Another characteristic that living things share is that they reproduce. They reproduce, or make new organisms of the same sort. In order for a species to survive, it is a necessity for them to reproduce because all organisms die eventually. There are two ways living things reproduce, sexually and asexually. Sexual reproduction needs two cells from two different organisms to merge and form the first cell of a new organism. Asexual reproduction is when only one organism can reproduce without the assistance of another.

Chemical compounds are represented just as elements are with chemical symbols. A chemical formula is made up of the chemical symbols that make the chemical compound. For example, water contains two hydrogen atoms and one oxygen atom. The chemical formula would be H2O. Table salt is made from one sodium atom and one chlorine atom, so the chemical formula is NaCl.

The fourth characteristic of a living thing is the ability to obtain and use energy. Living things obtain energy from their environment or their surroundings. All living things require energy to live and build their cells. This process is anabolism. Anabolism is the process in a living thing that involves putting together complex substances from simpler substances. Plants get their energy from the sunlight through a process called photosynthesis. Animals get their energy from food that is eaten. The food is then broken down through digestion, resulting in a release of energy called catabolism. Living things practice anabolism and catabolism through the whole time they are living. The balance of anabolism and catabolism is called metabolism.

A multicellular organism is a living thing that is made up of more than one cell. These organisms can contain hundreds, thousands, even billions of cells or more. We see multicellular organisms everyday: people, plants, and house pets.

In multicellular organisms, cells are organized in specialized groups, known as tissues. A tissue is a group of similar cells that preform similar functions. Different tissues form many different tasks. For example, a kind of tissue is made up of cells that produce digestive enzymes in the pancreas, and the cells in an eye respond to light. Most multicellular organisms have four main types of tissues: muscle, epithelial, nerve, and connective.

The cell membrane acts as the cell's outer wall and protects it from it's surroundings. It also moderates what goes in, and what comes out of the cell. The cell membrane is made up of several different types of molecules. The most important of these is lipids. Most of the cell membrane is made up of a double layer of lipids. The cell membrane is also made up of proteins and carbohydrates.

Ribosomes are the structures in which proteins are produced. They are made out of protein and RNA. Some ribosomes in a cell are attached to membranes, while some are free in the cytoplasm. Ribosomes are one of the smallest organelles in a cell.

Organic compounds are compounds that contain carbon. Carbon is a unique element because of its ability to form covalent bonds that are exceptionally strong and stable. The carbon atom has two electrons in the first energy level and four in the second energy level. There are four open positions in carbon's outermost energy level, allowing it to form four single covalent bonds. Carbon can easily bond with hydrogen, oxygen, nitrogen, phosphorus, and sulfur atoms. Carbon also has the extraordinary ability to form long chains with other carbon atoms. The bonds between carbon can be single, double, or triple covalent bonds. No other element has this rare ability. (See Figure 2)

Cytokenesis follows quickly after mitosis is finished. In cytokenesis the cytoplasm of the parent cell splits into two to form the daughter cells. In animals, the cell membrane moves together and pinches the cells, giving making the daughter cells have their own nucleus and organelles. In plants the cell plate appears and forms a barrier between the two daughter cells. The cell plate then forms into a cell membrane, then the cell wall develops. (See Figure 4)

Eukaryote cells divide in order to slow down cell growth. Cell division is the process in which a cell divides to form two daughter cells. The first stage of cell division is called mitosis. Mitosis is the process when the nucleus of a cell is divided into two nuclei, and both have the same number and type of chromosomes as the parent cell. Mi

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Approximate Word count = 4864
Approximate Pages = 19 (250 words per page double spaced)