Question

34) Polar molecules
    A. have covalent bonds with unequal distribution of electrons.    B. are either positive or negative ions.
    C. have an overall negative electric charge.            D. have an even distribution of electrons.

35) E coli is efficient in its protein expression. What happens to lactase gene expression when lactose is present for the bacterium to digest?
        A. Lactose sits on the operator and turns gene on.
        B. Lactose sits on the repressor (which can now NOT get to operator) so gene turns on.    
C. Lactose binds to permease allowing RNA polymerase into the cell to turn gene on.
D. Repressor sits on operator and calls RNA polymerase to site to turn gene on.

36) Transcription is the process of
    A. synthesizing a DNA molecule from an RNA template.
    B. assembling an RNA molecule without a template.
    C. synthesizing an RNA molecule using a DNA template.
    D. synthesizing a protein using information from a mRNA.
    E. replicating a single-stranded DNA molecule.

Answer 1

34.  A. have covalent bonds with unequal distribution of electrons

This unequal distribution of electrons is known as a polar covalent bond, characterized by a partial positive charge on one atom and a partial negative charge on the other. For example, the electrons in the H–Cl bond of a hydrogen chloride molecule spend more time near the chlorine atom than near the hydrogen atom.

35. B. Lactose sits on the repressor (which can now NOT get to operator) so gene turns on.

When lactose is added to the growth medium, the lac genes are expressed because allolactose binds to the Lac repressor protein and keeps it from binding to the lac operator. Allolactose is an isomer of lactose.

36.  C. synthesizing an RNA molecule using a DNA template.