Area of Study 3 - Roles of Organelles + endo/exocytosis Flashcards
What is the role of Ribosomes in the cell?
Where are they found?
Ribosomes are a cell structure that makes protein. Protein is needed for many cell functions such as repairing damage or directing chemical processes. Ribosomes can be found floating within the cytoplasm or attached to the endoplasmic reticulum.
What is the role of the endoplasmic reticulum?
Both rough and smooth
Smooth - It synthesizes lipids, phospholipids, and steroids.
Rough - Is involved in some protein production, protein folding, quality control and despatch. It is called ‘rough’ because it is studded with ribosomes
What is the role of the Golgi apparatus?
How does it work with the ER?
The job of the Golgi apparatus is to process and bundle macromolecules like proteins and lipids as they are synthesized within the cell. One major function is to modify, sort, and package proteins to be secreted.Helps with the transport of lipids throughout the cell and the creation of lysosomes.
The Golgi complex works closely with the rough ER. When the ER makes a protein, a transition vesicle is also made. It drifts through the cytoplasm to the Golgi apparatus where it gets absorbed. After the Golgi works on the molecules inside, it secretes a vesicle into the cytoplasm which releases the protein molecule out of the cell.
What is exocytosis?
In exocytosis, materials are exported out of the cell via secretory vesicles. In this process, the Golgi complex packages macromolecules into transport vesicles that travel to and fuse with the plasma membrane. This fusion causes the vesicle to spill its contents out of the cell. Exocytosis is important in expulsion of waste materials.
What is Endocytosis?
What are the three types?
The process by which materials move into the cell.
There are three types of endocytosis: phagocytosis, pinocytosis, and receptor-mediated endocytosis.
What happens in phagocytosis?
In phagocytosis or “cellular eating,” the cell’s plasma membrane surrounds a macromolecule or even an entire cell from the extracellular environment and buds off to form a food vacuole or phagosome. The newly-formed phagosome then fuses with a lysosome whose hydrolytic enzymes digest the “food” inside.
What happens in pinocytosis?
In pinocytosis or “cellular drinking,” the cell engulfs drops of fluid by pinching in and forming vesicles that are smaller than the phagosomes formed in phagocytosis.
What happens in receptor-mediated endocytosis?
What does the cell typically use this method to bring in?
Receptor-mediated endocytosis is an extremely selective process of importing materials into the cell. In receptor-mediated endocytosis, the cell will only take in an extracellular molecule if it binds to its specific receptor protein on the cell’s surface. Once bound, the coated pit on which the receptor protein is located then pinches in, to form a coated vesicle. This coated vesicle then fuses with a lysosome to digest the engulfed material and release it into the cytosol. Mammalian cells use receptor-mediated endocytosis to take cholesterol into cells. Cholesterol bind to specific receptor proteins on the cell surface.
What is an extracellular molecule?
A molecule in the fluid outside the cell.
