Unit 1 Sample Questions Flashcards
According to the concept of genomic equivalence
all cells of an organism have the same genome
Which of the following is the most obvious predictable outcome of replacing lysine residues in the amino terminal region of core histones (i.e. H2A, H2B, H3, and H4) with nonpolar or acidic amino acids?
a. failure to assemble the octameric histone core.
b. failure to create an 11 nm chromatin fiber.
c. failure to create a 30 nm chromatin fiber.
d. failure to create a nucleosome.
d. failure to create a nucleosome
What is the expected outcome (as related to nucleosomes) of a mutation that prevents the formation histone folds?
nucleosomes wouldn’t condense
Consider the chromatin loop identified by the red arrow in the above figure. If it is an extended loop that contains a gene undergoing transcription which of the following statements is also true of the loop?
I. It is 11 nm in diameter
II. It is contained in a region of heterochromatin
III. It does not contain histone proteins
IV. It would have a beads-on-a-string conformation
V. It would be excluded from nuclear neighborhoods
I and IV
Acetylation of lysine reduces histones
is associated with activation of gene expression and is usually mediated a chromatin- remodeling complex
What do we mean when we say that nucleosomes are dynamic?
the DNA associated with the histones undergoes cycles of wrapping around the histone, unwrapping and then re-wrapping
Your laboratory has used standard molecular biology techniques to create a chimeric transcription factor that contains the activation domain of the TF that regulates expression of the EpiX gne and the DNA binding domain of the transcription factor that controls expression of the lacZ gene. To test the function of this chimera, you have created two chimeric genes: one of these genes contains the gene regulatory sequences of the EpiX gene and the coding sequence of a reporter gene that encodes the glucosidase enzyme. The second chimeric gene contains the gene regulatory sequences for lac Z gene and the coding sequence of the reporter gene that codes for the galactosidase enzyme. If the chimeric transcription factors is transfected into cells that contain both of these chimeric genes, which molecule will be produced?
galactosidase
Which of the following is true of a protein that has reached the global minimum?
I. Entropy is minimized
II. Entropy is maximized
III. Energy is minimized
IV. Energy is maximized
II and III
An unfolded protein will return to its original folded conformation if conditions that favor protein folding are established? True or False
true
Molecular chaperones…
assist in the protein folding process of nascent proteins
Hsp 60 chaperones…
I. are also known as chaperonins.
II. interact directly with proteasomes.
III. aid in the folding/refolding of partially synthesized proteins.
IV. work primarily at the co-translational level.
V. contain an expandable core region.
I and V
Which of the following is not a function performed by the 19S cap of the proteasome?
a. Recognizes and binds ubiquitin.
b. Unfolds the target protein.
c. Removes ubiquitin from the target protein.
d. Adds an acetyl group to the amino terminus of the target protein.
e. None of the above; in other words a-d are all true.
d. adds an acetyl group to the amino terminus of the target protein
Under certain metabolic conditions, protein X become obsolete. In order to reduce the concentration of protein X, a specific E3 ligase (aka ubiquitin ligase) is activated. What role does this E3 ligase play in reducing the concentration of protein X.
the activated E3 ligase transfers ubiquitin from E2 to protein X.
What will happen to activity of a G-protein. If it is acted upon by a Guanine exchange factor?
the protein will be inactivated
