Download Chapter 2 Notes - Duplin County Schools

Chapter 2
The Chemistry of
Life
2.1 The nature of matter
•
•
Atom: the smallest particle of an
element that has the properties of that
element
Atom is made of three subatomic
particles:
1) Proton
* Positive, nucleus
2) Electron
* Negative, outside
nucleus in energy levels
 First energy level -- 2e
 Second energy level -- 8e
 Third energy level -- 18e
3) Neutron
* No charge, nucleus
• Number of protons usually is equal to the
number of electrons so that the overall
charge of an atom is neutral!!
• If atoms of the same element have
different number of neutrons, they are
called isotopes! EX. C - 12 , C - 13, C - 14
• When two or more atoms of different
elements are chemically combined you
create what is called a compound. EX.
Water
Compounds can be made with three different
kinds of bonds:
1) Covalent
 Share electrons to be
stable
 Strongest and most
common bond
 Molecule: group of
atoms held together with
covalent bonds with no
overall charge
 Van der Waals forces
(what holds molecules
together)
2) Ionic
 Gain / lose electrons
to be stable
 Ion: a charged
particle
 Less abundant in
living things than
covalent bonds
3) Hydrogen
Mixtures & Solutions
•
•
Mixture: a combination of substances
in which the individual components
retain their own properties
Solution: a mixture in which one or
more substances are distributed evenly
in another substance
– Two parts to every solution:
1. Solute --- What is being dissolved
2. Solvent -- What is doing the dissolving
* Most common... WATER
pH
• pH: a measure of how acidic or basic a
solution is
– Acid: substance that forms H+ ions in water
• 0-7
– Base: substance that forms OH- ions in
water
• 7 – 14
Acids & Bases
Acids
• Higher concentration of H+
ions
• pH value less than 7
• Sour taste
• React with metals
• Blue litmus paper will turn
red if an object is an acid
Bases
• Lower concentration of H+
ions
• pH value more than 7
• Bitter taste
• Slippery
• Turn red litmus paper blue if
an object is a base
2.2 Water and Diffusion
•
•
Perhaps the most important compound
in living organisms is water!
Properties of water:
1) Polarity
•
•
Has a positive and negative end
Gives water its dissolving property
2) Resists Temperature Changes
3) Water expands when it freezes
4) Adhesion  Graduated cylinder
•
Adhesion is greater between glass & water than
water & water!
2.3 Carbon Compounds
• The one element that defines living
organisms is Carbon!
• Carbon has four electrons in its
outermost shell; therefore, it can combine
with almost every other element
• Any compound that contains carbon is
considered to be an organic compound!
• If it does not contain carbon it is
inorganic.
Four types of Organic compounds:
1) Carbohydrates:




Made of C, H, O (C to H ration is 2 to 1)
Monomer: monosaccharide
Function: Provide quick energy
EX. Glucose: how animals store food
Starch: how plants store food
Cellulose: composes cell walls of plants
2) Lipids
• Made of C, H, O --- (C to H ratio higher
than 2 to 1)
• Monomer: Glycerol & 3 fatty acids
• Function: 1) Store energy 2) Insulation
3) Protection
• EX. Fats and Oils
3) Proteins
• Made of C, H, O, N, Sulfur
• Monomer: Amino Acid
– 20 AA
• Function: 1) Build Muscle
2)Transportation (blood -- hemoglobin)
3) Speed up chemical reactions (enzymes)
4) Nucleic Acids
•
•
•
•
Made of C, H, O, N, Phosphorus
Monomer: Nucleotide
Function: Store genetic information
EX. DNA (Deoxyribose Nucleic Acid) –
Master
RNA (Ribose Nucleic Acid) -- Copy of
DNA
2.4 Chemical Reactions and
Enzymes
•
•
Chemical reaction = changes one set of
chemicals into another set of chemicals
Chemical reactions have two parts:
1. Reactants
2. Products
•
CO2 + H2O  H2CO3
Reactants
Product
Enzymes
• Enzymes are proteins that act as a
biological catalyst.
• Catalyst: a substance that speeds up the
rate of chemical reaction
• Enzymes speed up chemical reactions
that take place in the cell.
Enzyme Action
• The enzyme-substrate complex
– Enzymes are substrate specific.
– They act like a lock and key.
– Enzymes will only catalyze their substrates.
• Regulation of Enzyme Activity
– Enzymes can be affected by:
•
•
•
•
Heat
pH
Concentration of Substrate
Proteins that turn enzymes “on” and “off”
Example of what an enzyme does!
How enzymes work
Potato + Peroxide  water + oxygen (catalase)
Where are enzymes?
• Enzymes regulate many chemical
reactions such as:
– Photosynthesis
– Cellular respiration
– Digestion
• Enzymes are reusable
– Once they work with one substrate they
release and go to another substrate.