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in the question stem, they are asking about a constant region. VDJ rearrangement is for the variable. It doesn't make sense :(
Both the constant (heavy chains) and the light chains undergo gene rearrangement. The heavy chain undergoes V(D)J random recombinations, while the light chain undergo VJ random recombinations. So gene rearrangement could work for both regions.
The constant region does not undergo recombination. That's why it's called constant. It's just right next to the variable region though, so they get expressed together as one protein. That's why the constant-labeled DNA region is variable length here.
pg. 47 on FA got the good visuals!
COPII* proteins are needed to coat vesicles from the RER to Golgi. "Two(COPII) steps forward; one(COPI) step back."
Anterograde goes RER -> Golgi -> Lysosomes/Secretory Vesicles -> Plasma membrane
and I thought large lysosomes due to lack of enzymes to degrade
The size of the lysosome is not affected by the presence or absence of protein, but its function is compromised (eg. protein is getting stuck in the RER)
I hope this helps to whomever was lost like me
Null mutation: A mutation (a change) in a gene that leads to its not being transcribed into RNA and/or translated into a functional protein product. For example, a null mutation in a gene that usually encodes a specific enzyme leads to the production of a nonfunctional enzyme or no enzyme at all.
I think you made a typo: COPII (RER -> cis-Golgi); COPI (trans-golgi -> cis-golgi and cis-golgi -> RER), clathrin (endocytosis and trans-golgi -> lysosome)
So my thought process was if there is no COP signal then instead of going to Golgi it would be sent astray into cytoplasm, akin to how in I-cell Dx the enzymes get sent out of the cell since there is no trafficking signal (therefore I presumed large lysosome due to eating the aggregated protein). Are we saying without COP or Clathrin that the vesicle will simply stay put where it is? If I can get a reply before my exam (2 weeks) that'd be much appreciated