Final answer:
Transposable elements, or 'jumping genes', are genetic elements in a bacterial cell that can move within the DNA. They can affect the phenotype of a cell by inactivating or activating genes, and by relocating additional genes to another location.
Step-by-step explanation:
Transposable elements, also known as transposons or 'jumping genes', are genetic elements in a bacterial cell that can move from one location to another within the DNA. They include special inverted repeat sequences at their ends and a gene encoding the enzyme transposase. Transposons can affect the phenotype of a cell they move to in two ways: by inactivating or activating a gene, and by carrying additional genes with them and relocating them to another location.