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What is the endoplasmic recticulum?
A 3-dimensional network of cavities surrounded by membranes,
The cavities some are sac-like, some are tubular, an the ER spreads through the cytoplasm.
The ER network links with the membrane around the nucleus, and is a large part of the transport system within a cell
As well as being the site of synthesis for many chemical substances.
Name a technique that is useful for scientist to study the function of ER and describe it.
By providing cells with radioactively labeled chemical substances that are building blocks for specific substances
And finding out where they appear in the cell.
The labeled products can be tracked through microscopy,
Or the cell can be broken open and the contents can be spinned in a centrifuge to separate the organelles of the cell and locate the radioactively labeled substances.
Describe the adaptations of the Rough Endoplasmic recticulum and describe what these adaptations can tell us about the function of a cell.
The outside of the rough endoplasmic recticulum is covered by granules, which are 80S ribosomes
The function of these ribosomes is to synthesize protein.
The RER has a large surface area for synthesis of all these proteins.
It then stores and transport these substances within the cell
Cells that secrete large amounts of materials,have a larger amount of RER ( like horomone secreting cells )
What is exocytosis ?
It is when material must be secreted without interfering with the cell’s own activities.
How is Smooth Endoplasmic recticulum different to RER ?
SER has no ribosomes on it’s surface,
It is also involved in synthesis and transport but in lipids and steroids.
What is the Golgi apparatus ?
The Golgi apparatus is stacks of parallel, flattened membrane pockets formed by vesicles from the ER fusing together.
What and how does the Golgi apparatus do ?
The Golgi apparatus modifies protein molecules by adding substances and sorts them to where they need to be.
Proteins are brought to the Golgi apparatus via vesicles that are separate from the RER,
The vesicles fuse with the membrane sacs of the Golgi apparatus and the protein enters the Golgi stacks,
They are modified and travel through the Golgi apparatus.
What are some examples of the Golgi apparatus modifying a protein ?
Carbohydrates are added to some proteins to form glycoproteins such as mucus.
It also seems to be involved in producing materials for plant and fungal cell walls and insect cuticles.
Some proteins in the Golgi apparatus are digestive enzymes, these may be enclosed in vesicles to form organelles as lysosomes.
What is present on the inner parts and outer parts of the Golgi apparatus, how does this relate to it’s function ?
The inner areas of the Golgi apparatus near the RER has a lot of enzymes that modify proteins in different ways. This is where most enzymes or membrane proteins are converted into the final product.
The outer areas of the Golgi apparatus are where lots of finished protein products reside but not a lot of enzymes that make them.
How is materials transferred from the RER to through the Golgi and out of the cell ?
Vesicles pinch of the RER and fuse to form flattened sacs,
Protein is modified in the Golgi apparatus and it pinches of each layer fusing with the new layer while being modified,
Then vesicles containing secretions are pinched off the Golgi apparatus
The vesicles fuse with the cell surface membrane and release secretions