Download Document

UNIT 4
CHAPTER 3
Section 1:
Cell Size, Microscopes,
and The Cell Theory

The cell is the basic structural and
functional unit of all known living
organisms. The cell is the smallest
unit of life that is classified as a
living thing, and is often called the
building block of life.

Most cells are much smaller
than a grain of sand.

Cells and cell structures are measured in
incredibly small metric units called ‘micro’
and ‘nano’ meters.

Cells are only visible with either light
microscopes or electron microscopes.

Surface area to volume ratios must be small so
substances can move in, move out, and move
throughout the cell easily and rapidly.

This limits the largest of cells in your body to
about 20 micrometers, or about 1/3 the width of a
human hair.


A compound light
microscope uses
two lenses to focus
light and magnify
an image on a
transparent slide.
4X Scanning
Objective Lens
10X Low
Power
Objective Lens
(Ocular lens)
40X High
Power
A compound light
microscope
magnifies images
up to 2,000 times.
Diaphragm


A transmission electron
microscope operates in a
vacuum and uses a stream
of electrons to bombard a
metal stained specimen,
creating a fluorescent
computer image.
It allows all but the
smallest cell structures to
be viewed (magnifies up to
200,000 times).

Scanning tunneling microscopes utilize a
needle-like probe to tract voltage differences
caused by electrons which ‘leak’ or ‘tunnel’
from the object being viewed.
the image
The STM
(scanning tunneling
microscope)

The cell theory was developed in the mid1800s, and was the work of several
scientists over many years.

The major scientists that contributed to the
cell theory were:

1665 – Robert Hooke – first used the name
‘cell’ after observing structures in cork

1674 – Anton van Leeuwenhoek – improved
the microscope and observed living cells

1838 – Matthias Schleiden – discovered that

1839 – Theodor Schwann – discovered that

1855 – Rudolph Virchow – proposed a theory

The observations of scientists such as
Schleiden, Schwann, and Virchow led to the
development of The Cell Theory.
plants were composed of cells
animals were composed of cells
that every cell comes from another living cell
The cell theory states:
1. All living things are
composed of one or more
cells.
2. Cells are the basic units of
structure and function in
all organisms.
3. New cells are produced
only from existing cells
(cells divide, or replicate).
Section 2:
Types of Cells, Cytoskeleton,
Cell Membranes, and
Membrane Proteins
 Cells are
classified based
on their structure
and the way they
obtain energy.
 Cells are
classified as
either
prokaryotes or
eukaryotes.


Prokaryotes are a group of
organisms that lack a cell nucleus
, or any other membrane-bound
organelles.
Most prokaryotes are unicellular,
but a few types have multicellular
stages in their life cycles.
Characteristics:
Examples: staph,
E. coli, strep, bacteria

Prokaryotes have no nuclear
membrane -- the genetic material is
dispersed throughout the
cytoplasm.

They have no membrane-bound
organelles.

