Cells

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Cells are considered the basic units of life in part because they come in discrete and easily recognizable packages. That's because all cells are surrounded by a structure called the cell membrane.

The cell is the very smallest unit of living matter. All living things including plants and animals are made up of cells. Cells are made of atoms, which are the smallest units of matter. There are many different kinds of cells. The two kinds you are most likely to be familiar with are animal and plant cells. Some of the differences between them are that plant cells have a cell wall and chloroplasts. Cells all have different sizes, shapes, and jobs to do.

The cells in a single organism may have different shapes, sizes, and jobs. Organisms like humans are made up of trillions of cells. There are also one-celled organisms such as euglenas, amoebas, and bacteria.

Two-thirds of a cell is water, which means that two-thirds of your whole body is water. The rest is a mixture of molecules, mainly proteins, lipids and carbohydrates. Your cells turn the raw materials in the food you eat into the molecules your body needs, using thousands of different chemical reactions.

In our body there are many different kinds of cells. We are made up of about 200 different types of cells. Our body also has non- living materials such as hair, fingernails, and the hard part of the bone and teeth. All these materials are made up of dead cells.

All cells have some parts in common. One part found in all cells is the cell membrane. The cell membrane surrounds the cell, holds the other parts of the cell in place, and protects the cell. Molecules can pass in and out of the cell membrane. Inside the membrane, all cells, except for bacterial cells, contain a nucleus and cytoplasm. The nucleus is a dark structure located in the middle of the cell. It controls the cell's activities, and acts like the cell's brain. Inside the nucleus there is DNA, which contains genetic information. The cytoplasm is a jelly-like substance inside the cell where most of the cell's activities take place. It's made out of water and other chemicals. All cell parts, except the nucleus, are located in the cytoplasm.

Each cell was made from an already existing cell. New cells are made through a process called cell division or mitosis. One cell turns into two cells and then two cells turn into four cells, etc. Even humans started life with only one cell. Most of the cells in many celled-organisms use mitosis to reproduce. The basic steps in mitosis are: 1) The start of mitosis chromosomes is in the nucleus.

2) The chromosomes in the nucleus will then make a copy of themselves 3) Next the cell divides.
4) Last one set of chromosomes goes to the new cell and one set remains in the parent cell.

*The cell is compose by different thing

Nucleus
- Large Oval body near the center of the cell.
- The control center for all activity.
- Surrounded by a nuclear membrane.

Nucleoplasm
- Is the protoplasm in the nucleus.
- Contains genetic material ---> CHROMOSOMES (DNA)

Nucleolus
- Is found in the nucleus.
- Contains more genetic information (RNA)

Cell Membrane
- The outer boundary of the cell.
- It separates the cell from other cells.
- It is porous ---> allows molecules to pass through.

Cell Wall (Plant Cells Only)
- Non-living structure that surrounds the plant cell.
- Protects + supports the cell.
- Made up of a tough fiber called cellulose.

Cyto Plasm
- Cell material outside the nucleus but within the cell membrane. - Clear thick fluid.
- Contains structures called organelles.

Vacuoles
- Are clear fluid sacs that act as storage areas for food, minerals, and waste. - In plant cell the vacuoles are large and mostly filled with water. This gives the plant support. - In animal cells the vacuoles are much smaller.

Mitochondria
- Powerhouse of the cell.
- Center of respiration of the cell.
- They release energy for cell...
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