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Cell Structure and Function
Table of Contents
Discovering Cells
Looking Inside Cells
Chemical Compounds in Cells
The Cell in Its Environment
Cell Structure and Function
What is a Cell?
*A cell is the basic
unit of life.
*All life activities
take place inside
cells.
Cell Structure and Function
Discovery of Cells
*Robert Hooke—first man to see cells (1663)
-looked at thin slices of cork
-saw empty boxes and called them cells
-never realized that cells are living things
Cell Structure and Function
*Anton van Leeuwwenhoek
-father of microbiology
(1600’s)
-improved and developed
many types of microscopes
-discovered microscopic, one
celled organisms and called
them “animalcules”,
meaning “little animals”.
Cell Structure and Function
*Matthias Schleiden (1838)
-stated all plants are
made of cells
*Theodor Schwann (1839)
-stated all animals are
made of cells
Cell Structure and Function
*Rudolph Virchow (1855)
-stated all cells come
from other cells.
*The work of these men
led to the “Cell Theory”
Cell Structure and Function - Discovering Cells
The cell theory states:
1. All living things are
made of cells.
2. Cells are the basic units of
structure and function in
living things.
3. All cells come from other
cells.
Cell Structure and Function - Discovering Cells
Links on Cell Theory
Click the SciLinks button for links on the cell theory.
Cell Structure and Function
Eukaryotic vs. Prokaryotic
*All cells are either eukaryotic or prokaryotic.
-Eukaryotic cells —complex cells with a
nucleus. All animal and plant cells are
eukaryotic.
-Prokaryotic cells—simple cells without a
nucleus. All bacteria and cyanobacteria
(blue-green bacteria) are prokaryotic.
Cell Structure and Function
Structure of Animal Cells
Animal cells are typical eukaryotic cells.
Most contain the following structures:
*Cell Membrane
-Surrounds the cell
-Has pores
-Controls what gets
in and out
Cell Structure and Function - Looking Inside Cells
*Nucleus—control center of cell
-directs all of the cell’s activities
Chromatin
Pores
Nucleolus
Nuclear Envelope
Cell Structure and Function
*Cytoplasm—gel-like
material inside the
cell.
*Organelles—many
tiny structures
inside the cell.
Each has its own
job to do.
-Organelles include:
Cell Structure and Function - Looking Inside Cells
1.Mitochondria—“powerhouses” of the
cell because they convert energy in
food molecules to energy the cell can
use to carry out its functions.
Cell Structure and Function - Looking Inside Cells
2. Endoplasmic reticulum —folded tube
like membranes that move materials
throughout the cell.
3. Ribosomes—small protein factories
found on the “er” or in the cytoplasm
Ribosomes
Endoplasmic
reticulum
Cell Structure and Function - Looking Inside Cells
4. Golgi bodies —packaging centers
that wrap up and package proteins
and send them to other parts of the
cell or out of the cell.
Golgi Body
Cell Structure and Function
5. Lysosomes—garbage
collectors that contain
enzymes used to break down
large molecules and old cell
parts.
Cell Structure and Function
6. Vacuoles—sacs that store water,
dissolved material or waste products.
They are larger in plant cells than in
animal cells.
Cell Structure and Function
Structure of Plant Cells
*Plant cells contain
all the same
structures and
organelles as
animal cells plus
a few more.
Plant cells can do
everything that animal
cells can do plus
make food.
Cell Structure and Function
-Cell wall—a ridged structure outside
the cell membrane made of
cellulose. It supports and protects
the plant cell.
-Chloroplasts—tiny disks that
contain chlorophyll. Photosynthesis
takes place here.
-Larger Vaculoes—to store water
Cell Structure and Function - Looking Inside Cells
Plant and Animal Cells
Cell Structure and Function
Cell Variety
*Cells differ in size, shape, and
function. They will not all look like the
diagrams.
Cell Structure and Function
*Examples:
-Nerve cell—0ne meter
long with many
extensions: carries
impulses to the brain.
-Red Blood Cell—
microscopic, round and
flexible: carries oxygen
throughout the body.
Cell Structure and Function
Structure of Bacteria Cells
*Bacteria cells have no nucleus and no
membrane-bound organelles.
-They are prokaryotic.
