Transcript cells - Bremen High School District 228

Cell Structure &
Function, Part I
Cells…
 Are so small that 50,000 can fit in this letter O
 Build and break down macromolecules
 Release energy from foods
 Use energy to make cell parts
7-1 Life Is Cellular
Consider this statement:
“The cell theory
revolutionized how
biologists thought about
living things.”
Before microscopes…
…people
believed that diseases were
caused by curses and supernatural
spirits. No idea of organisms such as
bacteria!
QuickTime™ and a
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are needed to see this picture.
Anton van Leeuwenhoek
(1600s)
o First described natural (living) cells as
seen through a simple microscope (a
magnifying glass). Drew what
he observed in a drop of
water: “animalcules”.
Qui ck Time™ and a
TIF F (Uncompres s ed) dec om press or
are needed to s ee t his pict ure.
Robert Hooke (1665)
o First used the word “cells” to describe
structure of slice of cork. Soon scientists
accepted that cells were basic units of all
forms of life.
Schleiden & Schwann
(1830s)
o Examined plants (Schleiden) and
animals (Schwann) and concluded that
“all living things are made up of cells”.
Rudolph Virchow
• “Cells come from
existing cells.”
Janet Plowe
“The cell
membrane is a
defined physical
structure.”
Review: Biologists and Their Discoveries
That Led to The Cell Theory
 Anton van
Leeuwenhoek
• First light microscope,
cork made of “cells”
• Simple microscope,
living organisms in
water
 Matthias Schleiden
• Plants made of cells
 Theodor Schwann
• Animals made of cells
 Rudolph Virchow
• Cells come from
existing cells
• Cell membrane is
physical structure
 Robert Hooke
 Janet Plowe
The Compound Light
Microscope
o Has a series of lenses that magnify an
object in steps.
o Visible light is passed through the object
and then through the lenses.
o Allowed biologists to achieve greater
magnification and see more details inside
cells.
Magnification
 The two lenses are called:
Eyepiece
 Objective

 The eyepiece has a magnification of “10x”
 The magnification of the objective lenses
vary and are marked on the lens
 Total magnification = (Eyepiece) X (Objective)
 Example: 10 X 40 =
400X
How Does a Microscope Work?
the specimen
the image
the eye
The image is always seen upside
down and backwards from its
actual position
The Parts of the Microscope and Their
Function
Maintains
proper distance
between lenses
Hold objectivesrotates to change
magnification
Magnification
Support body tube
Magnification
Supports slide
Holds slide
In place
Focuses image
Regulates
amount of light
Sharpens the image
Reflects light
towards eyepiece
Supports microscope
Proper Procedures
Carry the microscope
with one hand under
the base while grasping
the arm with the other
hand
2. Place microscope ~5
inches from the edge
of the table
Be careful of the cord
when moving around
the lab tables!!
1.
Proper Procedures
3. Rotate the nosepiece
to obtain the proper
objective lens
Make sure the lens clicks
into place!!
4. Look through the
eyepiece and switch
on the lamp
This is your field of view!
Proper Procedures
5. Place slide on stage,
center specimen over
stage
6. Locate specimen on
low power using coarse
adjustment
7. Carefully switch to
medium or high power
8. Focus image with fine
adjustment
Avoid damaging slide!
Do not use course adjustment with high power!
Storing the Microscope
Four steps prepare the microscope for storage:
the 10X objective
is in place
2. the stage is all the
way down
3. the power is off
4. the cord is
wrapped around
the base
1.
o All living things are composed of cells.
o Larger organisms (like humans) many cells.
o The cell is the basic unit of structure &
function in living things.
o Basic unit of matter --- atom. Basic unit of life
--- cell.
o New cells are produced from existing cells.
o Cells come from the reproduction of previously
existing cells making exact copies of themselves.
Basic Cell Structures in all
Cells
 Typical cells range in size from 5-50
micrometers.
 Bacteria- 0.2 micrometers
 Giant amoeba- 1000 micrometers (naked eye can
see)
 Cell membrane is thin, flexible barrier
surrounding cell. Plants have strong cell wall to
contain turgor pressure.
 Protects cell while allowing interaction with
environment.
Basic Cell Structures in all
Cells
 Nucleus or nucleoid- Structure or material
that contains genetic material and controls
activities.
