptides
• Two amino acids can bond to
form a dipeptide.
• Condensation reaction
• Creates water
• Forms a peptide bond
Peptide Bond
Polypeptide
• 3 or more peptides bind
together to make a polypeptide
chain.
• Some are very chains are so
long, they are bent or folded.
• Temperature can determine the
shape.
Enzymes
• Most enzymes are proteins.
• Enzyme reactions depend on a
physical fit between the
enzyme and its substrate (the
reactant being catalyzed).
Enzyme and Substrate
How Enzymes Work
• Reduce activation energy.
 Enzyme is unchanged.
 May be used many times.
• May fail to work if environment is
changed.
 Temperature or pH can cause a
change in the shape of the
enzyme or substrate.
Nucleic Acids
• Store important hereditary
information in the cell.
• 2 types: DNA and RNA
DNA/RNA Basic Info
• Both DNA and RNA are
polymers.
 Composed of 1000’s of linked
monomers called nucleotides.
• made of 3 components:
 Phosphate group
 5 carbon sugar
 Nitrogen base
Deoxyribonucleic acid
• DNA
• Double helix
• Contain
• nucleotides
• a deoxyribose sugar
• nitrogen bases (thymine, adenine,
cytosine, guanine)
• phosphate group
DNA
Ribonucleic acid
• RNA
• Stores and transfers
information essential for the
manufacture of proteins.
RNA
More terms to know
• Free energy
• ATP
• Hydrolysis