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Transcript
H-B Woodlawn AP EXAM REVIEW
Part 1. Chapters 1-5 of Campbell 6th Ed.
(Answers to Questions can be found at www.hbwoodlawnbiology.net/apreview)
Ten Themes In the Study Of Life
EXPLORING LIFE ON ITS MANY LEVELS

Each level of biological organization has emergent properties

Cells are an organism’s basic units of structure and function

The continuity of life is based on heritable information in the form of DNA

Structure and function are correlated at all levels of biological organization

Organisms are open systems that interact continuously with their environments

Regulatory mechanisms ensure a dynamic balance in living systems
EVOLUTION, UNITY, AND DIVERSITY

Diversity and unity are the dual faces of life on Earth

Evolution is the core theme of biology
THE PROCESS OF SCIENCE

Science is a process of inquiry that includes repeatable observations and testable
hypotheses

Science and technology are functions of society
Table 1-1. Review of Ten Unifying Themes in Biology
Theme
Description
1. Emergent
properties
The living world has a hierarchical organization, extending from
molecules to the biosphere. With each step upward in organizational
level, novel properties emerge as a result of interactions among
components at the lower levels.
2. The cell
Cells are every organism’s basic units of structure and function. The
two main types of cells are prokaryotic cells (in bacteria and archaea)
and eukaryotic cells (in protists, plants, fungi, and animals).
3. Heritable
The continuity of life depends on the inheritance of biological
1
information
information in the form of DNA molecules. This genetic information is
encoded in the nucleotide sequences of the DNA.
4. Structure/function
Form and function are correlated at all levels of biological
organization.
5. Interaction with the
environment
Organisms are open systems that exchange materials and energy with
their surroundings. An organism’s environment includes other
organisms as well as nonliving factors.
6. Regulation
Feedback mechanisms regulate biological systems. In some cases, the
regulation maintains homeostasis, a relatively steady state for internal
factors such as body temperature.
7. Unity and diversity
Biologists group the diversity of life into three domains: Bacteria,
Archaea, and Eukarya. As diverse as life is, we can also find unity,
such as a universal genetic code. The more closely related two species
are, the more characteristics they share.
8. Evolution
Evolution, biology’s core theme, explains both the unity and diversity
of life. The Darwinian theory of natural selection accounts for
adaptation of populations to their environment through the differential
reproductive success of varying individuals.
9. Scientific inquiry
The process of science includes observation-based discovery and the
testing of explanations through the hypothetico-deductive method.
Scientific credibility depends on the repeatability of observations and
experiments.
10. Science,
technology, and
society
Many technologies are goal-oriented applications of science. The
relationships of science and technology to society are now more crucial
to understand than ever before.
2
Review of the Chemistry of Living Things
Chapter 2 The Chemical Context of Life


Nutrients for plants are inorganic and most nutrients for animals (heterotrophs) are organic.
a balanced equation indicates not only the number of molecules required but also the
number of moles required.
CHEMICAL ELEMENTS AND COMPOUNDS
 Matter consists of chemical elements in pure form and in combinations called compounds
 Life requires about 25 chemical elements
ATOMS AND MOLECULES





Atomic structure determines the behavior of an element
Atoms combine by chemical bonding to form molecules
Weak chemical bonds play important roles in the chemistry of life
A molecule’s biological function is related to its shape
Chemical reactions make and break chemical bonds

A balanced equation indicates not only the number of molecules required but also the
number of moles required.
moles can be substituted for molecules in such equations.
a solution’s concentration or molarity does not change if you aliquot or subdivide the
solution into smaller volumes.


