1. Chapter 17: Cell Processes

2. Chapter: Cell Processes
Table of Contents
Section 3: Energy for Life
Section 1: Chemistry of Life
Section 2: Moving Cellular Materials

3. • Matter is anything that has mass and takes
up space.
• Energy is anything that brings about change.
• Everything in your environment, including
you, is made of matter.
The Nature of Matter
Chemistry of Life
1
• Energy can hold matter together or break it
apart.

4. • At the center of an atom is a nucleus that
contains protons and neutrons.
• Outside the nucleus
are electrons, each
of which has a
negative charge.
Atoms
Chemistry in Life
1
Click image to view movie.
• Although they have nearly equal masses, a
proton has a positive
charge and a neutron
has no charge.

5. • Electrons are the part
of the atom that is
involved in chemical
reactions.
• An atom is mostly
empty space. Energy
holds the parts of an
atom together.
Atoms
Chemistry in Life
1

6. • When something is made up of
only one kind of atom, it is called
an element.
• An element can’t be broken down
into a simpler form by chemical
reactions.
Elements
Chemistry in Life
1
• Scientists have given each element
its own one- or two-letter symbol.

7. • All elements are arranged in a chart known
as the periodic table of elements.
• The table provides information about each
element including its mass, how many
protons it has, and its symbol.
Elements
Chemistry in Life
1

8. Elements
Chemistry in Life
1

9. • Compounds are made up of two or more
elements in exact proportions.
• For example, pure water is always made up
of hydrogen atoms bonded to oxygen atoms
in a ratio of two hydrogen atoms to one
oxygen atom.
Compounds and Molecules
Chemistry in Life
1
• There are two types of compounds—
molecular compounds and ionic compounds.

10. • The smallest part of a
molecular compound is a
molecule.
• A molecule is a group of
atoms held together by
the energy of chemical
bonds.
Molecular Compounds
Chemistry in Life
1

11. Molecular Compounds
Chemistry in Life
1
• When chemical reactions
occur, chemical bonds
break, atoms are
rearranged, and new
bonds form.
• The molecules produced
are different from those
that began the chemical
reaction.

12. Molecular Compounds
Chemistry in Life
1
• Water does not have the
same properties as
oxygen and hydrogen.
• Molecular compounds form when different
atoms share their outermost electrons. Two
atoms of hydrogen
each can share one
electron on one atom
of oxygen to form one
molecule of water.

13. • A mixture is a combination of substances in
which individual substances retain their own
properties.
Mixtures
Chemistry in Life
1

14. Mixtures
Chemistry in Life
1
• Mixtures can be solids, liquids, gases, or any
combination of them.
• Most chemical reactions in living organisms
take place in mixtures called solutions.

15. • In a solution, two or more substances are
mixed evenly.
Mixtures
Chemistry in Life
1
• A suspension is formed when a liquid or a
gas has another substance evenly spread
throughout it.
• Unlike solutions, the substances in a
suspension eventually sink to the bottom.

16. • All living things are made up of compounds
that are classified as organic or inorganic.
Organic Compounds
Chemistry in Life
1
• Rocks and other nonliving things contain
inorganic compounds.
• Organic Compounds always contain carbon
and hydrogen and usually are associated with
living things.

17. • Organic molecules can contain hundreds or
even thousands of atoms that can be arranged
in many ways.
Organic Compounds
Chemistry in Life
1

18. Organic Compounds
Chemistry in Life
1
• Four groups of organic compounds make
up all living things—carbohydrates, lipids,
proteins, and nucleic acids.

19. • Carbohydrates are organic
molecules that supply
energy for cell processes.
Carbohydrates
Chemistry in Life
1
• Sugars and starches are
carbohydrates that cells
use for energy.
• Some carbohydrates
also are important parts
of cell structures.

20. • Lipids do not mix with water.
Lipids
Chemistry in Life
1
• Lipids such as fats and oils store and release
even larger amounts of energy than
carbohydrates do.
• One type of lipid,
the phospholipid, is
a major part of cell
membranes.

21. • Certain proteins called enzymes regulate
nearly all chemical reactions in cells.
• Proteins are made up of smaller molecules
called amino acids.
Proteins
Chemistry in Life
1
• Proteins are the building blocks of many
structures in organisms.
• Your muscles contain large amounts of
protein.
• Proteins are scattered throughout cell
membranes.

