Bio 2b03 exam review (updated)
questions and answers
is the RER dynamic or stationary? - correct answer ✔✔ dynamic
what is the function of the RER? - correct answer ✔✔ co-translational transport, protein
modification, formation of vesicles that will transport proteins from ER to Golgi
what is the function of the SER? - correct answer ✔✔ fatty acid and phospholipid synthesis,
carbohydrate metabolism, regulate Ca2+ conc in the cytosol
what are the post translational modifications in the ER? - correct answer ✔✔ - 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? - correct answer ✔✔ luminal
this protein modification is important for proteins that mediate cell interactions with the
extracellular matrix and for receptor-ligand recognition - correct answer ✔✔ glycosylation
this protein modification is common on proteins that are secreted from the cell and proteins
embedded in the cell membrane - correct answer ✔✔ glycosylation
what is the most common form of glycosylation? - correct answer ✔✔ N-linked
,N-linked glycosylation adds a polysaccharide to which group of which amino acid? - correct
answer ✔✔ NH2 group of the R-group of asparagine
these proteins recognize modified proteins and assist in protein folding in a similar way as
chaperones - correct answer ✔✔ lectins
what are the two types of lectins? - correct answer ✔✔ calnexin and calreticulin
where is calnexin found? - correct answer ✔✔ ER membrane
what is BiP? mention 3 functions - correct answer ✔✔ - 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? - correct answer ✔✔ Hsp40 and NEF
is cytoplasm a reducing or an oxidizing environment? - correct answer ✔✔ reducing
is ER a reducing or an oxidizing environment? - correct answer ✔✔ oxidizing
does disulphide bond formation occur in reducing or oxidizing environment? - correct answer
✔✔ 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 - correct answer ✔✔ RNAse A
, what is the protein that resides in the ER that promotes oxidation? - correct answer ✔✔ protein
disulphide isomerase (PDI)
does proteolytic cleavage in the ER happen in the lumen or the cytosol? - correct answer ✔✔
lumen
what is the N-terminal signal sequence of type I integral proteins cleaved by? - correct answer
✔✔ signal peptidase
what are the two responses of the unfolded protein response (UPR)? - correct answer ✔✔ 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? - correct answer ✔✔ 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 - correct answer ✔✔ BiP
this is a transmembrane protein that is involved in the UPR - correct answer ✔✔ Ire1
Ire1 endonuclease specifically targets which gene's mRNA? - correct answer ✔✔ Hac1
what does unspliced Hac1 do? - correct answer ✔✔ inhibit translation
this protein is a transcription factor that activates transcription of several genes including the
genes that code for BiP, lectins, PDI, and signal peptidases - correct answer ✔✔ Hac1
questions and answers
is the RER dynamic or stationary? - correct answer ✔✔ dynamic
what is the function of the RER? - correct answer ✔✔ co-translational transport, protein
modification, formation of vesicles that will transport proteins from ER to Golgi
what is the function of the SER? - correct answer ✔✔ fatty acid and phospholipid synthesis,
carbohydrate metabolism, regulate Ca2+ conc in the cytosol
what are the post translational modifications in the ER? - correct answer ✔✔ - 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? - correct answer ✔✔ luminal
this protein modification is important for proteins that mediate cell interactions with the
extracellular matrix and for receptor-ligand recognition - correct answer ✔✔ glycosylation
this protein modification is common on proteins that are secreted from the cell and proteins
embedded in the cell membrane - correct answer ✔✔ glycosylation
what is the most common form of glycosylation? - correct answer ✔✔ N-linked
,N-linked glycosylation adds a polysaccharide to which group of which amino acid? - correct
answer ✔✔ NH2 group of the R-group of asparagine
these proteins recognize modified proteins and assist in protein folding in a similar way as
chaperones - correct answer ✔✔ lectins
what are the two types of lectins? - correct answer ✔✔ calnexin and calreticulin
where is calnexin found? - correct answer ✔✔ ER membrane
what is BiP? mention 3 functions - correct answer ✔✔ - 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? - correct answer ✔✔ Hsp40 and NEF
is cytoplasm a reducing or an oxidizing environment? - correct answer ✔✔ reducing
is ER a reducing or an oxidizing environment? - correct answer ✔✔ oxidizing
does disulphide bond formation occur in reducing or oxidizing environment? - correct answer
✔✔ 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 - correct answer ✔✔ RNAse A
, what is the protein that resides in the ER that promotes oxidation? - correct answer ✔✔ protein
disulphide isomerase (PDI)
does proteolytic cleavage in the ER happen in the lumen or the cytosol? - correct answer ✔✔
lumen
what is the N-terminal signal sequence of type I integral proteins cleaved by? - correct answer
✔✔ signal peptidase
what are the two responses of the unfolded protein response (UPR)? - correct answer ✔✔ 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? - correct answer ✔✔ 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 - correct answer ✔✔ BiP
this is a transmembrane protein that is involved in the UPR - correct answer ✔✔ Ire1
Ire1 endonuclease specifically targets which gene's mRNA? - correct answer ✔✔ Hac1
what does unspliced Hac1 do? - correct answer ✔✔ inhibit translation
this protein is a transcription factor that activates transcription of several genes including the
genes that code for BiP, lectins, PDI, and signal peptidases - correct answer ✔✔ Hac1
