Biology 1200 Exam 3 Questions And Already Passed Answers.

A virus that infects bacterial cells is called a - Answer bacteriophage The expression of the lac structural genes is _______ when lactose is absent from the culture medium and is _______ when lactose is added, because lactose binds to the _______ and inactivates it. - Answer low; high; lac repressor A bacterial gene (gene A) ordinarily makes a protein that binds to DNA. A mutation of gene A decreases the expression of another gene, gene B. We can conclude that - Answer gene A is a positive regulator of gene B In eukaryotic gene regulation, a(n) _______ is similar in structure but opposite in function to a silencer. - Answer enhancer In the initiation of the transcription of structural genes in eukaryotes, _______ cannot bind directly to _______. Initiation requires _______ and other regulatory proteins called _______. - Answer RNA polymerase; an initiation site; TFIID; transcription factors A virus consists of - Answer a nucleic acid core surrounded by a protein capsid, and in some cases, a membrane Regulation of gene expression during the bacteriophage lytic cycle does not include - Answer enhancement of the host's gene transcription During lysogeny, the - Answer viral genome is integrated into the host's genome A herpes virus causes both chicken pox and shingles in humans. People who have had chicken pox may be afflicted with shingles much later in life. The most likely explanation for this is that - Answer the viral DNA had been incorporated into the host's genome and was later induced to enter the lytic phase. Which mechanism of posttranscriptional regulation of gene expression can produce several different proteins from a single gene? - Answer Alternative splicing Ribozymes are RNA molecules that have enzymatic activity. This conflicts with the belief of early molecular biologists that - Answer each enzyme is a polypeptide.