22. • Another nucleic acid, ribonucleic acid, or
RNA, is needed to make enzymes and other
proteins.
• Large organic molecules that store important
coded information in cells are called nucleic
acids.
Nucleic Acids
Chemistry in Life
1
• One nucleic acid, deoxyribonucleic acid, or
DNA—genetic material—is found in all cells
at some point in their life.

23. • Inorganic compounds are the source for many
elements needed by living things.
• Most inorganic compounds are made from
elements other than carbon.
Inorganic Compounds
Chemistry in Life
1
• Generally inorganic molecules contain fewer
atoms than organic molecules.

24. • Inorganic compounds can contain the
elements nitrogen, phosphorus, and sulfur.
Inorganic Compounds
Chemistry in Life
1
• One of the
most
important
inorganic
compounds
for living
things is
water.

25. • Living things are
composed of more
than 50 percent water
and depend on water
to survive.
Importance of Water
Chemistry in Life
1
• You can live for
weeks without food
but only a few days
without water.

26. Importance of Water
Chemistry in Life
1
• Although seeds and
spores of plants,
fungi, and bacteria
can exist without
water, they must have
water if they are to
grow and reproduce.

27. • All the chemical reactions in living things
take place in water solutions, and most
organisms use water to transport materials
through their bodies.
Importance of Water
Chemistry in Life
1
• Plants use water to move minerals and
sugars between roots and leaves.

28. • The atoms of a water molecule are arranged
in such a way that the molecule has areas
with different charges.
Characteristics of Water
Chemistry in Life
1
• Water molecules are like magnets.
• The negative part of a water molecule is
attracted to the positive part of another water
molecule just like the north pole of a magnet
is attracted to the south pole of another
magnet.

29. • This attraction, or force, between water
molecules is why a film forms on the surface
of water.
Characteristics of Water
Chemistry in Life
1
• The film is strong enough
to support small insects
because the forces between
the water molecules are
stronger than the force of
gravity on the insect.

30. • Because water molecules are so strongly
attracted to each other, the temperature of
water changes slowly.
Characteristics of Water
Chemistry in Life
1
• The large percentage of water in living
things acts like an insulator.
• The water in a cell helps keep its
temperature constant, which allows life-
sustaining chemical reactions to take place.

31. • When water freezes, ice crystals form.
Characteristics of Water
Chemistry in Life
1
• In the crystals, each water molecule is spaced
at a certain distance from all the others.
• Because this distance is greater in frozen
water than in liquid water, ice floats on water.
• Bodies of water freeze from the top down.
• The floating ice provides insulation and
allows living things to survive.

32. Question 1
Answer
_______ is anything that has mass and takes up
space.
The answer is Matter. Everything in your
environment is made of matter.
Section Check
1

33. Question 2
Answer
A(n) _______ is made up of only one kind of
atom.
The answer is element. An element can’t be
broken down into a simpler form by chemical
reactions.
Section Check
1

34. 1
Section Check
Question 3
Which best describes
the structure in this
illustration?
A. atom
B. element
C. molecular
compound
D. ionic compound

35. 1
Section Check
Answer
The answer is C. Molecular compounds form
when different atoms share their outermost
electrons.

36. Chapter: Cell Processes
Table of Contents
Section 3: Energy for Life
Section 1: Chemistry of Life
Section 2: Moving Cellular Materials

37. Passive Transport
• Cells take in food, oxygen, and other
substances from their environment.
• They also release waste material.
• A cell has a membrane around it that works
like a window screen.
Moving Cellular Materials
2
• A cell’s membrane is selectively permeable
(PUR mee uh bul). It allows some things to
enter or leave the cell while keeping other
things outside or inside the cell.

38. Passive Transport
• Which way things move through a cell
membrane depends on the size of the particles,
the path taken through the membrane, and
whether or not energy is used.
Moving Cellular Materials
2
• The movement of substances through the cell
membrane without the input of energy is
called passive transport.
• Three types of passive transport can occur.

39. Diffusion
• Molecules in solids, liquids, and gases
move constantly and randomly.
Moving Cellular Materials
2
• This random movement of molecules from
one area where there is relatively more of
them into an area where there is relatively
fewer of them is called diffusion, which is
one type of cellular passive transport.

