Honors Biology Arizona College Prep

Mrs. Glassmeyer Textbook Reference: 4.10-4.14, The Living

World 7th edition

Cell Transport

Unit Learning Goal: Student will be able to compare structure & analyze transport of materials into and out of prokaryotic & eukaryotic cells by accurately explaining the role of proteins & ATP.

Presentation Learning Goal(s):

1. How are the two types of cell transport associated with energy requirements & concentration gradients?

2. Why is cell transport essential to the maintenance and survival of cells?

Learning Goals

Review: plasma membrane

Composed of phospholipid bilayer and a mosaic of proteins –Non-polar molecules pass

through the lipid part

–Water soluble molecules must move through proteins

Selectively permeable (semi-permeable) –Allows some substances

in, excludes others

What’s a Gradient?

Active vs. Passive Visual

Active Passive

What is Passive Transport?

No Energy required!

Moves down a concentration gradient

(Particles move from high to low concentration)

Three Types of Passive Transport:

1. Diffusion

2. Facilitated Diffusion

3. Osmosis

What is Diffusion? Net movement of particles from an area of

high concentration to an area of low concentration as a result of random molecular motion.

End result Equilibrium

Example of Diffusion

What Variables Affect Diffusion?

Degree of concentration gradient

Area of membrane for diffusion – Lipid soluble: oxygen

– Membrane required: Na+, sugar molecules, amino acids

Physical characteristics of cell environment – Temperature

– Pressure

– Electrical Field

What is Facilitated Diffusion? Diffusion of a particle (ions & polar

molecules) naturally down a concentration gradient using a carrier protein

What are the Types of Protein Channels?

Open Channel

– Size determines whether molecule moves through

Carrier Proteins

– Surface “carrier” protein carries the molecule across the membrane

– “carrier” protein is specific to molecule

Example of Facilitated Diffusion

Receptor Mediated Facilitated Diffusion – a protein binds to a specific receptor on the cell membrane causing conformational changes of the associated carrier protein which allows the transport to the molecule to the other side of the membrane.

What is Osmosis?

Movement of water from an area of high concentration to an area of lower concentration (down a concentration gradient).

The difference in concentration is caused by the amount of solutes present on either side of a semi-permeable membrane!

Can result in changing volumes on either side of the membrane

Osmosis

(water moves to balance solution concentrations)

What is Active Transport? Energy IS required

Particles are being moved AGAINST a concentration gradient (Particles move from low concentration to high concentration)

Three Types of Active Transport:

1. Protein Pumps

2. Endocytosis

3. Exocytosis

What are Protein Pumps? • Proteins that carry materials across a membrane

against the concentration gradient

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uses energy, in the form of ATP, to pump three Na+ out of the cell and to pump two K+ into the cell

nearly 1/3 of the energy expended by the body’s cells is given over to driving these pumps

What is the Sodium-Potassium Pump?

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The result of the Na+-K+ pump is to generate a concentration gradient with more Na+ outside of the cell than inside

Cells exploit this gradient in key ways – for the conduction of signals along nerve cells

– for the transportation of important molecules into the cell against their concentration gradient

Why are Sodium-Potassium Pumps Important?

What is Endocytosis? The inward movement of molecules through a membrane by infolding and pinching off vesicles

Examples of Endocytosis

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What are the Forms of Endocytosis?

Phagocytosis is endocytosis of particulate (solid) matter

Pinocytosis is endocytosis of liquid matter

Figure 4.22(a) Endocytosis

Figure 4.22(b) Endocytosis

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Cytoplasm

Plasma membrane

(a) Phagocytosis

Cytoplasm

Plasma membrane

(b) Pinocytosis

What is Exocytosis? Release of material to the external

environment

Unit Learning Goal: Student will be able to compare structure & analyze transport of materials into and out of prokaryotic & eukaryotic cells by accurately explaining the role of proteins & ATP.

Presentation Learning Goal(s):

1. How are the two types of cell transport associated with energy requirements & concentration gradients?

2. Why is cell transport essential to the maintenance and survival of cells?

Learning Goals

Study Recommendations

Make sure to write a summary for the cornell notes highlighting key concepts and applications

Review key questions and highlight key words in the notes

Make sure to label anything emphasized in class as a potential T.Q.

Create flashcards for key concepts/vocab