Cellular Transport, Cell Biology - Biology - Lecture Slides, Slides of Biology

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Cellular Transport Notes

About Cell Membranes

1.All cells have a cell membrane

2.Functions :

a.Controls what enters and exits the cell to maintain an internal balance called homeostasis b.Provides protection and support for the cell (^) real cell membrane.TEM picture of a

Proteins

Polar heads love water & dissolve.

Non-polar tails hide from water. Carbohydrate cell markers

Fluid Mosaic Model of the cell membrane

About Cell Membranes (continued)

• 4. Cell membranes have pores (holes) in it

a.Selectively permeable : Allows some molecules in and keeps other molecules out b.The structure helps it be selective!

Pores

Types of Cellular Transport

• Passive Transport

cell doesn’t use energy

1. Diffusion
2. Facilitated Diffusion
3. Osmosis

• Active Transport

cell does use energy

1. Protein Pumps
2. Endocytosis
3. Exocytosis high

low

This is gonna be hard work!!

high

low

Weeee!! !

• Animations of Active Transport & Passive Transport

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Passive Transport

• cell uses no energy
• molecules move randomly
• Molecules spread out from an area of high concentration to an area of low concentration.

• (HighLow)

• Three types:

Passive Transport:

1. Diffusion

1. Diffusion : random movement of particles from an area of high concentration to an area of low concentration.

( High to Low )

• Diffusion continues until all molecules are evenly spaced ( equilibrium is reached)- Note: molecules will still move around but stay spread out.

2. Facilitated diffusion : diffusion of specific particles through transport proteins found in the membrane a. Transport Proteins are specific – they “select” only certain molecules to cross the membrane b.Transports larger or charged molecules

Facilitated diffusion (Channel Protein)

Diffusion (Lipid Bilayer)

Passive Transport :

2. Facilitated Diffusion

Carrier Protein

A B

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• 3. Osmosis : diffusion of water through a selectively permeable membrane
• Water moves from high to low concentrations - Water moves freely through pores. - Solute (green) to large to move across.

Passive Transport:

3. Osmosis

Active Transport

• cell uses energy
• actively moves molecules to where they are needed
• Movement from an area of low concentration to an area of high concentration
• (Low  High)
• Three Types:

Types of Active Transport

• 2. Endocytosis : taking bulky material into a cell
• Uses energy
• Cell membrane in-folds around food particle
• “ cell eating ”
• forms food vacuole & digests food
• This is how white blood cells eat bacteria!

Types of Active Transport

3. Exocytosis : Forces material

out of cell in bulk

• membrane surrounding the material fuses with cell membrane
• Cell changes shape – requires energy
• EX: Hormones or wastes released from cell

Hypotonic Solution

Hypotonic : The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water)

Result: Water moves from the solution to inside the cell): Cell Swells and bursts open ( cytolysis )!

Hypertonic Solution

Hypertonic : The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water)

Result: Water moves from inside the cell into the solution: Cell shrinks ( Plasmolysis )!

shrinks