Transcript Looking at Cells

Chapter Two
Section 1
Cell Structure
TYPES OF CELLS
Defined by having a
nucleus.
Defined by having
complex organelles.
• Plant and animal cells.
Defined by NOT having
a nucleus
• Bacteria cells.
Common Cell Features
Both prokaryotic and eukaryotic cells contain:
• ____________
• A cell membrane (protects cell and allows things in
and out of the cell).
• Ribosomes (protein making factories).
• ______________(water-based substance inside the
cell).
These are typically the only similarities between the
two different types of cells.
Eukaryotic cells contain organelles, a word that literally
means “little organ”.
Organelles have specific
functions that they employ
throughout the cell.
There are approximately a dozen different
organelles!
What is it?
a large, central membrane-bound organelle which
contains D.N.A.
Where is it found?
All eukaryotic cells!
(BOTH plant and
animal cells
have a nucleus).
What does it do?
Protects the DNA!
What is it?
A porous membrane that
encases the nucleus. These
“nuclear pores” allow
certain substances to pass
into and out of the nucleus.
Where is it found?
In all eukaryotic cells;
BOTH plant and animal.
What does it do?
The nuclear envelope protects the nucleus.
What is it?
A structure contained
within the nucleus.
Where is it found?
Inside the nucleus
of eukaryotic cells.
What does it do?
It is responsible for making ribosomes.
What is it?
Gelatin like mixture that flows inside the cell membrane
Where is it found?
In all eukaryotic cells;
BOTH plant and animal.
Also in prokaryotic cells.
What does it do?
Takes up all the “empty” space.
What is it?
A selectively permeable protection of the cell.
Where is it found?
In all eukaryotic cells;
BOTH plant and animal.
Also in prokaryotic cells.
What does it do?
Allows certain things to enter and leave the cell.
What is it?
A tunnel-like
network
of membranes.
Where is it found?
Connected to the nucleus and branching out into the
cytoplasm of all eukaryotic cells.
Endoplasmic Reticulum con’t
What does it do?
Transfers substances within the cell, as well as many
different chemical reactions including protein
modification and distribution. ER is like the highway
system of the cell!
T
W
O
T
Y
P
E
S
Smooth E.R.
(free of ribosomes)
Rough E.R.
(contains ribosomes)
What is it?
A membrane-bound
organelle, which
processes and
packages proteins.
Where is it found?
The cytoplasm of
all eukaryotic cells.
What does it do?
Acts like a post office by packaging proteins in vesicles and delivering them to
other parts of the cell.
What is it?
Ribosomes are cell
organelles that consist of
RNA and proteins.
Where is it found?
In all eukaryotic and prokaryotic cells.
What does it do?
They are responsible for assembling the proteins of the cell.
What are they?
Vesicles that
contain powerful
digestive enzymes.
Where are they found?
In all eukaryotic cells.
What do they do?
Break down old cell parts and fight off invading ____________.
What is it?
A unique, double
membrane-bound
organelle, which
contains its
own DNA.
Where is it found?
All eukaryotic cells.
What does it do?
Generates A.T.P. (cellular energy)
Vacuoles differ among plant and animal cells.
PLANT CELLS
ANIMAL CELLS
There is ONE, LARGE central vacuole.
The central vacuole of plants stores
water and nutrients, and also aids in
cellular digestion.
There are multiple, small vacuoles.
www.cellsalive.com
The vacuoles of animal cells do not store water or
nutrients, but rather waste as they aid in cellular
digestion.
What are they?
Nine triplets of microtubules.
Where are they found?
IN ANIMAL CELLS ONLY!
What do they do?
Assist during nuclear division.
What are they?
Membrane-bound organelles that
contain light-absorbing
pigments.
Where are they found?
______________cells only!
What do they do?
Harvest energy from the
sun for photosynthesis.
What is it?
A structure consisting of cellulose that surrounds
the cell membrane.
Where is it found?
Within eukaryotes the cell
wall is ONLY found in ________,
however all prokaryotes
also have a cell wall.
