Cell Theory and Cells PartsCell Theory and Cells PartsChapter 2 continuedChapter 2 continued

The Cell Theory:The Cell Theory:The first scientists to see cells with The first scientists to see cells with his his microscopemicroscope was was RobertRobert HookeHooke. . He looked at cork cells. Even He looked at cork cells. Even though he saw these cells, he did though he saw these cells, he did not know how not know how importantimportant the cells the cells actually were. In 1838, a scientist actually were. In 1838, a scientist named named Matthias SchleidenMatthias Schleiden looked looked at plant cells and concluded that at plant cells and concluded that plants are made of cells.plants are made of cells.

Theodor SchwannTheodor Schwann looked at looked at animal cells and concluded that animal cells and concluded that animals are made of cells. They animals are made of cells. They both decided, based on what they both decided, based on what they saw, that all living things are saw, that all living things are made up of cells. About 15 years made up of cells. About 15 years later, later, Rudolph VirchowRudolph Virchow came up came up with the cell theory.with the cell theory.

The cell theory states that:The cell theory states that:1. 1. All organisms are made up All organisms are made up

of one or more cells.of one or more cells.

2.2. Cells are the basic units of Cells are the basic units of structure and function in all structure and function in all organisms.organisms.

3. 3. All cells come from cells All cells come from cells that already exist.that already exist.

How Cells are organized:How Cells are organized:Cells have many things in Cells have many things in common. Some of these things common. Some of these things are a are a cell membranecell membrane, a cytoplasm , a cytoplasm and a control center. There are and a control center. There are two kinds of cells. They are two kinds of cells. They are eukaryoticeukaryotic and and prokaryotic prokaryotic cells. cells. ProkaryoticProkaryotic cells are cells that do cells are cells that do not have a nucleus. not have a nucleus. EukaryoticEukaryotic cells have a nucleus. Plant and cells have a nucleus. Plant and animal cells are considered animal cells are considered eukaryotic.eukaryotic.

Animal cell parts:Animal cell parts:Cell membraneCell membrane: : the structure that the structure that forms the outer boundary of the forms the outer boundary of the cell and allows only certain things cell and allows only certain things to move in and out of the cell. to move in and out of the cell. Because of this, the cell Because of this, the cell membrane is considered membrane is considered selectively permeableselectively permeable. It is also . It is also very flexible. It is made of fat and very flexible. It is made of fat and protein. It allows protein. It allows waterwater, , oxygenoxygen and food into the cell and waste and food into the cell and waste products out of the cell.products out of the cell.

The The nucleus nucleus is the largest organelle is the largest organelle in a cell. The in a cell. The nucleusnucleus is a structure is a structure that directs the all the activities of that directs the all the activities of the cell. The nucleus is protected the cell. The nucleus is protected from the cytoplasm by a from the cytoplasm by a nuclear nuclear membranemembrane. Materials move in and . Materials move in and out of the nucleus through openings. out of the nucleus through openings. The The nucleusnucleus also contains also contains hereditary material called hereditary material called chromatinchromatin. These are the genetic . These are the genetic blueprints for the operations of the blueprints for the operations of the cells. When cells get ready to cells. When cells get ready to divide, chromatin will begin to divide, chromatin will begin to thicken and become chromosomes.thicken and become chromosomes.

CytoplasmCytoplasm: a gel-like : a gel-like substance inside the cell substance inside the cell membrane and outside of the membrane and outside of the nucleus. It is mostly made of nucleus. It is mostly made of water. It also holds all of the water. It also holds all of the other organelles that help the other organelles that help the cell to run. cell to run.

OrganelleOrganelle: the structures : the structures within the cytoplasm of within the cytoplasm of eukaryotic cells.eukaryotic cells.

Endoplasmic ReticulumEndoplasmic Reticulum: also known as : also known as ER, it is the folded membrane that ER, it is the folded membrane that moves materials around in the cell. It moves materials around in the cell. It extends from the nucleus to the cell extends from the nucleus to the cell membrane. There are two types of ER, membrane. There are two types of ER, rough and smooth. Rough ER is rough and smooth. Rough ER is covered in covered in ribosomesribosomes. . RibosomesRibosomes: : place where cells make their own place where cells make their own proteins. They receive direction from proteins. They receive direction from the hereditary material in the nucleus the hereditary material in the nucleus about what kind of about what kind of proteinprotein to make. to make. Ribosomes can either be found on the Ribosomes can either be found on the rough ER or floating in the cytoplasm.rough ER or floating in the cytoplasm.

Another organelle in the Another organelle in the cytoplasm is the cytoplasm is the Golgi bodyGolgi body. The . The golgi bodiesgolgi bodies are stacks of are stacks of membrane-covered sacs that membrane-covered sacs that package ad move proteins to the package ad move proteins to the outside of the cell.outside of the cell.

Cells also require energy. They Cells also require energy. They get their energy from the get their energy from the mitochondriamitochondria. The . The mitochondriamitochondria are where food particles are are where food particles are broken down and energy is broken down and energy is released. The “Mighty” released. The “Mighty” mitochondria releases energy for mitochondria releases energy for the cell!!the cell!!

Cells are constantly producing Cells are constantly producing waste products and they need to waste products and they need to get rid of the waste. The get rid of the waste. The lysosomeslysosomes contain chemicals that contain chemicals that digest wastes and worn out cell digest wastes and worn out cell parts and also break down food.parts and also break down food.

VacuolesVacuoles are storage organelles. are storage organelles. They are fluid filled temporary They are fluid filled temporary storage areas. They can either storage areas. They can either store water or food.store water or food.

Plant Cells:Plant Cells:Animal and plant cells have all the Animal and plant cells have all the same organelles except for a few. same organelles except for a few. Plants have Plants have cell wallscell walls and and chloroplastschloroplasts. . A A cell wallcell wall is a rigid structure outside is a rigid structure outside of the cell membrane that supports of the cell membrane that supports and protects the plant cell. It is made and protects the plant cell. It is made of cellulose and other materials. of cellulose and other materials. Animal cells do not have a cell wall.Animal cells do not have a cell wall.

Plant cells also have Plant cells also have chloroplastschloroplasts. . ChloroplastsChloroplasts are organelles in plant are organelles in plant cells in which light energy is changed cells in which light energy is changed into chemical energy in the form of into chemical energy in the form of sugar. The chemical in the sugar. The chemical in the chloroplasts that capture the light chloroplasts that capture the light energy is energy is chlorophyllchlorophyll..

Cells differ in the way that they look Cells differ in the way that they look based on what their job is in an based on what their job is in an organism. Nerve cells look different organism. Nerve cells look different than red blood cells and red blood cells than red blood cells and red blood cells look different than white blood cells.look different than white blood cells.

Cells are organized in different ways. Cells are organized in different ways. A one celled organism performs all of A one celled organism performs all of its life functions in itself. Cells in its life functions in itself. Cells in many-celled organisms do not work many-celled organisms do not work alone. In many celled organisms, cells alone. In many celled organisms, cells are organized into are organized into tissuestissues. A . A tissuetissue is is a group of similar cells that work a group of similar cells that work together. Tissues are then organized together. Tissues are then organized into into organsorgans. . OrgansOrgans are structures are structures made up of different tissues. Groups made up of different tissues. Groups of organs combine to make up organ of organs combine to make up organ systems and then organ systems make systems and then organ systems make up an organism.up an organism.