Macromolecules: Superstructures of Life Biochemistry- study of the compounds of life Biochemicals- organic compounds produced by (or components of) living things Four main families- carbohydrates, lipids, proteins, and nucleic acids Often very large, called macromolecules All macromolecules except for lipids are formed by polymerization Repeating subunits (monomers) are bound in to chains of various lengths (polymers)

Carbohydrates Carbohydrates: Sugars and Polysaccharides Most can be represented by the general formula (CH2O)n, where n = the number of units of this combination of atoms

Carbohydrates Exist in a variety of configurations Sugar (saccharide)- a simple carbohydrate with a sweet taste Monosaccharide contains 3-7 carbons Disaccharide contains two monosaccharides Polysaccharide contains five or more monosaccharides Monosaccharides and disaccharides are specified by combining a prefix that describes a characteristic of the sugar with the suffix –ose Hexoses- six carbons Pentoses- five carbons Fructose- for fruit

Figure 2.14

The Nature of Carbohydrate Bonds Figure 2.15

The Functions of Polysacharides Structural support and protection Serve as nutrient and energy stores Cell walls in plants and many microscopic algae from cellulose Figure 2.16a

Other Important Polysaccharides Include agar, peptidoglycan, chitin, lipopolysaccharide, glycocalyx, and glycogen Figure 2.16b

Lipids: Fats, Phospholipids, and Waxes Lipids- a variety of substances that are not soluble in polar substances Will dissolve in nonpolar solvents Main groups of lipids Triglycerides-a single molecule of glycerol bound to three fatty acids Includes fats and oils

Figure 2.17

Phospholipids Phospholipids- Contain two fatty acids attached to the glycerol with a phosphate group on the third glycerol binding site Important membrane molecules Figure 2.18

Miscellaneous Lipids Steroids- complex ringed compounds commonly found in cell membranes and animal hormones Best known- cholesterol Waxes- esters formed between a long-chain alcohol and a saturated fatty acid

Figure 2.19

Proteins: Shapers of Life Predominant organic molecules Building blocks- amino acids 20 different naturally occurring forms Basic skeleton- a carbon (the α carbon) linked to an amino group (NH2), a carboxyl group (COOH), a hydrogen atom (H), and a variable R group Peptide bond forms between the amino group on one amino acid and the carboxyl group on another.

Figure 2.20

Protein Structure and Diversity Primary (1°) structure- the type, number, and order of amino acids in the chain Secondary (2°) structure- when various functional groups exposed on the outer surface of the molecule interact by forming hydrogen bonds Coiled configuration- α helix Accordion pattern- β-pleated sheet Tertiary (3°) structure- created by additional bonds between functional groups Quarternary (4°) structure- more than one polypeptide forms a large, multiunit protein

Figure 2.21

Protein Shape Each different type of protein develops a unique shape, so it can only react with molecules that fit its particular surface features Ex. enzymes and antibodies Native state- the functional three-dimensional form of a protein Denatured- when the protein’s native state has been disrupted

The Nucleic Acids: A Cell Computer and Its Programs DNA- specially coded genetic program DNA transfers its program to RNA Both are polymers of repeating units called nucleotides Nucleotides- composed of three smaller units: a nitrogen base, a pentose sugar, and a phosphate. The nitrogen base can be one of two forms- a purine (two rings) or a pyrimidine (one ring) Two types of purines: adenine (A) and guanine (G) Three types of pyrimidines: thymine (T), cytosine (C), and uracil (U) DNA contains all of the nitrogen bases except uracil RNA contains all of the nitrogen bases except thymine The nitrogen base is covalently bonded to ribose in RNA and deoxyribose in DNA Phosphate (PO43-) covalently bonds the sugars in series

Figure 2.22

Figure 2.23

The Double Helix of DNA Formed by two long polynucleotide strands Linked along their length by hydrogen bonds between complimentary pairs of nitrogen bases Adenine pairs with thymine Cytosine pairs with guanine

RNA: Organizers of Protein Synthesis Also consists of a long chain of nucleotides It is single stranded and contains ribose instead of deoxyribose anduracil instead of thymine Several functional types of RNA formed using the DNA template Messenger RNA (mRNA)- a copy of a gene that provides the order and type of amino acids in a protein Transfer RNA (tRNA)- a carrier that delivers the correct amino acids for protein assembly Ribosomal RNA (rRNA)- a major component of ribosomes

The Energy Molecule of Cells Adenosine triphosphate (ATP)- a nucleotide containing adenine, ribose, and three phosphates High-energy compound that gives off energy when the bond is broken between the outermost phosphates Releases and stores energy for cellular chemical reactions When the terminal phosphate bond is broken to release energy, adenosine diphosphate (ADP) is formed ADP can be converted back to ATP when the third phosphate is restored.

Figure 2.25