What does it do?
Protects the cell and maintains homeostasis.
Cell Structure
Cytoplasm (P&A)
Cell Membrane (P&A)
Nucleus (P&A)
Endoplasmic Reticulum
(P&A)
Gelatinlike mixture that
flows inside the cell
membrane
Allows materials to
move in and out cell
Directs all cell activities
(the “brain” of the cell)
Moves materials around
in cell
Cell Structure
Ribosomes (P&A)
Mitochondira (P&A)
Chloroplast (P)
Makes protein
Releases energy stored
in food
Captures light and
stores for energy
Cell Wall (P)
Protects the plant
Vacuole (P&A)
Stores water, waste
products, food, and
other cellular materials
Cell Structure
Golgi Bodies (P&A)
Package and sort
cellular substances for
export
Lyosome (P&A)
Breaks down food
molecules, cell wastes,
and worn-out cell parts.
Animal Cell v. Plant Cell
Animal Cell
Plant Cell
Lysosomes
Cell Wall
Cell Membrane
Cytoplasm
Nucleus
Ribosome
Endoplasmic Reticulum
Mitochondrion
Chloroplast
Vacuole
Gogli Body
The Cell Theory
• The Cell Theory arose after hundreds of years of
observation, and many scientists. A few key scientists
involved in the cell theory are Hooke, Schleiden,
Schwann and Virchow.
Robert Hooke- The first scientist to
describe what he saw as “cells”
when viewing samples of cork
under the microscope in 1665.
The Cell Theory
Nearly 200 years later, Matthias Schleiden
viewed living plant specimens under the
microscope and discovered they were made
up of cells.
Around the same time as Schleiden, Theodor
Schwann viewed nonliving animal parts
under a microscope and realized that they,
too were made up of cells.
The Cell Theory
Finally, Rudolf Virchow witnessed cell
division under the microscope and
learned that all cells arise from
preexisting cells.
The findings of these scientists, among others,
lead to the cell theory, which states:
Cell Theory
All organisms are
made up of one or
more cells
An organism can be one cell
or many cells like most
plants and animals
The cell is the basic
unit of structure and
function of life.
Even in complex organisms,
the cell is the basic unit of
structure and function
All cells come from
preexisting cells.
Most cells can divide to form
two new, identical cells.
Looking at Cells
Introduction to the Microscope
Looking at Cells
Measurement Review!
centimeter= 1/100 of a meter (cm) =approximate width of
a fingernail
millimeter= 1/1000 of a meter (mm) =equivalent to the
width of a pencil tip
micrometer= 1/1,000,000 of a meter (µm) = about the
length of half of one E. Coli
nanometer= 1/1,000,000,000 of a meter (nm) about the
size of a very large molecule
Looking at Cells
Cells are measured in micrometers, which is
abbreviated as µm. A micrometer is equal to one
millionth of a meter. Micrometers are also known as
microns.
Some cells are only half a micron in diameter, which
means you could fit two million cells along the length
of a meter stick. They are naked to the human eye!
Anton van Leeuwenhoek
• A Dutch scientist born in 1632
• He did NOT invent the microscope,
but he did improve it.
• His new improved microscope was
able to see things that no man had
ever seen before, i.e., bacteria,
yeast, blood cells and many tiny
animals swimming about in a drop
of water. He called these
“animalcules”.
Robert Hooke
• Robert Hooke, an English scientist who was the first
scientist to give cells their name.
• When looking at a wine cork under a microscope in
1665, he saw something similar to this:
Classroom Microscope
The compound light microscope:
• The compound microscope has multiple
lenses and needs a light source in order to
magnify objects.
• This microscope is ideal for looking at a
wide range of living or preserved specimens,
though it can only magnify up to 1,000-2,000x
larger.
Cells under a compound
light microscope.
Electron Microscopes
An electron microscope is any microscope that
uses a beam of electrons to form an image of a
specimen. However, they are generally NOT used
to view living specimens. The specimen is always
dead and preserved.
