• Molecules are the building blocks of life
• Four major types of biological macromolecules
• carbohydrates
• lipids
• proteins
• nucleic acids

• Molecules
• consist of 2 or more atoms bound together
• are small in comparison to what we see with our eyes
• some are "small"
• others are "gigantic"
• consisting of thousands of atoms
• organized into hundreds of smaller molecules linked together into long chains
• are almost always synthesized by living things

Molecules - life’s building blocks

• The carbon atom plays a central role in organic molecules
• forms 4 covalent bonds
• single, double, or triple w/ carbon atoms
• forms variety of molecular shapes
• combines with hydrogen to form hydrocarbons
• bonds with H, N, O, S
• forms isomers

• Chemistry of carbon
• forms 4 covalent bonds
• carbon’s outer electron shell, or valence shell, can hold 8 electrons
• an individual carbon atom contains only 4 electrons in its outer shell
• therefore, carbon can form up to 4 covalent bonds

• Chemistry of carbon
• can form single, double, or triple covalent bonds with other carbon atoms
• carbon can form single, double or triple bonds with itself
• therefore, can readily form chains of carbon atoms
• and molecules with complicated branching

• Chemistry of carbon
• forms variety of molecular shapes
• carbon chains, can be
• straight
• branched
• closed into rings
• can form greater variety of molecules than any other element

• Chemistry of carbon
• combines w/ H, forms hydrocarbons
• organic molecules consisting of C & H
• C - H covalent bonds store lot of energy
• make good fuels (fossil fuels), formed
• from organic compounds originating in organisms that lived and died millions of years ago
• when O is stripped from organic molecules under anoxic (no O) conditions

• Chemistry of carbon
• most biologically important molecules are not hydrocarbons
• carbon forms bonds with H, N, O, S
• to form many other biologically significant molecules
• such as sulfuric acid
• to form biologically important functional groups

The construction of biologically important organic molecules

• Most biologically important organic molecules are not hydrocarbons
• in general, any organic molecule can be thought of as a carbon-based core to which specific groups of atoms with specific chemical properties are attached
• carbon skeleton or core
• functional groups
• groups of atoms attached to C core of organic molecule, with definite chemical properties

The construction of biologically important organic molecules

• carbon skeleton or core
• to which specific groups of atoms with definite chemical properties are attached
• represented by R =, the"remainder" of the molecule of which the functional groups are a part
• functional groups

• functional groups (groups of atoms w/specific chemical properties attached to the C core)
• retain their chemical properties no matter where they occur
• most compounds present in cells contain two or more different functional groups
• ex., every amino acid contains at least two functional groups
• an amino group
• a carboxyl group

• functional groups
• there are several biologically important functional groups
• hydroxyl (R-OH)
• carbonyl (R-[C=O]-H, or (R-[C=O]-R)
• carboxyl (R-[C=O]-OH, R-COOH)
• amino (R-NH₂)
• phosphate (R-O-P[=O]-OH]-OH)
• sulfhydryl (R-SH)
• methyl (R-CH₃)

Making & Breaking Macromolecules

• Biological macromolecules (polymers) are made up of repeating subunits
• although the four categories of biological macromolecules contain different subunits
• the categories of macromolecules are
• assembled in the same way
• dehydration synthesis
• disassembled in the same way
• hydrolysis

Making & Breaking Macromolecules

• dehydration synthesis
• macromolecule is assembled by removing an –OH group from one subunit and an H from other subunit
• this, in effect, constitutes the removal of a molecule of water (H₂O) for every subunit that is added to a macromolecule
• also called water-losing reaction
• energy is required to break the chemical bonds when water is extracted
• cells must supply energy to assemble macromolecules

Making & Breaking Macromolecules

• dehydration synthesis
• anabolic reactions
• reactions in which macromolecules are built from smaller subunits, requires
• energy
• catalysis
• process of positioning (the reacting substances must be held close together)
• process of stressing bonds (the correct chemical bonds be stressed and broken)
• these processes carried out by a special class of proteins known as enzymes

Making & Breaking Macromolecules

• Cells also disassemble macromolecules into their constituent subunits by performing
• catabolic reactions
• reactions in which macromolecules are synthesized by disassembling other macromolecules into their constituent parts
• energy released
• are essentially the reverse of dehydration synthesis, called
• hydrolysis (digestion)

Making & Breaking Macromolecules

• hydrolysis (digestion)
• macromolecules created by disassembling other macromolecules into their constituent parts by adding an –OH group to form one subunit and an H to form the other subunit
• this, in effect, constitutes the addition a molecule of water (H₂O) for every macromolecule that is disassembled
• energy is released when the energy storing bonds are broken

• carbohydrates
• monosaccharides
• lipids
• glycerol
• fatty acids
• proteins
• amino acids
• nucleic acids (DNA, RNA)
• nucleotide

