Transcript Cells

Cells
The cell is the basic structure and unit of all known living organisms.
Definition
It is the smallest unit of life that is
classified as a living thing, and is
often called the building block of life.
Organisms can be classified as
unicellular (consisting of a single
cell; including most bacteria) or
multicellular (including plants and
animals). Humans contain about 10
trillion (10^13) cells. Most plant and
animal cells are between 1 and 100
µm and therefore are visible only
with the use of a microscope.
Escherichia bacterias
The discovery
The cell was discovered by Robert Hooke in
1665. All organisms are composed of one or
more cells which come from preexisting cells.
The vital functions of an organism take place
within cells, and all cells contain the hereditary
information necessary for regulating their
functions and for transmitting information to the
next generation of cells.
The word cell comes from the Latin cellula,
meaning "a small room". The descriptive term
for the smallest living biological structure was
coined by Robert Hooke in a book he published
in 1665 when he compared the cork cells he
saw through his microscope to the small rooms
monks lived in.
Prokaryotes &
Eukaryotes
There are two basic types of cell: prokaryotic, which is
smaller and does not show the nucleus and eukaryotic, which
contains the nucleus delimited by a membrane.
The structure of plant and animal cells is very similar
because they are both eukaryotic cells; however animal cells
seem simpler to study than plant cells, because they are
composed of fewer parts.
Animal and Plant cells
Eukaryotic cells are divided into two
main groups:
Animal and Plant cells.
Both of them have a cell membrane,
a cytoplasm and a nucleus.
But these two groups differ a lot from
each other, mainly because Plant
cells have a cell wall around the cell
membrane and only Plant cells can
do the photosinthesis. Also Plant
cells
have
a
vacuole
and
chloroplasts
DNA
Inside the nucleus we can find the most important cell
molecule: the DNA.
It is a giant archive containing all the genetic information
needed by the organism.
It contains proteic sequences, information about somatic
features, and other genes whose function is still unknown.
History and structure
DNA means DeoxyriboNucleic Acid.
Its structure was formulated by
Watson and Crick combining all the
previous knowledge discovered since
then.
The DNA has a double-helix structure
and can be folded several times to fit
in the tiny cell's nucleus.
Watson and Crick with the original DNA model
Mitosis
Mitosis is a type of cell division, and is
the process by which a eukaryotic cell
separates the chromosomes in its cell
nucleus into two identical sets, in two
separate nuclei. It is generally
followed immediately by cytokinesis,
which divides the nuclei, cytoplasm,
organelles and cell membrane into
two cells containing roughly equal
shares of these cellular components.
Mitosis and cytokinesis together
define the mitotic phase of the cell
cycle which is the division of the
mother cell into two daughter cells,
genetically identical to each other and
to their parent cell. This accounts for
approximately 10% of the cell cycle.
Stem Cells
Features
Stem cells are biological cells found in all
multicellular organisms, that can divide (through
mitosis) and differentiate into diverse specialized
cell types and can self-renew to produce more
stem cells. In mammals, there are two broad types
of stem cells: embryonic stem cells, which are
isolated from the inner cell mass of blastocysts,
and adult stem cells, which are found in various
tissues. In adult organisms, stem cells and
progenitor cells act as a repair system for the
body, replacing adult tissues. In a developing
embryo, stem cells can differentiate into all the
specialized cells (these are called pluripotent
cells), but also maintain the normal turnover of
regenerative organs, such as blood, skin, or
intestinal tissues.
Potency
Harvesting
There are three basic types of stem
cells. Fetal stem cells are found in
human beings during the fetal stage
of development and can be harvested
from aborted fetuses or from the
umbilical cord of a newly delivered
baby. Embryonic stem cells are found
in embryos and are generally
harvested from frozen embryos that
are designated to be incinerated as
medical waste. Adult stem cells, on
the other hand, are found in many
different tissues within the human
body and can be harvested, to a
limited extent, without harming the
individual or causing excessive pain.
Treatments
Medical researchers believe that stem cell
therapy has the potential to dramatically change
the treatment of human disease. A number of
adult stem cell therapies already exist,
particularly bone marrow transplants that are
used to treat leukemia. In the future, medical
researchers anticipate being able to use
technologies derived from stem cell research to
treat a wider variety of diseases including
cancer, Parkinson's disease, spinal cord
injuries, Amyotrophic lateral sclerosis, multiple
sclerosis, and muscle damage, amongst a
number of other impairments and conditions.
However, there still exists a great deal of social
and scientific uncertainty surrounding stem cell
research, which could possibly be overcome
through public debate and future research, and
further education of the public.
Stem cells are widely studied, for their potential
therapeutic use and for their inherent interest.
Controversy
One concern of treatment is the risk that
transplanted stem cells could form tumors and
become cancerous if cell division continues
uncontrollably.
The side effects for bone marrow and stem cell
transplants are really the same as for
chemotherapy. You are having the same drugs in
higher doses. So the side effects can be very
severe.
All these side effects are at their worst when you
have just had your transplant and for a couple of
weeks afterwards. When your blood counts start to
rise you will start to feel better.
In the longer term, these treatments may cause
infertility, although some people who have had a
transplant do go on to have children.
The End
Niccolò Izzo / Luca Panzoli
Sources: wikipedia.org and google.com