There are three types of electron microscopes:
1) Transmission electron microscope (TEM)
2) Scanning electron microscope (SEM)
3) Reflection electron microscope
Transmission Electron Microscope (TEM)
• Original electron microscope
• Invented in the 1930s
• Can magnify an object
750,000x its original size.
• Capable of revealing a cell’s
detailed structure.
• Ideal for use on cells because
TEM’s produce highly magnified
3-dimensial images of the cell, as
we will see in the virtual
microscope!
Scanning Tunneling Microscope
• Invented in the 1980’s
• Can magnify up to 2,000,000x
an object’s original size.
• Safe for living specimens .
• Produces color images.
• Used to view atoms and
molecules- even cells are too
big for the capacity of this
amazing instrument!
Vocabulary
1. _____________________: a measure of the image clarity.
Example) unclear pictures= poor resolution
2. __________________________: making an image look larger
than its actual size. This is done using lenses
(like a magnifying glass or eyeglasses).
3. SI units: a system of measurement based on
powers of 10. A compound microscope uses SI
because its eyepiece lens is 10x.
Lenses of the Microscope and Total
Magnification
4x
100x
40x
10x
Objective Lenses (3-4 total)
Eyepiece (piece you
look through) always
has a 10x lens!
Total magnification= eyepiece lens x objective lens!
The microscope is currently set on the 10x objective lens.
What is the total magnification?
Convex Lenses
-It is very important to note that the eyepiece is a
CONVEX lens.
-This is the same type of lens that is found in our
eyes.
The convex lens
Inverts an image
and makes it
backwards.
Image Quality
When you look at a specimen using a microscope, the
quality of the image you see is assessed by the following:
•Brightness - How light or dark is the image?
•Focus – A measure of the definition of the image. Is the
image blurry or well-defined?
•Resolution - the smallest distance between two objects
at which the objects still appear to be separate from
one another; measures the clarity of the image (allows
details to be observed).
•Contrast– The difference in lighting between adjacent
areas of the specimen.
Parts of the Light Microscope
eyepiece
body tube
nose piece
arm
objective lenses
stage
stage clips
diaphragm
light source
course adjustment
fine adjustment
base
Chapter Two
Section 3
Viruses
Viruses
• A ____________is a strand of hereditary material
surrounded by a protein coating. Viruses don’t
have a nucleus, other organelles or a cell
membrane.
• All viruses can do is make copies of themselves, but
can’t do that without the help of a
_________________.
How Viruses Attack
•
Active Virus
•
•
Causes host cell to make new viruses. This process
destroys the host cell
Process
1. The virus attaches to a specific host cell
2. The virus’s hereditary material enters the host cell
3. The hereditary material of the virus causes the cell to
make viral hereditary material and proteins
4. New viruses form inside of the host cell
5. New viruses are released as the host cell burst open
and is destroyed
How Viruses Attack
• Latent Virus
• This means that after the virus enters the cell, its
hereditary material can become part of the cell’s
hereditary material. It does not immediately make new
viruses or destroy the cell.
• As the cell multiplies the viral DNA is copied.
• Factors either inside or outside your body can activate
the virus.
Fighting Viruses
• Vaccine
• Used to prevent disease. Made from weakened virus
particles that can’t cause disease anymore.
• First Vaccine
• Edward Jenner developed 1st vaccine for small pox.
Treating and Preventing Viral
Diseases
• Antibiotics
• Used to treat bacterial infections and WILL NOT work
against viral infections.
• Antiviral drugs can be given to infected patients to
help fight a virus.
• Improving sanitary conditions will also prevent viral
infections (SO WASH YOUR HANDS!)
• Quarantining Patients
• Controlling animals that spread disease
• rabies
Gene Therapy
• There are some helpful uses to viruses.
• Cells with defective genes are given normal
hereditary material in place of the defective
hereditary material.
• This normal material is enclosed in viruses that
“infect” the targeted cells.
• Using gene therapy, scientists hope to help people
with genetic disorders and find a cure to cancer.