CHATGPT: Protein Transport (Module 4) Flashcards
Study for midterm 2
What is a signal sequence, and what role do signal sequences play in protein sorting?
A signal sequence is a short amino acid sequence that acts as a “tag” directing the protein to the appropriate location within the cell (e.g., ER, mitochondria). It is recognized by cellular receptors that mediate its transport.
So basically, along the length of the polypeptide, there will be a sequence of code that tags the protein with the info it needs to reach its destination.
How does the co-translational import process differ from post-translational import in protein sorting?
In co-translational import, proteins begin to enter the ER as they are being synthesized by ribosomes. In post-translational import, proteins are fully synthesized in the cytosol and then imported into organelles like mitochondria or peroxisomes.
Why is the endoplasmic reticulum (ER) important in protein sorting, especially for proteins destined for secretion?
The ER is crucial for protein sorting because it houses ribosomes for synthesizing membrane-bound and secretory proteins (in the rough ER). It also packages these proteins into vesicles for further processing and sorting, primarily through the Golgi apparatus.
What happens to proteins that are sorted to the Golgi apparatus? How are they processed further?
The Golgi apparatus modifies, sorts, and packages proteins received from the ER. Proteins undergo further modifications like glycosylation and are then sent to their final destinations, such as lysosomes, the plasma membrane, or for secretion.
How do proteins destined for the nucleus get sorted differently from those going to the mitochondria?
Proteins destined for the nucleus have a nuclear localization signal (NLS), which directs them through nuclear pores. Mitochondrial proteins contain specific signal sequences recognized by mitochondrial translocases, which import them into the organelle.
What is the significance of vesicular transport in protein sorting, and how does it ensure proteins reach their target destinations?
Vesicular transport is essential for moving proteins between organelles, especially from the ER to the Golgi apparatus and beyond. Vesicles can be transported along microtubules via motor proteins like kinesin and dynein.
Can you explain the difference between proteins sorted for exocytosis and those involved in endocytosis?
In exocytosis, proteins are packaged into vesicles and transported out of the cell. In endocytosis, the cell takes in materials, and the proteins involved in this process help internalize and sort these materials.
What are nuclear localization signals (NLS), and how do they assist in protein sorting to the nucleus?
NLS are sequences on proteins that direct them to the nucleus. These sequences are recognized by transport proteins that guide the protein through nuclear pore complexes.
How are proteins sorted for degradation in lysosomes, and what role do they play in the cell’s recycling system?
(answer is kinda specific)
Proteins destined for lysosomes have a specific tag, often a mannose-6-phosphate (M6P) marker, which directs them to the lysosomes for degradation.
(that’s quite specific, and not from the prof, just from chat gpt.)
What would happen if protein sorting went wrong and proteins didn’t reach their correct cellular compartments?
If protein sorting fails, proteins may accumulate in the wrong cellular compartments, which can lead to diseases like Alzheimer’s, cystic fibrosis, or other dysfunctions depending on the protein’s role.
