BiologySylvia S. MaderMichael Windelspecht

Chapter 3 The Chemistry

of Organic Molecules

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

Mills Biology 2012

Mills Biology 2012

Chapter 3Chemistry of Organic Molecules Read Ch 3 in textbook Read Ch appropriate pages in

CliffsAP Use McGraw Hill Site

– http://glencoe.mcgraw-hill.com/sites/0078802849/student_view0/

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Chapter 3Chemical Compounds of Life

Topics1. Organic Molecules2. Carbohydrates 3. Lipids4. Proteins5. Nucleic acids

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3.1 Organic Molecules

Organic vs inorganic Water-an important inorganic

compound Structure and types of organic

compounds

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Organic Molecules Organic vs inorganic

Inorganic substances

Organic substances

Usually no carbon, but exceptions(carbon dioxide, calcium carbonate)

All contain carbonMost contain HMany contain O or N

Usually contain positive and negative ions

All covalently bonded

Usually small and form non living things

Usually large and associated with living things

Examples:WaterOxygenCarbon dioxide

Examples:CarbohydratesLipidsProteinsNucleic acids

6

The Carbon Skeleton and Functional Groups

The carbon chain of an organic molecule is called its skeleton or backbone.

Functional groups are clusters of specific atoms bonded to the carbon skeleton with characteristic structures and functions.

– Determine the chemical reactivity and polarity of organic molecules

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Mills Biology 2012

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Organic Molecules Nature of C allows 4 bonds C can have double, single and triple bonds

Both of the above account for the formation of varied organic molecules and thus accounts for the unity and diversity of living things

Four major groups of organic compounds– Carbohydrates– Lipids– Proteins– Nucleic acids

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Biomolecules

PolymerCategory Subunit(s)

PolysaccharideCarbohydrates* Monosaccharide

Lipids

Proteins*

Nucleic acids*

Glycerol and fatty acids Fat

PolypeptideAmino acids

Nucleotide DNA,RNA

*Polymers© The McGraw Hill Companies, Inc./John Thoeming, photographer 10

Biomolecules Carbohydrates, lipids, proteins, and nucleic acids

are called biomolecules.– Usually consist of many repeating units

• Each repeating unit is called a monomer.• A molecule composed of monomers is called

a polymer (many parts).– Example: amino acids (monomer) are

joined together to form a protein (polymer)

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3.2 Carbohydrates

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Carbohydrates Carbohydrate means

hydrated carbon (add hydrogen and oxygen –water- to carbon)

Major source of energy for our body

Contain C,H,O - usually twice as much H as O (C6H12O6)

Provide building materials Classifications:

– monosaccharide– disaccharide– polysaccharide

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Carbohydrates

Monosaccharides– One sugar– 3-7 C’s– straight chain or ring– glucose(dextrose), fructose, galactose, ribose

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Carbohydrates Disaccharides

– 2 sugars (six C units)– sucrose(table sugar)(glucose + fructose)– lactose(milk sugar)( glucose + galactose)– maltose(malt sugar)(glucose + glucose)

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Carbohydrates Disaccharides (and other organic molecules)

– How are they made and unmade?– Condensation (Dehydration Reaction) synthesis– Hydrolysis

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Carbohydrates Polysaccharides

– Long chains of simple sugars, highly branched– In human body only chains of glucose important

• glycogen - animal starch - stored in skeletal muscle and liver. Can be broken down into glucose when needed for energy

• starch -(amylose) plant starch(grains, potatoes)- we digest and use

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(0.004” = 100 micrometers

1 micrometer = 1 x10-6 meters)

1 micrometer = 100 mm

What are they?

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Unique polysacharides

Cellulose Chitin

Structures similar to

starch, but molecules

oriented a bit differently

Form straight chains bonded together by hydrogen bonds. Humans can’t digest (ruminants can), but

adds bulk.

Contain amino groups. Found in exoskeletons. Also not digestible by

humans.

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What is it?

Cellulose fibers from paper SEM x 1080 David Kunkel

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3.3 Lipids Overview

– Contain C, H, O (less O than carbs)– Called fats and wax when solid, oils when liquid– Made of 1 glycerol and 3 fatty acids, so called

triglycerides– Glycerol backbone same, fatty acids change– Very large molecules– Not water soluble – Used for energy,insulate, protect, part of cell

walls, some hormones– Include fats, oils, waxes, phospholipids and

steroids

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lipids

Wax

Trivia: How fast does the average honeybee fly?

13-15mph

Oils

Fat

How many flowers does the average bee visit in a day?

50-1000

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LipidsFats and Oils

Glycerol portion has OH (hydroxyl groups) – which are polar, so this portion hydrophillic

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Lipids Fats and Oils

What is happening here?

Methyl group (CH3) non polar – so fatty acids are hydrophobic

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What do these have to do with fatty acids?

They have unsaturated triglycerides in their feet, which helps to keep them from freezing.

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Lipidssaturated fats Single covalent bonds between

carbons of fatty acids (carbons saturated with hydrogens-2)

Tend to be solid at room temp– animal fats,butter, meat fat, milk, cheese,

eggs, coconut and palm oil High levels can lead to

atherosclerosis/arteriosclerosis(obstruction of blood vessels) by increasing the cholesterol the body makes

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At high magnification, the dark red thrombus is apparent in the lumen of the coronary artery. The yellow tan plaques of atheroma narrow this coronary artery significantly, and the thrombus occludes it completely

http://www-medlib.med.utah.edu/WebPath/CVHTML/CV018.html

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Lipidsunsaturated fats Fatty acids contain one or more double

covalent bond between carbons of fatty acid (carbons not saturated with hydrogens-<2)

Tend to be liquid at room temp– cooking oils

• olive and peanut oil– monounsaturated

• corn, soy safflower oils– Polyunsaturated – more than one double or triple

bond

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An unsaturated fat can be saturated by adding hydrogen = hydrogenation hydrogenated fats.

Lots of processed foods have these. Taste good, but bad for you!

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Lipids