“There is 10% sugar in this solution. If I pour half of it into one beaker and the other half into
another beaker, what percent sugar will I have in each beaker?”
3
A Quick Review of Elements and Compounds
1. This table lists the chemical elements that occur naturally in the human body. Similar
percentages of these elements are found in most living organisms.
a. In what abiotic (nonlife)
chemical forms are these
elements often found in
nature?
These elements are most
commonly found as CO2,
N2, and O2 in the
atmosphere and as H20,
PO4, and S compounds on
Earth.
b. In what chemical form(s)
do animals need to
obtain these elements?
With the exception of
oxygen and water, animals
obtain the majority of these
elements in the form of
organic compounds.
c. In what chemical form(s)
do plants need to obtain
these elements?
Plants can obtain C as CO2,
N as ammonia or nitrite or
nitrates, phosphorus as
phosphates, sulfur as
sulfides or sulfates, and so
on. In other words, plants
obtain these elements as
inorganic compounds.
2. A chemical element cannot be broken down to other forms by chemical reactions. Each
element has a specific number of protons, neutrons, and electrons.
a. What is the name of the following element, and how many protons, neutrons, and electrons does
it have?
Name
Sodium
Number of protons
11
Number of electrons
11
Number of neutrons
12
b. What information do you need to calculate or determine the following?
The atomic number of an
element
The atomic number is equal
to the number of protons (or
electrons).
The mass number of an
element
The mass number is equal
to the number of protons
plus the number of
neutrons.
4
The weight in daltons of
one atom of an element
You can estimate the weight
in daltons as 1 dalton per
proton or neutron.
Therefore, the weight in
daltons of an element is
approximately equal to the
number of protons plus the
number of neutrons.
c. What are the atomic number, mass number, and weight in daltons of the element shown in part
a?
Atomic number
11
Mass number
23
Weight in daltons
23
3. One mole of an element or compound contains 6.02  1023 atoms or molecules of the element
or compound. One mole of an element or compound has a mass equal to its mass number (or
molecular weight) in grams. For example, 1 mol of hydrogen gas (H2) contains 6.02  1023
molecules and weighs 2 g.
a. What is the weight of 1 mole of pure
sodium (Na)?
23 g
b. How many molecules of Na are in
1 mole of Na?
6.02  1023
c. How would you determine how many grams are in a mole of any chemical element or
compound?
A mole of any chemical element or compound is equal to the mass number in grams of that mole or
compound. For example, the mass number of Na is 23; therefore, a mole of Na has a mass of 23 g.
The mass number of water is 18; therefore, a mole of water has a mass of 18 g.
4. One atom of Na can combine with one atom of Cl (chlorine) to produce one molecule of NaCl
(table salt).
a. If Cl has 17 electrons, 17
protons, and 18 neutrons,
what is its mass number?
35
b. What is the mass
number of NaCl?
23 + 35 = 58
c. How many grams of
NaCl equal a mole of
NaCl?
58 g
d. If you wanted to combine equal numbers of Na and Cl atoms in a flask, how much Cl would
you have to add if you added 23 g of Na? (Include an explanation of the reasoning behind your
answer.)
23
23 g of Na is equal to 1 mole of Na. A mole contains 6.02 
molecules of the substance. To
add an equal number of molecules of Cl, you need to add 1 mole of Cl, or 35 g.
5
5. The summary formula for photosynthesis is
6 CO2 + 6 H2
a. How many molecules of carbon dioxide
and water would a plant have to use to
produce three molecules of glucose
(C6H12O6)?
For each molecule of glucose produced, 6
molecules of carbon dioxide and 6
molecules of water are consumed.
Therefore, the plant would need to use 18
molecules of each.
6H12O6
+ 6 O2
b. How many moles of carbon dioxide and
water would a plant have to use to
produce 2 mole of glucose?
Because a mole of anything contains the
same number of molecules, the plant would
need to use 6 times as many moles of
carbon dioxide and water, or 12 moles of
each.
c. Refer to the summary formula for photosynthesis. If you know the number of molecules or
moles of any of the reactants used (or products produced), how would you calculate the number
of molecules or moles of all of the other reactants needed and products produced?
If the formula is balanced and if it is a true representation of the overall reactions that occur, then
the numbers in front of each reactant and product indicate the molecular or molar equivalents
required for the reactions.
(Note: To represent the actual reactants required and products produced, the overall formula for
photosynthesis is more correctly stated as:
6 CO2 + 12 H20  C6H12O6 + 6 O2 + 6 H20
In most texts, however, this is reduced to 6 CO2 + 6 H20  C6H12O6 + 6 O2.
6
Chapter 3 Water and the Fitness of the Environment
THE EFFECTS OF WATER’S POLARITY












