Endomembrane System & Bulk Transport Process Flashcards
What does the endomembrane system include?
nuclear envelope, endoplasmic reticulum (rough and smooth), Golgi apparatus, vesicles, lysosomes, vacuoles, plasma membrane
What is a endomembrane system
a membrane system interconnected by direct physical contact or transfer by vesicles
What is the process for moving proteins out of the cell?
Synthesis, Tag and Package, Deliver
What organelle is in charge of synthesising proteins?
Endoplasmic reticulum
What organelle is in charge of tagging and packaging the synthesised proteins?
Golgi apparatus
What organelle is in charge of delivering the synthesised proteins to where they need to go?
Vesicles. They can also fuse with membrane of organelles/the cell
What two regions is endoplasmic reticulum composed of?
Smooth and rough
What makes rough ER rough?
Ribosomes
What are the functions of smooth ER?
Metabolism of carbohydrates, lipid synthesis for membranes, detoxification of drugs and poisons, storage of calcium ions (which are used as a signal in the cell)
Can the amount of smooth ER be increased or decreased to meet demand?
Yes
What are the functions of rough endoplasmic reticulum?
Involved in protein synthesis. Secreted and membrane-bound proteins enter the lumen (interior) of the rough ER and are processed by the rough ER and the rest of the endomembrane system for release of the cell or retention of the cell membrane
Where does synthesis of cytoplasmic proteins occur on rough ER?
Free ribosomes
What are the basic functions of the organelle Golgi complex?
Receives, modifies, sorts and ships proteins arriving from the rough ER
What does the Golgi complex look like?
A series of membrane sacs and associated vesicles
What role does each of the polar faces of Golgi complex do? (cis/trans?
Cis = vesicles from ER arrive and bind to the cis face.
Trans = Processed vesicles leave at the trans face
List the names of the functions of the Golgi complex
Glycosylation, sorting proteins, directive vesicle trafficking
What is glycosylation?
Addition (or modification) of carbohydrates to proteins. It is important for secreted or surface cell proteins.
What are the names of the polysaccharides that Golgi may also secrete from the cell
Pectin and Hemicellulose
What is the Golgi complex function called sorting proteins?
When the Golgi adds molecular markers to direct proteins to the correct vesicles before ‘budding’ from the trans face. This ensures it gets to the right location
What is the Golgi complex function called directing vesicle trafficking?
When the Golgi adds molecular ‘tags’ to vesicles leaving the trans face to direct them to the correct targets. The tags are often short proteins exposed on the vesicle surface.
Where do the tags direct vesicles once they leave the trans face?
lysosomes or secretory pathways or to plasma membrane to add membrane proteins. The tags act as docking sites once they reach these targets
What are the names of the types of vesicles?
Transport vesicles, Secretory vesicles, vacuoles.
What are vesicles?
membrane bound, cytoplasm/fluid filled organelles
What is the name of the artificial vesicle that can be used for drug and vaccine delivery?
Liposomes
What are the names for the ways bulk transport across the plasma membrane can be carried out?
Exocytosis, Endocytosis, Phagocytosis, Pinocytosis, Receptor-mediated endocytosis
What is exocytosis?
Transports material out of the cell or delivers it to the cell surface
What are the two types of exocytosis and what are they?
Constitutive exocytosis = releases ECM proteins (bone)
Regulated exocytosis = releases hormones and neurotransmitters
What is endocytosis?
the cell takes in molecules and particulate matter at the plasma membrane
What is phagocytosis?
cell ‘eating’ and the uptake of ‘food particles. it forms a phagocytic vacuole which is digested by lysosomes
Where does phagocytosis occur in humans?
Macrophages
What is pinocytosis?
cell ‘drinking’ and the uptake of extracellular fluid containing various solutes such at protein and sugars. an uptake vesicle is formed with the aid of a coat protein.
What type of selection is pinocytosis?
Non-selective. It cannot choose what to bring into the cell
What is receptor-mediated endocytosis?
a specialised form of pinocytosis where the cell can take up bulk quantities of specific substances. receptor proteins are used to selectively capture the required solute
What are lysosomes?
membrane-bound organelles made by rER and Golgi body containing hydrolytic enzymes. They only work in acidic conditions which is why they are membrane bound.
What do lysosomes do?
They degrade proteins, lipids, carbohydrates, nucleic acids and release breakdown products into the cell. They digest and release unwanted cellular materials.
What is autophagy and why is it important?
The process of the lysosome digesting and releasing the unwanted cellular materials. It is important for cell health
Why is lysosome function so important?
It keeps the cell healthy and is important for programmed cell death (where the cells intentionally die). It is crucial!!!!
What are vacuoles?
Large vesicles derived from the rER and Golgi bodies. Food vacuoles are involved in phagocytosis
Why are vacuoles important in plants?
The can perform lysosome like functions, large central vacuole absorbs water allowing plant cells to grow without large increase in cytoplasm, usually largest compartment in a plant cell.
