Transcript The Cell - abdelbio

Cell Biology
www.edumediasciences.com/recherche.php?q=
Cell
Robert Hooke (1665)
English scientist
looked at a thin slice of cork
through a compound microscope
observed tiny, hollow, room like
structures called these structures
'cells' because they reminded him
of the rooms that monks lived in.He
only saw the outer walls (cell walls)
because cork cells are not alive
( dead cells)
Anton van Leeuwenhoek
Dutch scientist
looked at blood, rainwater,
scrapings from teeth through
a e microscope. He
observed living cells; called
some 'animalcules'
some of the small
'animalcules' are now called
bacteria
Matthias Schleiden (1838)
German botanist
viewed plant parts under a microscope
discovered that plant parts are made of
cells.
Theodor Schwann (1839)
German zoologist
viewed animal parts under a microscope
discovered that animal parts are made of
cells
Rudolph Virchow (1855)
German physician
stated that all living cells come only from
other living cells
CELL THEORY
1. ALL LIVING THINGS ARE COMPOSED OF CELLS
2. CELLS ARE THE BASIC UNIT OF STRUCTURE
AND FUNCTION IN LIVING THINGS
3.ALL CELLS ARE PRODUCED FROM OTHER
CELLS.
Theodor Schwann
All animals are made of cells
Matthias Schleiden
All plants are made of cells.
SPONTANEOUS GENERATION- an UNTRUE THEORY
stating that living things arise from nonliving sources
FRANCESCO REDI in the 1600’S DISPROVED THIS
IDEA
Rudolph Virchow
all living cells come only from other living cells
NERVE CELLS
Muscle cells
Skin Cells
Why do cells divide. A cell divides so as to maintain a favourable Surface
area to volume ratio.
A cell receives food and oxygen and turns out waste materials through
it's membrane. A cell membrane of specific area can serve the contents of
a particular volume only.Increase in the volume increases the
requirements of the cell and this increases the need for greater
membrane area.
Now,the Surface area of a sphere increase as the square of the radius and
the volume of a sphere increases as the cube of the radius or to say, in
simpler words,the volume of the cell increase more rapidly then the area
of its membrane.
Hence, as a cell grows,it's membrane in due course of time becomes
insufficient to move the required amount of substances in and out. The
cell by dividing has a more favourable surface area to volume ratio. Thus,
the cell divide so as to maintain it's size such that all it's requirements of
nutrition,respiration and excretion are met.
•
http://plaza.ufl.edu/alallen/pgl/modules/rio/stingarees/module/why.html
Colonial Organisms
The little stars we can see on the image of the stone are the colonial Tunicates.
Membranipora.
The Structure and Function of the Cell Membrane
telstar.ote.cmu.edu/.../membranes/index.html
http://www.ibiblio.org/virtualcell/textbook/chapter3/chapter3.htm
A Phosphlipid
A lipid bilayer
http://telstar.ote.cmu.edu/biology/downloads/membranes/index.htm
l
http://www.wisc-online.com/objects/index_tj.asp?objID=ap1101
http://www.bio.davidson.edu/people/macampbell/111/memb-swf/membranes.swf
http://www.susanahalpine.com/anim/Life/memb.htm
We will group the organelles into three catagories:
Nucleus
cytoplasm
Endoplasmic
reticulum
Ribosomes
Golgi apparatus
Mitochondria
Lysosome
Cytoskeleton
Vacuoles
Cilia and Flagella
Centrioles
Comparing animal and plant cells
Nucleus
The Cell Wall
Anatomy of the Plant Cell
cytoplasm
Central Vacuole
Endoplasmic
reticulum
Plastidschloroplasts
Ribosomes
Golgi apparatus
Mitochondria
Lysosome
Cytoskeleton
Vacuoles
Cilia and Flagella
Centrioles
Comparing animal and plant cells
The Nucleus
http://www.ibiblio.org/virtualcell/textbook/chapter3/chapter3.htm
The Cell
One or more per cell - Spherical shape - Denser than surrounding cytoplasm
Chromosomes
- Usually in the form of chromatin
- Contains genetic information
- Composed of DNA
- Thicken for cellular division
- Set number per species (i.e. 23 pairs for human)
Nuclear membrane
- Surrounds nucleus
- Composed of two layers
- Numerous openings for nuclear traffic
Nucleolus
- Spherical shape
