Cellular Transport

Cellular Transport The Cell and its Environment Cellular Transport

The Cell in its Environment

The Cell Membrane Selectively permeable membrane Lipids Transport Proteins

SELECTIVELY PERMEABLE

Diffusion across cell membrane NO! Can it be an impenetrable boundary? IN food carbohydrates sugars, proteins amino acids lipids salts, O2,H2O OUT waste ammonia salts CO2 H2O products OUT IN cell needs materials in & products or waste out

Channels through cell membrane inside cell H2O aa sugar salt outside cell NH3

Cellular Transport Two Kinds 1. Passive Transport 2. Active Transport

Types of Cellular Transport Passive Transport- cell doesn’t use energy Diffusion Facilitated Diffusion Osmosis Active Transport - cell uses energy Protein Pumps Endocytosis Exocytosis Weeee!!! high low This is gonna be hard work!! high low

Passive Transport Diffusion Facilitated Diffusion Osmosis

Passive Transport Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration.

Diffusion of Molecules

Diffusion • Diffusion • movement from highlow concentration

Facilitated Diffusion Diffusion through protein channels channels move specific molecules across cell membrane high low facilitated = with help open channel = fast transport “The Bouncer”

Passive Transport Comparison Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer) Carrier Protein

Osmosis The movement of water across a cell membrane

Isotonic the concentration of water outside and inside the cell is equal.

Hypotonic Solution

Hypotonic the concentration of water outside the cell is greater than the concentration of water inside the cell; water will flow into the cell, causing it to swell

Hypotonic Solution Solute less than Water

Water moves from the solution to inside of the cell. The cell Swells and bursts open. Cytolysis is cell bursting.

Hypertonic the concentration of water outside the cell is lower than the concentration of water inside the cell; therefore water will flow out of the cell, causing it to shrink

Hypertonic Solution Solute greater than Water

Water moves from inside the cell into the solution and the cell shrinks. Plasmolysis cell shrinking

Managing water balance Cell survival depends on balancing water uptake and loss.

Concentration of Solution Direction of osmosis is determined by comparing total solute concentrations         = = = =

How Organisms Deal with Osmotic Pressure Bacteria and plants havecell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called turgor pressure.

How Organisms Deal with Osmotic Pressure • Aprotistlike paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding.

How Organisms Deal with Osmotic Pressure • Salt water fish pump salt out of their specialized gills so they do not dehydrate. • Animal cells are bathed in blood. Kidneyskeep the blood isotonic by remove excess salt and water.

Active Transport Protein Channels Endocytosis and Exocytosis Phagocytosis and Pinocytosis

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

Types of Active Transport Protein Pumps Endocytosis Exocytosis

Protein Pumps transport proteins that require energy to do work Sodium / Potassium Pumps are important in nerve responses.

Endocytosis: taking bulky material into a cell • Uses energy • Cell membrane in-folds around food particle and forms food vacuole and digest food

TWO KINDS: • Phagocytosis – cell enguls solid particles of food “cell eating” 2. Pinocytosis – cell takes in droplets of fluid “ Cell drinking”

Phagocytosis Pinocytosis

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

Cytoplasm

Cellular Transport