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Cell Processes and Energy
Table of Contents
Photosynthesis
Respiration
Cell Division
Cancer
Cell Processes and Energy - Photosynthesis
Sources of Energy
Nearly all living things obtain energy either directly or
indirectly from the energy of sunlight captured during
photosynthesis.
Cell Processes and Energy - Photosynthesis
The Two Stages of Photosynthesis
During photosynthesis, plants and some other
organisms use energy from the sun to convert
carbon dioxide and water into oxygen and sugars.
Cell Processes and Energy - Photosynthesis
Sequencing
Sequence is the order in which the steps in a process occur.
As you read, create a flowchart that shows the steps in
photosynthesis. Put each step in a separate box in the
flowchart in the order in which it occurs.
Steps in Photosynthesis
Sunlight strikes leaf.
Chlorophyll captures light energy.
Cells use the energy to produce sugars and
oxygen from water and carbon dioxide.
Cell Processes and Energy
End of Section:
Photosynthesis
Cell Processes and Energy - Respiration
Two Stages of Respiration
During respiration, cells break down simple food molecules
such as sugar and release the energy they contain.
Cell Processes and Energy - Respiration
Photosynthesis and Respiration
You can think of photosynthesis and respiration as opposite
processes.
Cell Processes and Energy - Respiration
Using Prior Knowledge
Your prior knowledge is what you already know before you
read about a topic. Before you read, write a definition of
respiration in a graphic organizer like the one below. As you
read, revise your definition based on what you learn.
What You Know
Respiration is when an organism breathes in oxygen
because oxygen is needed by cells.
What You Learned
Respiration also means the process in which cells
break down simple food molecules such as sugar and
release the energy they contain.
Cell Processes and Energy - Respiration
Links on Cellular Respiration
Click the SciLinks button for links on cellular respiration.
Cell Processes and Energy
End of Section:
Respiration
Cell Processes and Energy - Cell Division
Mitosis
During mitosis, the cell’s nucleus divides into two new nuclei.
One copy of the DNA is distributed into each of the two
daughter cells.
Cell Processes and Energy - Cell Division
The Cell Cycle
Cell Processes and Energy - Cell Division
Length of the Cell Cycle
How long does it take for a cell
to go through one cell cycle? It
all depends on the cell. A human
liver cell, for example, completes
one cell cycle in about 22 hours,
as shown in the graph. Study the
graph and then answer the
following questions.
Cell Processes and Energy - Cell Division
Length of the Cell Cycle
Reading Graphs:
What do the three curved
arrows outside the circle
represent?
The longest curved arrow
represents the cell’s
interphase; the shortest
represents cytokinesis; and
the middle one represents
mitosis.
Cell Processes and Energy - Cell Division
Length of the Cell Cycle
Reading Graphs:
In what stage of the cell cycle
is the wedge representing
growth?
Interphase
Cell Processes and Energy - Cell Division
Length of the Cell Cycle
Interpreting Data:
In human liver cells, how long
does it take DNA replication
to occur?
10 hours
Cell Processes and Energy - Cell Division
Length of the Cell Cycle
Drawing Conclusions:
In human liver cells, what
stage in the cell cycle takes
the longest time?
Interphase
Cell Processes and Energy - Cell Division
Structure of DNA
The DNA molecule is shaped like a twisted
ladder.
Cell Processes and Energy - Cell Division
Replication of DNA
Because of the way in which the nitrogen bases pair with one
another, the order of the bases in each new DNA molecule
exactly matches the order in the original DNA molecule.
Cell Processes and Energy - Cell Division
Sequencing
As you read, make a cycle diagram that shows the events in
the cell cycle, including the phases of mitosis. Write each
even in a separate circle.
Cell grows, makes a
copy of DNA.
Cell pinches in two; each Chromosomes and spindle
daughter cell has same number fibers form; nuclear
of identical chromosomes. The Cell Cycle envelope breaks down.
Chromosomes stretch out; Chromosomes line up
new nuclear envelope forms across the center and
around chromosomes. attach to a spindle fiber.
Centromeres split;
chromatids separate and
move to opposite ends.
Cell Processes and Energy
End of Section:
Cell Division
Cell Processes and Energy - Cancer
What Is Cancer?
Cancer is a disease in which cells grow and divide
uncontrollably, damaging the parts of the body around them.
Cell Processes and Energy - Cancer
Previewing Visuals
When you preview, you look ahead at the material to be
read. Preview Figure 17. Then write two questions you have
about the illustrations in a graphic organizer like the one
below. As you read, answer your questions.
How Cancer Spreads
Q. What is a tumor?
A. A mass of abnormal cells that develops when cancerous cells
divide and grow uncontrollably.
Q. How does cancer spread?
A. Some of the tumor cells can break off and enter the
bloodstream.
Cell Processes and Energy - Cancer
Links on Cancer
Click the SciLinks button for links on cancer.
Cell Processes and Energy
End of Section:
Cancer
Cell Processes and Energy
Graphic Organizer
Comparing Photosynthesis and Respiration
Feature Photosynthesis Respiration
Water and carbon
Raw materials Oxygen and sugars
dioxide
Water and carbon
Products Oxygen and sugars
dioxide
Is energy released? No Yes