- Visible when cell is not dividing
- Contains RNA for protein manufacture
The Cell
cytoplasm
Collective term for cytosol and organelles contained within
Colloidal suspension
Cytosol mainly composed of water with free-floating molecules
Viscosity constantly changes
We will group the organelles into three categories:
Group 1 - Those organelles involved in protein production
Group 2 - Those organelles involved in energy production
Group 3 - Specialty organelles
The Cell
Endoplasmic reticulum
- Tubular network fused to nuclear membrane
- Goes through cytoplasm onto cell membrane
- Stores, separates, and serves as cell's transport system
- Smooth type: lacks ribosomes
- Rough type (pictured): ribosomes embedded in surface
The Cell
The Cell
The Cell
Ribosomes
- Each cell contains thousands
- Act as 'protein factories'
- Composes 25% of cell's mass
- Stationary type(Attached): embedded in rough endoplasmic reticulum,
produces proteins to be secreted from the cell.
- Mobile type( free): injects proteins directly into cytoplasm, produces
proteins to be consumed in the cell.
The Cell
Mitochondria
- Second largest organelle with unique genetic structure
- Double-layered outer membrane with inner folds called cristae
- Produce Energy in the form of ATP through chemical reactions take place on
cristae through a process called oxidative phosphorylation. This process uses
oxygen and simple sugars to create adenosine triphosphate (ATP), the cell’s main
energy source.
- Controls level of water and other materials in cell
- Recycles and decomposes proteins, fats, and carbohydrates, and forms urea
- Although most DNA is packaged in chromosomes within the nucleus, mitochondria
also have a small amount of their own DNA. This genetic material is known as
mitochondrial DNA or mtDNA. mitochondria originate only from other mitochondria.
- for the origin of mitochondria (and chloroplasts) suggests that mitochondria are
descended from specialized bacteria that became part of the cytoplasm of another
cell. The ability of symbiont bacteria to conduct cellular respiration in host cells that
relied on glycosis and fermentation would have provided a considerable evolutionary
advantage. Similarly, host cells with symbiont bacteria capable of photosynthesis
would also have an advantage. In both cases, the number of environments in which
the cells could survive would have been greatly expanded.
The Cell
The Cell
Golgi apparatus
- Protein 'packaging plant'
- A membrane structure found near nucleus
- Composed of numerous layers forming a sac
http://bcs.whfreeman.com/thelifewire/content/chp04/0402002.html
The Cell
Lysosome
- originating in part from the Golgi apparatus
- contain digestive enzymes
- sites for the breakdown of food and foreign objects taken up by the cell.
- Digestive 'plant' for proteins, lipids, and carbohydrates
- Transports undigested material to cell membrane for removal
- Vary in shape depending on process being carried out
- Cell breaks down if lysosome explodes
The Cell
Peroxisomes function to rid the
cell of toxic substances, in
particular, hydrogen peroxide -a common byproduct of cellular
metabolism. These organelles
contain enzymes that convert
the hydrogen peroxide to water,
rendering the potentially toxic
substance safe for release back
into the cell. Some types of
peroxisomes, such as those in
liver cells, detoxify alcohol and
other harmful compounds by
transferring hydrogen from the
poisons to molecules of oxygen.
Glyoxysomes They are small
bodies usually located near the
mitochondria.They help to
convert stored lipids (oils) into
energy for the developing plant
embryo.
The Cell
Vacuoles
- Membrane-bound sacs for storage, digestion, and waste removal
- Contains water solution
- Contractile vacuoles for water removal (in unicellular organisms)
The Cell
Cytoskeleton
- The cytoplasm contains a fine network of fibrous protein elements
that form a framework for supporting the extensively branched
membranes found in the relatively fluid cytoplasmic matrix.
