Download 2.2 Prokaryotic Cells 2.3 Eukaryotic Cells What is a Prokaryotic Cell

2.2 Prokaryotic Cells
Please use your text to complete the handout on the
Prokaryotic cell outcomes
2.2 PROKARYOTIC CELLS
2.3 EUKARYOTIC CELLS
AND MICROSCOPE
ANATOMY!
IB Bio SL
2.3 Eukaryotic Cells
Please use your text to complete the worksheet on
the Eukaryotic Cell outcomes
What is a Prokaryotic Cell?
The beginning of life
Prokaryotic cells are thought to be the first to have
appeared on earth.
Prokaryotic cells still play a large role in the world
today. Bacteria is a good example.
Are cells that lack membrane bound organelles or any
type of cells nucleus.
They are cells that are
much smaller and
simpler than Eukaryotic
cells.
In fact most Prokaryotic
cells are less than one
micrometre in
diameter!
Features of Prokaryotic Cells
The features of the Prokaryotic cell that you will
have to identify are:
Cell wall
Plasma membrane
Pili &Flagella
Ribosomes
Nucleoid
Cell wall
Plasma membrane
Protects and maintains the shape of the cell.
In most prokaryotes the cell wall is composed of a
carbohydrate-protein
complex called
peptidoglycan.
Some bacteria have an
additional layer outside
the cell wall that allows
them to stick to teeth,
skin and food.
Pili
Are hair-like growths on the outside of the cell wall.
They are used for attachment.
Their main function is in
joining bacteria cells in
preparation for the
transfer of DNA.
(sexual reproduction)
Function as the sites of protein synthesis.
Ribosomes typically
occur in very large
numbers in cells
with high protein
production.
The ribosomes in prokaryotic
are small (70s)
Controls the movement of materials into and out of
the cell.
It also plays a role in binary fission (stay tuned)
Flagella
Ribosomes
Are hair-like growths (longer than pili) that are used
for cell motility.
Nucleoid Region
cells
Because bacteria cells are non-compartmentalized
and contain a single, long, continuous, circular
thread of DNA...
This region is involved
in the control of the
cell as well as
reproduction.
Binary Fission
1.
2.
3.
Is the simple process by which prokaryotic cells
divide.
The circular DNA is copied
Two daughter chromosomes become attached to
different regions on the plasma memberane.
The cells divide into two genetically identical
daughter cells.
The process includes; elongating of the cell, and
partitioning of the newly produced DNA.
Endosymbiotic Theory
Binary Fission
http://learn.genetics.utah.edu/content/begin/cells/
organelles/
Global Connections...
Prokaryotes and clean water resources
Lifesaver bottle with Michael Pritchard
http://www.ted.com/talks/lang/eng/michael_pritc
hard_invents_a_water_filter.html
We’ll revisit this idea in the evolution unit!
2.3 Eukaryotic Cells
What do you need to know?
Draw a diagram of a
liver cell including...
Free ribosomes
rough endoplasmic
reticulum
lysosome
Golgi apparatus
mitochondrion
nucleus
Free Ribosomes
very small structures (about 80S) that carry out protein
synthesis in the cell.
Free ribosomes are found floating in the cytoplasm and
others are found attached to the rough ER.
Ribosomes are composed
of RNA and protein and are
larger in eukaryotic cells
than prokaryotic cells.
Eukaryotic ribosomes
are composed of two subunits.
The advantage of having ribosomes attached to ER
is that as the ribosomes synthesize proteins they can
be transported by the ER to become parts of cell
membranes, enzymes for the cell or messengers
between cells.
The smooth ER has many functions such as production
of membrane phospholipids, production of sex
hormones, breaks down harmful substances, stores
calcium ions, transports lipid based compounds, and
aid liver cells in releasing glucose into the blood
when needed.
Endoplasmic reticulum
an extensive network of channels that stretches from the
nucleus to the plasma membrane.
Its function is to transport materials through the cell.
There are two types of ER, rough ER and smooth ER.
The rough ER is
distinguished by the
ribosomes attached
to its exterior surface.
Lysosome
single membrane bound organelles produced by the
Golgi apparatus that contain strong hydrolytic enzymes
which break down biological molecules.
They can contain up to 40 different enzymes and can
also break down worn out
cell parts that are no longer
functioning properly.
Lysosomes are involved in
breaking down materials
brought into a cell via
phagocytosis.
Golgi apparatus
this organelle is composed of many flattened sacs called
cisternae which are stacked on top of each other and it is
normally located between the ER and plasma membrane.
The Golgi apparatus collects, packages, modifies and
distributes materials throughout the cell.
It is located close to the ER to receive products transported
by the ER and close to the plasma membrane so it can
discharge materials needed outside the cell.
This organelle is found in high numbers in cell that produce
and secrete substances (i.e. pancreas cells).
Mitochondrion
very large, double membrane bound rod-shaped organelles
that are found scattered in the cytoplasm and contain their
own DNA.
Their outer membrane
is smooth while their
inner membrane is highly
folded into cristae which
increase the surface area
of the inner mitochondria
for cellular respiration, the
main function of the mitochondria.
Due to its size and ability to produce energy in the form of
ATP, mitochondria also have their own ribosomes.
Mitochondria are found in high numbers in cells that have high
energy needs (i.e. muscle cells).
Nucleus
eukaryotic DNA is housed inside the double membrane
or nuclear envelop of the nucleus.
