Cell
The Cell is the basic structural and functional unit of life. Simplest plants and animals consist of a single cell. Higher animals including human can be regarded as a complex society of independent cells of many different types. The cell is the smallest unit of life in our bodies. In the body, there are brain cells, skin cells, liver cells, stomach cells, and the list goes on. All of these cells have unique functions and features.
Animal Cells are typical of the eukaryotic cell, enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles. Unlike the eukaryotic cells of plants and fungi, animal cells do not have a cell wall.
The size of human cells varies between 5 to 50 micrometer. However certain cells may be exceptionally large e.g., the mature ovum (diameter 120 micrometer)
The Cell is the basic structural and functional unit of life. Simplest plants and animals consist of a single cell. Higher animals including human can be regarded as a complex society of independent cells of many different types. The cell is the smallest unit of life in our bodies. In the body, there are brain cells, skin cells, liver cells, stomach cells, and the list goes on. All of these cells have unique functions and features.
Animal Cells are typical of the eukaryotic cell, enclosed by a plasma membrane and containing a membrane-bound nucleus and organelles. Unlike the eukaryotic cells of plants and fungi, animal cells do not have a cell wall.
The size of human cells varies between 5 to 50 micrometer. However certain cells may be exceptionally large e.g., the mature ovum (diameter 120 micrometer)
Animal
Cells are
typical of the eukaryotic cell, enclosed by a plasma membrane and containing a
membrane-bound nucleus and organelles. Unlike the eukaryotic cells of plants
and fungi, animal cells do not have a cell wall.
Cell
contains following parts:
Centrioles: Centrioles are self-replicating organelles made up of nine bundles
of microtubules and are found only in animal cells. They appear to help in
organizing cell division, but aren't essential to the process.
Cilia and Flagella: For single-celled eukaryotes, cilia and flagella are essential
for the locomotion of individual organisms. In multicellular organisms, cilia
function to move fluid or materials past an immobile cell as well as moving a
cell or group of cells.
Endoplasmic Reticulum: The endoplasmic reticulum is a network of sacs that
manufactures, processes, and transports chemical compounds for use inside and
outside of the cell. It is connected to the double-layered nuclear envelope,
providing a pipeline between the nucleus and the cytoplasm.
Endosomes and Endocytosis: Endosomes are membrane-bound
vesicles, formed via a complex family of processes collectively known as
endocytosis, and found in the cytoplasm of virtually every animal cell. The
basic mechanism of endocytosis is the reverse of what occurs during exocytosis
or cellular secretion. It involves the invagination (folding inward) of a
cell's plasma membrane to surround macromolecules or other matter diffusing
through the extracellular fluid.
Golgi Apparatus: The Golgi apparatus is the distribution and shipping department
for the cell's chemical products. It modifies proteins and fats built in the
endoplasmic reticulum and prepares them for export to the outside of the cell.
Intermediate Filaments: Intermediate filaments are a very broad class of fibrous
proteins that play an important role as both structural and functional elements
of the cytoskeleton. They function as tension-bearing elements to help
maintain cell shape and rigidity.
Lysosomes: The main function of these microbodies is digestion. Lysosomes
break down cellular waste products and debris from outside the cell into simple
compounds, which are transferred to the cytoplasm as new cell-building
materials.
Microfilaments: Microfilaments are solid rods made of proteins called actin.
These filaments are primarily structural in function and are an important
component of the cytoskeleton. They interact with myosin during contraction of
muscles.
Mitochondria: Mitochondria are oblong shaped organelles that are found in the
cytoplasm of every eukaryotic cell. In the animal cell, they are the
Mitochondria are rod-shaped organelles that can be considered the power
generators of the cell, converting oxygen and nutrients into adenosine
triphosphate (ATP). ATP is the chemical energy "currency" of the cell
that powers the cell's metabolic activities.
Nucleus: The nucleus is a highly specialized organelle that serves as the
information processing and administrative center of the cell. This organelle
has two major functions: it stores the cell's hereditary material, or DNA, and
it coordinates the cell's activities, which include growth, intermediary
metabolism, protein synthesis, and reproduction (cell division).
Peroxisomes: Microbodies are a diverse group of organelles that are found in
the cytoplasm, roughly spherical and bound by a single membrane. There are
several types of microbodies but peroxisomes are the most common.
Plasma Membrane: All living cells have a plasma membrane that encloses their
contents. In prokaryotes, the membrane is the inner layer of protection
surrounded by a rigid cell wall. Eukaryotic animal cells have only the membrane
to contain and protect their contents. These membranes also regulate the
passage of molecules in and out of the cells.
Ribosomes: All living cells contain ribosomes, tiny organelles composed of
approximately 60 percent RNA and 40 percent protein. In eukaryotes, ribosomes
are made of four strands of RNA. In prokaryotes, they consist of three strands
of RNA.
Thick Filaments: They are composed of protein myosin. They interact with
actin during contraction of muscles.
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