40. Diffusion
• Molecules of a substance will continue to
move from area into another until the relative
number of these molecules is equal in the two
areas. When this occurs, equilibrium is
reached and diffusion stops.
Moving Cellular Materials
2

41. Osmosis—The Diffusion of Water
• Water molecules move by diffusion into and
out of cells. The diffusion of water through a
cell membrane is called osmosis.
Moving Cellular Materials
2
• If cells weren’t surrounded by water that
contains few dissolved substances, water
inside of cells would diffuse out of them.

42. Osmosis—The Diffusion of Water
• Losing water from a plant cell causes its
cell membrane to come away from its cell
wall.
Moving Cellular Materials
2
• This reduces pressure
against its cell wall,
and a plant cell
becomes limp.
(Celery ? In the review )

43. Osmosis—The Diffusion of Water
• If water around the cells would move into
them, the cells would fill with water.
Moving Cellular Materials
2
• Their cell membranes
would press against
their cell walls.
• Pressure would
increase, and the cells
would become firm.

44. Facilitated Diffusion
• Some substances pass easily through the
cell membrane by diffusion.
Moving Cellular Materials
2
• Other substances, such as glucose
molecules, are so large that they can enter
the cell only with the help of molecules in
the cell membrane called transport proteins.
• This process, a type of passive transport, is
known as facilitated diffusion.

45. Active Transport
• Sometimes a substance is needed inside a
cell even though the amount of that
substance inside the cell is already greater
than the amount outside the cell.
Moving Cellular Materials
2
• For example, the roots of a plant already
might contain more of those mineral
molecules than the surrounding soil does.

46. Active Transport
• The tendency is for
mineral molecules to
move out of the root by
diffusion or facilitated
diffusion.
Moving Cellular Materials
2
• When an input of energy is
required to move materials
through a cell membrane,
active transport takes
place.

47. Endocytosis and Exocytosis
• Large protein molecules and bacteria, for
example, can enter a cell when they are
surrounded by the cell membrane.
Moving Cellular Materials
2
• The cell membrane folds in on itself,
enclosing the item in a sphere called a vesicle.
• Vesicles are transport and storage structures
in a cell’s cytoplasm.

48. Endocytosis and Exocytosis
• This process of taking
substances into a cell
by surrounding it with
the cell membrane is
called endocytosis (en
duh si TOH sus). Some
one-celled organisms
take in food this way.
Moving Cellular Materials
2

49. Endocytosis and Exocytosis
• The contents of a vesicle can be released by
a cell using the process called exocytosis
(ek soh si TOH sis).
Moving Cellular Materials
2
• Exocytosis occurs in the opposite way that
endocytosis does.
• A vesicle’s membrane fuses with a cell’s
membrane, and the vesicle’s contents are
released.

50. Question 1
What is diffusion?
Section Check
2
Diffusion is the type of passive transport in
which molecules in a more dense area
randomly move to an area that is less dense
until equilibrium is reached.
Answer
NC: 6.02

51. Question 2
Answer
_______ is the diffusion of water through a cell
membrane.
The answer is osmosis. Cells contain water
and are surrounded by water. These water
molecules move by diffusion into and out of
cells.
Section Check
2
NC: 6.02

52. 2
Section Check
Question 3
Which carries oxygen throughout your body?
A. red blood cells
B. white blood cells
C. sex cells
D. none of the above
NC: 6.04

53. 2
Section Check
Answer
The answer is A. Oxygen molecules from the
lungs diffuse into red blood cells which carry
oxygen throughout your body.
NC: 6.04

54. Chapter: Cell Processes
Table of Contents
Section 3: Energy for Life
Section 1: Chemistry of Life
Section 2: Moving Cellular Materials

55. Trapping and Using Energy
• Cells use chemical reactions to change the
chemical energy stored in food into forms
needed to perform activities.
• The total of all chemical reactions in an
organism is called metabolism.
Energy for Life
3
• The chemical reactions of metabolism need
enzymes.

56. Trapping and Using Energy
• Enzymes in cells cause a change, but the
enzyme is not changed and can be used again.
• Enzymes also can cause molecules to join.
Energy for Life
3
• Without the right
enzyme, a chemical
reaction in a cell
cannot take place.
• Each chemical reaction
in a cell requires a
specific enzyme. Click image to view movie.

57. Photosynthesis
• Living things are divided into two groups—
producers and consumers—based on how
they obtain their food.
• Organisms that make their own food, such
as plants, are called producers.
Energy for Life
3
• Organisms that cannot make their own food
are called consumers.

