Opening Questions Do you think the organelles that are found in the cell move around the cell or stay in one place in the cell? If you think they move…how do they?
Learning Outcomes Tell what molecules make up the cytoplasm. List the important parts of the cell that are found in the cytoplasm. Distinguish between cytoskeleton proteins and motor proteins. Discuss why the cytoplasm is a major part of every cell.
The Three Major Parts of the Cell
A.
The cytoplasm is found between the plasma (cell) membrane and the nucleus It is MADE UP of organic substances and water.
FOUND IN the cytoplasm : all the ORGANELLES AND CYTOSKELETON
1. C YTOSKELETON The cytoskeleton MADE UP OF protein filaments, motor proteins, and microtubules
These fibers extend from the nucleus to the cell(plasma) membrane Gives shape and allows the cell and organelles to move.
Cytoskeleton 1. Microtubules 2. Protein Filaments A. Intermediate B. Actin 3. MotorProteins A. B. C.
2. Tubules of the Cytoskeleton a. microtubules b. intermediate filaments c. actin filaments B and C are PROTEIN FILAMENTS
A. M ICROTUBULES Microtubules are small hollow cylinders composed of 13 chains of proteins. Their assembly is controlled by a structure called a centrosome.
The centrosome is a structure that is found very near the nucleus. Microtubules are said to radiate out from the centrosome.
This pattern of microtubules helps to maintain a cell’s shape. It also serves as a track system (like train tracks) in which organelles and materials move throughout the cell.
A centriole is a structure that comes in pairs and is said to work closely with the centrosome. The centrioles in the cell play a very important role in cell division (discuss later in the year)
B. I NTERMEDIATE F ILAMENTS They are called intermediate because they are medium in size. (between microtubules and actin filaments) They are rope like chains of proteins.
The intermediate filaments are found mainly between the nuclear envelope (membrane) and the plasma (cell) membrane.
The proteins that make up these filaments are unique to the cell they are found in. Example Intermediate fibers made up of keratin give strength to skin cells.
C. A CTIN F ILAMENTS Actin filaments are long filaments. They are the largest of the three filaments They are said to be made up of a globular protein.
These proteins tend to twist around each other in a helical manner. The actin filaments form a complex web just under the plasma(cell) membrane.
The web supports the cell and projections that may come of the membrane.
3. Major Motor Proteins of the Cytoskeleton a. myosin b. kinesin c. dynein
Help move organelles around the cell. Help move materials in and out of cell.
Myosin works hand and hand with the actin filaments to help with movement in the cell. They are helpful when the cell engulfs a large molecule. (pinocytosis or phagocytosis)
Myosin hand the actin filaments also are used by the cell to pinch the original cell into two new cells during cell division.
A process known as cytokinesis.
Myosin is also used by muscles cells When muscles contract, myosin pulls actin filaments to the middle of the cell
Finally kinesin and dynein are motor proteins that help move organelles around the cell… They attach to the organelle..unattach and then reattach to the organelle further down a microtubule.
They also perform the same way when moving material to and from the Golgi Apparatus
Wrap It Up
The cytoplasm is ONE of the THREE major parts of the EVERY cell.
Major Functions of Cytoplasm/Cytoskeleton 1. Helps give cell its shape. 2. Moves things for the cell. 3. Holds organelles.
The cytoplasm is ONE of the THREE major parts of the cell. It is made up of organic molecules (motor proteins/microtubules) and water Found floating and moving around it are organelles
Protein filaments and Motor Proteins together in the cytoplasm to give the cell shape and move organelles and materials around the cell.
These are the main reasons that the cytoplasm is considered ONE of the THREE major parts of every cell.