Most prokaryotes have a cell
membrane, cytoplasm, and cell
wall. They do not have a
nucleus, mitochondria, or
chloroplasts.
 A eukaryote is an organism
whose cells contain complex
structures enclosed within
membranes.
 Eukaryotes are generally more
complex and larger than
prokaryotes.
Characteristics:
 They have a distinct nucleus
and nuclear membrane
surrounding genetic material.
 They have numerous
membrane-bound organelles.
 Eukaryotes have a larger,
more complex internal
structure than prokaryotes.
All cells in multi-cellular
organisms are eukaryotic.
 Examples: plants, animals,
protists, and fungi
 Animals, plants, protists, and
fungi are all eukaryotes and have
a cell membrane, nucleus that
contains DNA, cytoplasm, and
mitochondria.
 Plants and fungi also have a cell
wall, but eukaryotes do not. Only
plants have chloroplasts.
 Flagella and cilia (short, hair-like
structures used for movement)
are a common features among
single-celled eukaryotes.
Amoeba
Diatom
Euglena
Dinoflagellate
Giardia
 There are some key
differences between
plant cells and
animal cells.
 In addition to a cell
membrane, plant
cells have a rigid
cell wall composed
of cellulose which
provides structure
and protection.
 Plant cells also contain unique organelles
called chloroplasts which use sunlight,
carbon dioxide, and water to make
carbohydrates (sugars) in a process called
photosynthesis.
Plant cells contain a large membrane bound central
vacuole which takes up the vast majority of the cell
volume.
The central vacuole is used for storage in plant
cells, and contains mostly water and other minerals.
Turgor pressure is the pressure caused when a
full central vacuole presses the cytoplasm against
the cell wall, creating rigidity that allows plants to
stand upright.
Animal Cell
Plant Cell
muscle cells with
nerve cell attached
nerve cell
red and
white
blood
cells
All Cells have several common structures:
1. Cell membrane
the protective layer around all cells
that give the cell shape and support
Animal Cell
Plant Cell
2. Cytoplasm
the watery gel-like fluid that
fills the inside of the cell
Animal Cell
Plant Cell
3. DNA or genetic material
controls cell functions and carries
hereditary information
Animal Cell
Plant Cell
4. Ribosomes
the site where proteins are
made
Animal Cell
Plant Cell

The cytoskeleton
provides the
interior framework
of an animal cell
and is composed of
an intricate
network of protein
fibers anchored to
the inside of the
plasma membrane.



There are three kinds of cytoskeleton
fibers:
(1.) Actin fibers – form a network just
beneath the cell surface that is anchored to
the membrane proteins embedded within
the cell membrane.
Actin fibers help determine the shape of an
animal cell by pulling on the plasma
membrane.


(2.) Microtubules – are within the
cytoskeleton and act as a transportation
system for information from the nucleus to
different parts of the cell. RNA is also
transported along microtubules.
(3.) Intermediate fibers – provide a frame on
which ribosomes and enzymes can be
confined to a particular region of the cell. The
cell can organize complex metabolic activities
efficiently by anchoring particular enzymes
near one another.
http://learn.genetics.utah.edu/
Click on Amazing Cells, and then Directing
Traffic: How Vesicles Transport Cargo.
Scroll down to Vesicles Travel Cellular
Highways to learn more about travel along
the microfilaments.

The cell membrane is the outer boundary
of the cell which is selectively permeable
to certain substances.

This selective permeability is caused
mainly by the way phospholipids interact
with water.

A phospholipid is a lipid made of a
phosphate group and two fatty acids.

In a cell membrane, the
phospholipids are arranged in a
double layer called a lipid bilayer.

Polar water molecules, both inside
and outside the cell, repel the
nonpolar fatty acid tails, forcing
them to the inside of the lipid
bilayer.

Ions and most polar molecules,
including sugars and some
proteins, are repelled by the
nonpolar interior of the lipid layer.

The lipid bilayer allows lipids and
substances that dissolve in lipids to
pass through.

Polar molecules have a slightly
negative charge at one end, and a
slightly positive charge at the other end.

Because of the
unequal pull of
electrons exhibited
by polar molecules,
they have a tendency
to attract one
another.

Non-polar molecules
do not attract one
another as much, and
therefore exhibit
different properties.

The nonpolar part of a membrane
protein is attracted to the interior of
the lipid bilayer, but is repelled by
the water on either side of the lipid
bilayer.

In contrast, the polar parts of the
protein are attracted to the water on
either side of the lipid bilayer.

This attraction helps to hold the
protein in the lipid bilayer.
Three Forms of Transport Across the Membrane
44

Receptor proteins, marker proteins,
channel proteins, transport proteins,
carrier proteins, and enzymes are all part
of the cell membrane.
receptor protein
transport protein

Receptor proteins recognize and bind to
substances outside the cell.

Marker proteins attached to a cell’s
surface advertise cell type.

Transport proteins (channel proteins,
carrier proteins) help substances move
across the cell membrane.