-Their parts include:
Capsule
Cell wall
Cell membrane
Some have flagella
Cytoplasm
DNA floating in cytoplasm
Ribosomes
Cell Structure and Function
Diagram of a Bacteria Cell
Cytoplasm
DNA
Capsule
Cell wall
Cell Membrane
Ribosomes
Flagella
Cell Structure and Function - Looking Inside Cells
Plant and Animal Cells Activity
Click the Active Art button to open a browser window and
access Active Art about plant and animal cells.
Cell Structure and Function - Looking Inside Cells
Previewing Visuals
Before you read, preview Figure 12. Then write two
questions you have about the illustrations in a graphic
organizer like the one below. As you read, answer your
questions.
Plant and Animal Cells
Q. How are animal cells different from plant cells?
A. Plants cells have a cell wall and chloroplasts, which animal
cells to not have.
Q. What do mitochondria do?
A. Mitochondria convert energy in food molecules to energy the
cell can use.
Cell Structure and Function - Looking Inside Cells
The Cytoplasm and Organelles
Click the Video button to watch a movie about cytoplasm and
organelles.
Cell Structure and Function - Looking Inside Cells
Specialized Cells
Click the Video button to watch a movie about
specialized cells.
Cell Structure and Function
End of Section:
Looking Inside
Cells
Cell Structure and Function
What are Cells Made Of?
*Cell Chemistry begins with atoms:
-Atom—basic units of matter
-Elements—any substance that
cannot be broken down into
simpler substances (made of
only one type of atom)
Cell Structure and Function
-All known elements are listed on
the Periodic Table of the Elements
Cell Structure and Function
-The elements found in living cells
include mostly carbon, hydrogen,
nitrogen, oxygen, phosphorus
and sulfur: (CHNOPS)
Cell Structure and Function
Molecules and Compounds
*Atoms combine to form molecules.
-Molecules—two or more atoms
bonded together (different or
same) Ex: H2O O2 NaCl
-Special molecules made of different
elements only are called
compounds Ex: H2O CO2
Cell Structure and Function - Chemical Compounds in Cells
Carbon dioxide, which is found in gas
bubbles, is a chemical compound. So is
water.
Cell Structure and Function
-When just the right molecules and
compounds get together in just
the right way, cells are formed.
-Compounds in living organisms
are classified as either organic or
inorganic.
Cell Structure and Function
*Organic compounds contain the
elements; carbon and hydrogen.
*They make up foods and cell membranes.
*Four basic groups:
Cell Structure and Function
1.Carbohydrates—make up 1% of
a cell; contain carbon, hydrogen,
and oxygen; used for energy;
examples are sugars and
starches; most important
carbohydrate for living things is
glucose.
Cell Structure and Function
2. Lipids—make up 10% of a cell;
contain carbon, hydrogen and
oxygen; store and release
energy; found in cell membranes;
examples are fats, oils and waxes.
Cell Structure and Function
3. Proteins—make up 15% of a cell;
made of amino acids that contain
carbon, hydrogen, oxygen and
nitrogen; used to build cell parts
and for growth and repair of cell;
examples are enzymes.
Cell Structure and Function
4. Nucleic Acids—make up 4% of a
cell; contain carbon, hydrogen,
oxygen, nitrogen, and phosphorus;
carry genetic information; found
in chromosomes, mitochondria,
chloroplasts, and nucleus;
examples are DNA and RNA
Cell Structure and Function - Chemical Compounds in Cells
Compounds in Bacteria and Mammals
All cells contain carbohydrates,
lipids, proteins, and nucleic
acids, as well as water and other
inorganic compounds. But do all
cells contain the same
percentages of these
compounds? The graph
compares the percentage of
some compounds found in a
bacterial cell and a cell from a
mammal.
Cell Structure and Function - Chemical Compounds in Cells
Compounds in Bacteria and Mammals
Reading Graphs:
What do the red bars
represent? What do the blue
bars represent?
Red bars represent
percentages of compounds in
bacterial cells; blue bars
represent percentages of
compounds in mammalian
cells.
Cell Structure and Function - Chemical Compounds in Cells
Compounds in Bacteria and Mammals
Interpreting Data:
What percentage of a
mammalian cell is made up of
water? How does this
compare to the percentage of
water in a bacterial cell?
About 70%; the percentages
are the same.
Cell Structure and Function - Chemical Compounds in Cells
Compounds in Bacteria and Mammals
Interpreting Data:
Which kind of compound–
proteins or nucleic acids–
makes up the larger
percentage of a mammalian
cell?
