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Cell Organelles website

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All living organisms on Earth are divided into cells. The main concept of cell theory is that cells are the basic structural unit for all organisms. Cells are small compartments that hold the biological equipment necessary to keep an organism alive and successful. Living things may be single-celled or they may be very complex such as a human being.

There are smaller pieces that make up cells such as macromolecules and organelles. A protein is an example of a macromolecule while a mitochondrion is an example of an organelle. Cells can also connect to form larger structures. They might group together to form the tissues of the stomach and eventually the entire digestive system. However, in the same way that atoms are the basic unit when you study matter, cells are the basic unit for biology and organisms.

In larger organisms, the main purpose of a cell is to organize. Cells hold a variety of pieces and each cell type has a different purpose. By dividing responsibilities among different groups of cells, it is easier for an organism to survive and grow.

If you were only made of one cell, you would be very limited. You don't find single cells that are as large as a cow. Cells have problems functioning when they get too big. Also, if you were only one cell you couldn't have a nervous system, no muscles for movement, and using the internet would be out of the question. The trillions of cells in your body make your way of life possible.

There are many types of cells. In biology class, you will usually work with plant-like cells and animal-like cells. We say "animal-like" because an animal type of cell could be anything from a tiny microorganism to a nerve cell in your brain. Biology classes often take out a microscope and look at single-celled microbes from pond water. You might see hydra, amoebas, or euglena.

Plant cells are easier to identify because they have a protective structure called a cell wall made of cellulose. Plants have the wall; animals do not. Plants also have organelles such as the green chloroplast or large, water-filled vacuoles. Chloroplasts are the key structure in the process of photosynthesis.

Cells are unique to each type of organism. If you look at very simple organisms, you will discover cells that have no defined nucleus ( prokaryotes) and other cells that have hundreds of nuclei ( multinucleated).

Humans have hundreds of different cell types. You have red blood cells that are used to carry oxygen (O ₂) through the body and other cells specific to your heart muscle. Even though cells can be very different, they are basically compartments surrounded by some type of membrane.

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Biology4Kids.com! This tutorial introduces cell structure. Other sections include plants, animal systems, invertebrates, vertebrates, and microorganisms.

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Animal Cell Video-by Crash Course

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Eukaryopolis - The City of Animal Cells: Crash Course Biology #4

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Primary Contributers to Cellular Biology
The cell was first discovered and named by Robert Hooke in 1665. He remarked that it looked strangely similar to small rooms which monks inhabited. However what Hooke actually saw was the dead cell walls of plant cells (cork).  he first man to witness a live cell under a microscope was Anton van Leeuwenhoek, who in 1674 described the algae Spirogyra and bacteria he called "animicules."
In 1838, Theodor Schwann (animal cells) with help from Matthias Schleiden (plant cells) stated but the cell theory but promoted the idea of Free-cell formation (spontaneous generation of cells) (kind of crystalized into being) which was popular at the time. Rudolph Virchow then changed this idea into modern cell theory that pre-existing cells produce cells.
As with the rapid growth of molecular biology in the mid-20th century, cell biology research exploded in the 1950’s. It became possible to maintain, grow, and manipulate cells outside of living organisms. The first continuous cell line to be so cultured was in 1951 by George Otto Gey.  It was also aided by development of sterile cell culture techniques; the prior advances in electron microscopy, and later advances such as development of transfection methods, discovery of green fluorescent protein in jellyfish, and discovery of small interfering RNA (siRNA), among others.

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Diffusion-movement of materials spontaneously from an area of high concentration to an area of lower concentration.

Osmosis-diffusion of water through a selectively permeable membrane.

While active transport requires energy and work, passive transport does not. There are several different types of this easy movement of molecules. It could be as simple as molecules moving freely such as osmosis or diffusion. You may also see proteins in the cell membrane that act as channels to help the movement along. And of course there is an in-between transport process where very small molecules are able to cross a semi-permeable membrane.
Endocytosis - substances moving into a cell.
Exocytosis - substances being exported out of a cell.
Facilitated diffusion - proteins are used to help move molecules more quickly.

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1. All known living things are made up of cells.

2. The cell is structural & functional unit of all living things.

3. All cells come from pre-existing cells by division. (Spontaneous Generation does not occur).

4. Cells contains hereditary information which is passed from cell to cell during cell division.

5. All cells are basically the same in chemical composition.

6. All energy flow (metabolism & biochemistry) of life occurs within cells.

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Prokaryotic-comes from the Greek πρό (pro) "before" and καρυόν (karyon) "nut or kernel". NO membrane defined organelles.  For example no nucleus in this type of cell.
This type of life can be divided into two domains: Archaea and Bacteria. Both simple and unicellular.

Eukaryotic- comes from the Greek 'eu' means "true"   καρυόν (karyon) "nut or kernel". An organism with a complex cell or cells, in which the genetic material is organized into a membrane-bound nucleus or nuclei. Has many membrane defined organelles. They are classification kingdoms of: animals, plants, and fungi, protists.

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Atoms/Elements make up Chemicals/Compounds

Organic (made of carbon and hydrogen atoms with other elements often)
Inorganic Compounds (other chemicals not organic)

Carbohydrates-sugars, starches, and cellulose (fiber)

Proteins-made up of amino acids; enzymes (chemically active); structural (i.e microtubules, etc.)

Lipids-oils, fats, wax, and phospholipids (membranes of cells and organelles)

Nucleic Acids-DNA (double stranded main storage of genetic
information) and RNA (single stranded copy of
DNA used to make proteins).

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Organelle-part of a cell. Compartment of special function.
Mitochondria
Lysosomes (animal cells only)
Nucleus

Vacuoles
Central water vacuole (plant cells only)
Centrioles (animal cells only)
Golgi Complex-makes vesicles

Cell Membrane
Cytoskeleton

Cell Wall (plants only)
Cytoplasm

Chloroplasts (plants only)
Ribosomes

Endoplasmic Recticulum (rough and smooth)