Question

cellular boundaries all cells are surrounded by a cell membrane. many cells also have a cell wall. both cell membranes and cell walls separate cells from the environment and provide support.

• cell walls support, shape, and protect the cell. most prokaryotes and many eukaryotes have them. animals do not have cell walls. cell walls lie outside the cell membrane. most cell walls allow materials to pass through them.
• a cell membrane consists of a lipid bilayer, a strong but flexible barrier between the cell and its surroundings. the cell membrane regulates what enters and leaves the cell and also protects and supports the cell. most biological membranes are selectively permeable, allowing some substances, but not others, to pass across them.

cell organization

1. describe the relationship between the cytoplasm and the nucleus of a cell.
2. what does the term organelle mean literally?

for questions 3 - 5, refer to the visual analogy comparing the cell with a factory.

1. visual analogy in the visual analogy of a cell as a factory, what two functions of the nucleus are represented? how are these functions illustrated?
2. which feature of the nucleus is not clearly shown by the visual analogy?
3. what is another possible analogy that could be compared with the structure and function of a cell?

Explanation:

1. The cytoplasm is the jelly - like substance outside the nucleus that contains organelles and is the site of many cellular processes. The nucleus contains the cell's genetic material (DNA) and controls the cell's activities by directing protein synthesis. The nucleus sends out instructions (mRNA) that are translated into proteins in the cytoplasm.
2. The term "organelle" literally means "little organ". Just as organs in the body have specific functions, organelles have specific functions within the cell.
3. In the cell - factory analogy, the nucleus represents the control center (like a manager's office) that contains the plans (DNA) for making products (proteins). The two functions are: 1) storing genetic information (illustrated by the "plans" in the office), 2) directing cellular activities (illustrated by the manager giving out instructions).
4. The nuclear envelope with its pores, which controls the movement of substances in and out of the nucleus, is not clearly shown in the visual analogy.
5. A cell could be compared to a city. The nucleus is like the city hall that controls the activities, mitochondria are like power plants that generate energy, and ribosomes are like factories that produce goods (proteins).

Answer:

1. The cytoplasm is the site outside the nucleus where many cellular processes occur. The nucleus contains DNA and controls cell activities by sending instructions to the cytoplasm for protein synthesis.
2. Little organ.
3. Storing genetic information (illustrated by "plans" in the office - like nucleus) and directing cellular activities (illustrated by a manager giving instructions).
4. The nuclear envelope with its pores.
5. A city.