• carbohydrates
• loosely defined group of molecules that contain C, H, and O in molecular ratio of 1:2:1, with empirical formula of (CH₂O)_n
• functions
• energy storage molecules
• due to large number of C-H & C-C bonds, which release energy when broken
• structural elements

• Carbohydrates
• are named based on the number of sugar units they contain
• monosaccharides
• one sugar unit (mono-)
• disaccharides
• two sugar units (di-)
• polysaccharides
• many sugar units (poly-)

• carbohydrates
• monosaccharides
• function
• play central role in energy storage
• glucose most important, has 6 Cs, w/7 energy storing C-H bonds
• examples
• glucose
• fructose
• glyceraldehyde phosphate

• Carbohydrates
• disaccharides
• structure
• two monosaccharides joined by a covalent bond
• function
• play a role in the transport of sugars
• examples
• sucrose
• lactose

• carbohydrates
• polysaccharides
• structure
• many monosaccharides put together
• repeating units of simple sugars, usually glucose
• precise number of sugar units varies
• typically, thousands of sugar units are present in a single molecule
• chains can be single or branched

• carbohydrates
• polysaccharides
• functions
• storage of energy
• starch = formed in plants, consists of glucose units
• glycogen = formed in animals, consists of glucose units

• carbohydrates
• polysaccharides
• functions
• structural
• cellulose = formed in plants, consists of glucose units, component of plant cell walls
• chitin = formed in insects, fungi and certain other organisms, consists of glucosamine units (contains N)

• Lipids
• loosely defined group of molecules sharing one main characteristic; insoluble in water
• main type
• fats (triglycerides or triacylglycerols)
• other types
• phospholipids
• terpenes
• steroids
• oils
• waxes

• lipids
• fats (triglycerides or triacylglycerols)
• structure = glycerol + 3 fatty acids
• glycerol = a 3-carbon alcohol with each carbon bearing a hydroxyl group
• fatty acids = long hydrocarbon chains ending in a carboxyl group
• the three fatty acids of a triacylglycerol are not necessarily the same

• Lipids
• fats (triglycerides or triacylglycerols)
• functions
• energy storage
• efficient energy storage molecules because of their high concentrations of C-H bonds
• insulation
• cushioning

• Lipids
• saturated and unsaturated fats
• based on absence/ presence of double bonds between carbon atoms and number of hydrogen atoms

• Lipids
• saturated fats
• all internal C atoms are bound to at least two H atoms, no double bonds between C atoms
• results in maximum number of H atoms
• therefore, said to be saturated w/H
• tend to be straight and fit close together
• most are solid at room temperature
• such as butter

• Lipids
• unsaturated fats
• double bonds between at least one pair of C atoms
• results in less than maximum number of hydrogen atoms
• because the double bonds replace some of hydrogen atoms
• therefore, said to be unsaturated
• most are liquid at room temp. (ex., oil)

• Lipids
• unsaturated fats
• polyunsaturated fats
• double bonds between 2+ pairs of C atoms
• have low melting points because the fatty acids chains can’t closely align
• double bonds cause kinks
• most are liquid at room temperature
• such as corn oil

• lipids
• fats (triglycerides or triacylglycerols)
• other types and their function
• phospholipids
• modified fats with two fatty acid chains rather than three
• one of the fatty acid chains is replaced by a phosphate group
• has hydrophillic head, hydrophobic tail
• structure of cell membranes = phospholipid bilayer

• lipids
• fats (triglycerides or triacylglycerols)
• other types and their function
• terpenes
• long chain lipids which are components of many biologically important pigments
• chlorophyll and other plant pigments
• vitamin A (retinol)
• retinal – visual pigment of eyes of mollusks, insects, and vertebrates
• rubber and other plant products

• lipids
• fats (triglycerides or triacylglycerols)
• other types and their function
• prostaglandins = modified fatty acids w/ 2 nonpolar tails attached to 5 C ring
• local chemical messengers in animal tissues
• waxes
• waterproof coating on leaves, bird feathers, mammalian skin, arthropod exoskeleton

• lipids
• fats (triglycerides or triacylglycerols)
• other types and their function
• steroids = lipids composed of 4 carbon rings
• hormones
• regulatory
• cholesterol
• found in eukaryotic cell membrane
• bile salts (emulsify fats)

• proteins
• perform many functions, are all polymers of only 20 amino acids
• structure
• amino acids joined by peptide bonds
• levels of structure
• functions
• types of

• proteins
• structure
• made up of various combinations of 20 types of repeating subunits called amino acids
• are joined together by peptide bonds
• are organic molecules
• consist of
• two characteristic end groups
• a side group (or side chain)

• structure of amino acids
• two end groups
• an amino group (-NH₂)
• a carboxyl group (-COOH)
• a side group
• bonded to the C atom between the two end groups
• varies from one amino acid to another
• determines the unique chemical properties of the amino acid