The double membrane allows the DNA to remain
separate from the rest of the cell and carry out its
functions without interference from the other parts of
the cell.
The nuclear membrane
contains pores that allows
for communication with
the rest of the cell.
DNA is contained in the form of chromosomes within the
nucleus.
The nucleus is normally located in the center of the eukaryotic
cell but is often pushed to the side in plant cells due to the
large vacuole.
Most cells have one nuclei but some have multiple nuclei
while others have
none (i.e. red blood cells).
If there is no nucleus the
cell cannot reproduce.
Most nuclei often have a
nucleolus a dark area inside
the nucleus where ribosomes
are manufactured.
See inside a cell!
http://learn.genetics.utah.edu/content/begin/cells/
insideacell/
http://www.cellsalive.com/cells/3dcell.htm
Comparison between prokaryotic and
eukaryotic cells
Feature
Genetic material
Location of genetic
material
PROKARYOTIC CELLS
Feature
Located inside the double
membrane of the nucleus;
sometimes referred to as the
nuclear envelop.
PROKARYOTIC CELLS
EUKARYOTIC CELLS
Mitochondria
Prokaryotes do not contain
Eukaryotic cells all contain
mitochondria. The surface of
hundreds of mitochondria.
the cell membrane and the
mesosome are used to produce
cellular energy.
Ribosomes
Ribosomes are smaller in
prokaryote cells. (70S)
Ribosomes are larger in
eukaryote cells. (80S)
Membrane bound
organelles or
internal membranes
Few or none are present.
Eukaryotic cells contain several
membrane bound organelles
such as ER, Golgi apparatus and
lysosomes.
Size
Measure less than 10
micrometers.
Measure more than 10
micrometers.
EUKARYOTIC CELLS
Contain a naked loop of
Contain four or more chromosomes
DNA. Sometimes referred to as consisting of strands of DNA
a nucleoid.
associated with protein.
Naked DNA found in region of
the cytoplasm called nucleoid.
Cont’d
Difference between plant and animal
cells
FEATURE
ANIMAL CELL
PLANT CELL
Cell wall
No cell wall. Cells have a
plasma membrane only.
Contains a cell wall with a
plasma membrane just inside.
Chloroplasts
Not found in animal cells.
All plants that carry out
photosynthesis contain
chloroplasts.
Carbohydrate
storage
Animal cells store
carbohydrates in the form of
glycogen.
Plant cells store carbohydrates
in the form of starch.
Cont’d
Extracellular components
FEATURE
ANIMAL CELL
PLANT CELL
Vacuole
Not normally present in animal
cells. Some small vesicles are
sometimes formed.
Plant cells contain one large
central fluid filled vacuole.
Shape
Centrioles
Usually a rounded shape but the Plant cells have a fixed shape
plasma membrane is flexible and due to the cell wall. Often boxcan change shape.
like or angular in shape.
Contains centrioles within a
centrosome area.
Do not contain centrioles within
a centrosome area.
The Cell Wall
The cell wall is composed of
cellulose
microfibrils which form a thick wall surrounding the entire
cell.
The cell wall grows with the cell, continually adding
more cellulose to maintain its thickness.
The cell wall protects the plant cell and helps to
maintain its shape.
The cell wall also protects the cell from too much water
entering and helps the cell maintain osmotic balance.
Since it is made of cellulose, the plant cell can use the
cell wall to store carbohydrates.
Extracellular matrix of animal cells
The extracellular matrix of animal cells is composed
of glycoproteins and collagen fibres.
Together they form a fibre-like structure that
anchors the matrix to the plasma membrane.
The ECM adds strength to the plasma membrane,
allows cell to cell interactions, and allows adjacent
cells to attach to
one another
Cartilage is made of cells with a
lot
of extracellular material which
gives
cartilage its firm, resilient
structure
Extracellular components are structures outside the
plasma membranes of cells.
One commonly known example is the cell wall in
plant cells.
Another example of an extracellular component is
the extracellular matrix of animal cells as well as
bone and cartilage.
The Parts of a Light Microscope
Light Microscopes
• The ocular lens in the eyepiece magnifies and
transmits the image to your eye
•
Light source: Could be a mirror, but
most likely it is a bulb built into the
base
•
Diaphragm: Adjusts the amount of
light striking an object
•
Objective lens: Gathers light and
magnifies image
• The magnification of the ocular lens is 10X
•
• To find the total magnification of the microscope you
are using, multiply the magnification of the objective
lens by the magnification of the ocular lens.
Ocular lens (eyepiece): Magnifies
objects and focuses light to your eye
•
Stage: Holds slide
• For example: 40X (objective lense) x 10X (ocular
lense) = 400X magnification
•
Stage clips: Hold slide in place
•
Base and arm: Structural support for
the microscope
Can you name the parts?
Start on the left side and work from the top down. Then go to the right side
and work from the top down.
– Can be moved using the coarse or fine
adjustment knobs to bring the object
into focus
Images Produced by Light Microscopes
Ocular lens (eyepiece)
Arm
Objective Lenses
Stage clip
Stage
Amoeba
Streptococcus bacteria
Anthrax bacteria
Human cheek cells
Plant cells
Yeast cells
Course adjustment
Diaphragm
Fine adjustment
Light Source
Base
Nice Job !
Fun in the lab!
Cells that you eat! Yumm!
You will examine several plant and animal cells
under the light microscope – super-fun!