Chapter 2
Chemistry of Life
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
2-1
2.1 Basic Chemistry
• Matter—anything that occupies ______ & has _____
(weight). What’s not matter?
• All matter is composed of elements.
• 90% of the body is made up of C, N, O, & H.
• _______—smallest unit of an element that still retains
the chemical & physical properties of the element.
• ______—positive charge, 1 atomic unit, in nucleus.
• ______—neutral charge, 1 atomic unit, in nucleus.
• ______—negative charge, 0 atomic units, electron cloud.
(inner shell can hold up to 2 e - / others up to 8 e -)
At. No. = P
At. Wt. = P + N
2-2
2.1 Basic Chemistry
Fig 2.1 Elements & Atoms
2-3
1
2.1 Basic Chemistry
• __________—same type of atom with varying numbers of
neutrons.
12 C
13C
14C (radioactive)
*Radioactive isotopes—same type of atom with varying
numbers of neutrons & can be used as a tracer.
131I—used to check the condition of the _______ gland.
PET—a way to
determine comparative
activity of tissues.
Ability of radiation to
kill cells is often applied
to cancer cells.
Fig 2.2 Use of radiation to
aid a diagnosis
2-4
2.1 Basic Chemistry
• Molecules and Compounds:
• _______—bonding of atoms to form a chemical
unit.
H2
N2
O2
hydrogen gas
nitrogen gas
oxygen gas
• Compound—_______ atoms bond together.
NaCl
H 2O
NaOH
salt
water
sodium hydroxide
• Ionic bonding—the attraction between __________
charged atoms.
NaCl (table salt)
2-5
2.1 Basic Chemistry
Fig 2.4 Ionic Bonding
Ionic Bonding
2-6
2
2.1 Basic Chemistry
• ________ bonding—occurs when atoms share a
pair of electrons.
H2O
O2
Fig 2.5 Covalent Bonding
2-7
2.2 Water and Living Things
• ______—most abundant molecule in living organisms.
(60-70% of total body weight)
• Hydrogen bonding—_____ bond can be broken
easily.
• Properties of water:
1.Water is _____ at room temperature.
2.Temperature of liquid water rises & falls _____.
3.Water has a ____ heat of vaporization.
4.Frozen water is ____ dense than liquid water.
5.Water molecules are cohesive.
6.Water is a solvent for polar molecules, facilitates
chemical reactions both outside & within our
bodies.
2-8
2.2 Water and Living Things
• Acids and Bases:
• ______—substances that dissociate in H2O,
releasing H+.
HCl
H+ + Cl- (dissociates in H2O)
(Acidic solutions—high H+ concentration)
• _______—substances that either take up H+ or
release OH -.
NaOH
Na+ + OH(Basic solutions—high OH- concentration)
2-9
3
2.2 Water and Living Things
• pH Scale—used to indicate the acidity and
basicity of a solution.
pH scale ranges from 0
to 14. As we move
toward a higher pH,
each unit has 10
times the basicity of
the previous unit, and
as we move toward a
lower pH, each unit has
10 times the acidity of
the previous unit.
Fig 2.8 The PH Scale
2-10
2.3 Molecules of Life
• Macromolecule—a molecule that contains many
subunits.
Synthesis—occurs
when subunits bond
following a dehydration
reaction.
Degradation—occurs
when the subunits in a
macromolecule separate
after the addition of H 2O.
Fig 2.9 Synthesis & degradation
of macromolecules
2-11
2.4 Carbohydrates
• ____________—always contain C and H atoms & serve
as quick or short-term energy storage.
1. Monosaccharide—simple sugar made up of carbon atoms.
(glucose, fructose, & galactose)
2. Disaccharide—made by joining only two monosaccharides
together by a dehydration reaction.
maltose
(glucose + glucose)
sucrose
(glucose + fructose)
3. Polysaccharide—made up of many glucose units.
________—stored carbohydrates in plant cells.
Glycogen—stored carbohydrates in the liver.
Cellulose—found in plant cell walls, serves as dietary
fiber in humans.
2-12
4
2.5 Lipids
• Triglyceride—made up of one ______ molecule
plus three fatty acid molecules and used for longterm energy storage.
1.Fats—usually of animal origin and are solid at room
temperature. (lard & butter / saturated fatty acids)
2.Oils—usually of plant origin & are liquid at room
temperature. (peanut oil / unsaturated fatty acids)
*Emulsifiers like bile, produced in the
liver, act on fats in the duodenum.
2-13
2.5 Lipids
3. Phospholipids—
primary component
of _______ ___________
and are soluble in
H2O because they
have a hydrophilic
group.
Fig 2.14 Phospholipid
Structure & Function
2-14
2.5 Lipids
4. _______—type of
lipid molecule having
a complex of four carbon
rings—like cholesterol,
estrogen, progesterone,
& testosterone. A diet
high in saturated fats &
cholesterol can cause
plaque to build up inside
the lining of blood vessels.
Fig 2.15 Steroids
2-15
5
2.6 Proteins
• Proteins—macromolecules with _____ ____ subunits.
(keratin, collagen, actin & myosin, hormones, &
hemoglobin)
* Amino acids—end product of protein
digestion.
*___________—control nearly all the chemical
reactions that occur in the body and when exposed
to extremes in heat & pH, they undergo a change in
shape called DENATURATION.
How Enzymes Work
2-16
2.6 Proteins
Levels of Protein Organization:
1. _______ structure—linear sequence of amino
acids joined by peptide bonds.
(polypeptide chain)
2. Secondary structure—occurs when polypeptide
takes on a certain orientation in space.
3. ________ structure—final 3-dimensional shape.
4. Quaternary structure—polypeptide with its own
primary, secondary, & tertiary structures.
(hemoglobin and most enzymes)
2-17
2.6 Proteins
Fig 2.16 Levels Of Protein Organization
Protein Synthesis
2-18
6
2.7 Nucleic Acids
• ____ (deoxyribonucleic acid)—stores genetic
information in the cell & codes for the order in
which amino acids are to be joined.
*polymers of nucleotides.
*nucleotide—phosphate, sugar (deoxyribose), and
base.
*double stranded helix.
*bases—(A) adenine, (T) thymine, (C) cytosine,
(G) guanine.
*Adenine ALWAYS pairs with _______.
*_______ ALWAYS pairs with Guanine.
a
2-19
2.7 Nucleic Acids
Fig 2.17 Overview of DNA Structure
2-20
2.7 Nucleic Acids
• RNA (ribonucleic acid)
*Single stranded.
*Polymers of nucleotides.
*Nucleotide—phosphate, sugar (_______), and a
base.
*Bases—(A) adenine, (U) uracil, (C) cytosine, and
(G) guanine.
*Adenine ALWAYS pairs with Uracil.
*Cytosine ALWAYS pairs with Guanine.
2-21
7
2.7 Nucleic Acids
• ATP (adenosine triphosphate)—nucleotide that is
a high ______ carrying molecule in all
cells—may be cashed in for energy when
needed.
Fig 2.18 ATP Reaction
2-22
8