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Cell Theory and Cells Parts. Chapter 2 continued.
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Cell Theory and Cells Parts Chapter 2 continued
The Cell Theory:The first scientists to see cells with his microscope was RobertHooke. He looked at cork cells. Even though he saw these cells, he did not know how important the cells actually were. In 1838, a scientist named Matthias Schleiden looked at plant cells and concluded that plants are made of cells.
Theodor Schwann looked at animal cells and concluded that animals are made of cells. They both decided, based on what they saw, that all living things are made up of cells. About 15 years later, Rudolph Virchow came up with the cell theory.
The cell theory states that: 1. All organisms are made up of one or more cells. 2. Cells are the basic units of structure and function in all organisms. 3. All cells come from cells that already exist.
How Cells are organized:Cells have many things in common. Some of these things are a cell membrane, a cytoplasm and a control center. There are two kinds of cells. They are eukaryotic and prokaryotic cells. Prokaryotic cells are cells that do not have a nucleus. Eukaryotic cells have a nucleus. Plant and animal cells are considered eukaryotic.
Animal cell parts:Cell membrane: the structure that forms the outer boundary of the cell and allows only certain things to move in and out of the cell. Because of this, the cell membrane is considered selectively permeable. It is also very flexible. It is made of fat and protein. It allows water, oxygen and food into the cell and waste products out of the cell.
The nucleus is the largest organelle in a cell. The nucleus is a structure that directs the all the activities of the cell. The nucleus is protected from the cytoplasm by a nuclear membrane. Materials move in and out of the nucleus through openings. The nucleus also contains hereditary material called chromatin. These are the genetic blueprints for the operations of the cells. When cells get ready to divide, chromatin will begin to thicken and become chromosomes.
Cytoplasm: a gel-like substance inside the cell membrane and outside of the nucleus. It is mostly made of water. It also holds all of the other organelles that help the cell to run.
Organelle: the structures within the cytoplasm of eukaryotic cells.
Endoplasmic Reticulum: also known as ER, it is the folded membrane that moves materials around in the cell. It extends from the nucleus to the cell membrane. There are two types of ER, rough and smooth. Rough ER is covered in ribosomes. Ribosomes: place where cells make their own proteins. They receive direction from the hereditary material in the nucleus about what kind of protein to make. Ribosomes can either be found on the rough ER or floating in the cytoplasm.
Another organelle in the cytoplasm is the Golgi body. The golgi bodies are stacks of membrane-covered sacs that package ad move proteins to the outside of the cell.
Cells also require energy. They get their energy from the mitochondria. The mitochondria are where food particles are broken down and energy is released. The “Mighty” mitochondria releases energy for the cell!!
Cells are constantly producing waste products and they need to get rid of the waste. The lysosomes contain chemicals that digest wastes and worn out cell parts and also break down food.
Vacuoles are storage organelles. They are fluid filled temporary storage areas. They can either store water or food.
Plant Cells:Animal and plant cells have all the same organelles except for a few. Plants have cell walls and chloroplasts. A cell wall is a rigid structure outside of the cell membrane that supports and protects the plant cell. It is made of cellulose and other materials. Animal cells do not have a cell wall.
Plant cells also have chloroplasts. Chloroplasts are organelles in plant cells in which light energy is changed into chemical energy in the form of sugar. The chemical in the chloroplasts that capture the light energy is chlorophyll.
Cells differ in the way that they look based on what their job is in an organism. Nerve cells look different than red blood cells and red blood cells look different than white blood cells.
Cells are organized in different ways. A one celled organism performs all of its life functions in itself. Cells in many-celled organisms do not work alone. In many celled organisms, cells are organized into tissues. A tissue is a group of similar cells that work together. Tissues are then organized into organs. Organs are structures made up of different tissues. Groups of organs combine to make up organ systems and then organ systems make up an organism.
