McGraw-Hill Ryerson. High School Biology

708 Pages·2001·2.12 MB·English

by  Don Galbraith

Ripped by Jack Truong, if you bought this, you got ripped off.
U N I T
1 Cellular Functions
Overall I
t has been said that we are made of the stuff of
Expectations
stars. What do you think this means? The pine
wood cells pictured on the right and all other
In this Unit, you will
organisms on Earth are made mostly of only six
discover
common chemical elements. These elements
What molecules make up
originated under the conditions of massive
cells
gravity and heat found in stars. Evidence that the
How the cell membrane molecules of life — compounds containing carbon,
separates cells from their hydrogen, and oxygen — exist throughout the
external environment but
universe is found in comets like Hale-Bopp, shown
allows substances into
below. Scientists have recently found that such
and out of the cell
rocks, travelling through space, transport compounds
What special functions cell and molecules that form the basis of life on Earth.
structures have and how
Within cells, these molecules are transformed
these contribute to
into living organisms with a multitude of complex
keeping an organism alive
strategies for survival. The same few molecules are
What processes in cells used over and over in different combinations to
capture and release the
make literally millions of different structures and to
energy needed for survival
carry out all the different functions needed by
and how we harness these
living things. The processes involved in sustaining
processes
life all begin at the molecular level within the
microscopic spaces of the cell. This includes the
Unit
storage and release of the energy needed to power
Contents cellular process — which ultimately comes from
the Sun.
Chapter 1
Exploring the Micro-
universe of the Cell. 4
Chapter 2 The image below may look like a single-
Organizing Life. . . . 42 celled organism, but it is actually a comet
called Hale-Bopp. What does a comet have
Chapter 3
to do with the pine wood cells on the right?
Cells, Energy, and
Technology. . . . . . . 78
Unit
Investigation. . . . . 110
UNIT INVESTIGATION
Look ahead to pages
110–111.
You can start planning
your investigation well in
advance by knowing what
you will need.
As you work through the
unit, watch for ideas and
materials that will help you
prepare your experimental
design.
2
3
C H A P T E R 1
Exploring the
Micro-universe of the Cell
Reflecting
Questions
What are the key
molecules of life?
T
How does the cell he micro-universe of the cell is a happen, you would not get the
membrane define the world of stunning beauty, high nutrients you need to feed the cells
living cell and separate it drama, and battles to the death. All of your body.
from its environment?
of it relies on and revolves around Earlier courses introduced you to
How does a cell control the molecules of life. Why does the cells and cell reproduction. In this
the movement of materials didinium in the photograph on the chapter, you will discover the
that enter and leave it? right hunt the paramecium — a larger molecules of life. In particular, you
micro-organism? The didinium will investigate the large molecules
cannot make all the molecules it — carbohydrates, lipids, proteins,
needs, such as proteins, from the and nucleic acids — that nourish,
substances dissolved in its watery build, and direct the living cell. You
environment. So the didinium must will also examine the role that the
acquire these molecules from its prey. cell membrane plays in transporting
It then uses the molecules to build substances into and out of the cell.
and repair cellular structures and as a
source of energy for cellular processes.
The didinium and paramecium, as
well as the vorticella pictured below,
separate themselves from the outside
world with a cell membrane. How
then does the didinium “eat” the
paramecium? If the didiniumopened Beautiful but deadly, the single-
a hole in its cell membrane large celled vorticella pictured below use
the coiled spring in their cilia to leap
enough to take in the paramecium,
out to grab their prey (bacteria).
the didinium’s own cell contents
would leak out into the water
surrounding it. Indeed, how do any
of these cells take in molecules they
need or excrete wastes? Clearly, the
cell membrane must do much more
than separate the cell contents from
the external environment. How does
this living edge of the cell function?