Water is the solvent of life.
The polarity of water molecules results in hydrogen bonding.
Water’s unusual behaviors is due to H bonding.
H2O molecules are cohesive; they form hydrogen bonds with each other.
Organisms depend on the cohesion of water molecules
H2O molecules are adhesive; they form hydrogen bonds with polar surfaces.
Water is a liquid at normal physiological (or body) temperatures.
Water moderates temperatures on Earth.
Water has a high specific heat (heat to raise 1g 1oC = 1 calorie/g/ oC).
Water has a high heat of vaporization (absorbed heat to convert 1g H20 from liquid to gas) .
Water’s greatest density occurs at 4
Oceans and lakes don’t freeze solid because ice floats.
THE DISSOCIATION OF WATER MOLECULES



Organisms are sensitive to changes in pH
pH is related to both the ionization constant of pure water and the concentration of H+ ions
in a solution.
Acid precipitation threatens the fitness of the environment
7
A Quick Review of the Properties of Water
1. Compounds that have the capacity to form hydrogen bonds with water are said to be hydrophilic
(water loving). Those without this capacity are hydrophobic (water fearing).
Is the molecule on the left hydrophilic or
hydrophobic? Explain your answer.
This molecule is acetic acid. The –COOH
group is polar, which makes this molecule
hydrophilic.
2. In addition to being polar, water molecules can dissociate into hydronium ions (H3O+, often
described simply as H+) and hydroxide ions (OH–). The concentration of each of these ions in pure
water is 10–7. Another way to say this is that the concentration of hydronium ions, or H+ ions, is
one out of every 10 million molecules. Similarly, the concentration of OH– ions is one in 10
million molecules.
a. The H+ ion concentration of a solution can be represented as its pH value. The pH of a solution
is defined as the negative log10 of the hydrogen ion concentration.What is the pH of pure water?
The hydrogen ion concentration of pure water is 10–7. The log10 of 10–7 is –7. The negative log10
of 10–7 is therefore +7.
b. Refer to the diagram of the molecule of acetic acid in question 1. The COOH group can ionize
to release a H+ ion into solution. If you add acetic acid to water and raise the concentration of
H+ ions to 10–4, what is the pH of this solution?
The pH of a solution with a H+ ion concentration of 10–4 is 4.
8
Carbon and Macromolecules (Chapters 4 & 5)
The C:H:O ratio of carbohydrates is approximately 1:2:1. For many lipids, it is approximately
1:2:very few. For proteins and nucleic acids, there is no reliable ratio.
Something that is polar is usually also hydrophilic;
The characteristics of key functional groups modify macromolecular structure function.
Phospholipids can form bilayers or micelles in aqueous environments, but not necessarily under
any circumstance.
Chapter 4 Carbon and the Molecular Diversity of Life
THE IMPORTANCE OF CARBON

Organic chemistry is the study of carbon compounds

Organic compounds were once thought to arise only within living organisms, but this idea
(vitalism) was disproved when chemists were able to synthesize organic compounds in the
laboratory.

Carbon atoms are the most versatile building blocks of molecules FIGURE 4.2)

A covalent-bonding capacity of four contributes to carbon’s ability to form diverse
molecules.

Carbon can bond to a variety of atoms, including O, H, and N.

Carbon atoms can also bond to other carbons, forming the carbon skeletons of organic
compounds.

Variation in carbon skeletons contributes to the diversity of organic molecules (FIGURE
4.4)

The carbon skeletons of organic molecules vary in length and shape and have bonding sites
for atoms of other elements.

Hydrocarbons consist only of carbon and hydrogen.

Carbon’s versatile bonding is the basis for isomers, molecules with the same molecular
formula but different structures and thus different properties. Three types of isomers are
structural isomers, geometric isomers, and enantiomers (mirror image, spatial
arrangements)
9
FUNCTIONAL GROUPS

Functional groups contribute to the molecular diversity of life (TABLE 4.1)

Functional groups are specific chemically reactive groups of atoms within organic
molecules that give the overall molecule distinctive chemical properties.

The hydroxyl group (--OH), found in alcohols, has a polar covalent bond, which helps
alcohols dissolve in water.

The carbonyl group ( CO) can be either at the end of a carbon skeleton (aldehyde) or within
the skeleton (ketone).

The carboxyl group (--COOH) is found in carboxylic acids. The hydrogen of this group can
dissociate, making the molecule a weak acid.

