Macromolecules

1. Macromolecules • Large Molecules • Macromolecules are formed when monomers are linked together to form longer chains called polymers. • The same process of making and breaking polymers is found in all living organisms.

2. Condensation Reaction • Consider some generic monomers with OH groups on their ends. • These monomers can be linked together by a process called dehydration synthesis (also called a condensation reaction) in which a covalent bond is formed between the two monomers while a water molecule is also formed from the OH groups. • This reaction is catalyzed by a polymerase enzyme. • This same type of condensation reaction can occur to form many kinds of polymers, from proteins to carbohydrates, nucleic acids to triglycerides.

3. Hydrolysis Reactions • Polymers of all sorts can be broken apart by hydrolysis reactions. In hydrolysis the addition of a water molecule (with the help of a hydrolase enzyme) breaks the covalent bond holding the monomers together.

4. Four major types of Macromolecules • Lipids • Carbohydrates • Nucleic Acids • Proteins

5. Four major types of Macromolecules Diverse groups of molecules in nonpolymorphic form • Lipids • Carbohydrates • Nucleic Acids • Proteins Sugars Nucleotides Amino Acids

6. Proteins • Proteinsconsist of one or more polymerscalled polypeptides, which are made by linking amino acids together with peptide linkages. • Peptide linkages are formed through condensation reactions. • All proteins are made from the same 20 amino acids. • Different amino acids have different chemical properties.

7. Proteins • Protein’s primary structure largely determines its secondary, tertiary (and quaternary) structure. • Proteins subjected to extreme conditions (large changes in pH, high temperatures, etc.) often denature. • Proteins act as enzymes, and catalyze very specific chemical reactions.

8. Proteins

9. Carbohydrates • Carbohydratesare always composed of carbon, hydrogen and oxygen molecules • Monosaccharides typically have five or six carbon atoms. • Monosaccharides can, such as the ribose and deoxyribose of RNA and DNA, can serve very important functions in cells.

10. Carbohydrates • Condensation reactions form covalent bonds between monosaccharides, called glycosidic linkages. • Monosaccharides are the monomers for the larger polysaccharides. • Polysaccharides play various roles, from energy storage (starch, glycogen) to structure (cellulose).

11. Nucleic Acid • Two types of nucleic acids: • DNA • RNA • DNA stores the genetic information of organisms; RNA is used to transfer that information into the amino acid sequences of proteins. • DNA and RNA are polymers composed of subunits called nucleotides. • Nucleotides consist of a five-carbon sugar, a phosphate group and a nitrogenous base. • Five nitrogenous bases found in nucleotides: • the purines • adenine (A) • guanine (G) • the pyrimidines • cytosine (C) • thymine (T) (DNA only) • uracil (U) (RNA only)

12. Nucleic Acid • DNA is transmitted from generation to generation with high fidelity, and therefore represents a partial picture of the history of life.

13. Nucleic Acid

14. Lipids • Lipids constitute a very diverse group of molecules that all share the property of being hydrophobic. • Fatsand oilsare lipids generally associated with energy storage. • Fatty acids, which make up fats and oils, can be saturated or unsaturated, depending on the absence or presence of double bonded carbon atoms. • Other types of lipids are used for a other purposes, including pigmentation (chlorophyll, carotenoids), repelling water (cutin, suberin, waxes) and signaling (cholesterol and its derivatives).

15. Lipids • Lipids are joined together by ester linkages. • Triglyceride is composed of 3 fatty acid and 1 glycerol molecule • Fatty acids attach to Glycerol by covalent ester bond • Long hydrocarbon chain of each fatty acid makes the triglyceride molecule nonpolar and hydrophobic

16. Lipids

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