Cellular dramas are also taking
place in the human body. For example,
cells that line your stomach live no
longer than four days because the
acid produced there eventually
destroys them. As the old cells die,
replacement cells emerge to face the
acidic battleground. If this did not
4
Chapter
Contents
1.1 The Molecular Basis of Life 6 MiniLab: Manipulating Design Your Own Investigation
Macromolecules 20 1-B: Osmosis in a Model Cell 28
Thinking Lab:
Life: A Winning Experiment 6 1.2 Cell Membrane Structure 21 Thinking Lab: Relative
Concentration Challenge 32
MiniLab: The Resolving 1.3 Through the Cell
Power of Skin 7 Membrane 25 1.4 Bulk Membrane Transport 35
MiniLab: Modelling Sugars 11 MiniLab: Random Walking 26 MiniLab: Freezing Cells 37
Investigation 1-A: What’s Here?
Testing for Macromolecules 18
5
The Molecular Basis of Life
S E C T I O N
1.1
EXPECTATIONS
Describe the structure and
function of important
biochemical compounds.
Test for macromolecules
found in living organisms.
Use three-dimensional models
of important compounds.
Figure 1.1 These bacteria
remained dormant in a salt
crystal, probably from before
the time of the dinosaurs. In
2000, scientists revived them
by giving them water and
carbon-containing compounds.
W
hen you think about cells, what first comes to Less than two hundred years ago, people did
mind? How small they are? How such tiny living not know of the existence of cells. The development
things can do so much work? How a single of the first microscopes finally gave scientists
fertilized egg cell can produce all the many access to the miniature world of the cell. Early
specialized cells of a large organism, such as a investigators discovered what you now take for
human being? This chapter, and the other chapters granted: that all living things are made up of one or
in this unit, will help you answer these questions more cells. Other scientists determined that cells
— and perhaps also help you find new ones to ask. are also the fundamental functional units of life.
What does this mean?
THINKING LAB
Life: A Winning Experiment
Background
Where do cells come from? Prior to the development and
acceptance of the cell theory in 1864, at least one early
investigator thought that mice could be generated
spontaneously by leaving a dirty shirt in a bucket. In 1860,
the Paris Academy of Sciences offered a prize to anyone
who could prove or disprove the spontaneous generation of
life. The biologist Louis Pasteur took up the challenge. The
two Erlenmeyer flasks shown here reproduce the results of
Pasteur’s winning experiment. Each flask and the stopper
were sterilized. Each contains 100 mL of vegetable broth
that was boiled for 10 min. Then, the sterilized stopper
was placed in one flask, while the second was left Analyze
unstoppered. This is what the flasks looked like five days
1.Describe any differences you observe in the broth of the
after they were filled.
two flasks.
2.If you see any evidence of life generating life in these
photographs, where did the living organisms come from?
6 MHR • Cellular Functions
FAST FORWARD
To review the cell theory, turn to Appendix 1.
Word
LINK
Look at the ingredients list on a milk package. You will see the
word pasteurizedconnected with the ingredients. Find out what
this word means. Why does it appear on a milk carton? Explain
in your own words where this term came from and how it
relates to cells.
What must the cells pictured in Figure 1.1 do to
stay alive? Like you, they have to obtain and ingest
food and water, get rid of wastes, grow, and respond
to changes in their environment. At some point,
Figure 1.2 The flat, undulating cells (trypanosomes) you see
they will reproduce, creating more cells. Each one
among the red blood cells enter the bloodstream when a
of these cells has to perform key life processes. tsetse fly bites and cause a disease called African sleeping
How does one cell do all that? Each cell uses sickness. The structure of their cell membranes can make
energy to fashion the structures it needs out of them difficult for the human immune system to destroy.
materials available in its external environment —
atoms and molecules. Each cell also maintains a the two features as if they consisted of a single
sophisticated barrier between itself and the outside point. The features are too close together to block
world: the cell membrane. For example, the parasites the light wave separately, which would reveal them
pictured in Figure 1.2 have cell membranes that as two points.