 Cytoplasm- “juice” material inside cell
membrane- contains many important structures
o Prokaryotes - no true nucleus
or organelles
o Eukaryotes - containing
membrane-bound nucleus as
well as membrane bound
organelles
Prokaryotes
o Organism with a cell that lacks internal
o
•
o
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o
o
structures surrounded by membranes.
Have cell membrane and cytoplasm
No nuclei, but contain DNA within
cytoplasm
Most are single-celled organisms- smaller
& simpler
All bacteria are prokaryotes
Carry out every activity associated with
life
o Grow, reproduce, respond to changes in
environment
Eukaryotes
• Vary in shape, some
large
• Have cell membrane
and cytoplasm
• Have nuclei and many
other organelles
• Some single-celled
beings
• Many multi-celled
beings
• All plants, animals,
fungi, and many
microorganisms are
eukaryotes
7-2 Eukaryotic
Cell Structures
The Cell Membrane
Location?
• Outer boundary of animal and protist cells.
Outer edge of cytoplasm.
o Also called a plasma membrane, it serves
as the boundary between the cell and the
external environment.
o Flexible- allows cell to change its shape if
needed.
Function?
o Controls the movement of materials that
enter and exit the cell.
o
Oxygen
Nutrients
o Waste products
Excess water
Cell Membrane cont’d
o Some materials exit and enter through protein
passageways.
o Some materials pass directly through the
membrane.
QuickTime™ and a
TIFF (Uncom pres s ed) decom pres s or
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Cell Wall
 Location?
 Outer most boundary in plant, bacteria and fungi cells
o In plants, cell walls contain cellulose molecules which


•
•
form fibers to protect the cell & give it support.
In fungi, walls made of chitin, a nitrogen-containing
polysaccharide.
Function?
Provides support and
protection for the cell
Helps maintain cell shape
Nucleus
Location?
•In all cells but bacteria
cells
•Often most prominent
structure in center of
cell
o Function?
o Is the organelle that
manages cell function in a
eukaryotic cell.
o Surrounded by a nuclear
envelope, four layers thick.
Large pores allow materials
to pass between the
nucleus and the rest of the
cell.
o Contains DNA, the master
instructions for building
proteins.
Stores hereditary
information of DNA
Nucleus cont’d
o DNA forms strands of
chromatin, which is packed into
chromosomes at reproduction.
o Also inside the nucleus is the
nucleolus, which produces tiny
cell particles. These particles
are ribosomes, which are the
sites where proteins and
enzymes are assembled.
Ribosomes do not have a
membrane.
Nucleolus
Location?
•Dark spherical
mass inside the
nucleus
Function?
•Assembly of
ribosomes begin
here
Nuclear
Envelope
Location?
•Surrounds nucleus
Function?
•Double membrane
layer that contains
pores which allow
material to move into
and out of the nucleus
•Steady stream of
RNA and other infocarrying molecules to
the rest of the cell
 Most cells need to make proteins and store other
materials. Most of this work is done in the fluid
of the cell- the cytoplasm.
Cytoplasm
Location?
•The clear fluid composing
about 50% of the cell.
•Contains many structures
called organelles
•Some cells may contain
cytoskeleton
Function?
•Establishes living condition to
supply and transport materials
for cell activities
Assembly and Transport (cont’d)
 Endoplasmic reticulum (ER): a
folded system of membranes
where the cell’s chemical reactions
take place. Enzymes to make lipids
are also found here
Location?
•Extend from nuclear envelop to cell membrane
Description?
Rough E.R. – contain ribosomes
Smooth E.R. – do not contain ribosomes
Function?
•Transport materials
•Rough E.R. modify proteins for secretion
•Smooth E.R. contains enzymes that make lipids
Ribosome
Location?
•In nucleus,
cytoplasm, and
Rough E.R.
Function?
•Produce proteins
following coded
instruction that
come from the
nucleus
Protein Storage
 Golgi apparatus: a series of
membrane sacs that take lipids
and proteins made on the ER and
distributes them where neededto other organelles and the cell
membrane. Proteins travel in
little packages called vesicles.
Vesicles may be sent out of the cell,
absorbed into other organelles, or
stay at the Golgi until needed.
Vacuoles
Location?
•Saclike structures in the
cytoplasm
Description?
Animal & Protists – Small,
multiple vacuoles
Function?
