Biomolecules

H C Structural formula Ball-and-stick model Space-filling model Models of Methane

The Molecular Logic of Life Small molecules, common to all organisms, are arranged into unique macromolecules (Campbell p. 62)

Macromolecules Many complex biological activities require large macromolecules Macromolecules are polymers poly: “many” mer: “units” ex: proteins, nucleic acids, starches

Polymers are built by covalently linking together small similar (or in some cases, identical) subunits/building blocks called monomers mono: “one” mer: “unit” ex: amino acids, nucleotides, monosaccharides

4 Classes of Organic Compounds “Biomolecules” Proteins are polymers of amino acids Nucleic acids are polymers of nucleotides Starches are polymers of simple sugars called monosaccharides Lipids aren’t REALLY polymers, since they don’t have repeating chains. BUT they are important biomolecules. The building blocks (monomers) of some types of lipids are glycerol and fatty acids

Macromolecules- why are they so important? Each macromolecule performs complex tasks with precision The basic structure and function of each class of macromolecules is similar in all organisms (from the simplest bacteria to complex humans)– indicates an evolutionary link.

Basic Function Carbo’s Lipids N. Acids Proteins Energy Storage Structure Strength Long term storage Insulation Protection Hormones Inheritance Blueprint for metabolism Catalysts Defense Sugars (glucose) Starch/ Glycogen Cellulose/ Chitin Fats Oils/Waxes Phospholipids Steroid hormones DNA RNA ATP Enzymes

Carbohydrates Sugars Monomer =(CH2O)n Monosaccharides:Glucose Oligosaccharides: Sucrose Polysaccharides: Cellulose Energy storage and structure

Sugars Monosaccharides Five carbon: Ribose Six carbon: glucose and fructose Disaccharides Sucrose Lactose Polysaccharides Starch Glycogen Chitin Cellulose

glucose fructose + H2O sucrose

Cellulose chains Starch chain

cellulose glycogen amylose (a starch)

Two Types for Storage Glycogen – animal energy storage animal energy storage product that accumulates in the liver/muscles Highly branched 2. Starch – plant energy storage Helical Easily digested by animals through hydrolysis

Lipids Functions: Long-term energy storage/insulation (fats) Structural components of cells (phospholipids) Cellular messengers (hormones)

Lipids Fats and oils Monomer = CH2 Fats 1,2 or 3 fatty acids attached to glycerol Sterols- Cholesterol, Steroids Waxes- Beeswax Used for waterproofing, insulation and cell membranes

Figure 2.21c Page 29

FATS Fatty acids are composed of CH2 units and are hydrophobic Triglycerides are composed of three fatty acids covalently bonded to one glycerol molecule Fatty acids are composed of CH2 units and are hydrophobic Fatty acids can be saturated (all single bonds) or unsaturated (one or more double bonds) A fat (mostly saturated) is solid at room temp., while an oil (mostly unsaturated) is liquid at room temp.

hydrophilic head hydrophobic tails

stearic acid oleic acid linolenic acid

hydrophilic head two hydrophobic tails one layer of lipids cell membrane section

Cholesterol Sterol backbone

Proteins 50% dry weight of body Mammal cell contains 10,000 proteins Enzymes (regulate chemical reactions) Structural elements (cell membrane, muscles, ligaments, hair, fingernails) Carriers (regulate what goes into/out of cells) Send and receive messages (hormones) Movement

Proteins Monomer= Amino Acid Enzymes- Catalyze metabolic reactions Transport proteins- move things across membranes Structural proteins-keep the structure of cells

(20 kinds with distinct properties) Amino group (basic) Carboxyl group (acidic) R group (20 kinds with distinct properties)

Protein Assembly AA’s are linked together by joining the amino end of one molecule to the carboxyl end of another Peptide bond forms a chain called a polypeptide http://www.biotopics.co.uk/as/aminocon.html

Protein Structure Primary structure Specific linear sequence of AA’s in a polypeptide Determined from code in inherited genetic material Changes in primary structure can alter proper functioning of the protein

Linear primary structure one peptide group Linear primary structure

Secondary structure the tendency of the polypeptide to coil or pleat due to H-bonding between R- groups -helix, -pleated sheet, or random coil

Tertiary structure Secondary structure

Secondary structure Tertiary structure

Tertiary structure shape of entire chain; folded, twisted, or globular shape related to function and properties

Quaternary structure more than one polypeptide chain

heme group helically coiled globin molecule alpha chain beta chain

Nucleic Acids Polymers composed of monomer units known as nucleotides Information storage DNA (deoxyribonucleic acid) Protein synthesis RNA (ribonucleic acid) Energy transfers ATP (adenosine tri-phosphate) and NAD (nicotinamide adenine dinucleotide)

Nucleic Acids Monomer: Nucleotide ATP is a Nucleotide Molecules of inheritance: hold the code for how to make proteins Deoxyribose Nucleic Acid- DNA Ribose Nucleic Acid- RNA

Ball-and-stick model of ATP nitrogen- containing base Ball-and-stick model of ATP sugar 3 phosphate groups

Functions of Nucleic Acids DNA – Physical carrier of genetic information Restricted to nucleus RNA – key component of protein synthesis Messenger RNA (mRNA) – blueprint for construction of a protein Ribosomal RNA (rRNA) – construction site where the protein is made Transfer RNA (tRNA) – truck delivering the proper AA to the site of construction

Adenine (a base) Thymine phosphate group sugar (deoxyribose) Guanine Cytosine

Single strand of DNA or RNA base phosphate connected by covalent bond sugar

covalent bonding in carbon backbone hydrogen bonding between bases