Transcript Chapter 2 Chemistry of Life ppt.

The Chemistry of Life
Atoms
• The basic unit of matter
• Greek, atomos meaning “unable
to cut”
• Named after Democritus...there
has to be a limit =atom.
Atoms
• What does an atom consist of?
• Subatomic particles: protons (+),
neutrons, and electrons (-).
• What is the center of an atom
called?
• Nucleus
• Where do we find electrons?
• Constant motion surrounding the
nucleus.
SUBATOMIC
PARTICLES
• Why are atoms
neutral despite
having charged
particles?
• Atoms have equal
numbers of
electrons and
protons/have
equal, but
opposite charges.
(they balance
out)
Elements and
Isotopes
• What is a chemical element?
• A chemical element is a pure
substance that consists entirely of
one type of atom (C, Na, H, N, O,
etc.)
• What is an isotope?
• Atoms of the same element w/
different number of neutrons.
Isotopes of Carbon
Nonradioactive carbon-12
6 electrons
6 protons
6 neutrons
Nonradioactive carbon-13
6 electrons
6 protons
7 neutrons
Radioactive carbon-14
6 electrons
6 protons
8 neutrons
Because they have the same number of electrons, all isotopes of an
element have the same chemical properties.
Chemical
Compounds
• What is a chemical compound?
• Substance formed by the chemical
combination of two or more
elements.
• H20, NaCl, C6H1206
Chemical Bonds
• What are the main types of
chemical bonds?
• Ionic & Covalent
• Ionic- electrons transfer from one atom to the
other.
Sodium atom (Na)
Chlorine atom (Cl)
Sodium ion (Na+)
Chloride ion (Cl-)
Transfer
of electron
Protons +11
Electrons -11
Charge
0
Protons +17
Electrons -17
Charge
0
Protons +11
Electrons -10
Charge
+1
Protons +17
Electrons -18
Charge
-1
Chemical bonds
• Covalent Bonds- electrons are
shared b/w atoms = molecule.
What molecule is
this?
Hydrogen Bonds
• A single water molecule may be
involved in as many 4 hydrogen
bonds at the same time.
• Cohesion: attraction b/w molecules
of the same substance.
• Adhesion: attraction b/w different
substances.
• Meniscus
Properties of Water
• Water is polar: there is an uneven
distribution of electrons b/w the
oxygen and hydrogen atoms.
• Why is this important?
• Water can react to form
ions:
H20 -> H+ + OHHydrogen ion
Hydroxide ion
Acids, Bases, and pH
• pH: ranges 0 to 14
• Acids: contain higher
[ ] of H+ ions than
pure water and have
a pH below 7.
• Bases: contain lower
[ ] of H+ ions than
pure water and have
pH values above 7.
Buffers
• Weak acids or
bases that can
react w/ strong
acids or bases to
prevent changes
in pH.
• Why is this
important?
Carbon Compounds
• What is the difference b/w
organic/inorganic chemistry?
• Carbon
• Carbon forms strong covalent bonds
and can join other carbon atoms to
from long chains (carbon-carbon
bonds)
• Four valence electrons
• No others like it.
Macromolecules
• Four groups of organic compounds
• “Giant molecules”
• Carbohydrates (starch and sugar)
− Living things main source of energy
− Monosaccharide's/polysaccharides, “ose”
• Lipids (cooking oil)
− Mostly CH, used to store energy
− Saturated, unsaturated
• Nucleic Acids (RNA & DNA) (CHNOP)
• Proteins (polymers of amino acids) (CHNO)
− AA are compounds w/an amino group (-NH2)
and a carboxyl group (-COOH), what
distinguishes each AA?
Amino Acids
General
Structure
Recognizing Macromolecules
Organic or Inorganic?
Nucleic Acid
Glucose
Lipids
Chemical Reactions &
Enzymes
• Why are chemical reactions important?
• Chemical reaction: a process that changes into
another set of chemicals.
• CO2 + H2O
H2CO3
• H2CO3
CO2 + H2O
• What are reactants? What are products?
• Chemical reactions always involve the breaking
of bonds in reactants and the formation of new
bonds in products.
Energy in Reactions
• To stay alive organisms
need to carry out reactions.
•
Growing, breathing, think, etc.
• Activation energy: the
energy needed to get a RxN
started.
• Can you tell which is an
energy absorbing
reaction/energy releasing
reaction?
Enzymes
• Some chemical
reactions are too slow...
• Catalyst: substance that
speeds up the rate of a
chemical reaction;
lowers activation energy
• Enzymes (“ase”) are
biological catalyst;
speed up chemical
reactions that take
place in the cell.
• Lipase
• Carbonic anhydrase
• Amylase
Enzyme Action
• How do they work?
• Enzyme-Substrate
Complex
• The reactants of
enzyme-catalyzed
reactions are known as
substrates.
• Not random; active site
and substrate fit like
“lock and key”
• What happens after?
• What factors affect
enzyme function?