Download Biochemistry Power Point - District 196 e

“atomos” Greek meaning unable to cut
Subatomic Particles
 Democritus thought matter had a limit to how far it
could be cut. He used the term “ atom” to describe this
smallest particle.
 Protons (in nucleus, positive charge, atomic number)
 Neutrons (in nucleus, no charge, mass only)
 Electrons ( orbit nucleus, negative charge, little mass,
move fast)
Elements & Isotopes
 Element: pure substance, all one type of atom
 Elements Listed on the Periodic Table (Names &
Symbols
 Isotopes: alternative forms of an element, that vary by
neutron number, have the same chemical properties
 Radioactive isotopes: those having unstable nuclei
that can break down at a constant rate over time
Compounds
 2 or more elements chemically c0mbined in specific
proportions (H2O)
 Physical and chemical properties of the elements
making up a compound are usually different from what
they are when they are alone. (Na & Cl combine to
make NaCl. ) Not a good idea to use Na and Cl
separately.
Chemical Bonds-Ionic
 Ionic bonds: forms when one or more electrons is
transferred from one atom to another, creating
oppositely charged ions in the process.
 Oppositely charged ions attract each other, forming an
Ionic Bond (+ attracts -)
 Gain electrons=negatively charged ion
 Lose electrons= positively charged ion
Chemical Bonds-Covalent
 Covalent bond forms when atoms share electrons,
forming a “molecule”
 Molecule: the smallest unit of most compounds
 H2O is an example of a covalent bond
 Covalent compounds ( those containing covalent
bonds)
Van der Waals Forces
 A slight attraction that develops between the
oppositely charged regions of nearby molecules
 These forces help creatures like the gecko grip smooth,
vertical surfaces
H2O (the universal solvent)
 Water is electrically neutral (8 protons, 8 electrons)
but is a polar molecule
 One side of the water molecule has a higher
probability of the electrons being closer than the other
side. (nearer the Oxygen side)
 Water is a “bent” molecule. That is to say, water is
polar. It has an uneven distribution of electrons
between the hydrogen and oxygen atoms.
Hydrogen bonds
 The polarity of H2O molecules allows for a somewhat
weak attraction between water molecules. This is a
“hydrogen bond”
 Cohesion: an attraction between molecules of the
same substance. (water attracted to water)
 Adhesion: an attraction between molecules of
different substances. (Capillary action)
 Capillary action is what draws water up into a narrow
tube against the force of gravity.
 This is how plants (tall trees) get water up to their
highest regions
Solutions and Suspensions
 Mixtures: 2 or more elements or compounds
physically mixed together but not chemically
combined.
 Solution: in a salt/water solution, the salt is the solute
and the water is the solvent
 Suspensions: material suspended, but not dissolved
in a liquid
 Some body fluids are solutions and some are
suspensions. (blood is both)
Acids,Bases, and pH
 pH scale
 H2O = H+
+ OH-
pH Scale
 pH runs from 1-14
 Neutral is 7, <7 is acid, >7 is base
 Base=alkaline
 Buffers are weak acids or bases that can react with
strong acids or bases to prevent sharp, sudden pH
changes
Carbon Compounds
 Organic chemistry: carbon based chemistry
 Macromolecules: giant molecules
 Monomers (small) join together to form polymers
(large)
 Organic compounds found in living things include
carbohydrates, lipids(fats), nucleic acids, and proteins
Organic compounds
Every carbon atom must make 4 bonds
This is methane
Ethene
 4 bonds around each C
 C bonded to C with a double bond
 This is ethene
Acetylene
 Unsaturated (not the maximum number of H bonds)
 Each C has 4 bonds
Carbohydrates
 Contain C, H, and O in a 1:2:1 ratio
 Provide the main source of energy for living things
 Carbohydrates provide some material for structural
development in plants
 monosaccharides : single sugar molecules
 Polysaccharides: carbohydrates macromolecules
( glycogen)
Lipids
 Mostly C & H
 Includes fats, oils, and waxes
 Energy storage
 Important is some biological membranes and
waterproof coverings
 Saturated: contains the maximum possible number of
hydrogen atoms
 Polyunsaturated: contains at least one carboncarbon double bond
Nucleic acids
 Macromolecules containing H, O,N, C and P
 Polymers assembled from individual nucleotides
 A nucleotide consists of a 5-carbon sugar, a phosphate
group, and a nitrogenous base
 Nucleic acids store and transmit genetic information
 2 types of nucleic acids.
 Deoxyribonucleic acid (DNA)
 Ribonucleic acid (RNA)
Proteins
 Proteins are macromolecules that contain N along
with C, H, & O
 Proteins are polymers of molecules called amino acids
 Amino acids are compounds with an amino group
(-NH2) on one end and a carboxyl group (–COOH) on
the other end
Each amino acid is different from the other by a side
chain called an R-group
Amino acid structure
Alanine and Serine
(2 amino acids)
What proteins do.
 Some proteins control the rate of reactions and
regulate cell processes
 Some proteins are used to form bones and muscles
 Some proteins transport substances in and out of cells
or help fight disease
Proteins have up to 4 levels of
organization.
 First level is the sequence of amino acids in a protein
chain
 Second, the amino acids within a chain can be twisted
or folded
 Third, the chain itself may be folded
 Proteins with more than one chain may have a specific
spatial arrangement
Chemical Reactions and
Enzymes
 Chemical reaction-a process that changes one set of
chemicals into another set of chemicals
 Some chemical reactions are slow (oxidation/rust)
some are fast (oxidation of hydrogen)
 Reactants-the elements or compounds that enter the
reaction
 Chemical reactions always involve the breaking and
making of chemical bonds and thus new products
 Energy is involved (exothermic or endothermic)
An exothermic chemical
reaction
 http://www.youtube.com/watch?v=4FROxZ5i67k
Energy in reactions
 Exothermic reactions often occur spontaneously or
need some “activation energy) ie. Kick start but once
they get started, energy is released.
 Endothermic reactions absorb energy.
 Example of absorbing energy is using electricity to
break the bonds of H2O to get the components of
H2O
Activation Energy
 Even exothermic reactions may need a “spark” to get
started.
 Activation energy is the energy needed to get a
reaction started.
 The match to light the firecracker would provide the
activation energy.
Enzymes
 Catalyst-a substance that speeds up the rate of a
chemical reaction. This works when the catalyst
lowers the activation energy needed.
 Enzymes are biological catalysts
 Enzymes provide a site where reactants in cells can be
brought together to react.
 The reactants of enzyme-catalyzed reactions are
known as substrates.