#Question id: 4299
#Unit 3. Fundamental Processes
Lactate dehydrogenase (LDH) can exist as various tetrameric isozymes. Extracts from different rat tissues were run on a nondenaturing polyacrylamide gel and stained for LDH activity, as shown below. Standard tetramers of M subunits (M4) and H subunits (H4) were run alongside the tissue extracts. Which of the following is the subunit composition of the isozyme running at position 2 ?
#Question id: 4300
#Unit 3. Fundamental Processes
Find correct order of cotranslational translocation in endoplasmic reticulum
A. Transfer of the nascent polypeptide–ribosome to the translocon leads to opening of this
translocation channel to admit the growing polypeptide adjacent to the signal sequence, which is transferred to a hydrophobic binding site next to the central pore. Both the SRP and SRP receptor, once dissociated from the translocon, hydrolyze their bound GTP and then are ready to initiate the insertion of another polypeptide chain.
B. As the polypeptide chain elongates, it passes through the translocon channel into the ER lumen, where the signal sequence is cleaved by signal peptidase and is rapidly degraded.
C. The SRP and the nascent polypeptide chain–ribosome complex bind to the SRP receptor in
the ER membrane. This interaction is strengthened by the binding of GTP to both the SRP and its receptor.
D. The ER signal sequence emerges from the ribosome; it is bound by a signal recognition particle (SRP).
#Question id: 4301
#Unit 3. Fundamental Processes
Which of the following proteins prevents eukaryotic mRNAs from being recruited to the ribosome prior to egg fertilization
#Question id: 4302
#Unit 3. Fundamental Processes
Which one of the following proteins is involved in promoter recognition in eukaryotes?
#Question id: 4303
#Unit 3. Fundamental Processes
Which component is not directly involved in translation?
#Question id: 4304
#Unit 3. Fundamental Processes
Using codon table, identify a 5′ → 3′ sequence of nucleotides in the DNA template strand for an mRNA coding for the polypeptide sequence Phe-Pro-Lys.