the subcomponents of biological molecules and their ... · the four classes of life’s organic...

Copyright © Rebecca Rehder Wingerden

Lecture Presentations for

Biology Eighth Edition

Neil Campbell and Jane Reece

Pearson Education, Inc., publishing as Person Benjamin Cummings College Board, AP Biology Curriculum Framework 2012-2013

Interaction within biological systems lead to complex properties. (4.A.1)

Big Idea 4: Interactions

5.1-5.5

The subcomponents of biological molecules and their sequence determine the properties of that molecule. (4.A.1)

Four major biological molecules found in living things.

• Nucleic acids

• Proteins

• Lipids

• Carbohydrates

Copyright © 2012 Rebecca Rehder Wingerden


a.Structure and function of polymers are derived from the way their monomers are assembled.

Dehydration reaction: synthesizing a polymer



Macromolecules are polymers, built from monomers. The macromolecules in three of the four classes of life’s organic compounds - carbohydrates, proteins, and nucleic acids - are chain-like molecules called polymers. A polymer is a long molecules consisting of many similar or identical building blocks linked by covalent bonds. The repeating units that serve as the building blocks of a polymer are smaller molecules called monomers.

Hydrolysis: breaking down a polymer



1. In nucleic acids, biological information is encoded in sequences of nucleotide monomers. • Each nucleotide has

structural components: - a five-carbon sugar

(deoxyribose or ribose) - a phosphate - nitrogen base (adenine,

thymine, guanine, cytosine or uracil).

• DNA and RNA differ in function and differ slightly in structure, and these structural differences account for the differing functions.

Components of nucleic acids. (a) A polynucleotide has a sugar-phosphate backbone with variable appendages, the nitrogenous bases. (b) A nucleotide monomer includes a nitrogenous base, a sugar, and a phosphate group. Without the phosphate group, the structure is called a nucleoside. A nucleoside includes a nitrogenous base and a five-carbon sugar.

Copyright © 2012 Rebecca Rehder Wingerden Copyright © 2012 Rebecca Rehder Wingerden

DNA - RNA - Protein


2. In proteins, the specific order of amino acids in a polypeptide (primary structure) interacts with the environment to determine the overall shape of the protein which also involves secondary, tertiary and quaternary structure and, thus, its function.

Primary Structure

Transthyretin is a protein which transports vitamin A (retinol) and a hormone called thyroxine throughout the body.



• The R group of an amino acid can be categorized by chemical properties: - hydrophobic - hydrophilic - ionic

All amino acids share a common structure. Amino acids are organic molecules possessing both carboxyl and amino groups. The illustration shows the general formula for an amino acid At the center of the amino acid is an asymmetric carbon atom called the alpha carbon. Its four different partners are an amino group, a carboxyl group, a hydrogen atom, and a variable group symbolized by R. The R group, also called the side chain, differs with each amino acid.

• The interactions of these R groups determine structure and function of that region of the protein.



Nonpolar side chains; hydrophobic

Polar side chains; hydrophilic

Acidic (negatively charged)

Basic (positively charged)

Copyright © 2012 Rebecca Rehder WingerdenA single amino acid substitution in a protein causes sickle-cell disease.


3. In general, lipids are nonpolar; however, phospholipids exhibit structural properties, with polar regions that interact with other polar molecules such as water to determine the structure of a biological membranes.

Bilayer structure formed by self-assembly of phospholipids in an aqueous environment. The phospholipid bilayer shown here is the main fabric of biological membranes. Note that the hydrophilic heads of the phospholipids are in contact with water in this structure, whereas the hydrophobic tails are in contact with each other and remote from water.The structure of a phospholipid.



• The structure of the hydrocarbon chains of fatty acids can determine the structure and function of lipids.

In making a fat, three fatty acid molecules each join to glycerol by an ester linkage, a bond between a hydroxyl group and a carboxyl group. The resulting fat, also called a triacylglycerol, consist of three fatty acids linked to one glycerol molecule. Fatty acid vary in length and in the number and location of double bonds. If there are no double bonds between carbon atoms composing the chain, then as many hydrogen atoms as possible are bonded to the carbon skeleton. Such a structure is described as being saturated with hydrogen, so the resulting fatty acid is called saturated fatty acid. An unsaturated fatty acid has one or more double bonds, formed by the removal of hydrogen atoms from the carbon skeleton. The fatty acid will have a kink in its hydrocarbon chain wherever a double bond occurs.

Hard fat (saturated): Fatty acids with single bonds between all carbon pairs.

Oil (unsaturated): Fatty acids that contain double bonds between one or more pairs of carbon atoms



4.Carbohydrates are composed of sugar monomers whose structures and bonding with each other by dehydration synthesis determine the properties and functions of the molecules.



b.Directionality influences structure and function of the polymer.1.Nucleic acids have ends, defined by the 3' and 5' carbons of

the sugar in the nucleotide, that determine the direction in which complementary nucleotides are added during DNA synthesis and the direction in which transcription occurs (from 5' to 3').



2.Proteins have an amino (NH2) end and a carboxyl (COOH) end, and consist of a linear sequence of amino acids connected by the formation of peptide bonds by dehydration synthesis between the amino and carboxyl groups of adjacent monomers.



3.The nature of the bonding between carbohydrate subunits determines their relative orientation in the carbohydrate, which then determines the secondary structure of the carbohydrate.

Glucoses monomers make up the storage polysaccharides of plants (starch) and animals (glycogen). Cellulose is also a polymer of glucose and a major component of plant cell walls. The differing glycosidic linkages in starch and cellulose give the two molecules distinct three-dimensional shapes.



Bozeman Biology: Biological Molecules (15:00 min.) http://www.bozemanscience.com/042-biologoical-molecules


the subcomponents of biological molecules and their ... · the four classes of life’s organic...

Documents