The amino group (--NH2) can accept a proton (H+), thereby acting as a base.

The sulfhydryl group (--SH) helps stabilize the structure of some proteins. The phosphate
group ( PO4 ) has an important role in the transfer of cellular energy.

Living matter is made mostly of carbon, oxygen, hydrogen, and nitrogen, with some sulfur
and phosphorus.

Biological diversity has its molecular basis in carbon’s ability to form a huge number of
molecules with particular shapes and chemical properties.
10
Chapter 5 The Structure and Function of Macromolecules
POLYMER PRINCIPLES

Most macromolecules are polymers (FIGURE 5.2)

Carbohydrates, lipids, proteins, and nucleic acids are the four major classes of organic
compounds in cells. Some of these compounds are very large and are called
macromolecules.

Most macromolecules are polymers, chains of identical or similar building blocks called
monomers.

Monomers form larger molecules by condensation reactions in which water molecules are
released (dehydration). Polymers can disassemble by the reverse process, hydrolysis.

An immense variety of polymers can be built from a small set of monomers

Each class of polymer is formed from a specific set of monomers. Although organisms
share the same limited number of monomer types, each organism is unique because of the
specific arrangement of monomers into polymers.
CARBOHYDRATES--FUEL AND BUILDING MATERIAL

Sugars, the smallest carbohydrates, serve as fuel and carbon sources (FIGURES 5.3-5.5)

Monosaccharides are the simplest carbohydrates. They are used directly for fuel, converted
to other types of organic molecules, or used as monomers for polymers.

Disaccharides consist of two monosaccharides connected by a glycosidic linkage.

Polysaccharides, the polymers of sugars, have storage and structural roles (FIGURES 5.65.9)

The monosaccharide monomers of polysaccharides are connected by glycosidic linkages
(covalent bonds between monosaccharides formed by dehydration).

Starch in plants and glycogen in animals are both storage polymers of glucose.

Cellulose is an important structural polymer of glucose in plant cell walls. Starch, glycogen,
and cellulose differ in the positions and orientations of their glycosidic linkages.
LIPIDS--DIVERSE HYDROPHOBIC MOLECULES

Fats store large amounts of energy (FIGURES 5.10-5.11)

Fats, also known as triacylglycerols, are constructed by the joining of a glycerol molecule to
three fatty acids by dehydration reactions.
11

Saturated fatty acids have the maximum number of hydrogen atoms. Unsaturated fatty acids
(present in oils) have one or more double bonds in their hydrocarbon chains.

Phospholipids are major components of cell membranes (FIGURE 5.12-5.13) Where fats
have a third fatty acid linked to glycerol, phospholipids have a negatively charged
phosphate group, which may be joined, in turn, to another small hydrophilic molecule.
Thus, the "head" of a phospholipid is hydrophilic.

Steroids include cholesterol and certain hormones (FIGURE 5.14) Steroids have a basic
structure of four fused rings of carbon atoms.
PROTEINS--MANY STRUCTURES, MANY FUNCTIONS

A protein consists of one or more polypeptide chains folded into a specific threedimensional conformation

A polypeptide is a polymer of amino acids connected in a specific sequence (FIGURES
5.15-5.16, TABLE 5.1)

Polypeptides are constructed from 20 different amino acids, each with a characteristic side
chain (R group). The carboxyl and amino groups of adjacent amino acids link together in
peptide bonds.

A protein’s function depends on its specific conformation (FIGURES 5.17-5.27)

o
The primary structure of a protein is its unique sequence of amino acids.
o
Secondary structure is the folding or coiling of the polypeptide into repeating
configurations, mainly the a helix and the b pleated sheet, which result from
hydrogen bonding between parts of the polypeptide backbone.
o
Tertiary structure is the overall three-dimensional shape of a polypeptide and results
from interactions between amino acid side chains.
Proteins made of more than one polypeptide chain (subunits) have a quaternary level of
structure. The structure and function of a protein are sensitive to physical and chemical
conditions. Protein shape is ultimately determined by its primary structure, but in the cell,
proteins called chaperonins may help the folding process.
NUCLEIC ACIDS--INFORMATIONAL POLYMERS

Nucleic acids store and transmit hereditary information (FIGURE 5.28)

DNA stores information for the synthesis of specific proteins. RNA (specifically, mRNA)
carries this genetic information to the protein-synthesizing machinery.