•Store materials such as
water, salts, proteins and
carbohydrates
•Remove excess water from
cell (contractile vacuole)
Plant Vacuoles
Location?
•Saclike structure in the
cytoplasm
Description?
Plant cells – Single, large
central vacuole
Function?
•Store materials such as
water, salts, proteins and
carbohydrates
•Pressure in plant vacuole
aid in support of plant cell
(lack of water – wilting)
Lysosomes:
Location?
•Throughout the
cytoplasm of the cell
•Rare in plant cells
Function?
•Small organelles filled with enzymes
that break down lipids,
carbohydrates and proteins from
food into particles that can be used
by the rest of the cell.
•Also a “cell cleaner” to break down
old organelles and dead pathogens.
Energy Transformers: Mitochondria
Location?
•Throughout the cytoplasm
•More numerous in cells that
have high energy requirements.
Function?
•Organelles that release energy
in the form of ATP from stored
food molecules (glucose)
•The name of this process?
Cellular Respiration
Note: Mitochondria contain
some of their own genetic info
or DNA that is essential to the
function of the mitochondrion.
Chloroplasts
Location?
•Found in cytoplasm of plants,
some protists and bacteria
Function?
•Use energy from sunlight to
make energy-rich food
molecules (glucose).
•The name of this process?
Photosynthesis
Chlorophyll pigment transforms light
energy directly into chemical energy Note: Chloroplasts
some of their
and stores it as sugars and starches.contain
own genetic info or
Chloroplasts contain stacks of sacs DNA that is essential
to the function of the
called grana surrounded by a fluid chloroplast.
called stroma.
Plant Mitochondria
Human Liver Cell Mitochondria
Structures for Support &
Locomotion
 Cytoskeleton: a
framework of tiny rods and
threads within the
cytoplasm.
 Provides support for
organelles.
 Helps maintain cell wall
shape.
 Composed of microtubules
(hollow) and microfilaments
(solid).
Structures for Support & Movement
Location?
•Extending from nucleus to cell
membrane in some cells
Description?
•Made up of protein filaments
called microtubules and
microfilaments
Function?
•Helps cell maintain shape and
involved in many forms of cell
movement
Cilia & Flagella
 Both are structures adapted for movement.
 Cilia are short hairs that beat in a “wave”. Moves fluids
over surface rather than moving cell itself.
 Flagella are larger, whiplike projections.
Structures for
Reproduction: Centrioles
Location?
•Paired structures just outside the
nuclear envelope in the cytoplasm
•Only in animal cells
Function?
•During cell division, centrioles
separate and take up positions on
opposite sides of the nucleus
•Help organize the spindle that
separate the chromosomes
Review: Cell Structures and Functions
Cell Quiz Answer Key
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E
J
D
K
M
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M
Smooth E.R.
Ribosome
Rough E.R.
Lysosome (Special vesicle)
Vesicle/Vacuole
Chromosome
Nucleus
Nucleolus
Smooth E.R.
Cell Membrane
Centriole
Golgi Apparatus
Mitochondrion
Vesicle/Vacuole
Electron Microscopes
(1940s-present)
o Rather than using light, they
use a focused beam of
electrons that pass over or
through the surface of an
object in a vacuum, and finally
onto a fluorescent screen
where it forms an image. Only
dead cells or organisms can be
observed.
Organization of
o Cells
Cells
o Unicellular or
multicellular
o Tissues
o Function to perform
activity
o Organs
o Two or more tissues
o Organ systems
o Group for life functions
Analogies: The Cell As a
Factory
 Walls & roof
 Transportation System
 Main Office
 Assembly line
 Packaging & Shipping
 Energy source
A Comparison of Cells
Structure
Prokaryotic Eukaryotic Cells
Cells
Animal
Plant
Cell
Yes
membrane
Cell Wall
Yes
Yes
Yes
No
Yes
Nucleus
No
Yes
Yes
Ribosomes Yes
Yes
Yes
Structure
Prokaryotic
Cells
Eukaryotic Cells
Animal
Plant
Endoplasmic No
reticulum
Golgi App.
No
Yes
Yes
Yes
Yes
Lysosomes
No
Yes
Yes
Vacuoles
No
Yes
Mitochondria No
Small or
none
Yes
Chloroplasts
No
No
Yes
Cytoskeleton No
Yes
Yes
Yes