Transcript CHAPTER 6: THE CHEMISTRY OF LIFE

CHAPTER 6: THE CHEMISTRY OF LIFE
WHAT YOU WILL LEARN:
1. You will relate the structure of an atom to how
it interacts with other atoms.
2. You will explain how water is important to life.
3. You will compare the role of carbon compounds
in organisms.
WHY IT’S IMPORTANT:
• Living organisms are made of
simple elements as well as
complex carbon compounds.
With an understanding of these
elements and compounds, you
will be able to relate them to how
living organisms function.
6.1 Atoms and their Interactions
Both living and nonliving things are
composed of the same basic building
blocks called Atoms
I. Elements
Substance that can’t be broken down
into simpler chemical substances.
90 naturally occurring elements
A. Natural elements in living things
Only about 25 of the natural
occurring elements are essential to
living organisms.
Four out of the 90 make up 96% of a human
(1) Carbon
(2) Hydrogen
(3) Oxygen
(4) Nitrogen
• B. Trace Elements
• Elements found in living things in very small
amounts
• Plants obtain trace elements by absorption
• Animals get their trace elements by eating
II Atoms: The Building Blocks of
Elements. The smallest part of an
Element that has the characteristics of
that Element.
• A. The structure of an atom
• The center of the Atom the Nucleus made of
positively charged protons and particles that
have no charge - Neutrons.
• Forming a cloud around the outside are
negatively charged Electrons.
• B. Electron energy levels
•
Electrons travel around the Nucleus in
certain
regions known as energy levels
• The first level is the smallest it hold only two
electrons
• The second level is larger, it can hold 8 electrons
• The third can hold 18 electrons.
• Atoms contain equal numbers of electrons and
protons
III. Isotopes of an Element
• Atoms of the same element that have
different numbers of Neutrons are Isotopes
• C12 C13 C14
• Isotopes such as C12 tend to break apart –
they are radioactive
Atoms of the same element that have
different numbers of Neutrons are
Isotopes C12 C13 C14
Isotopes such as C12 tend to break
apart – they are radioactive
•
•
A. How covalent bonds form
Atoms combine to become more stable
•
Atoms like to have their outer energy shell filled
•
Elements can fill their outer shell by sharing electrons.
•
A covalent bond is make by sharing electrons
•
A molecule is a group of Atoms held together by covalent bonds. H2O
• B. How Ionic Bonds Form
• An Atom that has lost or gained an electron
becomes charged thus it is an ion Na + Cl• The attractive force between two atoms of the
opposite charge is an ionic bond
• Less abundant in living things than Covalent
bonds but, still very important --sodium/potassium ions for nerve impulses and
calcium ions for muscle contractions.
V. Chemical Reactions
Chemical reactions occur when bonds are
formed or broken
All the chemical reactions in an organism are
referred to as Metabolism – breaking down and
building up
• A. Writing chemical equations
•
•
Reactants – undergo chemical reactions H + O
Products – substances formed by chemical
reactions H2O,Table sugar C12H22O11,
glucose C6H12O6
VI. Mixtures and Solutions
A mixture is a combination of substances in which the
individual components retain their own properties Sand/Sugar
A solution is a mixture in which one or more substances
(solute) are distributed evenly in another (solvent) Kool – Aid
• A. Acids and Bases
• Chemical reactions can occur only when
conditions are right.
• Temperature
• Energy
• pH
The pH is measure of how acid or basic a solution is.
Scale
0
7
14
Acid
Neutral
Base
H+
0H-
6.2 Water and Diffusion
• I. Water and its Importance
• Most life processes can occur only when molecules
and ions are free to move and collide with one another
• Water allows movement.
• A. Water is polar
•
A polar molecule is a molecule with
unequal distribution of charge.
•
O•
H+
H+
•
Water attracts to water
• Hydrogen bonds - attractions between
hydrogen and oxygen
•
Capillary action
• B. Water resists temperature changes
•
Water is like an Insulator helps maintain
a steady
environment
• C. Water expands when it freezes
•
Ice on ponds
•
Ice breaking rocks
II. Diffusion
Particles of matter are in constant motion,
colliding with each other.
• A. Early observation: Brownian motion
•
Brown – pollen grain in water
•
Dye particles
• B. The process of Diffusion
• The net movement of particles from area of high
concentration to areas of low concentration.
• Slow process because it relies on random
molecular motion.
•
Key factors: Concentration
•
Temperature
•
Pressure
• C. Diffusion in living systems
• The difference in concentrations of a substance across
space is called Concentration Gradients.
• Diffusion is one way cells move things in and out of the cell
(air/blood)
6.3 Life Substances “you are what you eat”
• I. Role of Carbon in Organisms
• Single bond shares 1 pair of electrons
• Double bond shares 2 pairs of electrons
• Triple bond shares 3 pairs of electrons
• Carbon--because of its 4 outer electrons can form:
•
Straight chains
•
Branched chains
•
Rings
• Compounds that have the same simple formula (what and how much) but
different structures are Isomers
• A. Molecular Chains
• Carbon compounds vary in size from two
carbons to thousands
• A polymer is a large molecule formed when
many smaller molecules bond together.
• Condensation - water is removed from two
smaller molecules that have H+ and an OH• Hydrolysis - Polymers are broken apart by the
insertion of a water molecule
•
B. The Structure of Carbohydrates
•
Contain C H O 2H to 1O
•
•
Monosaccharides – simple sugar
( glucose and fructose)
•
•
Disaccharide – two monosaccharide linked together.
( sucrose)
•
Polysaccharide – polymers composed of many monosaccharides. ( starch, glycogen, and cellulose )
C. The structure of Lipids
Contain C H O called fats and oils
Used for energy storage, insulation and protective coatings.
• D. The structure of Proteins
• Contain C H O N
• Basic building blocks of protein are amino acids.
• 20 common amino acids
• Peptide bonds hold amino acids together to form
proteins
• Proteins are the building blocks of our bodies
• Proteins called Enzymes control the rate of many
chemical reactions within the body
• E. The structure of Nucleic acids
• Consist of Carbon, Hydrogen, Oxygen, and Nitrogen
•
Made of smaller units called NUCLEOTIDES
•
A Nucleotide has three groups of molecules:
•
Five carbon sugar
•
A phosphate group
•
A base