Chapter 3. Cells

Question 1

Cells

Answer 1

Are the basic structural and functional units of living organisms
- they vary in size, shape, and function
- consists of 3 main parts.
- Plasma (cell) membrane
- Cytoplasm
- Nucleus

Question 2

Cell Number 1: Plasma Membrane

Answer 2

• The edge of life!
• Forms the boundaries of the cell —> separates inside fluids from outside fluids
• lipid component of membrane is 75% phospholipids, 20% cholesterol and 5% glycolipids
• Phospholipid molecules are arranged in 2 layers (Bilayer)
• Phospholipid molecules have polar heads (attracted to water) and non polar tails (water-fearing)
• Phospholipid molecules are organized with their heads facing both sides of the membrane and their tails pointing toward each other.
• Functions as a selectively permeable barrier that regulates the flow of materials into and out of cells.

Question 3

Two types of membrane proteins

Answer 3

1. Integral (transmembrane) proteins: extend through the phospholipid bilayer
2. Peripheral membrane proteins: are associated loosely with on side of the membrane

Many membrane proteins are glycoproteins with branching sugar groups facing the extracellular fluid

Question 4

Membrane Protein Functions

Answer 4

• Transporters —> as channels or carriers
• receptors for chemical messengers
• enzymes that catalyze reactions
• Markers in cell recognition
• Anchors to cell’s cytoskeleton