Cellular Transport

Biology Honors

Review of Concepts and Introduction to the Current

Concepts • https://www.youtube.com/watch?v=Ptmlvtei

8hw

Passive Active

• No energy • Requires / needs energy

Passive Transport- 3 Types

• Diffusion

• Osmosis

• Facilitated Diffusion

What does concentration mean?

• Concentration is the abundance of something.

Diffusion

• The movement of particles across a semi-permeable membrane from an area of high to low concentration; until equilibrium is met.

• Results in natural motion of particles; which causes the molecules to collide / bump into one another and scatter.

• Concentration gradient: the difference in the concentration of a substance from one location to another.

What does diffusion move?

• Small lipids

• Nonpolar molecules such as CO2 and O2

• Water

Osmosis • The diffusion of water across a semi-permeable

membrane from an area of higher water concentration to an area of lower water concentration; until equilibrium is reached.

https://pmgbiology.com/tag/osmosis/

• Most cells have special water proteins called aquaporins.

–Type of channel protein that facilitates the passage of water.

• The higher the concentration of dissolved particles in a solution, the lower the concentration of water molecules in the same solution.

• Water diffuses across a membrane from the region of lower solute concentration to the region of higher solute concentration until the solute concentration is equal on both sides.

Review Terminology

• Solute: The substance that is found in the lesser amount. For example, glucose, salt, or potassium.

• Solvent: The substance that is found in the greatest amount. For example, water.

• Solutions are described based on their tonicity, or concentration of solutes in the water (inside and outside the cell).

• Isotonic

• Hypertonic

• Hypotonic

A way to remember the direction of the water

• SALT SUCKS WATER.

• WHEREVER THERE IS MORE SALT, SUGAR, OR ANY OTHER SOLUTE, THAT IS WHERE THE WATER WILL FLOW.

Write this below the table!

Isotonic • Concentration of water molecules and solutes are

the same inside and outside the cell.

• Animal cells need isotonic solutions to maintain homeostasis.

• Water does not stop moving.

• Cells reach dynamic equilibrium.

Hypertonic • Concentration of water molecules

inside the cell is higher than outside the cell. Solutes are higher outside the cell. Therefore, the water moves out of the cell.

• Causes the cell to shrivel or “crenate,” because the water is leaving the cell.

• When plants lose water they wilt.

• Plasmolysis- process of water moving out of the cell.

Hypotonic • The concentration of water molecules is higher

outside the cell than inside the cell. There are more solutes inside the cell, causing the water to flow into the cell.

• The cells swell and can burst or lyse. • Bursting of cells is cytolysis. • Takes in water. • Plant cells need this tonicity to maintain

homeostasis. • Turgor Pressure= results from water inside a

plant cell pushing the cell membrane out against the plants cell wall.

• More solutes inside the cell.

Label the diagrams

Osmosis Video

• https://www.youtube.com/watch?v=IaZ8MtF3C6M

Facilitated Diffusion

• The diffusion of molecules across a membrane through transport proteins.

• Facilitate means “to make easier”

• Some bind to only one molecule. Some bind to two different molecules.

• Examples: glucose, amino acids, ions, and polar / charged molecules.

Several Types of Transport Proteins

– Channel proteins: act like a pore in the membrane that lets water molecules (aquaporins) or small ions through quickly.

– Carrier proteins: They "carry" the ion, or molecule across the membrane by changing shape. Typically specific to a molecule. Occurs in both passive and active transport.

– Gated channels: A protein "gate," that allows a molecule to pass through the membrane. Gated channels have a binding site that is specific for a given molecule or ion, such as glucose. A stimulus initiates the opening and closing of the gate (temperature, chemical signal).

Why is it important for glucose to pass through the membrane

quickly?

ACTIVE TRANSPORT • Moves materials from areas of low to high

concentration.

• Uses energy / ATP to move the molecules

• Moves materials against the concentration gradient.

• The proteins are often referred to as pumps

• USES ATP

• Why use active transport?

Where does the energy come from?

Bulk Transport Endocytosis and Exocytosis transports materials across the membrane in vesicles.

Endocytosis • Endo=within Cytosis= cell

• Cell takes in large particles by engulfing them. The cell membrane folds into a pouch, called a vesicle. Lysosomes break down the vesicle, releasing the contents.

• Ex- Large molecules, food, liquids, and other substances.

Pinocytosis

• “Cell drinking”

• The process of taking up liquid (just a pinch) from the surrounding environment. Tiny pockets form along the membrane, fill with liquid, and pinch off.

phagocytosis • “Cell eating" – key role in your immune system

• Engulf and destroy particles (bacteria and food).

• Examples: White blood cells / macrophages

This image depicts a cancer cell being attacked by a cell of the immune system. Cells of the immune system consistently destroy pathogens by essentially "eating" them.

http://www.ck12.org/biology/Exocytosis-and-Endocytosis/lesson/Exocytosis-and-Endocytosis-BIO/

Exocytosis • Exo= out of Cytosis= cell

• Release of substances out of the cell by the fusion of a vesicle with the membrane.

• Ex- cell is exporting proteins, getting rid of toxins, or helping messages travel through nerve cells.

http://www.ck12.org/biology/Exocytosis-and-Endocytosis/lesson/Exocytosis-and-Endocytosis-BIO/

Sodium potassium pump • Exchanges sodium ions for potassium ions across the

cell membrane of animal cells.

• Uses ATP to pump molecules through a carrier protein.

• “Pumping” the molecules through.

• Three sodium ions bind with the protein pump inside the cell. In doing so, it pumps the three sodium ions out of the cell. At that point, two potassium ions from outside the cell bind to the protein pump. The potassium ions are then transported into the cell, and the process repeats (http://www.ck12.org/biology/Sodium-Potassium-Pump/lesson/Sodium-Potassium-Pump-BIO/) .

https://online.science.psu.edu/biol011_active002/node/4182

Identify the Process

Bellwork / exit slip

COMPARE/CONTRAST the

kinds of transport

Active (ATP) or

Passive

(KINETIC

ENERGY)

What does it use to

help:

Membrane proteins?

Vesicles? Needs no

help (phospholipids)?

Example of substance(s)

that use this kind of

transport in cells

DIFFUSION

FACILITATED

DIFFUSION

OSMOSIS

SODIUM-POTASSIUM

(NA+ -K+) PUMP

(ANIMALS)

ENDOCYTOSIS

(PHAGOCYTOSIS)

ENDOCYTOSIS

(PINOCYTOSIS)

EXOCYTOSIS

Identify the Diagrams