What are hollow tubes of protein that maintain cell shape and permit movement of cell organelles

Suppose you are provided with an actively dividing culture of e. coli bacteria to which radioactive thymine has been added. what would happen if a cell replicates once in the presence of this radioactive base?

Facilitated diffusion move large molecules and/or polar molecules across the cell membrane. what does facilitated diffusion use to do this?

How do water’s relative densities as a solid and a liquid differ from that of most other substances? water’s solid and liquid forms have different densities, while most other substances have solid and liquid forms with similar densities. water’s solid and liquid forms have similar densities, while most other substances have solid and liquid forms with different densities. water’s liquid form is less dense than its solid form, while the opposite is true of most other substances. water’s solid form is less dense than its liquid form, while the opposite is true of most other substances.