Download Why is the cell membrane so important?

Why is the cell membrane so
important?
Cell Membrane Basics
1. Also known as the plasma membrane
2. Semi-permeable-only some material can get in or out
3. Has a phospholipid bilayer
inside cell
outside cell
Semi-Permeable Membrane
• Controls what gets in or out
• Needs to allow some materials — but not all — to pass
through the membrane
inside cell
waste
outside cell
lipid
salt
sugar aa
H 2O
Semi-Permeable Membrane
What gets in easily?
1. Lipids
2. Water
Why?
1. Channels are made out
protein; “likes” both
water and lipids
Semi-Permeable Membrane Movement
• Movement Types:
• Passive Transport- No energy
required
• Active Transport- Energy required
(ATP)
Passive (No Energy) Transport
• Diffusion – molecules move from a high to low concentration
• Osmosis- water moves from a high to low concentration
• Wants to create homeostasis!
High
Low
Osmosis
Water balance is important!
1. Hydrated
2. Dehydrated
3. “Drown”
Hypotonic Solution:
Higher concentration
of fresh water
outside of the cell.
Cell swells and
bursts.
Hypotonic
Solution: Equal
amount of fresh
water inside and
outside of cell.
Hypertonic
Solution: Lower
concentration of
fresh water
outside of the
cell. Cell shrinks.
Two Types of Diffusion
• Simple Diffusion: Osmosis and Diffusion
• Facilitated Diffusion:
• Uses protein pump due to size of molecules
Active Transport
• Molecules move from low to high
• Requires energy (ATP)
VS
Active Transport
• Endocytosis: Engulfs/Brings in molecules
• Exocytosis: Allows molecules and waste to exit a
cell