Unit 2
Chemical Basis for Life
Chapter 6
Chemistry in Biology
Section 1: Atoms, Elements, & Compounds
Section 2: Chemical Reactions
Section 3: Water & Solutions
Section 4: The Building Blocks of Life
(p. 148-155)
(p. 156-160)
(p. 161-165)
(p. 166-171)
Section 1
Atoms, Elements, and Compounds
Objectives
• Living things consist of atoms of different elements
• Ions form when atoms gain or lose electrons
• Atoms share pairs of electrons in covalent bonds
The atom
• The _______ is the smallest basic unit of _______________
• Atoms are very small
The atom
• There are ____________ parts of a an atom
Subatomic
particle
Charge
Location
Proton
Positive
Nucleus
Neutron
Neutral
Nucleus
Electron
Negative
Surrounding
nucleus
Elements
• An _________is one particular type of atom, and it cannot be broken
down into a simpler substance by ordinary chemical means
• Gold
• Aluminum
• Helium
Key Elements
• In biology, there are SIX very important elements
•
•
•
•
•
•
Carbon
Hydrogen
Oxygen
Phosphorus
Sulfur
Nitrogen
How are elements different
• The number of protons determines the __________of an element
• Carbon: 6 protons
• Oxygen: 8 protons
• The number of electrons determines the _________of an element
• Carbon: 6 electrons, 4 on OUTSIDE
• Oxygen: 8 electrons, 6 on OUTSIDE
Carbon diagrams
Lonely Atoms
• Atoms rarely are found _____________in nature
• They will do ANYTHING to get to ____electrons on the outside
• Steal
• Dump
• Share
Compounds
• A ____________is a substance made of atoms of different elements
bonded together
• Result of sharing, stealing, or dumping electrons
• Atoms bonded in a specific ratio
Carbon Compounds (more about this later)
• Carbon can form many various bonds to form
•
•
•
•
Carbohydrates
_____________
Nucleic acids
_____________
Ionic Bond
• _________bonds are formed through the electrical force between
oppositely charged ions
• Opposites attract!
• Ex: Salt aka sodium chloride (NaCl)
• Positive sodium (Na+)
• Negative chloride (Cl-)
NaCl – ionic bond
Ions
• ________are atoms that have gained or lost one or more electrons.
• Results in a change in electrical charge
• Gain e• Lose e-
becomes ______________
becomes ______________
Ions, cont.
• Very important to organisms
• Hydrogen ions (H+) needed to produce chemical energy in cells
• Calcium ions (Ca2+) needed for all muscle movement in your body
• Chloride ions (Cl-) needed for many chemical signals in the brain
Covalent Bond
• Not all atoms easily gain or lose their electrons!
• Some atoms share their electrons instead!
• ___________Bond: forms when atoms share a pair of electrons
• Usually a very strong bond
• Atoms may have several covalent bonds to share several electrons
H2O – covalent bond
CO2 – covalent bond
Covalent Bond, cont.
• ____________: two or more atoms held together by covalent bonds
• Ex: carbon dioxide (CO2)
• Carbon atoms needs 4 electrons to fill outer level, oxygen needs two
• Carbon shares with 2 oxygen!
Review
• What are atoms?
• How are the particles that make up atoms diagrammed?
• What are the similarities between covalent and ionic bonds?
Section 2
Chemical Reactions
Objectives
• Bonds break and form during chemical
reactions.
• Chemical reactions release or absorb energy.
Evidence of a chemical reaction
_______________change
Formation of a solid (precipitate)
Color change (sometimes)
Odor (sometimes)
Formation of _____________
 Bonds


break & form during chemical reactions
Plant/Animal cells break down sugars to get usable
energy
Cells build protein molecules by bonding amino acids
together
 Chemical
reactions change substances into
different substances by breaking and forming
chemical ______________
 ___________are
the substance changed during a
chemical reactions