Enzymes are a type of protein that assist
in the chemical reactions inside the cell.
Section 3:
Cell Organelles
Parts of the Animal Cell
Cell Membrane
The cell membrane, or
plasma membrane, is
the outer layer that
surrounds a cell.
It allows food, water
and gases into the cell
while allowing waste
to leave the cell.
The cell membrane is
found in both plant and
animals cells.
Parts of the Animal Cell
Cell Membrane
The cell membrane
is made up of a lipid
bilayer (two layers).
A lipid bilayer is a
thin membrane
made of two layers
of lipid molecules.
These membranes
are flat sheets that
form a continuous
barrier around the
cell.
The Lipid Bilayer
The lipid bilayer is the barrier that keeps
ions, proteins and other molecules where
they are needed and prevents them from
diffusing into areas where they should not
be.
The polar heads are hydrophilic -- “water loving.”
The nonpolar tails are hydrophobic -- “water fearing.”
This makes the membrane “selective” in what
crosses into and out of the cell.
53
Parts of the Animal Cell
Cytoplasm
Cytoplasm is the
thick, clear, gellike fluid that
holds all the
other organelles
in place.
Cytoplasm is
between the cell
membrane and
the nucleus.
Parts of the Animal Cell
The Nucleus
The nucleus is the
“control center,” or
nerve center of the
cell that contains the
cell's hereditary
information and
controls the cell's
growth and
reproduction.
The nucleus is the
largest cellular
organelle in animals.
Parts of the Animal Cell
The Nucleus
The nucleus has three
major parts:
The nuclear pores are
protein complexes that
allow the transport of
water-soluble molecules
across the nuclear
envelope.
The nucleolus is the home
of the transcription of
ribosomal RNA.
The nuclear membrane is
a double lipid bilayer that
encloses the genetic
material in eukaryotic cells.
Mitochondria
Mitochondria are the
cell’s power sources that
function in the conversion
of the potential energy of
food molecules into ATP.
Mitochondria are
membrane-enclosed
organelles distributed
through the cytosol of
most eukaryotic cells.
cristae – folded membranes which
are the sites of chemical reactions that
convert food molecules into ATP
Mitochondria are found in
cells that use a lot of
energy, such as muscle
cells.
Golgi Apparatus
The Golgi apparatus is a
system of membranes
that modifies and refines
proteins built in the
endoplasmic reticulum
and prepares them for
export outside of the cell,
or for transport to other
locations in the cell.
Proteins are modified
according to where in the
cell they will be sent and
their role in the cell.
The Golgi apparatus is
often considered the
“distribution and shipping
department” for the cell's
chemical products.
Parts of the Animal Cell
Lysosomes
Lysosomes are
organelles that
contain digestive
enzymes (acid
hydrolases). They
are the cell’s
“recycling bin.”
Lysosomes digest
excess or worn-out
organelles, food
particles, and
engulfed viruses or
bacteria.
Parts of the Animal Cell
Centrioles
Centrioles are a pair
of cylindrically-shaped
organelles that
organize the mitotic
spindle and help
regulate cell division.
Centrioles are found in
most eukaryotic cells,
and are usually absent
in plants and most
fungi.
A centriole is made of 9
sets of centrosome
triplets.
Rough Endoplasmic Reticulum
The rough endoplasmic
reticulum is the
transport system that
consists of a series of
tubes and membranes
that moves materials,
(water, protein, oxygen
and food) throughout the
cell.
The rough endoplasmic
reticulum is covered in
ribosomes, which are
organelles that produce
proteins needed to
perform tasks.
Smooth Endoplasmic Reticulum
The smooth endoplasmic
reticulum does not have
ribosomes attached to its
surface, and functions in
the regulation of several
metabolic processes.
For example, the smooth
