Plasma Membrane-Gateway to the Cell

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Slide 28

Cell in Hypertonic Solution

CELL

15% NaCL 85% H2O

5% NaCL

95% H2O

What is the direction of water movement?

ENVIRONMENT

Slide 29

Cells in Solutions

Slide 30

Isotonic Solution

NO NET MOVEMENT OF H2O (equal amounts entering & leaving)

Hypotonic Solution

CYTOLYSIS

Hypertonic Solution

PLASMOLYSIS

Slide 31

Cytolysis & Plasmolysis

Cytolysis

Plasmolysis

Slide 32

Osmosis in Red Blood Cells

Isotonic

Hypotonic

Hypertonic

Slide 33

What Happens to Blood Cells?

Slide 34

hypotonic

hypertonic

isotonic

hypertonic

isotonic

hypotonic

Slide 35

Three Forms of Transport Across the Membrane

Slide 36

Passive Transport

Simple Diffusion

Doesn’t require energy

Moves high to low concentration

Example: Oxygen or water diffusing into a cell and carbon dioxide diffusing out.

Slide 37

Passive Transport

Facilitated diffusion

Doesn’t require energy

Uses transport proteins to move high to low concentration

Examples: Glucose or amino acids moving from blood into a cell.

Slide 38

Proteins Are Critical to Membrane Function

Slide 39

Types of Transport Proteins

Channel proteins are embedded in the cell membrane & have a pore for materials to cross

Carrier proteins can change shape to move material from one side of the membrane to the other

Slide 40

Facilitated Diffusion

Molecules will randomly move through the pores in Channel Proteins.

Slide 41

Facilitated Diffusion

Some Carrier proteins do not extend through the membrane.

They bond and drag molecules through the lipid bilayer and release them on the opposite side.