was looking through a crude microscope

Robert Hooke was looking through a crude microscope at some

is the most striking thing about a cell.

If we chemically analyze cells, we find that they are made up primarily of four elements-

is needed for blood clotting (among other things.

Iron is necessary to make

which carries oxygen in the blood.

is required to make the thyroid hormone that controls metabolism.

In their ionic form, many of the metals (such as calcium, sodium, and potassium) can carry an electrical charge; when they do they are called

are essential if nerve impulses are to be transmitted and muscles are to contract.

Cells vary tremendously in length- ranging from

also vary dramatically in the functions, or roles, they play in the body.

In general, all cells have three main regions or parts-a

headquarters,” or the control center, is the gene-containing

The nucleus contains one or small, dark-staining, essentially round bodies called

are sites where ribosomes are assembled.

most of which eventually migrate into the cytoplasm, serve as the actual sites of protein synthesis, as described shortly

The nucleus is bound by double membrane barrier called

The nuclear membrane encloses a jellylike fluid called

When a cell is not dividing, its DNA is combined with protein and forms a loose network of bumpy threads called

When a cell is dividing to for two daughter cells, the chromatin threads coil and condense to form dense, rodlike bodies called

is a fragile, transparent barrier that contains the cell contents and separates them from the surrounding environment.

is important in defining the limits of the cell, it is much more than a passive envelope, or “baggie”

makes up the cell membrane and is critical to a cell’s ability to function.

Some proteins are

Branching sugar groups are attached to most of the proteins abutting the extracellular space. Such “sugar -proteins “are called

and because of their presence, the cell surface is a fuzzy, sticky, sugar – rich area called

determine your blood type, act as receptors that certain bacteria, viruses, or toxins can bind to, and play a role in cell -to -cell interactions.

Definite changes in glycoproteins occur in cells that are being transformed into

little shaggy hairs “, are tiny fingerlike projections that greatly increase the cell’s surface area for absorption so that the process occurs more quickly.

vary structurally depending on their roles.

is an impermeable junctions that bind cells together into leak proof sheets that prevent substances from passing through the extracellular space between cells .

are anchoring junctions that prevent cells subjected to mechanical stress ( such as skin cells ) from being pulled apart .

It is commonly seen in the heart and between embryonic cells, function mainly to allow communication.

The jelly like material inside the outer membrane of a cell that hold the nucleus, organelles and other component of the cell.

The site of most cellular activities known as the” factory area” of the cell.

is a semitransparent fluid that suspends the other elements.

are the metabolic machinery of the cell.

are chemical substances that may or may not be present, depending on the specific cell type.

are best known for their role in generating microtubules, and during cell division

They are rod-shaped bodies that lie at right angles to each other; internally they are made up of fine microtubules.

breakdown bodies “ , which appear in different sizes , are membranous “ bags “ containing powerful digestive enzymes.

It appears as a stack of flattened membranous sacs associated with swarms of tiny vesicles.

It is generally found close to the nucleus and is the principal “traffic director “for cellular proteins.

They are tiny, bilobed, dark bodies made of proteins and one variety of RNA called ribosomal RNA.

Organelle where cellular respiration occurs “powerhouse” of the cell.

serves important functions particularly in the synthesis, folding, modification, and transport of proteins.

An elaborate network of protein structures extends throughout the cytoplasm.

acts as a cell’s “bones and muscles” by furnishing an internal framework that determines cell shape, supports other organelles, and provides the machinery needed for intracellular transport and various types of cellular movements.

acts as a cell’s “bones and muscles” by furnishing an internal framework that determines cell shape, supports other organelles, and provides the machinery needed for intracellular transport and various types of cellular movements.

acts as a cell’s “bones and muscles” by furnishing an internal framework that determines cell shape, supports other organelles, and provides the machinery needed for intracellular transport and various types of cellular movements.

determine the overall shape of a cell and the distribution of organelles.

determine the overall shape of a cell and the distribution of organelles.

such as actin and myosin) are most involved in cell motility and in producing changes in cell shape.

help form desmosomes.

The elongated shape of this cell lies along the cable-like fibers that it secretes.

This cell carries oxygen in the bloodstream. Its concave disk shape provides extra surface area for the uptake of oxygen and streamlines the cell so it flows easily through the blood stream.

The hexagonal shape of this cell is exactly like a “cell” in a honeycomb of a beehive. This shape allows epithelial cells to pack together in sheets.

has abundant intermediate filaments that resist tearing when the epithelium is rubbed or pulled.

These cells are elongated and filled with abundant contractile filaments, so they can shorten forcefully and move the bones or change the size of internal organs.

The huge spherical shape of a fat cell is produced by a large lipid droplet in its cytoplasm.

This cell extends long pseudopods (false feet”) to crawl through tissue to reach infection sites.

This cell has long processes for receiving messages and transmitting them to other structures in the body

The largest cell in the body, this egg cell contains several copies of all organelles, for distribution to the daughter cells that arise when the fertilized egg divides to become an embryo.

This cell is long and streamlined, built for swimming to the egg for fertilization. Its flagellum acts as a motile whip to,propel the sperm.