Proteins
Cell Structure and Function - Chemical Compounds in Cells
Compounds in Bacteria and Mammals
Drawing Conclusions:
In general, how do a bacterial
cell and mammalian cell
compare in their chemical
composition?
They are similar, though
mammalian cells have a
lower percentage of nucleic
acids, and bacterial cells have
a lower percentage of lipids
and fewer proteins.
Cell Structure and Function - Chemical Compounds in Cells
*Most inorganic compounds
are made from elements
other than carbon.
Example: Water
-water makes up two-thirds
of your body
-70% of a cell’s cytoplasm
is water
-many substances must
be dissolved in water in
order to be used by cells.
Cell Structure and Function - Chemical Compounds in Cells
Comparing and Contrasting
As you read, compare and contrast carbohydrates, proteins,
and lipids in a table like the one below.
Type of
Compound
Carbohydrate
Protein
Lipid
Elements
Carbon, hydrogen,
oxygen
Carbon, hydrogen,
oxygen, nitrogen, and
sometimes sulfur
Carbon, hydrogen,
oxygen
Functions
Store and provide
energy and make up
cellular parts
Make up much of the
structure of cells and
speed up chemical
reactions
Store energy
Cell Structure and Function - Chemical Compounds in Cells
Links on Proteins
Click the SciLinks button for links on proteins.
Cell Structure and Function
Cell Transport
*The cell membrane controls what
gets in and out of the cell. This is
called Cell Transport.
-Substances pass through pores.
-The membrane is
selectively-permeable (meaning
only molecules of a certain size can
get through).
Cell Structure and Function - The Cell in Its Environment
A Selective Barrier
The cell membrane protects the contents of the cell and
helps control the materials that enter and leave.
Cell Structure and Function
Types of Transport
*Passive Transport —cell uses
no energy to move materials into or out
of the cell.
-Two types of Passive Transport:
1. Diffusion
2. Osmosis
Cell Structure and Function
*Diffusion is a type of passive transport
in which molecules move from high to
low concentration.
-Oxygen and carbon dioxide move
into a cell by diffusion.
-Molecules move through tiny pores in
the cell membrane.
-Diffusion requires no energy from the
cell.
Cell Structure and Function
Cell Structure and Function - The Cell in Its Environment
Diffusion
In diffusion, molecules move from an area of higher
concentration to an area of lower concentration.
Cell Structure and Function - The Cell in Its Environment
Ratios
The concentration of a solution can be expressed as a ratio.
A ratio compares two numbers. It tells you how much you
have of one item in comparison to another. For example,
suppose you dissolve 5 g of sugar in 1 L of water. You can
express the concentration of the solution in ratio form as
5 g:1 L, or 5 g/L.
Practice Problem
Suppose you dissolve 7 g of salt in 1 L of water. Express the
concentration of the solution as a ratio.
7 g:1 L or 7 g/L
Cell Structure and Function
*Osmosis is a type of passive
transport in which water moves
from high to low concentration.
-Plants get water into their roots
by osmosis.
-Osmosis also requires no energy
from the cell.
Cell Structure and Function
Cell Structure and Function - The Cell in Its Environment
Osmosis
In osmosis, water diffuses through a selectively permeable
membrane.
Cell Structure and Function
Equilibrium
*Both diffusion and osmosis will
continue until the cell reaches a point
where the concentrations are equal
both inside and outside the cell. This
is called equilibrium.
Cell Structure and Function
*Active Transport —cell must
use energy to move substances
in or out.
-Cell will move things from low to
high concentration.
-Transport proteins are needed.
Cell Structure and Function - The Cell in Its Environment
Passive and
Active Transport
Passive and active transport
are two processes by which
materials pass through the cell
membrane. Active transport
requires the cell to use its own
energy, while passive transport
does not.
Cell Structure and Function
Endocytosis—
process used by
cells to move very
large substances
into the cell.
Cell Structure and Function
Exocytosis —process used by cells
to move very large substances out
of the cell.
Cell Structure and Function
Cell Structure and Function - The Cell in Its Environment
More on Cellular Transport
Click the PHSchool.com button for an activity
about cellular transport.
Cell Structure and Function
Graphic Organizer
Organic
Compounds
types
Carbohydrates
Lipids
Proteins
Nucleic
acids
include
include
made of
types
Fats, oils,
and waxes
Amino
acids
Sugars
Starches
DNA
RNA