A nucleic acid strand is a polymer of nucleotides (FIGURE 5.29)

Each nucleotide monomer consists of a pentose sugar covalently bonded to a phosphate
group and to one of four different nitrogenous bases (A, G, C, and T or U).
12

RNA has ribose as its pentose; DNA has deoxyribose. RNA has U and DNA, T.

In making a polynucleotide, nucleotides join to form a sugar-phosphate backbone from
which the nitrogenous bases project. The sequence of bases along a gene specifies the
amino acid sequence of a particular protein.

Inheritance is based on replication of the DNA double helix (FIGURE 5.30)

DNA is a helical, double-stranded macromolecule with bases projecting into the interior of
the molecule. Because A always hydrogen-bonds to T, and C to G, the nucleotide sequences
of the two strands are complementary.

One strand can serve as a template for the formation of the other. This unique feature of
DNA provides a mechanism for the continuity of life.

We can use DNA and proteins to measure evolution (TABLE 5.2) Molecular comparisons
help biologists sort out the evolutionary connections among species.
13
Carbon and Macromolecules - Quick review activities:
Part A. Answer the questions. Then use your answers to develop simple rules for identifying
carbohydrates, lipids, proteins, and nucleic acids.
1. What is the approximate C:H:O ratio in each of the following types of macromolecules?
Carbohydrates
Lipids
1:2:1
1:2:very few
Proteins
There is no reliable
C:H:O ratio for
proteins.
Nucleic acids
There is no reliable
C:H:O ratio for
nucleic acids.
2. Which of the compounds listed in question 1 can often be composed of C, H, and O alone?
Carbohydrates and lipids can often be composed of C, H, and O alone.
3. Which of the compounds can be identified by looking at the C:H:O ratios alone?
Only carbohydrates and some lipids can be identified using C:H:O ratios alone.
4. What other elements are commonly associated with each of these four types of macromolecules?
Contain P
carbohydrates
No
Contain N
No
lipids
No (except for
phospholipids)
No
Contain S
No
No
No
proteins
nucleic acids
Yes
Yes
Yes
Yes
No
5. Functional groups can modify the properties of organic molecules. In the table below, indicate
whether each functional group is polar or nonpolar and hydrophobic or hydrophilic. Which of these
functional groups are found in proteins and lipids?
Functional
group
Polar or
Nonpolar?
Hydrophobic or
Hydrophilic
Found in all
proteins
Found in many
proteins
—OH
Polar
Hydrophilic
No
In some R
groups
—CH2
Nonpolar
Hydrophobic
No
Yes in side
groups
—COOH
—NH2
—SH
Polar
Polar
Polar
Hydrophilic
Hydrophilic
Hydrophilic
Yes
Yes
No
—PO4
Polar
Hydrophilic
No
14
Found in
cysteine
Only if they
have been
phosphorylated
Found in many lipids
In fatty acids as
terminal reactive
group
Yes
No
No
No
In phospholipids
6. You want to use a radioactive tracer that will label only the protein in an RNA virus. Assume
the virus is composed of only a protein coat and an RNA core. Which of the following would you
use? Be sure to explain your answer.
a. Radioactive P
b. Radioactive N
c. Radioactive S
d. Radioactive C
a. Radioactive P. To distinguish between protein and RNA in a virus, you could use radioactively
labeled P compounds. If you grew viruses on cells with radioactively labeled P compounds, the
phosphate groups in the virus’s RNA would become labeled but the protein would not become
labeled.
7. Closely related macromolecules often have many characteristics in common. For example, they
share many of the same chemical elements and functional groups. Therefore, to separate or
distinguish closely related macromolecules, you need to determine how they differ and then target
or label that difference.
a. What makes RNA different from DNA?
RNA contains ribose sugar, whereas DNA contains deoxyribose sugar. In addition, RNA contains
uracil and not thymine. DNA contains thymine but not uracil.
b. If you wanted to use a radioactive or fluorescent tag to label only the RNA in a cell and not the
DNA, what compound(s) could you label that is/are specific for RNA?
You could label either ribose or uracil.
c. If you wanted to label only the DNA, what compound(s) could you label?
You could label either deoxyribose or thymine.