58. Photosynthesis
• Plants and many other
producers can convert light
energy into another kind of
energy—chemical energy.
• The process they use is called
photosynthesis.
Energy for Life
3
• During photosynthesis, producers use light
energy to make sugars, which can be used as
food.

59. Producing Carbohydrates
• Producers that use photosynthesis are usually
green because they contain a green pigment
called chlorophyll (KLOR uh fihl).
• Chlorophyll and other pigments are used in
photosynthesis to capture to capture light
energy.
Energy for Life
3
• In plant cells, these pigments are found in
chloroplasts.

60. Producing Carbohydrates
• The captured light
energy is used to
drive chemical
reactions during
which the raw
materials, carbon
dioxide and water,
are used to
produce sugar and
oxygen.
Energy for Life
3

61. Producing Carbohydrates
• Some of the
captured light
energy is stored
in the chemical
bonds that hold
sugar molecules
together.
Energy for Life
3

62. Storing Carbohydrates
• Plants make more sugar during
photosynthesis than they need for survival.
Energy for Life
3
• Excess sugar is changed and stored as
starches or used to make other carbohydrates.
• Plants use carbohydrates as food for growth,
maintenance, and reproduction.
• Consumers take in food by eating producers
or other consumers.

63. Respiration
• Some of the energy from the food you eat is
used to make you move.
Energy for Life
3
• Some of it becomes thermal
energy, which is why you
feel warm or hot when you
exercise.
• Most cells also need oxygen
to break down food.

64. Respiration
• During respiration, chemical reactions
occur that break down food molecules into
simpler substances and release their stored
energy.
Energy for Life
3
• Just as in photosynthesis, enzymes are
needed for the chemical reactions of
respiration.

65. Breaking Down Carbohydrates
• The type of food molecules most easily
broken down by cells is carbohydrates.
Energy for Life
3
• Respiration of carbohydrates begins in the
cytoplasm of the cell.
• The carbohydrates are broken down into
glucose molecules.
• Each glucose molecule is broken down
further into two simpler molecules.
• As the glucose molecules are broken down,
energy is released.

66. Breaking Down Carbohydrates
• The two simpler molecules are broken
down again. This breakdown occurs in the
mitochondria of the cells of plants, animals,
fungi, and many other organisms.
Energy for Life
3
• This process uses oxygen, releases much
more energy, and produces carbon dioxide
and water as wastes.

67. Breaking Down Carbohydrates
• When you exhale you
breathe out carbon
dioxide and some of
the water.
Energy for Life
3
• Respiration occurs in
the cells of all living
things.

68. Fermentation
• When cells do not have enough oxygen for
respiration, they use a process called
fermentation to release some of the energy
stored in glucose molecules.
Energy for Life
3
• Like respiration, fermentation begins in the
cytoplasm.

69. Fermentation
• Again, as the glucose molecules are broken
down, energy is released.
Energy for Life
3
• But the simple molecules from the
breakdown of glucose do not move into the
mitochondria.
• Instead, more chemical reactions occur in the
cytoplasm.

70. Fermentation
• These reactions release some energy and
produce wastes.
Energy for Life
3
• Depending on the type of cell, the wastes
may be lactic acid, alcohol, and carbon
dioxide.
• The presence of lactic acid is why your
muscle cells might feel stiff and sore after
you exercise.

71. Related & Opposite Processes
• During photosynthesis and respiration,
what is produced in one is used in the other.
Energy for Life
3
• Photosynthesis produces sugars and oxygen,
and respiration uses these products,
• The carbon dioxide and water produces during
respiration are used during photosynthesis

72. Question 1
Answer
_______ is the total of all chemical reactions in
an organism.
The answer is metabolism. All of the
activities of an organism involve chemical
reactions in some way.
Section Check
3
NC: 6.04

73. 3
Section Check
Question 2
Which does this equation represent?
A. respiration
B. fermentation
C. photosynthesis
D. chemosynthesis
NC: 6.02, 6.04

74. 3
Section Check
Answer
The answer is C. During photosynthesis, plants
take in carbon dioxide and water and combine
it with light energy to make sugars, which they
use for food.
NC: 6.02, 6.04

75. Question 3
Answer
_______ is the type of food molecules most
easily broken down by cells.
The answer is carbohydrates. As
carbohydrates are broken down, energy is
released.
Section Check
3
NC: 6.02, 6.04