Oxygen (O2) & Glucose (C6H12O6)
 _________are
the substances made by a chemical
reaction

Carbon Dioxide (CO2) & Water (H2O)
6O2 + C6H12O6
6CO2 + 6H2O
 Energy


Bond energy is the amount of energy that will break a
bond between two atoms.
Every atom has different bond energy


A SPECIFIC amount of energy is needed to break bonds in an
oxygen molecule
A SPECIFIC amount of energy is needed to break bonds in a
glucose molecule
 Energy

is needed to break bonds in molecules
is released when bonds are formed
The amount of energy released is equal to the energy
that breaks the same bond

Energy needed to break apart water molecule = energy
released when hydrogen & oxygen atoms bond to form a
water molecule
 All


chemical reactions involve changes in ___________
Energy added to the reactants breaks their chemical bonds
When new bonds form in the products, energy is released
 Energy
is both absorbed and _______during a chemical
reaction!


Some release more energy than they absorb (Generous)
Some absorb more energy than they release (Greedy)
 Generous chemical RXNs
that release more energy
than they absorb



= ______________reaction
Excess energy is the difference in bond energy
between the reactants and products
Excess energy is often released as heat or light

Cellular respiration releases usable energy for your cells &
heat!
 Greedy chemical RXNs
that absorb more energy
than they release

= _______________reaction

In photosynthesis, plants absorb energy from sunlight and use
that to make sugars and carbohydrates
Exothermic VS. Endothermic graphs
But how does a rxn start?
• Some energy must first be absorbed by the reactants in ANY chemical
reaction
• The amount of energy needed will vary
• _________energy is the amount of energy that needs to be absorbed
for a chemical reaction to start
• Push a rock up a hill
Catalysts & Enzymes
• A ________is a substance that lowers the activation energy needed to
start a chemical reaction.
• Special proteins called _______are the biological catalysts that speed
up the rate of chemical reactions in biological processes.
Review
• What are the parts of a chemical reaction?
• How can energy changes be related to chemical reactions?
• What is the importance of enzymes in living organisms?
Section 3
Water and Solutions
Objectives
• Life depends on hydrogen bonds in water.
• Many compounds dissolve in water.
• Some compounds form acids or bases.
•Organisms’ bodies, (their _____________),
are made up of mostly ____________________
•The water in cells gives the cell _______________
and ___________________ materials within
organisms.
•All of the processes necessary for an
organism’s life take place within the
______________________________ of the cell
1. ______________________
2. ______________________
3. ______________________
Negative Charge
•Water is a “______________” molecule
•Form when atoms in a molecule
have ____________ pulls on the
_____________ they share.
Positive Charge
•Opposite charges of polar molecules can
interact to form ____________________
bonds.
•An attraction between a slightly
_______________ hydrogen atom
and a slightly ______________
atom.
(Usually
_______________________________)
•Hydrogen bonds are part of the
structures of _______________ and
of ______________
Positive Charge
Shared Electrons
Cohesion: the attraction among
__________________ of the same
substance.
Cohesion from hydrogen bonds makes
water molecules _____________________.
Cohesion produces __________________,
( “skin on water” )
Adhesion: the attraction among
__________________ of ______________
substances.
For example, water molecules stick to other
things.
Water in a test tube, (water is attracted
to the ____________)
Materials such as
________________ and
____________ cannot be
transported form one part
of an organism to another
unless they are dissolved
in blood, plant sap, or
other water based fluids.
______________:
Mixture of a substance
that is the same
throughout.
___________:
Substance that is present
in the greater amount and
dissolves another
substance.
___________:
Substance that dissolves
in a solvent.
Mixtures
____________________
____________________
• A mixture with easily separated
parts with their distinct
properties
• A mixture that it the SAME
throughout and hard to tell
individual characteristics
Some compounds form ______________ or _____________
because they _______________ into _______________
when they dissolve in ___________.
BASE:
ACID:
Compounds
that release
a proton
- a hydrogen ion(H+) –
when it dissolves
in water
Compounds that
remove H+ ions
from
a solution
More basic
More acidic
neutral
Review
• How does the structure of water make it a good solvent?
• What are the similarities and differences between solutions and
suspensions?
• What are the differences between acids and bases?
Section 4
The Building Blocks of Life
Objectives
• Carbon atoms have unique bonding properties.
• Four main types of carbon-based molecules are found in living things.
____________________
____________________
____________________
____________________
____________________
 _______________are
molecules composed of
carbon, hydrogen, and oxygen



