Biology Chapter 5 Flashcards

Macromolecules

• Macromolecules are large molecules formed by joining smaller ones through dehydration reactions, encompassing polysaccharides, proteins, and nucleic acids.

Polymer and Monomer

• Polymers are long molecules made of many identical or similar monomers linked by covalent bonds.
• Monomers serve as the building blocks of polymers.

Enzymes and Reactions

• Enzymes are macromolecules that act as catalysts, increasing reaction rates without being consumed themselves, predominantly composed of proteins.
• Dehydration reactions bond two molecules together while removing water, whereas hydrolysis adds water to break these bonds, disassembling polymers into monomers.

Carbohydrates

• Carbohydrates include monosaccharides (simple sugars), disaccharides (two monosaccharides), and polysaccharides (long chains of monosaccharides).
• Glucose (C6H12O6) is the core monosaccharide, while maltose (C12H22O11) results from the dehydration of two glucose molecules.

Types of Polysaccharides

• Starch functions as an energy-storage polysaccharide in plants formed by α glycosidic linkages.
• Glycogen, found in liver and muscle tissues, is the animal equivalent of starch.
• Cellulose is a structural polysaccharide in plant cell walls formed by β glycosidic linkages and is not digestible by humans.
• Chitin is another structural polysaccharide found in fungal cell walls and arthropod exoskeletons.

Lipids

• Lipids, including fats, phospholipids, and steroids, are hydrophobic molecules that do not form polymers.
• Fats (or triglycerides) consist of three fatty acids linked to a glycerol molecule.
• Saturated fatty acids have no double bonds, maximizing hydrogen attachment, while unsaturated fatty acids contain one or more double bonds, reducing hydrogen count.

Steroids and Cholesterol

• Steroids have a carbon skeleton of four fused rings and include cholesterol, vital for cell membranes and hormone precursor synthesis.

Proteins

• Proteins are formed by polypeptides linked by peptide bonds and exhibit diverse structures (primary, secondary, tertiary, and quaternary), influencing their functions.
• Primary structure refers to the amino acid sequence; secondary structures include α helices and β pleated sheets formed by hydrogen bonds within the polypeptide backbone.
• Tertiary structure denotes the overall protein shape, while quaternary structure involves the arrangement of multiple polypeptides.

Nucleic Acids

• Nucleic acids, including DNA and RNA, consist of polymers known as polynucleotides made from nucleotide monomers.
• DNA is typically double-stranded, formed from deoxyribose sugars, while RNA is single-stranded and contains ribose sugars.
• Base pairing in nucleic acids ensures accurate replication and functioning, vital for genetic fidelity and protein synthesis.

Genetic Information and Protein Function

• Sickle-cell disease is a genetic disorder caused by a mutation in the β-globin gene affecting hemoglobin structure.
• Denaturation occurs when proteins lose their shape due to broken bonds, rendering them nonfunctional.
• Chaperonins assist in proper protein folding to achieve their functional conformation.

Importance of Structural Diversity

• Variations in primary structures of proteins lead to diverse forms and functions, essential for biological activities.
• The shape of proteins is critical in determining specific roles, with interactions among amino acid side chains influencing folding and functionality.

Distinctions Between Biological Macromolecules

• The four main classes of biological macromolecules are proteins, carbohydrates, lipids, and nucleic acids, with lipids not being classified as polymers due to their structure.