Plants The Cell Membrane example essay topic

Cells are some of the smallest organisms around. All living things consist of cells, and yet they are invisible to the naked eye. Cells are the basic structural and functional units of life. Cells are made up of many different parts which allow them to function properly. All cells are separated from their surrounding by a cell membrane. The cell membrane regulates what enters and leaves the cell and also aids in the protection and support of the cell.

A cell membrane is similar to the walls surrounding your house. In plants the cell membrane is surrounded by a cell wall. The cell wall is outside the cell membrane, and its purpose is to help the membrane protect and support the cell. Since the cell wall is very porous, water, oxygen, carbon dioxide, and other substances can pass through easily. A cell wall is similar to a fence around your house, because it helps protect other things from getting inside the cell. In many cells there is a the nucleus, which was first described by Robert Brown.

If a cell does or does not have a nucleus has been used by scientists to divide cells into two general categories. The two categories are Eukaryotic's, which are cells with a nucleus, and Prokaryotic, which are cells without a nucleus. The nucleus has been found to be the information center of the cell and contains DNA. It also directs all activities that occur in a living cell.

It's like a mini me of the heart and brain of a human body. Most nuclei contain a small area called the nucleolus that is made up of RNA in which ribosomes are made. The DNA in the nucleus of eukaryotic cells is attached to proteins and forms chromosomes. Chromosomes contain the genetic information that must be passed to each new generation of cells. Chromosomes are what you pass on to your children to make them who they are, it's the DNA of a cell.

The cytoplasm is the area between the nucleus and the cell membrane. The cytoplasm contains many important structures. This area is basically the main place where you will find structures that help the cells stay alive. Mitochondrion is an importance structure that lies in the cytoplasm area. Mitochondrion is the plural word for mitochondria, which is the key organelle that converts energy from one form to another.

Mitochondria changes the chemical energy stored in food into compounds that are more convenient for the cell to use. The mitochondrion contains two special membranes. The outer membrane surrounds the organelle, and the inner membrane has many folds that increase the surface area of the mitochondrion. Ribosomes are the structures in which proteins are made. Cells that are active in protein synthesis are often crowded with ribosomes. Ribosomes are composed of RNA and protein.

Some ribosomes are attached to the membranes, and some are free in the cytoplasm. Ribosomes are among the smallest of organelles. They are no larger than 25 nanometers in diameter. A nanometer is equal to one billionth of a meter. Many cells are filled with a complex network of tube like things known as the endoplasmic reticulum.

The endoplasmic reticulum transports materials through the inside of the cell. There are two types of endoplasmic reticulum. In the smooth endoplasmic reticulum, the walls of the channels looks smooth and do not have particles or granules. The other form is involved in the synthesis of proteins. This form is called the rough endoplasmic reticulum, because the ribosomes that are stuck to its surface give it a rough appearance. The endoplasmic reticulum delivers many types of proteins to the Golgi body.

The function of the Golgi body is to coat protein with a molecular layer that allows the protein to leave the cell. Lysosomes are small membrane bordered structures that contain chemicals and enzymes necessary for digesting certain materials in the cell. Lysosomes are formed by the Golgi apparatus. Plant cells do not have lysosomes. Many cells contain sac like structures, called vacuoles that store materials such as water, salts, proteins, and carbohydrates. In many plants cells there is a single large central vacuole filled with liquid.

The pressure of the liquid-filled vacuole in these cells makes it possible for plants to grow quickly and to support heavy structures such as leaves and flowers.