Bio Chap 3 - Cell Theory and Membranes

Ten flashcards covering cell theory, cell types, cell membranes, DNA localization, cell walls, osmosis, diffusion, and tonicity.

What does the cell theory state about the origin of new cells?

New cells come from the division of preexisting cells.

How do prokaryotic and eukaryotic cells differ in nucleus presence and size?

Prokaryotic cells are smaller and lack a membrane-bound nucleus; DNA floats in the cytoplasm. Eukaryotic cells are larger and contain a membrane-bound nucleus that houses DNA.

What is the composition of the cell membrane and its primary function?

A phospholipid bilayer with embedded proteins that forms a barrier between the cell interior and exterior.

Where is DNA located in prokaryotic vs. eukaryotic cells?

In prokaryotes, DNA floats freely in the cytoplasm; in eukaryotes, DNA is housed in the nucleus.

Do all cells have a nucleus?

No. Prokaryotic cells lack a true nucleus.

Which organisms have cell walls and what about animal cells?

Fungi, plants, and algae have cell walls (made of different materials); animal cells do not have cell walls.

What is the role of bacterial cell walls?

They enclose the cell membrane, provide a rigid structure, help maintain cell shape and homeostasis, and aid survival in watery environments.

Which molecules move across the cell membrane most easily?

Nonpolar molecules (and very small water molecules) move across easily; large polar molecules and ions do not.

What are osmosis and diffusion?

Osmosis is the diffusion of water across a membrane; diffusion is the diffusion of other molecules across the membrane.

What is tonicity and how do hypertonic, hypotonic, and isotonic solutions affect cell shape?

Hypertonic solutions cause cells to shrink; hypotonic solutions cause cells to swell or burst; isotonic solutions do not affect cell shape.