Chemistry of Life:Carbon Compounds

Ch. 2

Biology

Ms. Haut

Carbon Compounds• Organic Compounds

– Contain Carbon– Derived from living

things

• Carbon atom has four outer electrons, which can covalently bond with an electron from another atom

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Properties of Carbon

• A carbon atom forms four covalent bonds– It can join with other carbon atoms to make chains

or rings

ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and Reece, 2007

– The simplest organic compounds are hydrocarbons.

• These are organic molecules containing only carbon and hydrogen atoms.

• The simplest hydrocarbon is methane.

– Larger hydrocarbons• Are the main molecules in the gasoline we burn in

our cars.

– The hydrocarbons of fat molecules provide energy for our bodies.

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ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and Reece, 2007

Macromolecules• Most of the large molecules

in living things are macromolecules called polymers– Polymers are long

chains of smaller molecular units called monomers

– A huge number of different polymers can be made from a small number of monomers

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Building Macromolecules

• Cells link monomers to form polymers by dehydration synthesis

ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and Reece, 2007

Breaking Down Macromolecules

• Polymers are broken down to monomers by the reverse process, hydrolysis

ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and Reece, 2007

Major Groups of Biological Macromolecules

• Carbohydrates

• Lipids

• Nucleic Acids

• Proteins

Carbohydrates

• Compounds made up of carbon, hydrogen, and oxygen

– 1C:2H:1O (C6H12O6)

• Monomer units are monosaccharides (simple sugars)

• Disaccharides are made up of 2 simple sugars

http://www.bio.miami.edu/~cmallery/150/protein/c8.8x13.hydrolysis.sucrose.jpg

Glucose Glucose

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Carbohydrates• Polysaccharides —long chains of simple sugars• Function as storehouse of energy

– Starches —storage form of glucose in plants– Glycogen —storage form of glucose in animals

• Cellulose —tough fibers give plant strength and rigidity (found in wood and paper)

ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and Reece, 2007

Types of Lipids

• Large nonpolar molecules, made mostly of carbon and hydrogen– Fats– Waxes– Phospholipids– Steroids

• Can be used to store energy– Carbon-hydrogen bond store a lot of energy

• Lipids do not mix with water (hydrophobic)

Fats

• They are also called triglycerides– One glycerol molecule linked to three fatty acids

Fatty acidGlycerol

Fats• Saturated fatty acid —

carbons contain the maximum number of hydrogen (animal fats, butter, lard)– Solid at room temp.

• Unsaturated fatty acid—carbons have double bonds; chains get kinked (plant oils, some fish oils)– Liquid at room temp.

Lipids

• Fats store energy efficiently– Have many more hydrocarbon (high

energy) bonds than carbohydrates

• Fats perform essential functions in the human body:

• Energy storage• Cushioning • Insulation

Fats

Phospholipids

• Make up the lipid bilayer of cell membranes

• Makes cell membrane selectively permeable

http://www.uic.edu/classes/bios/bios100/lecturesf04am/phospholipid.jpg

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Lipids

• Waxes—effective hydrophobic coatings (insects, plants, even humans)

• Fatty acid linked to alcohol

Beeswax

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Waxy cuticle

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Steroids• 6 carbon rings; no fatty acid component• Functions

– Found in cell membranes—keeps fluid at temps.– Serve as chemical messengers in the body

(hormones)– Cholesterol-functions in the digestion of fats and

starting material for hormones

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• Nucleic acids are information-rich polymers of nucleotides

• Nucleic acids such and DNA and RNA store and transmit hereditary, or genetic, information.

• They ultimately control the life of a cell

Nucleic Acids

• The monomers of nucleic acids are nucleotides

Phosphategroup

Sugar

• Nucleotides consist of three parts:• a 5-carbon sugar

• a phosphate group

• a nitrogenous base

Nitrogenousbase (A)

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

Nucleic Acids

• There are two kinds of nucleic acids, ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).– RNA contains the sugar

ribose.– DNA contains the sugar

deoxyribose.

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Deoxyribonucleic acid

• DNA consists of two polynucleotides twisted around each other in a double helix

• The sequence of the four kinds of nitrogenous bases in DNA carries genetic information E

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• Stretches of a DNA molecule called genes program the amino acid sequences of proteins– DNA information is transcribed into Ribonucleic

acid (RNA), a single-stranded nucleic acid– RNA is then translated into the primary structure

of proteins

ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and Reece, 2007

• A protein is a polymer constructed from amino acid monomers.

• Proteins perform most of the tasks the body needs to function – cellular structure– movement– defense– transport– communication – Enzymes regulate chemical reactions

Proteins

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

• Proteins are the most structurally and functionally diverse of life’s molecules– Their diversity is based on different

arrangements of amino acids

Proteins are made from just 20 kinds of amino acids

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

• Each amino acid contains:– an amino group– a carboxyl group – an R group, which distinguishes each of the 20

different amino acids

Aminogroup

Carboxyl (acid)group

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

• Each amino acid has specific properties

Leucine (Leu) Serine (Ser) Cysteine (Cys)

HYDROPHOBIC HYDROPHILIC

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

Amino acids can be linked by peptide bonds

• Cells link amino acids together by dehydration synthesis

• The bonds between amino acid monomers are called peptide bonds

• A protein, such as lysozyme, consists of polypeptide chains folded into a unique shape– The shape determines the protein’s function – A protein loses its specific function when its

polypeptides unravel

Overview: A protein’s specific shape determines its function

Figure 3.14A Figure 3.14B

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

Protein Structure

• Primary structure• The specific

sequence of amino acids in a protein

• A slight change in the primary structure of a protein affects its ability to function.

• The substitution of one amino acid for another in hemoglobin causes sickle-cell disease. ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and

Reece, 2007

Amino acid

Hydrogen bond

Alpha helix

Pleated sheet

Primarystructure

Secondarystructure

• Secondary structure is polypeptide coiling or folding produced by hydrogen bonding

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

Protein Structure

Polypeptide(single subunitof transthyretin)

Transthyretin, with fouridentical polypeptide subunits

Tertiarystructure

Quaternarystructure

• Tertiary structure is the overall shape of a polypeptide

• Quaternary structure is the relationship among multiple polypeptides of a protein

Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

What Determines Protein Structure?

•A protein’s shape is sensitive to the surrounding environment.– Unfavorable

temperature and pH changes can cause a protein to unravel and lose its shape.

– This is called denaturation.

http://www.yellowtang.org/images/protein_denaturatio_c_la_784.jpg

Acknowledgements

• Unless otherwise noted, illustrations are credited to Prentice Hall and have been borrowed from Biology by Miller and Levine, © 2007. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without express written permission from the publisher.

• ESSENTIALS IN BIOLOGY WITH PHYSIOLOGY 2nd edition, by Campbell and Reece, 2007. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without express written permission from the publisher.

• BIOLOGY: CONCEPTS AND CONNECTIONS 4th Edition, by Campbell, Reece, Mitchell, and Taylor, ©2003. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without express written permission from the publisher.

• BIOLOGY: CONCEPTS AND CONNECTIONS 4th Edition, by Campbell, Reece, Mitchell, and Taylor, ©2001. These images have been produced from the originals by permission of the publisher. These illustrations may not be reproduced in any format for any purpose without express written permission from the publisher.