2.3 Carbohydrates and Lipids

GuidanceThe structure of starch should include amylose and amylopectin.Named examples of fatty acids are not required.Sucrose, lactose, and maltose should be included as examples of disaccharides produced by combining monosaccharides.

Understandings• Monosaccharide monomers are linked

together by condensation reactions to form disaccharide and polysaccharide polymers

• Fatty acids can be saturated, monounsaturated, or polyunsaturated.

• Unsaturated fatty acids can be cis or trans isomers.

• Triglycerides are formed by condensation reactions from three fatty acids and one glycerol.

Applications/Skills• A: Structure and function of cellulose and

starch in plants and glycogen in humans.• A: Scientific evidence for health risks of trans

fats and saturated fatty acids.• A: Lipids are more suitable for long-term

energy storage in humans than carbohydrates.• A: Evaluation of evidence and the methods

used to obtain the evidence for health claims made about lipids.

• S: Use of molecular visualization software to compare cellulose, starch, and glycogen.

• S: Determination of body mass index by calculation or use of a nomogram.

Carbohydrates

Monosaccharide: one sugar unit

Examples: glucose (C6H12O6)deoxyriboseriboseFructoseGalactose

https://cdavies.wordpress.com/2009/01/27/simple-sugars-fructose-glucose-and-sucrose/

Carbohydrates

Disaccharide: two sugar unitExamples: • Sucrose (glucose+fructose)• Lactose (glucose+galactose)• Maltose (glucose+glucose)

http://www.cheesescience.com/wp-content/uploads/2011/09/glulac.jpg

Polysaccharides

Polysaccharide

Function

Cellulose Provide rigidity and support in plants

Starch Product of photosynthesis; stored as granules in roots/root structures

Glycogen Stored excess glucose in liver and muscle tissue

http://bio.classes.ucsc.edu/bio20L/glossary/struc/starch.gif

All composed of the same monomer (glucose)

1,4 linkages

GlycogenAn insoluble storage molecule in the liver. When blood glucose is high, the pancreas releases insulin, telling the liver to capture blood glucose and combine molecules of glucose to make the polysaccharide glycogen, through condensation reactions.

This stores energy for later.

When blood glucose drops, the hormone glucagon causes the glycogen to be broken down (hydrolysis reactions) to glucose and then released back into the blood.

Liver from: http://en.wikipedia.org/wiki/File:Leber_Schaf.jpg

Fatty Acids

There are two kinds of fatty acids you may see these on food labels:1. Saturated fatty acids: no double bonds (bad)2. Unsaturated fatty acids: double bonds (good)

http://foodscienceacademy.org/wp-content/uploads/2013/06/fat_f2.jpg

Unsaturated Fatty Acids• Monounsaturated

• Only one double bond present

• Animal fats• Usually solid at room temp• Bent shape

• Polyunsaturated• Two or more double bonds

present• Usually from plants• Usually liquid at room temp• Curved shape

Adapted from http://e004777c130eade00234-5ddb36df15af65ab8482e83373c53fe5.r41.cf1.rackcdn.com/images/30.jpg

Cis vs trans fatty acidsTrans Fatty Acids Cis Fatty Acids- Processed foods

- Hydrogenated

- Straightened out

- Ex: hydrogenated oils

- More curved

- Generally considered healthier

- Ex: omega-3

http://www.nutrientsreview.com/wp-content/uploads/2014/12/Trans-cis-fatty-acid.jpg

Triglycerides

Formed by condensation reaction between three fatty acids and a glycerol

http://erichamber.ca/departments/science/dfung/pages/biology/biologic/fatty_acid_glycerol.gif

Lipids for Energy Storage

• Lipids can be hydrolyzed into 2 carbon segments for cell respiration• Twice the energy per gram compared to glucose• Not soluble in water, so won’t disrupt osmotic balance in

cells• Carbohydrates are soluble in water, so water would enter the cell,

causing it to swell.

BMI

• Formula 1 (metric):weight in kg/(height in m)(height in m)

• Formula 2 (imperial): [weight in lb/(height in in)(height in in)] X 703

http://www.vertex42.com/ExcelTemplates/Images/body-mass-index-chart.gif

Homework

Vocab• Triose• Pentose• Hexose• Saturated fatty acid• Monounsaturated fatty acid• Polyunsaturated fatty acid• Omega-3 fatty acid• Triglyceride• Glycogen • BMI

Other• Challenge yourself 3-6• Exercises 6-8• Nature of science (choose

one)