• Examples of amino acid side groups
• leucine
• serine
• cysteine

• proteins
• structure
• amino acids
• grouped into 5 chemical classes based on their side groups
• nonpolar
• polar
• ionizable
• aromatic (rings)
• special function

• proteins
• structure
• peptide bonds join amino acids together
• covalent
• forms by dehydration reaction btwn amino and carboxyl groups on a pair of amino acids
• has partial double bond characteristic
• is stiff
• amino acids are not free to rotate around the C-N linkage
• makes it possible for chains of amino acids to form coils and other regular shapes

• proteins
• levels of structure
• primary
• secondary
• motifs
• tertiary
• domains
• quaternary

• proteins
• levels of structure
• primary
• result from the specific amino acid sequence
• one dimensional

• proteins
• levels of structure
• secondary
• results from hydrogen bonding between individual amino acids
• two dimensional
• two patterns of hydrogen bonding
• b pleated sheets
• a helix

• proteins
• levels of structure
• tertiary
• final folded shape of protein resulting from hydrophobic interactions with water, globular (three dimensional)
• domains
• when different sections of a protein fold into a structurally independent globular protein like knots on a rope

• proteins
• levels of structure
• quaternary
• when two or more polypeptide chains associate to form a functional protein

• proteins
• levels of structure
• how proteins fold and unfold
• denaturation
• process by which a protein changes its shape (secondary & + structure) or even unfolds when its "tolerance range" for some factor is exceeded
• results from breaking hydrogen bonds, disrupting polar - nonpolar interactions

• proteins
• levels of structure
• how proteins fold and unfold
• denaturation can be caused by
• heats
• acids
• bases
• salts

• proteins
• functions
• regulation
• structural
• contractile
• transport
• energy storage
• defense
• osmotic regulation

• proteins
• functions
• regulation
• enzymes catalysts in metabolic pathways
• hormones
• in gene expression

• proteins
• functions
• structural
• cell membranes
• cell cytoskeleton components
• collagen
• elastin
• keratin

• proteins
• functions
• contractile
• muscle fibers
• transport
• hemoglobin
• myoglobin

• proteins
• functions
• energy storage
• egg albumin
• plant seeds
• defense
• antibodies
• osmotic regulation
• globulins

• nucleic acids
• are the information storage devices of cells
• long polymers of repeating subunits called nucleotides
• two types
• DNA
• deoxyribonucleic acid
• RNA
• ribonucleic acid

• nucleic acids
• nucleotides
• consist of three components
• a five-carbon sugar
• ribose in RNA
• deoxyribose in DNA
• a phosphate group
• a nitrogenous base

• nucleic acids
• nucleotides
• two types of organic nitrogen-containing bases occur in nucleotides
• purines
• pyrimidines

• nucleic acids
• nucleotides
• two types of organic bases
• purines = large, double-ringed molecules
• adenine (A) - found in RNA and DNA
• guanine (G) - found in RNA and DNA

• nucleic acids
• nucleotides
• two types of organic bases
• pyrimidines = smaller, single-ringed molecules
• cytosine (C) – found in RNA and DNA
• thymine (T) – found in DNA only
• uracil (U) – found in RNA only

• nucleic acids
• nucleotides
• nucleotides are linked together with phosphodiester bonds
• result when the phosphate group of one nucleotide binds to the hydroxyl group of another nucleotide, releasing water

• nucleic acids
• types of and functions
• DNA
• RNA
• ATP and other high energy molecules

• nucleic acids
• types of and functions
• DNA
• forms genetic blueprint in genes or chromosomes
• organisms encode the information specifying the amino acid sequences of their proteins as sequences of nucleotides

• nucleic acids
• types of and functions
• RNA
• interprets genetic blueprint through protein synthesis
• transcribing the DNA message into a chemically different molecule such as RNA allows the cell to tell which is the original information storage molecule and which is the transcript

• nucleic acids
• types of and functions
• RNA
• 3 types
• mRNA = messenger RNA
• tRNA = transfer RNA
• rRNA = ribosomal RNA

• nucleic acids
• types of and functions
• ATP and other high energy molecules)
• nucleotides play critical roles in molecules which serve as the energy currency of the cell
• ATP = adenosine triphosphate
• NAD⁺ = nicotinamide adenine dinucleotide
• FAD⁺ = flavin adenine dinucleotide

• nucleic acids
• which came first – DNA or RNA
• by storing the information in DNA while using a complimentary RNA sequence to actually direct protein synthesis, the cell does not expose the information-encoding DNA chain to the dangers of single-strand cleavage every time the information is used
• DNA is thought to have evolved from RNA as a means of preserving the genetic information and protecting it from the ongoing wear and tear associated with cellular activity