Transcript Chapter 2

Chapter 2
The Chemistry of Life
Objectives 2-1
1. Differentiate between atoms
and elements.
2. Analyze how compounds are
formed.
3. Distinguish between covalent
bonds, ionic bonds, and
hydrogen bonds.
I. Nature of Matter
A. Atoms – Smallest unit of matter
that cannot be broken down by
chemical means.
1. All matter consists of atoms.
2. Atoms consist of protons,
neutrons and electrons.
I. Nature of Matter Cont.
a. Protons – positive charge in
nucleus
b. Electrons – tiny, negative
charge outside nucleus
c. Neutrons- neutral charge in
nucleus
The Atom
I. Nature of Matter Cont.
B. Elements – pure substance made
of one kind of atom
1. Represented by symbols
2. Elements differ in the number of
protons.
3. Isotopes – atoms of the same
element with different numbers of
neutrons
Periodic Table of Elements
I. Nature of Matter Cont.
C. Chemical bond – force that joins
more than one atom
1. Compound – Two or more
elements chemically joined
2. Covalent Bonds – two or more
atoms share electrons
a. A molecule is held together
with covalent bonds.
I. Nature of Matter Cont.
b. Electrons are grouped in
different levels.
i. The outer level determines
bonding.
ii. The max. outer level for
hydrogen and helium has
two electrons.
iii. The max. outer level for
all other elements is eight.
Covalent bond
I. Nature of Matter Cont.
c. An atom is stable when its
outer electron level is full.
d. Atoms react readily when
outer electron level is not full.
3. Hydrogen Bonds – weak
chemical bonds between polar
molecules.
I. Nature of Matter Cont.
a. Polar molecule – partially
negative end and partially
positive end
b. Partial positive end of one
molecule is attracted to the
partial negative end of another.
I. Nature of Matter Cont.
4. Ionic Bonds – attraction between
positively charged ions and
negatively charged ions.
I. Nature of Matter Cont.
a. Atoms that lack full outer
electrons levels will donate or
accept electrons to have a full
outer electron level.
b. Ion – atom with an unequal
number of protons and
electrons.
Ionic Bond
II. Water and Solutions
• Objectives
–Analyze the properties of
water.
–Describe how water dissolves
substances.
–Distinguish between acids
and bases.
II Water and Solutions
A. Water in living things
1. Storage of energy
a. Changes in water
temperature happen
slowly.
b. Aids in maintaining
homeostasis.
2. Cohesion and adhesion
A. Cohesion- attraction between
substances of the same kind due
to hydrogen bonding.
B. Adhesion- attraction between
different substance due to
polarity.
ex: Capillary action
Cohesion
Adhesion
B. Aqueous Solutions- one
substance is evenly distributed
through water.
1. Polarity
a. Ionic compounds and
polar molecules dissolve in
water.
b. Ions become surrounded
by water.
c. Nonpolar molecules do not
dissolve in water.
Surface Tension
Hydrogen Bonding
Nonpolar vs. Polar
Cell Membrane
2. Acids and Bases
a. Hydrogen ion (H+) –
Broken water molecule
forms a positively charged
ion
b. Hydroxide ion (OH-) –
Broken water molecule
forms a negatively charged
ion
c. Acid- a compound that
forms hydrogen ions in
water
Acids and Bases
2. Acids and bases cont.
d. Base – a compound that forms
hydroxide ions in water or
decreases the number of hydrogen
atoms
e. pH scale – 0 to 14
i. 0 to 7- acidic
ii. 7 – neutral
iii. 7-14 – basic
iv. Factor of 10 scale
pH Scale
III. Chemistry of
Cells
2-3 Objectives
• Summarize the characteristics
of organic molecules.
• Compare the structure and
function of organic
macromolecules.
Carbon Compounds:
Most non-water matter in your
body is made of organic
compounds containing carbon.