help them evade the human immune system. Before the invention of the electron microscope,
How have scientists learned so many of the cell’s how did biologists gather information about the
secrets? Technology and scientific inquiry have inner workings of the cell? Living things depend
provided many answers. The technology for on chemical reactions, which take place at the
examining cells you probably know best is the level of the molecule. So scientists used chemical
compound light microscope. However, its glass knowledge and procedures to learn about the world
lenses can only magnify the cell enough to allow of the cell: the molecules that living cells use,
you to see some of the larger cell features. Light form, excrete, and interact with. This section will
microscopes cannot resolve — or form distinct introduce you to that world.
images of — objects as close together as are most
structures in the cell. PAUSE RECORD
The nature of visible light itself limits the Explain why biologists describe the cell as the unifying
resolving power of a light microscope. When a light structure that links all life.
wave passes through a specimen with structures
less than 0.2 µm apart, the wave bounces back from
MINI LAB
The Resolving Power of Skin Ask your classmate to record what you felt each time, two
points or one.
You may not think of your skin as an exploratory tool that
has resolving power, but that is one of its functions. The Analyze
network of nerves in your skin gives you greater resolving 1.Which part of your skin has the greatest resolving
power in some places than in others. What does this power (lets you clearly distinguish the two pencil
mean? Tape two pencils together, and ask a classmate to points)? Which has the least resolving power?
touch both pencil points gentlyon the following spots while
2.Suggest how differences in sensitivity to touch are
you keep your eyes closed: a fingertip, the palm of your
related to differences in the number and closeness of
hand, the back of your hand, and the back of your neck.
nerve endings in your skin.
Exploring the Micro-universe of the Cell • MHR 7
Living Organisms Rely on Small Thus, the carbon dioxide and water you exhale are
Molecules waste products of this reaction, which occurs in
your cells. The compounds produced by the
You may not think of your body in terms of
process of converting food into energy are small
chemical reactions, yet you rely on your cells to
molecules. Figure 1.3 uses models to illustrate how
perform trillions of chemical reactions every second.
atoms in molecules of water, oxygen, and carbon
Without these, you could not remain alive. The
dioxide are arranged.
study of these reactions and the molecules and
processes involved in them is called biochemistry. Water: The Primary Molecule of Life
Some of the smallest molecules involved in Water is the most abundant molecule in any cell.
biochemical reactions are the most important. The unique chemical properties of water enable it
Your breath contains three kinds of small to act as a carrier for dissolved molecules inside and
molecules critical to life. When you “see your outside the cell, and as a raw material in essential
breath” on winter days, what you are seeing? Like cell reactions. It also functions as a lubricant
clouds, your visible breath consists of condensed between organs, tissues, and individual cells.
water vapour molecules (H2O) released through These properties of water make possible life as
your lungs. Your exhaled breath also contains two we know it.
other kinds of small molecules important to your
remains liquid over a wide temperature range,
cells: oxygen (O ) and carbon dioxide (CO ). The
2 2 including temperatures at which most small
oxygen is left over from the previous inhalation
molecules are gases (such as room temperature)
(your body absorbs only a small fraction of the
dissolves most substances involved in living
oxygen you take in with each breath).
processes, such as oxygen, carbon dioxide,
Your cells use the oxygen molecules that do
glucose, amino acids (components of proteins),
pass in through your lungs to help release energy
and sodium chloride (salt)
from simple food molecules. This process,
called cellular respiration, can be summarized in changes temperature gradually when heated or
an equation: cooled, so it protects cells from rapid temperature
C H O +6O 6CO +6H O+energy changes and provides a stable environment for
6 12 6 2 2 2
cell reactions
glucose oxygen carbon water
dioxide is the only pure substance that expands when it
becomes a solid, which means that it floats when
it freezes (see Figure 1.5)
O
2
CO
2
H O
2
Figure 1.3 Life as we know it would not exist without these Figure 1.4 Water molecules cling together, which helps
small molecules. water to creep up thin tubes, such as those running from
the roots to the tops of plants.
