Download Chemistry notes

CHAPTER 6
The Chemistry of Life
Atoms & Their Interactions
• elements - make up earth &
organisms (O, C, H, N,
S, P, K, Si, Al, Fe, Ca)
–cannot be broken down by a
chemical process into a simpler
substance
Atoms & Their Interactions
Natural elements in living things
114 elements in all
Only 25 are essential to living things
Carbon(C), Hydrogen(H), Oxygen(O),
and Nitrogen(N) make up 96% of human
body
Trace elements – elements found in
living things in very small amounts
Atoms & Their Interactions
•Atoms - smallest
particle of an
element that has
the elements
properties
Atoms & Their Interactions
Structure of an atom
protons (+) = Atomic number
neutrons (no charge)
electrons (-)
Atoms & Their Interactions
Electron Energy Levels
– electrons exist around
a nucleus in energy
levels
1st level – 2 electrons
2nd level – 8
electrons
3rd level – 18
electrons
12
18
17
8
34
7 56
1
6
1
15
16 2
13 14 3
7
58
2
9
4 10
11 12
7
N
14.0067
Nitrogen
Atoms & Their Interactions
Atoms that contain equal amounts of
protons and electrons have a neutral
charge.
Isotopes: atoms of the same element
that have a different number of neutrons
Ex. Carbon-12 6p+ & 6n0
Carbon-14 6p+ & 8n0
Atoms & Their Interactions
Isotopes - have an unstable
nucleus that breaks
apart
giving off energy in the form of radiation
used to tell age of fossils
preserve food
treat cancer
Atoms & Their Interactions
Compound: atoms of 2 or more
different elements that are
chemically combined
Ex. NaCl – salt
H2O - water
Atoms & Their Interactions
Covalent Bond: chemical bond
formed when two atoms share
electrons
Ex. H2
Molecule: group of atoms held
together by covalent bonds
No overall charge
Ex. H2O
Atoms & Their Interactions
Electrons shared in a
chemical bond (each
atom donates one
electron)
Outer energy level in
both elements is full
(stable)
Double covalent bonds
have four electrons
Triple covalent bonds
have six electrons
Atoms & Their Interactions
Atoms & Their Interactions
Ion: an atom that gains or loses electrons
Ionic Bond: attractive force between two ions
of opposite charge
Electrons are lost by one
element and gained by
another
Outer energy level in both
elements is full (stable)
Atoms & Their Interactions
Atoms & Their Interactions
Chemical Reactions
Occur when bonds are formed or broken
Substances recombine into different
substances
In organisms, reactions occur inside cells
Metabolism = all of the chemical
reactions that occur within an organism
Atoms & Their Interactions
Chemical Reactions
Reactants: substances that undergo chemical
reactions
Products: substances formed by chemical
Reactants
Products
reactions
Atoms are neither created or destroyed in a
chemical reaction … they are simply rearranged
Atoms & Their Interactions
Mixtures
Combination of substances in
which individual components retain
their own properties
Components do not combine
chemically
Ex. Sand & sugar mixture
Atoms & Their Interactions
Solutions
Mixture in which one or more substances (solutes)
are distributed evenly in another substance
(solvent)
One dissolved in another
Ex. Kool-aid
Concentration: amount of solute dissolved in
solvent
Organisms can’t survive unless concentrations
stay within a specific narrow range
Atoms & Their Interactions
Acids & Bases
Chemical reactions in organisms depend
on pH of the environment
pH is the measure of how acidic or basic a
solution is Scale 0-14
acid: 0 to < 7
bases: > 7 to 14
Atoms & Their Interactions
Acids - - release hydrogen ions (H+)
in water
Ex. HCl (hydrochloric acid)
Bases - - produce hydroxide ions
(OH-) in water
Ex. NaOH (sodium hydroxide)
6.2 Water & Diffusion
Why is Water Important?
Life process
Transport materials
Makes up 70-95% of
most organisms
MOST IMPORTANT
COMPOUND IN LIVING
ORGANISMS
6.2 Water & Diffusion
What is a polar molecule?
POLAR BOND: atoms
in a covalent bond do not
share electrons equally
POLAR MOLECULE:
molecule with an unequal
distribution of charge
Molecule has a
positive end and a
negative end
Positively
charged
end
Negatively
charged end
6.2 Water & Diffusion
Water is a polar molecule.
Shared electrons spend more time near
the oxygen nucleus that near the
Hydrogen nucleus
Attracts other polar molecules
Can dissolve many ionic compounds
(salt) and other polar molecules (sugar)
Attracts other water molecules
6.2 Water & Diffusion
What is a Hydrogen Bond?
Positively charged hydrogen atom of one
water molecule attract the negatively charged
oxygen atom of another water molecule =
weak hydrogen bond
IMPORTANCE:
Helps hold biomolecules together
(proteins)
Creeps up thin tubes (capillary action in
plants)
6.2 Water & Diffusion
Water resists temperature change.
Requires more heat to increases
temperature
Loses a lot of heat when cools
Acts as an insulator to help
maintain steady environment
Helps cells maintain
Homeostasis
6.2 Water & Diffusion
What is Diffusion?
Net movement of particles from an
area of higher concentration to an
area of lower concentration
6.2 Water & Diffusion
What affects the rate of diffusion?
Concentration
Temperature
Pressure
6.2 Water & Diffusion
How does concentration affect diffusion?
