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LB145 Sec 001-004. Today’s Outline. HAND IN StudyNotes – front of classroom. Homework Assignment due on Tuesday. Create a Classroom Code of Conduct. Protein review. Lipids + Membranes A human experiment Membrane transport. What is a protein?. What do proteins do?.

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LB145 Sec 001-004

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Lb145 sec 001 004

LB145Sec 001-004


Today s outline

Today’s Outline

  • HAND IN StudyNotes– front of classroom.

  • Homework Assignment due on Tuesday.

  • Create a Classroom Code of Conduct.

  • Protein review.

  • Lipids + Membranes

  • A human experiment

  • Membrane transport


What is a protein

What is a protein?


What do proteins do

What do proteins do?


Where do you get proteins from

Where do you get proteins from?

  • Discuss with your neighbor:

    • What are some foods that are high in protein content?

    • What are some foods that contain no protein?


What is a protein1

What is a protein?

  • A protein is a chain of amino acids.

  • ALL foods contain proteins – because all living cells contain proteins.

  • When we eat proteins, our body breaks them down into their composite amino acids. We use these amino acids to make our own proteins.


A chain of amino acids

A Chain of Amino Acids


Lipids

Lipids


Clicker question what is a lipid

Clicker Question: What is a lipid?

  • Is a group of molecules that includes: fats, steroids and phospholipids.

  • Molecules that have fatty-acid side chains.

  • Carbon-containing compounds that are non-polar and hydrophobic.

  • A molecule with a hydrophilic head and a hydrophobic tail that is a major component in cell membranes.


Lipids1

Lipids

  • A lipid is an organic compound, found in organisms, that is primarily non-polar and hydrophobic.

  • Three types to know

    • Fats (triacylglycerol)

    • Phospholipids

    • Steroids

Campbell 8e, Fig. 5.15

Campbell 8e, Fig. 5.13b


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Fatty acids form ester bonds with glycerol


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Fats consist of glycerol linked to three fatty acids


Biological membranes are composed of phospholipids

Biological Membranes are Composed of Phospholipids


Biological membranes are composed of phospholipids1

Biological Membranes are Composed of Phospholipids

Campbell 8e, Fig. 5.13


What is a membrane

What is a Membrane?

  • A phospholipid bilayer (a fluid mosaic).


Membrane fluidity

Membrane Fluidity

The individual phospholipid molecules in lipid bilayer membranes are in constant motion

Membranes are dynamic structures


Membrane fluidity1

Membrane Fluidity

The Role of Steroids


Steroids

Steroids

Which is true?

  • Cholesterol reduces fluidity and reduces permeability of membranes.

  • Cholesterol increases fluidity and increases permeability of membranes.

  • Cholesterol increases fluidity and decreases permeability of membranes.

  • Cholesterol decreases fluidity and increases permeability of membranes.


Role of cholesterol

Role of Cholesterol


Back to talking about things that have fatty acid side chains

Back to talking about things that have fatty acid side chains…


Saturated vs unsaturated a fat question

Saturated vs. Unsaturated(a fat question)

Which of the following statements about unsaturated fat is true?

  • They are more common in animals than plants.

  • They have double bonds in the carbon chains of their fatty acids.

  • They generally solidify at room temperature.

  • They contain more hydrogen that saturated fats having the same number of carbon atoms.

  • They have fewer fatty acid molecules per fat molecule.


The shape of phospholipids

The Shape of Phospholipids…

  • Why is one leg of the phospholipid bent?


Saturated vs unsaturated

Saturated vs. Unsaturated


Membrane permeability

Membrane Permeability

A human experiment…


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Tonicity


Osmosis can cause the shrinking or swelling of cells

Osmosis can cause the shrinking or swelling of cells


Building mental models

Building Mental Models

  • Think about a cell membrane – how would you draw one?

Membrane?

Membrane?


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Proteins

Cell exterior

Phospholipid

bilayer

Cell interior


Transmembrane proteins and transport

Transmembrane Proteins and Transport

Transmembrane proteins are imperative for cellular transport.

Channels

Carrier proteins or transporters

Pumps

Passive facilitated processes

Active facilitated process


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Hydrophilic interior

Outside cell

Hydrophobic exterior

H2O

Inside cell


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Gated Channels

Potassium ions enter

the channel

Outside cell

Inside cell

Closed

Positive charge triggers channel to open.

Electrochemical gradient.

Open


Active transport by pumps

Active Transport by Pumps

Molecules can be transported againstan electrochemical concentration gradient.

This requires energy.


Summary of membrane transport

Summary of Membrane Transport

Diffusion

Small, non-polar, uncharged

Facilitated diffusion

Channel Protein

Carrier Protein

Active transport

Requires Energy


Your homework

Your HOMEWORK

This homework is worth 5 points. Once you hand it in, you will be asked to evaluate someone else’s homework – the quality of your evaluation will be worth an additional 2 points. All point-determinations will be made by the teaching team.

Instructions:

- Use a word-processor (12 pt. font) for your responses.

- You MUST upload a copy of your homework to the Angel TurnItInDropbox folder.

- DO NOT INCLUDE YOUR NAME ON THIS ASSIGNMENT.

- When you upload your assignment to the Angel TurnItInDropbox folder it should have no identifying marks.

- When you bring a copy to hand in at class on January 15th (12:40pm), you should identify yourself using ONLY the last four digits of your PID #. If your name is on the assignment it will not be accepted.

The Question:

Compare and contrast simple diffusion, facilitated diffusion, and active transport across a biological lipid bilayer membrane.

- Define each process as applied to a biological lipid bilayer membrane.

- Provide a specific example of each process as applied to a biological lipid bilayer membrane.

- Describe each example (what’s going on? how does it work?).

REMEMBER – It’s OK to discuss ideas with friends, but YOU MUST TURN IN YOUR OWN UNIQUE WORK!!!


For tuesday

For Tuesday:

  • Homework #1 is due

    • Available on the website.

    • Be sure to follow instructions!!

    • TurnItIn + Paper Copy.

  • Register your clicker.

  • StudyNotes #2 is due onThursday. It’s a big one!7.0, 7.1, 7.2, 7.5


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