What is the relationship among cells, chromosomes, genes, and DNA?

DNA is a double-helix structure found in the cell nucleus. Chromosomes straighten out the DNA so the code can be read by genes.

Tightly wound strands of chromosomes contain genes and are found in cells. The genes are coded sequences of nucleotides read by DNA.

DNA is straightened by genes which are contained in the chromosomes of a cell.

Chromosomes are tightly wound strands of DNA located in cells. Genes are sections of DNA.

The kidney filters potentially toxic substances in the blood, and thus “clears” the blood of those substances. this clearance function is dependent upon and proportional to the diffusion gradient of the substance across filtering capillaries, i.e. if the concentration of the substance is doubled, twice as much will be cleared from each ml of blood that is filtered. suppose that the body produces a constant amount of a substance x per unit of time. the kidneys eliminate substance x at a rate directly proportional to the concentration of the substance and the volume of blood cleared each minute (c): elimination = c × [x], where [x] is the steady-state concentration of substance x. imagine an individual with an initial concentration of x equal to [x]0 who develops kidney disease. her baseline clearance c0 drops to one half of the original (½c0). what is the new steady state concentration of x? (for simplicity, assume that substance x is 100% filtered by the kidney).