Cell membrane and transport

15
Structure and Function of the Cell Membrane

description

 

Transcript of Cell membrane and transport

Page 1: Cell membrane and transport

Structure and Function of the Cell Membrane

Page 2: Cell membrane and transport

Cell Membrane

• Gatekeeper• Regulates what comes in and out

of the cell• Main components: proteins and

phospholipids• The cell membrane is selectively

permeable• Allows some things through without energy,

but not everything

Page 3: Cell membrane and transport

Cell Wall• Found only in plant cells and bacteria

cells• Main function is support

Page 4: Cell membrane and transport

Cell membrane parts• phosopholipids

• made of two sides: head and tail• the head is hydrophillic (able to

interact with water)• the tail is hydrophobic (not able to

interact with water)

Page 5: Cell membrane and transport

Cell membrane parts• carrier proteins

• allow larger or difficult molecules to get through the membrane

• sometimes they require energy to open/close like a door

• other times they simply act as a tunnel

Page 6: Cell membrane and transport

Diffusion• The movement of molecules from

an area of high concentration to an area of low concentration

• Molecules tend to “spread out”• Requires no energy

Page 7: Cell membrane and transport

Equilibrium• When molecules are evenly

spread throughout a space

Page 8: Cell membrane and transport

Osmosis

• The diffusion of water across a membrane

• H2O molecules are able to go in between the phospholipids based on size and a slight electrical charge.

• Water will travel to where there is a lower concentration• If you add something like salt to the solution…

Page 9: Cell membrane and transport

Rule for Osmosis:

Water will get sucked to wherever there is a higher concentration of salt.

The following slides illustrate what direction water travels if a cell is placed in different solutions.

Page 10: Cell membrane and transport

Cells In Different Solutions

"ISO" means the same; water stays in equilibrium.

Page 11: Cell membrane and transport

Hypo = less Cell fills with water and may burst, or organelles called “contractile vacuoles” remove excess water

Page 12: Cell membrane and transport

Hyper = more Cell will shrink or die, plant leaves wilt and droop.

Why is it dangerous to drink sea water?

Why does pouring salt on a slug kill it?

Page 13: Cell membrane and transport

Passive Transport• Requires no energy• Diffusion & Osmosis• Facilitated Diffusion: carrier

proteins “help” molecules across the membrane like a tunnel

Page 14: Cell membrane and transport

ACTIVE TRANSPORT

• Requires the cell to use energy• Carrier Proteins or Pumps found in

the membrane move materials across• Open/close like a door

Page 15: Cell membrane and transport

Endocytosis/Exocytosis

• Taking “in” or letting “out” large molecules by the cell

• Phagocytosis = “phood”, taking in food particles

• Pinocytosis = liquid substances