What's an animal cell?
A cell is the structural and functional element that makes
up the tissues and organs of living beings. It contains the genetic information
of the individual and it is the origin of biological creation. It is complex
and consists of various elements allowing it to be autonomous, but in interaction
with other cells. The living beings are created in the base of a single cell
that divides by an iterative phenomenon (called mitosis) to compose the body. The multiplication of cells is a regulated phenomenon that allows the
development of the body and different organs. Abnormal and uncontrolled cell
proliferation is a fundamental element for the development of a cancer.
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| Animal cell composition |
Cell elements: It is composed of:
- Plasma membrane :
All cells (eukaryotic and prokaryotic) are separated from
their environment by a plasma membrane.
it determines what enters the cell and what comes out. Like
all biological membranes, the plasma membrane has a selective perméablilité,
means it allows certain substances to pass through more easily than others. The
plasma membrane consists of a double lipid layers, wherein proteins are
inserted.
- Cytoplasm :
the cytoplasm is mainly composed of water and therefore the
whole cell activity is carried out in aqueous medium in which the different
solutes are in solution and different organelles are in suspension.
The cytoplasm is the privileged place of intense biochemical
activity and in which several metabolic ways find their origin. Thus chemical
reactions of catabolic type leading to
energy release can occur in the cytoplasm and anabolic reactions such as the
biosynthesis of big molecules such as proteins and glycogen may also occur in
the cytoplasm.
- Cytoskeleton :
The cell shall maintain its shape and collapse resistance to
the presence of an internal cytoskeleton. Note that the cytoskeleton is not,
however, a rigid or articulated structure as the word "skeleton" may
suggest. The cytoskeleton appears in the cytosol as an impressive scaffolding
formed of fibrillar proteins called "fibrils" : these protein
fibrils are not covered by a membrane envelope. There are two major types of
different fibrils by their size and chemical composition, microfilaments and microtubules in bundles or
more complex training.
- Nucleus:
holds the genetic information of the cell and governs all
cellular activity. It includes:
- The nuclear envelope: double membrane cytoplasmic type
punctuated nuclear pores for the exchange with the cytoplasm.
- The nucleoplasm: colorless substance that fills the spaces
of the nucleus. It has close to those properties of the cytoplasm.
- Chromatin: denser than the nucleoplasm, chromatin is
formed of entangled filaments of DNA.
- The nucleolus: is a small dense mass without membrane.
- Endoplasmic reticulum:
intervened in the intracellular transport of different
substances, it is smooth, or rough (granular) and, in the latter case, lined
with ribosomes whose role is to synthesize proteins.
- Golgi apparatus ( Golgi complex):
Organelle in eukaryotic cells consisting of a stack of
cisternae "baggies" flattened.
The Golgi apparatus receives proteins and lipids from the endoplasmic
reticulum and redirects after processing and sorting, to a number of internal
or external destinations in the cell.
- Ribosomes :
Ribosomes are organelles present in eukaryotic and
prokaryotic cells. Ribosomes play an extremely important role: they assemble
amino acids to form proteins which then go into the endoplasmic reticulum.
- Lysosomes :
Lysosomes are organelles in eukaryotic cells that contain a
mixture of digestive enzymes used to degrade macromolecules.
Lysosomes are considered like "stomach" of the
cell.
- Mitochondrion :
Organelles present in eukaryotic cells. The mitochondrion is
constituted by a double membrane, the inner membrane is folded into a mitochondrial
cristae.
Mitochondrions are organelles that produce energy in the
cell. So mitochondrion have a central role in energy for the cell. They are the
ones who perform cellular respiration.
- Centriole :
Centriole is a cell
element specific of the animal cells.
it is cylinders formed of nine microtubules arranged in a
circle. Each cell contains two of these organelles, located close to the nucleus.
Centrioles play an important role in cell division.