Exam 8: Microbial Genetics

Assume the two E.coli strains shown below are allowed to conjugate. Hfr: pro⁺,arg⁺,his⁺,lys⁺,met⁺,ampicillin-sensitive F-: pro⁻,arg⁻,his⁻,lys⁻,met⁻,ampicillin-resistant What supplements would you add to glucose minimal salts agar to select for a new recombinant cell that is lys⁺,arg⁺,amp-resistant?

Figure 8.1 -In Figure 8.1,which colonies are streptomycin-resistant and leucine-requiring?

Figure 8.2 -In Figure 8.2,if base 4 is adenine,what is base 4'?

Explain why the following statement is false: Sexual reproduction is the only mechanism for genetic change.

Recombination will always alter a cell's genotype.

An enzyme that makes covalent bonds between Okazaki fragments in the lagging strand of DNA being replicated is

Cell-to-cell contact is required for transduction to occur.

Which of the following statements regarding a bacterium that is R⁺ is FALSE?

An enzyme that copies DNA to make a molecule of RNA is

Which of the following statements about bacteriocins is FALSE?

In the Ames test,any colonies that form on the control plates,in the absence of chemical being tested,should be the result of spontaneous mutations.

According to the operon model,for the synthesis of an inducible enzyme to occur,the

The miRNAs in a cell inhibit protein synthesis by forming complementary bonds with rRNA.

Synthesis of a repressible enzyme is stopped by the

Table 8.2 Codons in mRNA molecule and their corresponding amino acids UUU Phenylalanine UAU tyrosine UUA leucine UAA nonsense GCA alanine AAU asparagine AAG lysine UGC cysteine GUU valine UCG, UCU serine -Refer to Table 8.2.When amino acid sequences from a cell cycle control protein from a patient with cancer and a healthy person are aligned,the sequence from the cancer patient indicates one amino acid has changed from phenylalanine (Phe)to leucine (Leu).A mutation in the cancer patient's DNA must have taken place.Identify the result of this DNA change in the mRNA codon that led to this change in the protein sequence.

Transposition (insertion of a transposon into a DNA sequence)results in the formation of base substitution mutations in a cell's DNA.

An enzyme produced in response to the presence of a substrate is called a(n)

The cancer gene ras produces mRNA containing an extra exon that includes a number of UAA codons.Cancer cells produce ras mRNA missing this exon.This mistake most likely is due to a mistake by

Genetic change in bacteria can be brought about by

When two genes from two different people are sequenced and aligned,it is discovered that there are multiple sequence differences in the coding segment DNA level.However,when the proteins formed by the genes have their amino acids sequenced,there is no difference observed between the two.What is the most likely explanation for this observation?