Exam 3 Clicker Questions Flashcards
The NaCl concentration in physiological saline solutions is 0.9%. If animal cells are transferred from physiological saline to a solution of 0.1% NaCl, which of the following will happen?
Initially, the number of water molecules moving into the cell will exceed the number moving out of the cell; at equilibrium, the numbers of molecules moving in and out will be equal. The cells will swell.
The NaCl concentration in physiological saline solutions is 0.9%. If animal cells are transferred from physiological saline to a solution of 0.1% NaCl, which of the following will happen?
Initially, the rate of the movement of water molecules into the cell will equal the rate of movement out of the cell and these rates will not change at equilibrium. The cells will swell.
You need to count cells for your experiment. You make a vital dye solution to add to the cells to check for viability (life). You add an equal volume of this dye to equal volume of cells and look under the microscope. To your shock, you see a few humongous cells and shreds of membrane debri. What did you do wrong?
you dissolved the dye in water instead of saline
You want to repeat Griffith’s experiment to investigate all possibilities. You inject mice with heat killed R bacteria mixed with live S bacteria. Do the mice live or die?
mice die because the live S bacteria are virulent
If replication were dispersive (such that the newly replicated strands and the parental strands were cut and resealed randomly as DNA replication proceeded) what chromosomes labeled as in the Messelson Stahl experiment look like after each round of replication?
first round H-H, second round all H-L, third round all H-L
Which molecular tags can be used to visualize ONLY DNA replication?
3H-thymidine
If replication is unidirectional (as seen in some double stranded DNA viruses) which of the following is true?
there is only one origin of replicaion and one newly replicated strand is a leading strand and one is a lagging strand
Imagine that a mutation occurred in the gene encoding the single-stranded DNA binding protein such that it was non-functional. What would be the effect of this mutation?
DNA synthesis would not be able to start
Imagine that a mutation occurred in the gene encoding the 3’ to 5’ editing function of DNA polymerase such that it was nonfunctional. What would be the effect of this mutation?
DNA synthesis would continue but there would be more mistakes in the newly replicated strand
Imagine that a mutation occurred in the gene encoding the 5’ to 3’ exonuclease function of DNA polymerase such that it was non-functional. What would be the effect of this mutation?
primers in the lagging strand would not be removed
The reason that mice have different colored fur is:
the genetic code is the same, a codon in the gene for fur color is different in different mice
The enzyme glucose kinase catalyzes the addition of a PO4 to glucose during glycolysis. This enzyme is found in many different cells. If you compare the messenger RNAs for this enzyme isolated from a bacterial cell and a human cell you would observe
that the sequence of codons on the mRNA for the bacterial enzyme would be similar to the seqence of codons on the mRNA for the human enzyme
When comparing the genes for bacterial and human glucose kinase enzymes you would observe
that the genetic code for the bacterial gene was identical to the genetic code for the human gene
Imagine that a mutation occurs in the gene encoding the sigma subunit of RNA polymerase in E. coli. What would be the effects of this mutation?
transcription would continue but at random sites rather than at promoters
There are viruses, called bacteriophage, that infect bacterial cells. Once the virus enters the bacterial cell it begins to synthesize viral DNA and then viral proteins leading to the production of mature virus and the death of the bacterial cell. During the course of viral infection, bacterial transcription is turned off. Which of the following is the most likely explanation for how the virus manages to shift transcription from bacterial genes to its own genes?
it synthesizes a viral sigma subunit that directs the bacterial RNA polymerase to viral promoters