- Supports cell and provides shape.
- composed of three types of organelles microtubules, microfilaments
and microbodies.
- Aids movement of materials in and out of cells.
The Cell
The Cell
Cilia and Flagella
-Whiplike appendages extend from the surface of many types of eukaryotic
cells.
- If there are many of them, they are called cilia; if only one, or a few, they
are flagella.
- Flagella also tend to be longer than cilia but are otherwise similar in
construction.
- Cilia and flagella move liquid past the surface of the cell.
For single cells, such as sperm, this enables them to swim.
-For cells anchored in a tissue, like the epithelial cells lining our air
passages, this moves liquid over the surface of the cell (e.g., driving
particle-laden mucus toward the throat).
-Structure of Cilia and Flagella
The Cell
Structure of Cilia and Flagella
Both cilia and flagella consist of:
•a cylindrical of 9 pair of microtubules and a pair of single microtubules
running up through the center of the bundle,.
•The entire assembly is sheathed in a membrane that is an extension of
the plasma membrane.
Cilia and Flagella
Cilia and Flagella
Cilia and Flagella
trachea
Cilia and Flagella
Cilia and Flagella
Cilia and Flagella
Centrioles are cylindrical structures that
are composed of groupings of microtubules
arranged in a 9 + 3 pattern. The pattern is
so named because a ring of nine
microtubule "triplets" are arranged at right
angles to one another. Centrioles are found
in animal cells and play a role in cell
division.
The Cell
The Cell Wall The rigid cell wall of plants is made of fibrils of
cellulose embedded in a matrix of several other kinds of polymers
such as pectin and lignin.
Primary cell walls. Although each plant cell is encased in a
boxlike cell wall, it turns out that communication between cells is
just as easy, if not easier, than between animal cells. Fine strands
of cytoplasm, called plasmodesmata, extend through pores in the
cell wall connecting the cytoplasm of each cell with that of its
neighbors.
Plant Cell
Vacuoles are membrane-bound sacs
within the cytoplasm of a cell that function
in several different ways. In mature plant
cells, vacuoles tend to be very large and
are extremely important in providing
structural support, as well as serving
functions such as storage, waste disposal,
protection, and growth. Many plant cells
have a large, single central vacuole that
typically takes up most of the room in the
cell (80 percent or more). Vacuoles in
animal cells, however, tend to be much
smaller, and are more commonly used to
temporarily store materials or to transport
substances.
http://www.cellsalive.com/cells/vacuole.htm
Plant Cell
The structure of the secondary cell wall, built up of a series of layers of
cellulose
Plant Cell
Plastids
- large organelles found on plants
and some protists but not in
animals.
-Chloroplasts represent one group
of plastids.
-Chloroplasts are the organelles in
which photosynthesis takes place. - Photosynthesis is an important
process by which autotrophic cells
manufacture their own food.
Chloroplasts contain the green
pigment chlorophyll (this is why
plant leaves are green) which
absorbs light to provide the energy
necessary to complete
photosynthesis
-
Plant Cell
Group 1 - Those organelles involved in protein production
The endoplasmic reticulum
Ribosomes
The golgi apparatus
cytoplasm
Lysosomes
Group 2 - Those organelles involved in energy production
Mitochondria
Plant & Animal cells
Chloroplasts
Plant Cell
cytoplasm
Group 3: Specialty Structures
This last group of cell structures described here
and only grouped together for convienence. While
the other structures we have talked about are
found in all cells these structures are usually
found only in certain kinds of cells.
Animal cells generally contain centrioles.
Plant cells generally contain storage vacuoles, cell
walls, and plastids.
Cilia and flagella are found in many different life
forms.
Be aware that there are many other kinds of living
things besides plants and animals.
cytoplasm
Comparing Plant and Animal Cells
Plant
Animal