Lipids

https://chelseaharripersad.wordpress.com/tag/lipids/

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• Made up of C, H, and a little bit of O

• This group has fats and oils (including phospholipids), and steroids

• They are not water soluble

*STOP AND THINK: Write down your answers for the following

• What does that mean?*

• How might that be useful for something like a cell membrane?*

Lipids – Macromolecule #1

Fats & Oils

• Structure: – Glycerol + fatty acids

– Fatty acids are chains of carbon atoms bonded to hydrogen atoms • Saturated vs. Unsaturated

• Function: – Store large amounts of chemical energy

– Main component in cell membranes

• E.g. Triglycerides (i.e. Olive Oil, Beef Fat)

Fats & Oils: Structure

• Many lipids contain 3 fatty acids bonded to the glycerol – Called triglycerides

• These fatty acids are bonded to the glycerol via dehydration synthesis – (*Animation*)

http://www.spaceflight.esa.int/impress/text/education/Images/Glossary/GlossaryImage%20052.png

Fatty Acids

• Fatty acids have long hydrocarbon chains

http://burnanenergyjournal.com/tag/hydrocarbons/

Twig:

Hydrocarbons

Hydrocarbons

• There is a shorthand for drawing this part of the fatty acid chains

– To simplify a hydrocarbon, we draw a kinked line

– Each bend or end of a line is a carbon atom

Practice Shorthand for Hydrocarbons

• Try drawing the two molecules below:

Chemical Name Ethanol Heptane

Chemical Formula

Ball & Stick Model

Abbreviated (Shorthand)

Model OH

C2H5OH C7H16

Example Triglyceride Sketch

Saturated vs. Unsaturated

• A lipid’s function can be affected by the saturation of the fatty acids

– Saturated: it is “saturated” with hydrogen atoms (maximum number of hydrogen, every spot filled).

– Unsaturated: at least one double bond between carbon atoms thus the chain has fewer hydrogen.

Saturated vs. Unsaturated

• Saturated fats are solid at room temperature and unsaturated fats are liquid. – Saturated fats are found in

animals • E.g. butter and meat.

– Unsaturated fats are found in plants • E.g. olive or peanut oils.

• Based on their structure (right) can

you guess why saturated fats are solid and unsaturated are liquid at room temp? Share with a neighbor.

http://yourbestyou90.com/wp-content/uploads/2011/07/saturated_unsaturat_c_la_784.jpg

“Butter Manatee and Diver” sculpted by Jim Victor, Palmetto, FL

Manatee County Fair, Jan. 2012

http://www.jimvictor.com/AssetsFood/foodsculpture.html

Natural peanut butter can separate into both types!

Saturated vs. Unsaturated

• Saturated and unsaturated fats have different properties because of how the molecules pack together.

• Which molecule do you think would pack together more closely?

Saturated vs. Unsaturated

• Unsaturated fatty acids have lower melting points than saturated fatty acids.

• What does it mean to melt on a molecular level? What would that look like?

• If molecules are stacked closer to each other do you think the substance would melt faster or slower?

http://www.elmhurst.edu/~chm/vchembook/551fattyacids.html

OH

O

O

OH

OH

O

OH

O

stearic acid m.p. 70ºC

oleic acid m.p. 16ºC

linoleic acid m.p. -5ºC

linolenic acid m.p. -11ºC

1. How would the bottom 3 fatty acids look different from stearic acid?

2. Of the 4, which one would be able to pack together the most?

3. THUS, which melting point would be highest??? •Share your thoughts with your neighbor! Don’t forget to give them time to think it out on their own.

stearic acid

oleic acid

linoleic acid

linolenic acid

Melting Point Wrap-Up

• THINK, PAIR, SHARE: What statement can you make about the relationship between the number of double bonds in fatty acid chains and its melting point?

– What evidence could you gather to support your claim?

OH

O

O

OH

OH

O

OH

O

stearic acid - m.p. 70ºC

oleic acid - m.p. 16ºC

linoleic acid - m.p. -5ºC

linolenic acid - m.p. -11ºC

Saturated vs. Unsaturated Fatty Acids in Fats and Oils

THINK, PAIR, SHARE:

• If you want the most unsaturated fatty acids in your diet, which is the most healthy oil you should use the most?

• Which fat or oil contains the most saturated fatty acids?

http://www.elmhurst.edu/~chm/vchembook/551fattyacids.html

Phospholipid • Cell membranes are made up of a lipid

similar to triglycerides; a phospholipid

• Structure: Glycerol backbone attached to a phosphate group “head” and 2 fatty acid “tails” – The tails can be saturated or unsaturated – (*Animation*) About 80% of the way down…

• Function: Provide a selective barrier between the inside and outside of the cell and cellular compartments.

http://media1.shmoop.com/images/module_images/PhospholipidFlashcard_640x480.jpg

Phospholipid

http://myhome.sunyocc.edu/~weiskirl/cell_membrane2.gif

How we will picture a Phospholipid

Steroids

• Structure:

– 4 interconnected rings

• Function:

– Aids in fluidity/flexibility of cell membrane (cholesterol)

– Hormones that act as signaling molecules (i.e. testosterone and estrogen)

http://2012books.lardbucket.org/books/principles-of -general-chemistry-v1.0/s28-06-the-molecules-of-life.html http://www.people.vcu.edu/~urdesai/intro.1.gif

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OH

O

testosterone

O

O

progesterone

O

OHO

O OH

cortisone

HO

O

androsterone

HO

O

estrone

O

OHO

HO OH

cortisol

Hormones = Signaling Molecules Androgens (male sex hormones) •Produced in the testes •Responsible for development of male sex characteristics

Estrogens (female sex hormones) •Produced in the ovaries •Responsible for development of female sex characteristics

Cortisone Hormones •Produced in the adrenal cortex •Regulate metabolism of carbohydrates, decrease inflammation, involved in reaction to stress

Let’s Fill in Your Macromolecule Table for Lipids!

Macromolecule Lipids

Types of Atoms

Monomers made of

Function(s)

Examples

Sketch