endoplasmic reticulum aids
in the synthesis of lipids
and steroids, metabolism of
carbohydrates, regulation
of calcium concentration,
drug detoxification,
attachment of receptors on
cell membrane proteins,
and steroid metabolism.
Ribosomes
Ribosomes are the
places where cells make
new proteins.
Most ribosomes are
scattered throughout the
cytoplasm, and others
are attached to the
surface of the rough
endoplasmic reticulum.
Unlike most organelles,
ribosomes are not
surrounded by
membranes.
Ribosomes are made up
of proteins and RNA that
are bound together.
http://www.youtube.com/watch?v=JnlULOjUhSQ
white blood cell chases bacteria on You Tube
http://www.youtube.com/watch?v=Ow0jH2Eg8v4&feature=related
INTRODUCTION TO CELLS IN 3-D
http://www.youtube.com/watch?v=LKN5sq5dtW4&feature=related
FLUID MOSAIC CELL MEMBRANE VIDEO
http://www.youtube.com/watch?v=cqzGWgAr4Ww&feature=related
PODCAST OF CELL ORGANELLES
http://www.youtube.com/watch?v=36Duq-v8Ysk&feature=related
BILL NYE CELLULAR HAZE
http://www.youtube.com/watch?v=jqUhWDp73bM&feature=related
SCIENCE TEACHER RAPS ABOUT CELL ORGANELLES
http://www.youtube.com/watch?v=-zafJKbMPA8
CELLS, CELLS…THEY’RE MADE OF ORGANELLES
http://www.bing.com/videos/search?q=cell++rap&mid=465289358E
4E70FA7353465289358E4E70FA7353&view=detail&FORM=VIRE5
THREE GIRLS SING CELL RAP REALLY WELL
http://www.youtube.com/watch?v=gfzVWG2DnQ4&feature=related
PROKARYOTE/EUKARYOTE SONG
Additional Parts of the Plant Cell
…so which
parts of a
PLANT
CELL make it
so
different?
Cell Organelles Found Only in
Certain Eukaryotic Cells
Cell Wall
The cell wall is the
rigid outer wall that
gives plants additional
shape and support.
The cell wall has tiny
pores that allow
materials to enter and
exit.
The cell wall is found
in plant cells, bacteria,
some protists, and
fungi.
Cell Organelles Found Only in
Certain Eukaryotic Cells
Chloroplasts
Chloroplasts are the
organelles where
photosynthesis
occurs.
Chloroplasts contain
the green pigment
chlorophyll that traps
the energy of sunlight
and makes plants
green.
Plants and some
protists such as algae
contain chloroplasts.
Cell Organelles Found Only in Certain
Eukaryotic Cells
Vacuoles
Vacuoles are sacs that
store water and
dissolved materials.
In plants, there is one
large central vacuole.
In animal cells, smaller
vacuoles are spread out
in the cell.
The turgor pressure
from the liquid-filled
vacuole allows plants to
support heavy
structures such as
leaves and flowers.
Plasmodesmata in Plant Cells
Plasmodesmata
Plasmodesmata
are narrow channels
that act as
intercellular
cytoplasmic bridges
that are found in the
cell walls of plants.
Plasmodesmata
function to facilitate
communication and
transport of materials
between plant cells.
Organelles of the Plant Cell - - REVIEW
Mitochondria
Lysosomes
Nucleus
Golgi Apparatus
Rough
Endoplasmic
Reticulum
Smooth
Endoplasmic
Reticulum
Cell Wall
Cell Membrane
Special Structures for Movement
Flagella
Flagella are long, thread-like
appendages which provide some
live single cells with the ability to
move.
Bacteria which have flagella are
either rod or spiral-shaped.
Cocci, or round bacteria, are
almost all nonmotile.
Animal sperm cells also have
flagella.
The flagella in prokaryotic cells
such as bacteria are made of a
different proteins than those of
eukaryotic cells.
Special Structures for Movement
Cilia
Cilia are tiny tubes on single-
cell organisms that use wavelike hairs to move the cell
around, or can be used to move
something around in the cell of
a multicellular organism.
Cilia are responsible for such
things as protecting us from
germs in our lungs and pushing
an ovum down the fallopian
tube.
Single-celled organisms use
cilia to move through liquid.
Prokaryotic cells lack organelles bound by
membranes.
Mitochondria and chloroplasts have their
