An investigator is studying the function of the endoplasmic reticulum in genetically modified lymphocytes. A gene is removed that facilitates the binding of ribosomes to the endoplasmic reticulum. Which of the following processes is most likely to be impaired as a result of this genetic modification?
AProduction of secretory proteins
BNeutralization of toxins
CUbiquitination of proteins
Dα-Oxidation of fatty acids
ESynthesis of ketone bodies
A medical student is studying digestive enzymes at the brush border of the duodenum. He isolates and inactivates an enzyme in the brush border that has a high affinity for the pancreatic proenzyme trypsinogen. When the enzyme is inactivated, trypsinogen is no longer converted to its active form. Which of the following is the most likely underlying mechanism of this enzyme?
AAttachment of a carbohydrate to a side chain
BPhosphorylation of an amino acid side chain
CCarboxylation of a glutamate residue
DCleavage of a propeptide from an N-terminus
EConjugation of ubiquitin to lysine residue
DNA replication is a highly complex process where replication occurs on both strands of DNA. On the leading strand of DNA, replication occurs uninterrupted, but on the lagging strand, replication is interrupted and occurs in fragments called Okazaki fragments. These fragments need to be joined, which of the following enzymes is involved in the penultimate step before ligation can occur?
ADNA gyrase
BDNA ligase
CDNA helicase
DDNA polymerase I
EDNA polymerase III
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