Macromolecules Chapter 5

Macromolecules Large complex molecules Carbohydrates, proteins, lipids & nucleic acids

Macromolecules Polymer Large molecule Carboydrates, proteins, nucleic acids Monomers Smaller repeating units Build polymers

Macromolecules Monomers are connected by a dehydration reaction Condensation reaction

Fig. 5-2a Dehydration removes a water molecule, forming a new bond Short polymerUnlinked monomer Longer polymer Dehydration reaction in the synthesis of a polymer HO H2OH2O H H H (a)

Macromolecules Polymers are broken apart into monomers by hydrolysis Bonds are broken by adding water

Fig. 5-2b Hydrolysis adds a water molecule, breaking a bond Hydrolysis of a polymer HO H2OH2O H H H (b)

Carbohydrates Simple sugars to complex polymers Stored energy Structure

Carbohydrates Monosaccharides Single sugar –Glucose, fructose, galactose Molecules contain carbon, hydrogen & oxygen in a 1:2:1 ratio CH 2 O End in –ose Aldose: aldehyde sugar Ketose: ketone sugar

Fig. 5-3a Aldoses Glyceraldehyde Ribose GlucoseGalactose Hexoses (C 6 H 12 O 6 ) Pentoses (C 5 H 10 O 5 )Trioses (C 3 H 6 O 3 )

Fig. 5-3b Ketoses Dihydroxyacetone Ribulose Fructose Hexoses (C 6 H 12 O 6 ) Pentoses (C 5 H 10 O 5 )Trioses (C 3 H 6 O 3 )

Carbohydrates Dissaccharides Two monosaccharides combined Glycoside linkage: Covalent bond between two sugars Sucrose (glucose & fructose) Maltose (glucose & glucose) Lactose (glucose & galactose)

Fig. 5-5 (b) Dehydration reaction in the synthesis of sucrose GlucoseFructose Sucrose MaltoseGlucose (a) Dehydration reaction in the synthesis of maltose 1–4 glycosidic linkage 1–2 glycosidic linkage

Carbohydrates Polysaccharides Many monosaccharides combined Starch (plant), glycogen (animal), cellulose (plant), chitin

Fig. 5-7 (a)  and  glucose ring structures  Glucose  Glucose (b) Starch: 1–4 linkage of  glucose monomers(b) Cellulose: 1–4 linkage of  glucose monomers

Fig The structure of the chitin monomer. (a) (b) (c) Chitin forms the exoskeleton of arthropods. Chitin is used to make a strong and flexible surgical thread.

Lipids Insoluble in water –Hydrophobic Store energy Make membranes

Lipids Fats –Unsaturated –Saturated Phospholipids –Glycerol, phosphate, fatty acid Steroids

Fats Glycerol and fatty acids Triglyceride 3 fatty acids attached to a glycerol

Fatty acid (palmitic acid) (a) Dehydration reaction in the synthesis of a fat Glycerol

Fig. 5-11b (b) Fat molecule (triacylglycerol) Ester linkage

Fig Structural formula of a saturated fat molecule Stearic acid, a saturated fatty acid (a) Saturated fat Structural formula of an unsaturated fat molecule Oleic acid, an unsaturated fatty acid (b) Unsaturated fat cis double bond causes bending

Phospholipids Cell membrane Tails are hydrophobic Hydrophilic head

Fig Hydrophilic head Hydrophobic tail WATER

Steroids

Proteins Amino acids Building blocks of proteins 20 different amino acids Peptide bond Polypeptide

Peptide bond Fig Amino end (N-terminus) Peptide bond Side chains Backbone Carboxyl end (C-terminus) (a) (b)

Fig Nonpolar Glycine (Gly or G) Alanine (Ala or A) Valine (Val or V) Leucine (Leu or L) Isoleucine (Ile or I) Methionine (Met or M) Phenylalanine (Phe or F) Trypotphan (Trp or W) Proline (Pro or P) Polar Serine (Ser or S) Threonine (Thr or T) Cysteine (Cys or C) Tyrosine (Tyr or Y) Asparagine (Asn or N) Glutamine (Gln or Q) Electrically charged AcidicBasic Aspartic acid (Asp or D) Glutamic acid (Glu or E) Lysine (Lys or K) Arginine (Arg or R) Histidine (His or H)

Protein Function Enzyme catalysis Defense Transport Support Motion Regulation Storage

Protein structure Primary Secondary Tertiary Quaternary

Primary Structure Sequence of amino acids

Secondary Structure Hydrogen bonds between amino acids Pleats or helix

Tertiary structure Attraction between side chains Hydrophobic interaction Disulfide bridges Ionic bonds Hydrogen bonds

Quaternary structure Two or more polypeptide chains aggregate

Sickle cell anemia

Fig Primary structure Secondary and tertiary structures Quaternary structure Normal hemoglobin (top view) Primary structure Secondary and tertiary structures Quaternary structure Function  subunit Molecules do not associate with one another; each carries oxygen. Red blood cell shape Normal red blood cells are full of individual hemoglobin moledules, each carrying oxygen. 10 µm Normal hemoglobin     Val His Leu ThrPro Glu Red blood cell shape  subunit Exposed hydrophobic region Sickle-cell hemoglobin   Molecules interact with one another and crystallize into a fiber; capacity to carry oxygen is greatly reduced.   Fibers of abnormal hemoglobin deform red blood cell into sickle shape. 10 µm Sickle-cell hemoglobin GluPro Thr Leu His Val

Structure Denaturation: Alter, unravel shape of protein Temperature, pH, salt Chaperonins: Proteins that help with structure

Nucleic Acids DNA and RNA Transfer & store genetic information Nucleotides are the subunits Nitrogenous base 5 carbon sugar Phosphate group

Nucleic Acids Pyrimidines Cytosine, thymine and uracil Single carbon ring Purines Adenine, guanine Double ring structure

Nitrogenous Bases

Fig. 5-27c-1 (c) Nucleoside components: nitrogenous bases Purines Guanine (G) Adenine (A) Cytosine (C) Thymine (T, in DNA)Uracil (U, in RNA) Nitrogenous bases Pyrimidines

Fig. 5-27c-2 Ribose (in RNA)Deoxyribose (in DNA) Sugars (c) Nucleoside components: sugars

DNA Double helix Sugar-phosphate backbone is on the outside of helix Run in opposite direction Antiparallel Base pairs held together by hydrogen bonds Adenine-thymine (uracil) Cytosine-guanine

DNA

Fig Sugar-phosphate backbones 3' end 5' end Base pair (joined by hydrogen bonding) Old strands New strands Nucleotide about to be added to a new strand