4 Classes of Organic
Compounds:
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•
•
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Carbohydrates
Lipids
Proteins
Nucleic Acids
A. Carbohydrates:
1) Organic compounds made of
Carbon, Hydrogen, & Oxygen in
a 1:2:1 ratio
A. Carbohydrates:
2) Key source of energy
3) Found in most foods, including
fruits, vegetables, and grains
A. Carbohydrates:
4) Made of single sugars called
monosaccharides…2 sugars
are disaccharides.
5) Starch is a carbohydrate that
stores energy in plants
A. Carbohydrates:
6. Glycogen is a carbohydrate
made by animals to store
energy
A. Carbohydrates:
7. Cellulose is an indigestible
carbohydrate that provides
structural support for plants
B. Lipids:
1. Mostly insoluble in water
2. Include fats, phospholipids,
steroids, and waxes
B. Lipids:
3. Important part of cell
membranes
4. Fats are lipids that store
energy
Fats
a. Contain 3 fatty acids bonded
to a glycerol molecule
backbone
Fats
b. Glycerol is a 3-carbon organic
molecule
c. A fatty acid is a long chain of
carbon atoms with attached
hydrogen atoms
Fats
d. Unsaturated fats – liquid at
room temperature. Contain
double bonds.
e. Saturated Fats – Solid at room
temperature. No double bonds.
Fat
C. Proteins
1. Protein – large molecule formed
by linked amino acids.
2. Twenty amino acids make up all
proteins.
a. Order and number of amino
acids determine protein.
b. Amino acids fold and twist into
a compact protein.
Hemoglobin
C. Proteins
3. Importance
a. Structural
b. Enzymes- speed up
chemical reactions
c. Immune system
d. Muscle contraction
Actin and Myosin
D. Nucleic Acids
1. Nucleic Acid – long chain of
nucleotides, codes for genetic
information.
2. Nucleotides – contains a sugar
phosphate back bone and a base.
a. There are 4 bases
b. Variation on pattern and number
of bases creates genetic
variation.
DNA
D. Nucleic Acid
3. DNA – deoxyribonucleic acid,
two strands form a double
helix. Contained in
chromosomes.
4. RNA – Ribonucleic acid,
single or double stranded,
involved in manufacture of
proteins.
E. ATP
1. ATP – Adenosine
Triphosphate, Energy storage
molecule used by all living
things.
2. Cells require ATP to function.
ATP
IV. Energy and
Chemical Reactions
Objectives
Evaluate the importance of
energy to living things.
Relate energy and chemical
reactions.
Describe the role of enzymes
in chemical reactions.
IV. Energy and
Chemical Reactions
Energy- the ability to change or
move matter.
Types- heat, light, mechanical,
chemical,
Chemical reactions convert
store or release energy.
A. Energy
a. Depicted by chemical
equations
B. written: reactants products
i. reactant is starting material
ii. Product- newly formed
substance
B. Energy in Chemical
Reactions
1. Energy is absorbed or
released during a chemical
reaction.
2. Metabolism is the sum total of
all chemical reactions.
C. Activation Energy
1. Activation energy – energy
needed to begin a chemical
reaction.
Activation Energy
D. Enzymes
1. Enzymes – substance that
increase the speed of a
chemical reaction or lower the
activation energy.
a. Most are proteins.
b. Without enzymes chemical
reaction would not happen
quickly enough to sustain life.
Enzymes
D. Enzymes
Ex: CO2 + H2O  H2CO3\
c. Carbonic anhydrase
converts carbon dioxide and
water to hydrochloric acid
and back.
D. Enzymes
2. Enzymes are highly specific.
a. Substrate- the substance on
which an enzyme acts.
b. Active site – deep fold on
enzyme at which the
substrate attaches.
D. Enzymes
c. Process
i. Substrate(s) attach(es) to
enzymes active site changing
the enzymes shape.
ii. Enzyme reduces the
activation energy of the
reaction
iii. Substrate leaves and enzyme
returns to the starting position.
D. Enzymes
d. Factors that affect an enzymes
shape affect its activity.
i. Temperature
ii. pH
Temp. affects enzymes