Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

72 Cards in this Set

  • Front
  • Back
The ways in which macromolecular components essential for cell function are delivered to their sites of function.
3 Hereditary disesases of Trafficking:
1. Cystic fibrosis
2. Familial hypercholesterolemia
3. Congenital sucrase isomaltase deficiency
Where is the trafficking abnormality in these hereditary disease?
In going from the ER to the Golgi
What surrounds the nucleus?
A double membrane nuclear envelope.
Where does transport occur across the nuclear envelope?
Through pores.
Site of synthesis of exportable protein and membrane proteins:
Rough Endoplasmic reticulum
Where is smooth ER particularly well-developed?

What is necessary for proteins to get into the ER?
In liver cells and cells that make steroid hormones.

A Signal Recognition Particle
What makes up the Golgi complex?
A system of smooth membranes and vesicles.
What do the vesicles in the golgi complex contain?
-Enzymes for processing exportable and membrane proteins
-Lysosomal enzymes.
What is the importance of the golgi complex?
As a trafficking center.
Lysosomes and endosomes are found where:
throughout the cytoplasm.
What do lysosomes contain?
Acid hydrolases
What are lysosomes important in?
Macromolecular turnover.
What is the function of endosomes?
They are intermediate compartments involved in trafficking.
What is the internal pH of both endosomes and lysosomes?
What do we call the process of Synthesis of Protein for Export?
The Regulated Secretory Pathway.
What is a great model for Synthesis of Protein for Export?
The pancreatic exocrine cell.
How does the regulated secretory pathway progress?
1. ER makes protein
2. Protein is processed through Golgi complex
3. Secretory vesicles form from the trans-golgi network
4. Proteins in vesicles leave cell via exocytosis
What are the pancreatic exocrine cells where this occurs?
Acinus cells
What pathway is responsible for continuous delivery of membrane components and ECM content?
The unregulated constitutive secretory pathway.
What makes the regulated and unregulated pathways different?
The regulated pathway only secretes in response to a specific signal stimulus.
Where does the process of protein trafficking begin?
Protein synthesized on ribosomes of RER is destined for:
the lumen of the RER
What 2 processes occur co-translationally in the RER?
1. Translocation into the lumen
2. Insertion of membrane proteins
What is necessary for a protein to be translocated into the RER lumen?
A signal sequence
Where is the signal sequence for proteins destined for lumen import?
At the amino terminal region of the nascent protein.
What binds the signal sequence? Why?
SRP - signal recognition particle; to stop translation.
Why does translation need to stop?
To allow the ribosome to associate with a ribosomal receptor on the RER membrane, and with an SRP receptor too.
What happens once the ribosome binds its receptor and the SRP binds its receptor?
Continued translation of the protein, but now into the lumen of RER.
What happens to the signal sequence ultimately?
It is extruded in the RER by a signal peptidase.
What is needed for insertion of proteins into the membrane?
Stop-transfer sequences.
Where are most membrane lipid bilayers assembled?
In the ER.
What is the principal component of membrane lipid bilayers?
Phosphatidylcholine (lecithin)
Where is lecithin formed?
In 3 enzymatic steps on the cytosolic surface of ER.
Which side of the bilayer are lecthin molecules formed? How does a bilayer get made?
-Formed on cytosolic side
-Flippase flips phosphatidylcholines to the other side to form the bilayer.
How is it decided whether proteins will stay and function in the golgi, or get exported?
By the presence/absence of specific recognition signals for the ER.
If proteins lack recognition signals for the ER what happens?
They pass to the golgi complex by default.
3 components of the Golgi:
1. Cis cisternae
2. Medial cisternae
3. Trans cisternae
From which side of the Golgi do proteins enter?
What is the Trans cisternae referred to as? What happens here?
trans-Golgi network - where vesicles for secretion pop off.
What defines the sequential way in which the Golgi functions?
The orderly assembly-line way that it trims and elongates N-linked oligosaccharides on proteins.
What is the end result of core glycosylation?
N-linked glycoproteins.
When/where does Core glycosylation occur?
In the ER, just after synthesis of the protein and lumenal translocation.
What starts off core glycosylation?
Transfer of a high-mannose core oligosaccharide from Dolichol phosphate.
What does the oligosaccharide get transfered onto on a peptide?
What enzymes process the core oligosaccharide after transfer to Asn and make it more complex?
-Glycosyl transferases
What do glycosidases do?
Remove glucose and mannose from the core
What do glycosyl transferases do?
Add sugars to the oligosaccharide
Where does the sequence of processing begin?
Where does the oligosaccharide-peptide go after processing begins in the ER?
To the cis/medial Golgi
What happens in the cis/medial golgi?
-Additional mannose removed
-N-acetylglucosamine is added
What gets added in the trans Golgi?
-Sialic acid
Functions of N-linked glycosylation:
-Forming the Glycocalyx
-Calnexin-Calreticulin cycle
What is the glycocalyx?
A polyanionic protein coat on the cell surface that can interact with molecular components of the ECM.
Why is processing of the core oligosaccharide started by the RER important?
Because it plays an important role in the proper folding of glycoproteins.
What is the initial event in processing the core oligosaccharide? What is the resulting molecule?
Removal of a terminal glucose by glucosidases I and II - forms a Monoglucosylated Oligosaccharide
Why is it essential that the Monoglucosylated Oligosaccharide be formed?
Becuase it permits binding of chaperones to ensure proper folding.
What are the chaperone proteins?
What other protein aids in folding?
What happens after ERP57 does its job?
Glucosidase II removes the other glucosyl residue and results in the free Glycoprotein.
What is ERGIC53?
An RER membrane-bound protein that only binds glycoproteins if they're properly folded to allow them to leave the Golgi.
What happens if the protein is NOT properly folded?
It gets reglucosylated by Glucosyl transferase.
How does Glucosyl transferase know to reglucosylate proteins?
It recognizes improperly folded proteins.
And we know what happens to monoglucosylated proteins:
They bind Calnexin or Calreticulin and get folded.
What is required for movement of macromolecules from RER to Golgi?
Small coated vesicles
What vesicles transport from RER to golgi?
COPII vesicles
What coats COPII vesicles?
Coatamer proteins
What vesicles move in the backwards direction in the Golgi stacks? (Trans -> cis)
COPI vesicles
2 Processes that Golgi vesicles are involved in:
1. Transport between golgi stacks
2. Retrograde transport back to the RER
Why is retrograde transport from golgi to RER important?
It returns resident proteins to the RER.
What happens to the stacks of Golgi cisterns themselves?
They also move from cis to trans direction.
What is involved in the final steps of secretion from the trans-golgi network?
-Prodution of secretory granules
-Their fusion with the plasma membrane