8. Based on your answers to questions 1–7, what simple rule(s) can you use to identify the
following macromolecules?
carbohydrates
lipids
proteins
nucleic acids
DNA vs RNA
Look for a 1:2:1 C:H:O ratio.
Many carbohydrates will contain no P, N, or S.
Look for a 1:2 ratio of C:H and only very small amounts of O.
Most will contain no S. Phospholipids can contain P and N (as
part of the choline group; see Figure 5.12 in Biology, 6th edition).
Look for amino and carboxyl groups. Some contain S. All
proteins can be identified by the presence of peptide bonds. (See
Figure 5.16 for the structure of a peptide bond.)
Look for nucleotides made up of a five-carbon sugar, a phosphate
group, and a nitrogenous base.
DNA contains phosphate, deoxyribose sugar, and adenine,
guanine, cytosine, and thymine.
RNA contains phosphate, ribose sugar, and adenine, guanine,
cytosine, and uracil.
15
Part B. Carbohydrate, lipid, protein, or nucleic acid? Name that structure!
Based on the rules you developed in Part A, identify the compounds below (and on the following page)
as carbohydrates, lipids, amino acids, polypeptides, or nucleic acids. In addition, indicate whether each
is likely to be polar or nonpolar, hydrophilic or hydrophobic.
1) fat or triglyceride
2) amino acid
3) There is an error in the
structure as drawn. The third
carbon in the chain (counting
from the left) and its associated
CH3 group should be deleted.
When these are deleted, the
structure becomes a tripeptide
made up of 3 amino acids.
16
Part B. Continued
4) single strand of 4 bases in DNA
5) disaccharide sugar or carbohydrate
6) fatty acid
7) ribonucleotide
8) amino acid
9) polysaccharide
10) 5 carbon sugar
Copyright © Pearson Education, Inc., publishing as Benjamin Cummings
17
Predictions about the behavior of organic macromolecules if you know
their structure:
1. Polypeptides and proteins are made up of linear sequences of amino acids. In its
functional form, each protein has a specific three-dimensional structure or shape.
Interactions among the individual amino acids and their side chains play a major role in
determining this shape.
a. How are amino acids linked together to form polypeptides or proteins? What is this
type of bond called?
Amino acids are covalently linked together via peptide bonds to form polypeptides or
proteins. (See Figure 5.16)
b. Define the four structures of a protein.
Primary:
The linear sequence of amino acids in a
polypeptide or protein
Secondary:
 helix or  pleated sheet conformations
occurring at regular intervals along the
polypeptide
Tertiary:
The folded or functional conformation
of a protein
Quaternary:
The folded or functional conformation
of a protein made up of more than one
polypeptide chain
c. What kinds of bonds hold each of these
together?
Covalent peptide bonds formed by
dehydration reactions hold the individual
amino acids together in the polypeptide chain.
The secondary structure results from H
bonding relationships set up between the H
attached to the N in one amino acid and the O
attached to the C of another amino acid. (See
Figure 5.20, page 76.)
Hydrogen and covalent bonds between side
chains (R groups) of various amino acids
contribute, as do hydrophobic interactions and
van der Waals interactions.
Hydrogen and covalent bonds between side
chains (R groups) of various amino acids
contribute, as do hydrophobic interactions and
van der Waals interactions.
2. Lipids as a group are defined as being hydrophobic, or insoluble in water. As a result,
this group includes a fairly wide range of compounds—for example, fats, oils, waxes, and
steroids like cholesterol.
Dehydration reactions between the OH of the carboxyl group on the fatty acid and the
OH group on the glycerol molecule bond the fatty acids to the glycerol moleculea. How
are fatty acids and glycerol linked together to form fats (triglycerides)?
b. What functions do fats serve in living organisms?
In general, fats are energy storage molecules.
c. How do phospholipids differ from triglycerides?
Phospholipids have one of the OH groups of the glycerol interacting with a phosphatecontaining side group—for example, phosphatidylcholine as in Figure 5.12, page 70.
Copyright © Pearson Education, Inc., publishing as Benjamin Cummings
18