ap bio unit 2.1

unit 2 of ap bio

What do all living cells share?

Plasma membrane, cytosol, ribosomes, and genetic material (DNA).

What is the structure of the plasma membrane?

Made of a phospholipid bilayer with hydrophilic heads and hydrophobic tails.

What property does the plasma membrane have?

It is selectively permeable.

What can cross the plasma membrane easily?

Small, nonpolar molecules such as O₂ and CO₂.

What needs help crossing the plasma membrane?

Large molecules, ions, and polar molecules (water via aquaporins).

Why is a high surface area-to-volume ratio important for cells?

It improves diffusion, heat exchange, nutrient uptake, and waste removal.

How does cell size affect surface area-to-volume ratio?

As a cell increases in size, its volume increases faster than its surface area, leading to low SA:V and inefficient exchange.

How do cells increase their surface area?

By folding membranes.

What are examples of membrane folding in cells?

Mitochondria cristae, chloroplast thylakoids, and intestinal epithelial microvilli.

What are key differences between prokaryotic and eukaryotic cells?

Prokaryotes lack membrane-bound organelles and a nucleus, while eukaryotes have both.

Why are organelles important in eukaryotic cells?

They create compartments to increase efficiency and specialize functions.

What is compartmentalization in cells?

The formation of local environments with specific conditions to enhance metabolic efficiency.

What are examples of cell compartments?

Lysosomes (acidic), mitochondria (ATP production), and chloroplasts (photosynthesis).

What does the endosymbiotic theory propose?

Mitochondria and chloroplasts evolved from free-living prokaryotes.

What evidence supports the endosymbiotic theory?

Double membranes, own DNA (circular), reproduction by binary fission, and ribosomes similar to prokaryotes.