Cell differentiation is governed by genes. Depending on where in the body it is located, a given gene can be turned off, weakly on, or strongly on. For example, the gene for globin, which composes hemoglobin, is strongly on in cells that will mature into red blood cells and off in every other cell type.

Cells control gene expression by using molecular tags that lure an enzyme to insure the transcription of certain genes. They also use tags that repel the same enzyme for genes that are turned off. The enzyme that controls the transcription is

A) replicatase.
B) transcriptase.
C) DNA polymerase.
D) RNA polymerase.

Ascientist and her team counted 200 individual deer in an area of 10 square kilometers. what is the population density?

You have been asked to lead a demonstration for the undergraduate microbiology lab course about the uses of negative staining when studying bacteria. a "negative" stain does not stain the bacterial cell itself but stains the space between cells. under magnification, the acidic (negativelycharged) nature of the stain will be repelled by the negatively charged bacterial cell wall and willleave the cell colorless in a stained background. negative stains are used primarily to reveal the presence of negatively charged bacterial capsules; therefore, they are also called capsule stains. encapsulated cells appear to have a halo surrounding them. the negative stain procedure does not require heat fixation, which limits any chances of alteration in bacterial cell shape and size. the bacterial suspension is added to a drop of stain, such as nigrosin or eosin, and drawn across the glass slide using a coverslip.nigrosin staining-not safranin staining-of klebsiella pneumoniae will allow for the visualization of the cell shape and the determination of the presence of a capsule.true/false

In the diagram below, the northern hemisphere would be in what season at position a a.fall b. winter c.summer d.spring