Primary controlling factor
More concentrated = faster diffusion (more
collisions)
How does temperature affect diffusion?
Increase temperature = increase in energy
Particles move faster = faster rate of diffusion
How does pressure affect diffusion?
Increase pressure accelerates particle motion
which increases rate of diffusion
6.2 Water & Diffusion
What is the result of Diffusion?
Particles become evenly distributed
Motion and collisions still occur but no
further change in concentration
Dynamic Equilibrium
6.2 Water & Diffusion
What is the Concentration Gradient?
Concentration Gradient: difference in
concentration of substance across space
ions and molecules move with
concentration gradient
From higher concentration to lower
concentration
Diffusion will occur until there is no
longer a concentration gradient
6.2 Water & Diffusion
What does diffusion
have to do with
living organisms?
Diffusion is one
way cells move
substances in and
out of the cell
Material moving
out of cell equals
material moving
into cell
6.3 Life Substances
Organisms are made up of organic
compounds.
☞All organic compounds contain Carbon
(C)
☞To be stable, a carbon atom forms 4
covalent bonds
6.3 Life Substances
Ways a Carbon Atom Bonds:
☞When 2 carbon atoms form covalent
bonds they can share 1, 2 or 3 electron
pairs
☞Single Bond – share 1 pair electron
☞Double bond – share 2 pairs electrons
☞Triple Bond – share 3 pairs electrons
6.3 Life Substances
Shape of bonded carbon atoms can vary.
☞Straight Chains
☞Branched chains
☞Ring
The many different ways of bonding lead
to large number of carbon structure
possibilities.
6.3 Life Substances
What is an Isomer?
☞Compounds with same chemical formula but
different 3D structure
☞ Ex: Glucose (C6H12O6) & fructose (C6H12O6)
Fructose
Glucose
6.3 Life Substances
What are macromolecules ?
☞Large organic compounds
☞Cells build biomolecules by bonding small
molecules together to form polymers
☞Four main macromolecules
☞Carbohydrates
☞Lipids
☞Proteins
☞Nucleic Acids
6.3 Life Substances
Carbohydrates = ENERGY
☞Composed of C, H, O
☞Monosaccharides – simple sugars
☞Ex. Glucose –found in some fruits (less
sweet)
☞
Fructose – honey (more sweet)
☞Dissacharides - formed from 2 monosac.
☞Ex. Sucrose – table sugar
6.3 Life Substances
☞Polysaccharides – formed from many
monosaccharide subunits
☞Starch – energy storage of plants
☞Gylcogen – energy stored in liver
of mammals
☞Cellulose – cell wall of plants
6.3 Life Substances
Lipids = INSULATION / PROTECTION
☞Insoluble in water because nonpolar molecule
☞Examples: fats, oils, waxes, steroids
☞Importance to organisms
☞Some energy storage
☞Insulation
☞Protective covering
☞Major components of membranes that
surround all living cells
6.3 Life Substances
Proteins = STRUCTURE
☞Made up of amino acids – building
blocks of proteins
☞20 Amino Acids
☞Held together by peptide bonds
6.3 Life Substances
Proteins come in many shapes & sizes.
☞ # of amino acids and how they interact
determines 3D shape and twist of protein
☞Shape is important in function of protein
in a cell
☞If amino acid sequence changes, shape of
protein changes and it won’t function
properly
6.3 Life Substances
Importance of proteins
☞Functions of body systems
☞Muscle contraction
☞Transporting oxygen in the blood
☞Provide immunity
☞Regulate other proteins
☞Chemical reactions
6.3 Life Substances
Enzymes – protein that changes rate of a
chemical reaction
6.3 Life Substances
Action of enzymes:
1. Substrate fits into enzyme active
site (lock & key)
2. Enzyme alters substrate shape
3. Products are released
4. Enzyme ready to act on more
substrate
6.3 Life Substances
Nucleic Acids = CODE OF CELL
INFORMATION
☞Complex macromolecules that stores
cellular information
☞Made up of nucleotides
☞Examples: DNA & RNA
MACROMOLECULES SUMMARY
Macromolecule
subunits
Carbohydrates monosacchari
des
function
examples
Energy
storage
Starch
Gylcogen,
cellulose
MACROMOLECULES SUMMARY
macromolecule
subunits
function
examples
Carbohydrates
monosaccharid
es
Energy
storage
Starch
Gylcogen,
cellulose
Lipids
Gylcerol
Fatty acids
Energy storage
insulation
Animal fat
Vegetable oil
MACROMOLECULES SUMMARY
macromolecule
subunits
Carbohydrate monosacchar
s
ides
Lipids
Gylcerol
Fatty acids
Proteins
Amino acids
function
examples
Energy
storage
Starch
Gylcogen,
cellulose
Energy
storage
insulation
Structure
enzymes
Animal fat
Vegetable oil
Muscle
protein
immunity
MACROMOLECULES SUMMARY
macromolecule
subunits
Carbohydrates monosaccharid
es
function
examples
Energy
storage
Starch
Gylcogen,
cellulose
Lipids
Gylcerol
Fatty acids
Energy storage
insulation
Animal fat
Vegetable oil
Proteins
Amino acids
Structure
enzymes
Muscle protein
immunity
Nucleic Acids
nucleotides
Store
information
DNA
RNA