8 MHR • Cellular Functions
Ice acts as an insulator and prevents the water below it
from freezing, which protects aquatic organisms in the winter. ice 0˚
water 4˚
frog
hibernating
pond Water provides an external in mud
micro-organisms environment for many organisms
both single-celled and
multicellular.
Figure 1.5 All organisms require water to live.
The special properties of water are determined The molecules that form a more permanent part
by its chemical structure. The uneven distribution of living cells all have a carbon “backbone.” This
of electrical charges on a water molecule allows abundance of carbon in organic compounds is why
one water molecule to attract another water scientists call life on Earth carbon based. Each
molecule at room temperature enough to form a carbon atom can form up to four bonds with other
liquid. (Larger molecules such as oxygen and atoms. Hydrocarbon molecules (organic molecules
carbon dioxide remain gases at room temperature.) containing only carbon and hydrogen) come in an
Figure 1.4 shows how this property is important to enormous range of sizes and shapes, including
plants. Molecules with uneven charge distribution open-ended chains and closed, loop-like “rings,”
are said to be polar (because they have oppositely such as those shown in Figure 1.6. From previous
charged “poles”). Although carbon dioxide studies, you may recognize the lines joining the
contains oxygen, it has an even distribution of atoms in this figure as covalent bonds.
electrical charge. This means that it is nonpolar.
H H H H
H H H H
FAST FORWARD H C C C C C C C C H
To review chemical bonding, turn to Appendix 2. H H H H
H H H H
H
Organic Compounds H C H
C C
The term organic compound refers to molecules
that contain both carbon and hydrogen, which C C
means that molecules such as oxygen, water, and H H
C
carbon dioxide are inorganic. Although living
things require water to perform their life functions, H
and most also require oxygen, these molecules Figure 1.6 These hydrocarbon molecules have relatively
can be generated without the involvement of simple structures.
living things.
Exploring the Micro-universe of the Cell • MHR 9
In addition to carbon and hydrogen, many Math
LINK
organic molecules contain other elements, the
This chart gives you the chemical formulas for a number of
most important of which are oxygen, nitrogen,
important biological molecules and the mass of each in atomic
phosphorous, and sulfur. You may recall from
mass units. Use this information to determine the mass of a
earlier studies that normal air is about 20% oxygen
molecule of table sugar (sucrose), which has the chemical
and 78% nitrogen, so it is not surprising that many
formula C H O .
12 22 11
organic molecules contain these two elements.
Living cells make and use a variety of organic Molecule Chemical formula Atomic mass units
molecules, such as glucose (a sugar). The cells of
Water HO 18
2
plants and some other organisms manufacture
Oxygen O 32
glucose through the process of photosynthesis 2
summarized in this equation: Carbon dioxide CO 44
2
light
6CO2+6H2O 6O2+C6H12O6 Glucose C6H12O6 180
carbon water oxygen glucose
dioxide
Both plants and animals use glucose as a food from The Structure and Biological
which they obtain energy.
Function of Carbohydrates
In this chapter, you will explore only the
principal organic molecules contained in Very interested in the food produced by plants,
carbohydrates, lipids, and proteins, as well as early scientists chemically analyzed sugars and
the nucleic acids. that make up the DNA in starches. They discovered that these compounds
chromosomes. Figure 1.7 illustrates foods always contain carbon, hydrogen, and oxygen —
containing these molecules. All of these organic almost always in the same proportion: two atoms of
compounds are very large molecules, or hydrogen and one atom of oxygen for every atom of
macromolecules (macromeans large), composed carbon, or CH2O. Since the formula for water is
of smaller subunits. H2O, the scientists concluded that sugars and
starches consist of carbons with water attached to
them, or carbohydrates (hydro means water).
FAST FORWARD
Carbohydrates provide short- or longer-term energy
To view the periodic table, turn to Appendix 11.
storage for living organisms.
Figure 1.7 Foods rich in carbohydrates, lipids, and proteins.
10 MHR • Cellular Functions