CELL STRUCTURE EXPLAINED
There are around 75 trillion cells in the human body, but what are they and how do they work?
Cells
are life and cells are alive. You are
here because every cell inside your body has a specific function and a very specialised job to do. There are many different
types of cell, each one working to keep the body’s various systems operating. A
single cell is the smallest unit of living material in the body capable of
life. When grouped together in layers
or clusters, however, cells with similar jobs to do form tissue, such as skin
or muscle. To keep these cells working, there are thousands of chemical
reactions going on all the time.
All animal cells contain a nucleus, which acts like a control hub telling
the cell what to do and contains the cell’s genetic information (DNA). Most of
the material within a cell is a watery, jelly-like
substance called cytoplasm (cyto means cell), which circulates around the cell
and is held in by a thin external membrane, which consists of two layers.
Within the cytoplasm is a variety of structures called organelles, which all
have different tasks, such as manufacturing proteins – the cell’s key
chemicals. One vital example of an organelle is a ribosome; these numerous
structures can be found either floating around in the cytoplasm or attached to
internal membranes. Ribosomes are crucial in the production of proteins from
amino acids.
In turn, proteins are essential to building your cells and carrying out
the biochemical reactions the body needs in order to grow and develop and also
to repair itself and heal.
Cell anatomy
Cell membrane : Surrounding
and supporting each cell is a plasma
membrane that controls everything
that enters and exits.
Nucleus: The
nucleus is the cell’s ‘brain’ or control centre. Inside the nucleus is DNA
information, which explains how to make the essential proteins needed to run the cell.
Ribosomes: These
tiny structures make proteins and can be found either floating in the cytoplasm
or attached like studs to the endoplasmic reticulum, which is a conveyor
belt-like membrane that transports proteins around
the cell.
Endoplasmic reticulum The
groups of folded membranes (canals) connecting the nucleus to the cytoplasm are
called the endoplasmic reticulum (ER). If studded with ribosomes the ER is
referred to as ‘rough’ ER; if not it is known as ‘smooth’ ER. Both help
transport materials around the cell
but also have differing functions.
Mitochondria These organelles supply cells with the energy necessary for them to carry
out their functions. The amount of energy used by a cell is measured in
molecules of adenosine triphosphate (ATP). Mitochondria use the products of
glucose metabolism as fuel to produce
the ATP.
Golgi body Another organelle, the Golgi body is one that processes and packages
proteins, including hormones and enzymes, for transportation either in and
around the cell or out towards the membrane for secretion outside the cell
where it can enter the bloodstream.
Cytoplasm This is the jelly-like substance – made of water, amino acids and enzymes
– found inside the cell membrane. Within
the cytoplasm are organelles such as the nucleus, mitochondria and ribosomes, each
of which performs a specific role, causing chemical reactions in the cytoplasm.
Lysosomes This digestive enzyme breaks down unwanted substances and worn-out
organelles that could harm the cell by digesting the product and then ejecting it outside the cell.
