BIO 2B03 EXAM REVIEW QUESTIONS
AND ANSWERS 2026 VERIFIED.
Is the RER dynamic or stationary? - ANS dynamic
what is the function of the RER? - ANS co-translational transport, protein modification,
formation of vesicles that will transport proteins from ER to Golgi
what is the function of the SER? - ANS fatty acid and phospholipid synthesis, carbohydrate
metabolism, regulate Ca2+ conc in the cytosol
what are the post translational modifications in the ER? - ANS - glycosylation
- protein folding
- disulphide bond formation
- proteolytic cleavage
do modifications to proteins embedded in the ER membrane occur in the luminal portion or the
transmembrane domain or the cytosolic portion? - ANS luminal
this protein modification is important for proteins that mediate cell interactions with the
extracellular matrix and for receptor-ligand recognition - ANS glycosylation
1
,this protein modification is common on proteins that are secreted from the cell and proteins
embedded in the cell membrane - ANS glycosylation
what is the most common form of glycosylation? - ANS N-linked
N-linked glycosylation adds a polysaccharide to which group of which amino acid? -
ANS NH2 group of the R-group of asparagine
these proteins recognize modified proteins and assist in protein folding in a similar way as
chaperones - ANS lectins
what are the two types of lectins? - ANS calnexin and calreticulin
where is calnexin found? - ANS ER membrane
what is BiP? mention 3 functions - ANS - ER-resident HSP70 chaperone
- transfers proteins from ER through the translocon by binding to proteins as soon as they
appear on the luminal side of the membrane during co-translational transport
- initiate unfolded protein response in the ER
what are the co-chaperones of BiP? - ANS Hsp40 and NEF
is cytoplasm a reducing or an oxidizing environment? - ANS reducing
is ER a reducing or an oxidizing environment? - ANS oxidizing
2
, does disulphide bond formation occur in reducing or oxidizing environment? -
ANS oxidizing
this protein is one of many proteins secreted into the intestine where it aids in the digestion of
RNA by cleaving it into small pieces - ANS RNAse A
what is the protein that resides in the ER that promotes oxidation? - ANS protein
disulphide isomerase (PDI)
does proteolytic cleavage in the ER happen in the lumen or the cytosol? - ANS lumen
what is the N-terminal signal sequence of type I integral proteins cleaved by? - ANS signal
peptidase
what are the two responses of the unfolded protein response (UPR)? - ANS 1. restore
normal cell function by slowing down new protein translation or removing unfolded proteins
from the ER for degradation through ubiquitylation
2. increase production of chaperones
what are the proteins essential to UPR? - ANS BiP and Ire1
this protein is involved in the UPR and functions as a chaperone to assist in proper folding and
prevent aggregation of misfolded proteins - ANS BiP
this is a transmembrane protein that is involved in the UPR - ANS Ire1
Ire1 endonuclease specifically targets which gene's mRNA? - ANS Hac1
3
AND ANSWERS 2026 VERIFIED.
Is the RER dynamic or stationary? - ANS dynamic
what is the function of the RER? - ANS co-translational transport, protein modification,
formation of vesicles that will transport proteins from ER to Golgi
what is the function of the SER? - ANS fatty acid and phospholipid synthesis, carbohydrate
metabolism, regulate Ca2+ conc in the cytosol
what are the post translational modifications in the ER? - ANS - glycosylation
- protein folding
- disulphide bond formation
- proteolytic cleavage
do modifications to proteins embedded in the ER membrane occur in the luminal portion or the
transmembrane domain or the cytosolic portion? - ANS luminal
this protein modification is important for proteins that mediate cell interactions with the
extracellular matrix and for receptor-ligand recognition - ANS glycosylation
1
,this protein modification is common on proteins that are secreted from the cell and proteins
embedded in the cell membrane - ANS glycosylation
what is the most common form of glycosylation? - ANS N-linked
N-linked glycosylation adds a polysaccharide to which group of which amino acid? -
ANS NH2 group of the R-group of asparagine
these proteins recognize modified proteins and assist in protein folding in a similar way as
chaperones - ANS lectins
what are the two types of lectins? - ANS calnexin and calreticulin
where is calnexin found? - ANS ER membrane
what is BiP? mention 3 functions - ANS - ER-resident HSP70 chaperone
- transfers proteins from ER through the translocon by binding to proteins as soon as they
appear on the luminal side of the membrane during co-translational transport
- initiate unfolded protein response in the ER
what are the co-chaperones of BiP? - ANS Hsp40 and NEF
is cytoplasm a reducing or an oxidizing environment? - ANS reducing
is ER a reducing or an oxidizing environment? - ANS oxidizing
2
, does disulphide bond formation occur in reducing or oxidizing environment? -
ANS oxidizing
this protein is one of many proteins secreted into the intestine where it aids in the digestion of
RNA by cleaving it into small pieces - ANS RNAse A
what is the protein that resides in the ER that promotes oxidation? - ANS protein
disulphide isomerase (PDI)
does proteolytic cleavage in the ER happen in the lumen or the cytosol? - ANS lumen
what is the N-terminal signal sequence of type I integral proteins cleaved by? - ANS signal
peptidase
what are the two responses of the unfolded protein response (UPR)? - ANS 1. restore
normal cell function by slowing down new protein translation or removing unfolded proteins
from the ER for degradation through ubiquitylation
2. increase production of chaperones
what are the proteins essential to UPR? - ANS BiP and Ire1
this protein is involved in the UPR and functions as a chaperone to assist in proper folding and
prevent aggregation of misfolded proteins - ANS BiP
this is a transmembrane protein that is involved in the UPR - ANS Ire1
Ire1 endonuclease specifically targets which gene's mRNA? - ANS Hac1
3