own DNA. The DNA in the nucleus does
not instruct the cell to make mitochondria
or chloroplasts.
The endosymbiosis theory proposes that
some early prokaryotes evolved internal
cell membranes which eventually led to
the development of primitive eukaryotic
cells.
The theory goes on to say that
other prokaryotic organisms then
entered the primitive eukaryotic
cell and lived inside.
The eukaryotic cell formed a
mutualistic relationship with the
prokaryotes, one in which each
organism benefits from the other.
Over time, those
prokaryotes
evolved into the
cell organelles
of the modern
eukaryotic cell.
It is believed to
be the means by
which such
organelles as
mitochondria
and chloroplasts
arose within
eukaryotic cells.
Endosymbiosis is a type of symbiosis in which one
organism lives inside the other, and the two typically behave
as a single organism.
It is believed to be the means by which such organelles as
mitochondria and chloroplasts arose within eukaryotic cells.
Organelles in Both Plant and Animal Cells
PLASMA MEMBRANE - phospholipid bilayer barrier between outside and inside of
cell
- semi-permeable – made of phospholipids and proteins
NUCLEUS - control center of cell
- contains instructions for making proteins
- houses chromatin (blue prints) or strands of DNA
NUCLEOLUS - assembles ribosomes from subunits
- found inside the nucleus
NUCLEAR ENVELOPE - protects the DNA from the rest of the cell’s contents
(MEMBRANE) - made of a phospholipid bilayer with nuclear pores instead
of proteins
ROUGH ENDOPLASMIC - covered in ribosomes (appears rough)
RETICULUM (RER) - the ribosomes are the location where proteins are made
- folded membrane that continues off of nuclear envelope
SMOOTH ENDOPLASMIC - no ribosomes present (appears smooth)
RETICULUM (SER) - produces and store lipids and carbohydrates
CYTOPLASM - clear jelly-like fluid that suspends the organelles and is
made mostly of water
Organelles in Both Plant and Animal Cells
RIBOSOMES - organelles that makes proteins according to the directions of the
DNA - ribosomes are not bound by a membrane
- can be found on the rough endoplasmic reticulum, or loose in the
cytoplasm
GOLGI - modify and sorts proteins from the rough endoplasmic reticulum,
APPARATUS (or loads them into vesicles, and sends them to destinations
GOLGI BODY)
VESICLES - sacs that form around and transport substances such as proteins
(enzymes), lipids (steroids) and carbohydrates to specific locations
CYTOSKELETON - the framework or backbone of the cell – supports the cell shape,
(MICROTUBULES, anchors the organelles, provides highway system for cellular
MICROFILIMENTS) materials
- provides energy to the cell by breaking down glucose
MITOCHONDRIA - Mitochondria take in oxygen and release ATP, and are numerous in
muscle cells.
VACUOLES - compartment that serve as temporary storage of materials
PLANTS – one big vacuole ANIMALS – many small vacuoles
Organelles of the Animal Cell ONLY
CILIA / FLAGELLA Cilia – short hairs that work like oars on a row boat
Flagella – one or two long tails, whips back and forth
both provide movement (protista and sperm cells)
CENTRIOLE play an important role in cell division (guide the chromosomes to
the proper places)
Organelles of the Plant Cell ONLY
CELL WALL rigid structure outside the cell membrane
provides structure/support for plants, fungi &
bacteria – made of cellulose, porous, not selective
LARGE CENTRAL are sacs that store water and dissolved materials. Plants
VACUOLE have one large central vacuole, animals have several
smaller vacuoles.
PLASTIDS
(CHLOROPLAST,
CHROMOPLAST,
AMYLOPLAST)
Chloroplast – location of photosynthesis,
contain chlorophyll
Chromoplast – contain carotenoids, yellow to red color
Amyloplasts – no pigments, clear, store starch
grains