ch3 the chemical building blocks

• Carbon can form up to four covalent bonds
• Hydrocarbons are molecules consisting only of carbon and hydrogen, making them nonpolar
• Functional groups are specific molecular groups that bond to carbon-hydrogen cores
• Each functional group has unique chemical properties that influence the behavior of the entire molecule in reactions
• Isomers are molecules with the same molecular or empirical formula
• Structural isomers differ in the structure of the carbon skeleton, while stereoisomers differ in how groups are attached or arranged in space
• Enantiomers are mirror image stereoisomers with chiral carbon bound to 4 different groups
• Biological macromolecules include carbohydrates, nucleic acids, proteins, and lipids
• Polymers are built by linking monomers, which are small, similar chemical subunits
• Dehydration synthesis is the formation of large molecules by the removal of water, while hydrolysis is the breakdown of large molecules by the addition of water
• Carbohydrates have a 1:2:1 molar ratio of carbon, hydrogen, oxygen
• Carbohydrates are good energy storage molecules and some function in structural support
• Monosaccharides are the simplest carbohydrates, with glucose being a key example
• Disaccharides are two monosaccharides linked together by dehydration synthesis, used for sugar transport or energy storage
• Polysaccharides are long chains of monosaccharides linked through dehydration synthesis, with functions in energy storage and structural support
• Starch and glycogen are examples of polysaccharides used for energy storage in plants and animals, respectively
• Cellulose is a polysaccharide in plants, consisting of a chain of β-glucose molecules
• Cellulose is a polysaccharide found in plants
• Starch is a chain of α-glucose, while cellulose is a chain of β-glucose
• Cellulose is unbranched and forms long, strong fibers that are resistant to metabolic breakdown
• Starch-hydrolyzing enzymes in most organisms, including humans (not herbivores), cannot break the bond between 2 β-glucose units because they only recognize α linkages
• Nucleic acids, including RNA and DNA, are polymers made up of nucleotides
• Nucleotides consist of sugar, phosphate, and a nitrogenous base
• Sugar in nucleotides is a 5-carbon structure: deoxyribose in DNA and ribose in RNA
• Nitrogenous bases in nucleotides include purines (adenine and guanine) and pyrimidines (thymine, cytosine, uracil)
• Nucleotides connect by phosphodiester bonds formed between the phosphate of one nucleotide and the sugar of the next nucleotide
• DNA, a nucleic acid, encodes information for the amino acid sequence of proteins
• DNA is a double helix structure with two polynucleotide strands connected by hydrogen bonds
• Base-pairing rules in DNA: A with T (or U in RNA) held by 2 H-bonds, C with G held by 3 H-bonds
• The backbones of DNA run in opposite 5′ → 3′ directions, referred to as antiparallel
• RNA, similar to DNA, contains ribose instead of deoxyribose and uracil instead of thymine
• RNA is a single polynucleotide strand that uses information in DNA to specify the sequence of amino acids in proteins
• Proteins are polymers composed of one or more long, unbranched chains called polypeptides
• Amino acids are the monomers of proteins
• Amino acids have a central carbon atom, amino group, carboxyl group, single hydrogen, and a variable R group
• The peptide bond is a covalent bond formed between the amino group and carboxyl group of two adjacent amino acids
• Proteins have four levels of structure: primary, secondary, tertiary, and quaternary
• Protein motifs and domains are common elements of secondary structure and functional units within a larger protein structure, respectively
• Chaperone proteins help newly made proteins fold correctly and deficiencies in them are implicated in certain diseases like cystic fibrosis
• An incorrectly folded protein enters one chamber of a barrel, sealed by a cap