3.1 - 3.5 Chapter Review

According to the cell theory, what is required for an object to be considered alive?

According to the cell theory; for an object to be considered alive, it must be made of cells and cell products.

What role do membranes play in prokaryotic cells? in eukaryotic cells?

Prokaryotic cells do not have membrane bound organelles. Eukaryotic cells do have membrane bound organelles. The membrane controls movement in and out of the cell.

How do the cytoskeleton and the cytoplasm contribute to a cell's shape?

Cytoskeleton has microtubules (long hollow tubes) which give the cell its shape and act as tracks for movement of organelles. The cytoplasm fills the space between the nucleus and the cell membrane.

You know that many organelles are involved in protein production. Briefly explain where proteins are made, modified, and packaged within a cell.

The DNA contains genes for making proteins. The DNA is stored in the nucleus. The nucleus is where the ribosomes are formed which make proteins.

Explain what mitochondria do and why evidence suggest that they might have descended from free-living prokaryotes in the evolutionary past.

Supply energy to the cell. They convert molecules from food into usable energy. They have their own ribosomes and DNA unlike the prokaryotic cells.

If you were looking though a microscope at an unknown cell, how might you determine whether it was a plant cell or an animal cell?

Plant cells have cell walls and chloroplast which animal cells do not have.

Cells are surrounded by a watery fluid, and they contain water cytoplasm. Explain how the structure of the lipid bilayer is related to these two watery environments.

The lipid bilayer is an organic compound that is insoluble in water, but soluble in other non-polar solvents.

How are cells able to respond to signal molecules that are too large to enter the cytoplasm?

By the ligand receptors on the surface of the cell membrane.

How do transport proteins make it easier for certain molecules to diffuse across a membrane?

They create a channel/tunnel for them to go through the membrane without coming in contact with it.

Under what conditions would a molecule need to be actively transported across a membrane?

Low to high, make buildup.

Do you think that endocytosis and exocytosis can occur within the same cell?

Yes, Endocytosis and exocytosis can occur in the same cell. It is how a cell transport and export material in and out.