Include sugars & starches
Can be broken down to provide useable energy for
cells
Major part of plant cell structure
 The most
basic carbs are simple sugars,
monosaccharides
 Polysaccharides are
polymers of monosaccharides
•USED BY CELLS FOR __________ ___________ AND
__________ ____________.
SIMPLE CARBS = _______________________________
COMPLEX CARBS = _____________________________
_____________________________
________________________________
________________________________
 Proteins are

A
the most varied of the carbon-based molecules in organisms
Have a role in movement, eyesight, digestion, etc.
_______________is a polymer made of monomers called amino acids
 __________are
molecules that contain carbon, hydrogen, oxygen, nitrogen, and
sometimes sulfur


Organisms use 20 different amino acids to build proteins
The body makes 12 of the 20, the other 8 come from food
•MAKE UP _________________.
•INVOLVED IN ALL _______ ____________.
•BUILDING BLOCKS = _________ __________.
•_________________= TYPE OF PROTEIN THAT STARTS AND
SPEEDS UP CHEMICAL REACTIONS IN CELLS.
 _______are
nonpolar molecules that include fats,
oils, and cholesterol



Contain chains of carbon bonded to oxygen &
hydrogen
Some broken down for useable energy
Others are part of a cell’s structure
 Fatty
acids are chains of carbon atoms bonded to
hydrogen atoms.


Saturated fatty acids have single carbon-carbon bonds
Unsaturated fatty acids have double carbon-carbon
bonds
•DON’T MIX WITH ______________.
•PHOSPHOLIPIDS – MAKE UP ________ ______________.
•FATS AND OILS THAT _________ ___________.
•ORGANISMS USE FATS AND OILS WHEN THEY HAVE
USED UP ___________________.
•_________- SOLID AT ROOM TEMPERATURE.
•_________- LIQUID AT ROOM TEMPERATURE.
•MAJOR ___________ ___________ MOLECULE IN CELL.
•ENERGY IN __________________ AND __________ AND
_____________________ MUST BE TRANSFERRED TO
ATP IN CELL TO BE USED.
 Detailed instructions to
build proteins are stored
in extremely long carbon-based molecules called
nucleic acids

Nucleic acids are polymers that are made up of
monomers called nucleotides
 Nucleic
acids differ from the other carbon-based
molecules


The others have a large # of functions
Nucleic acids have just 1 function… make proteins


DNA stores info for putting amino acids together to make
proteins
RNA helps to build proteins
•HAVE ALL INFO NEEDED TO MAKE __________.
•“_______________” OF LIFE.
•BUILDING BLOCKS OF _____________.
•TWO TYPES: ________ AND _______.
 Each
subunit of a complete carbonbased molecule is called a _________
A
polymer is a large molecule, or
macromolecule, made of many
monomers bonded together


Monomers of a polymer may be the same
(ex. Starches)
Or different (proteins)
COMPOUND
BUILDING BLOCK
(POLYMER)
(MONOMER)
PROTEIN
AMINO ACID
LIPID (FAT)
FATTY ACID
CARBOHYDRATE
SUGARS
NUCLEIC ACIDS
NUCLEOTIDE
Review
• What is the role of carbon in living organisms?
• What are the four major families of biological macromolecules?
• What are the functions of each group of biological macromolecules?