2. Water
• It has the chemical formula H2O, meaning that one molecule of water is
composed of two hydrogen atoms and one oxygen atom
• The molecule is roughly tetrahedral in shape with two hydrogen bond
donors and two hydrogen bond acceptors
• The electronegative oxygen withdraws the electrons from the O–H covalent
bonds
• In general, ionic and polar substances such as acids, alcohols, and salts are
easily soluble in water, and nonpolar substances such as fats and oils are
not
3. Water
• Most abundant and important molecule in cells and tissues
• Humans are approximately two-thirds water
• Water is not only the solvent but also a reactant or product in
thousands of biochemical reactions
• Additionally, water forms hydrogen bonds with polar groups of many
cellular constituents
5. Proteins
• Proteins are major components of all cellular systems
• Proteins consist of one or more polypeptides composed of various
combinations of 20 different amino acids
• The sequence of amino acid residues in each type of polypeptide is unique
• Polypeptides range widely in length. Small peptide hormones, such as
oxytocin, consist of as few as nine residues, while the giant structural
protein titin has more than 25,000 residues
8. Properties of Amino Acids
• Amino acids are organic compounds that contain amine (-NH2)
and carboxyl (-COOH) functional groups, along with a side chain (R
group) specific to each amino acid
• They're needed for vital processes like the building of proteins and
synthesis of hormones and neurotransmitters
• From the diet, the 20 standard amino acids either are used to
synthesize proteins, other biomolecules, or are oxidized
to urea and carbon dioxide as a source of energy
10. Nucleic Acids
• Nucleic acids are polymers of building blocks called nucleotides
• They store and transfer all genetic information, the term nucleic acid is the
overall name for DNA and RNA
• Nucleotides consist of three parts: (1) a base built nitrogen atoms, (2) a
five-carbon sugar, and (3) one or more phosphate groups
• If the sugar is a compound ribose, the polymer is RNA (ribonucleic acid); if
the sugar is derived from ribose as deoxyribose, the polymer
is DNA (deoxyribonucleic acid)
11.
12. Carbohydrates
• A biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O)
atoms,
• Usually with a hydrogen–oxygen atom ratio of 2:1 (as in
water) empirical formula Cm(H2O)n
• The carbohydrates are technically hydrates of carbon
• it is a synonym of saccharide, a group that includes sugars, starch,
and cellulose
• The saccharides are divided into four chemical groups:
monosaccharides, disaccharides, oligosaccharides,
and polysaccharides
shells of water organized around ions compete effectively with other ions with which they might interact electrostatically
hydrogen bonding with water strongly competes with the hydrogen bonding that occurs between solutes, including macromolecules
water does not interact as favorably with nonpolar molecules as it does with itself, so the solubility of nonpolar molecules in water is low, and they tend to aggregate (hydrophobic effect)
leaving a partial positive charge on the hydrogens and a partial negative charge on the oxygen
biochemical reactions catalyzed by enzymes, including the synthesis and degradation of proteins and nucleic acids and the synthesis and hydrolysis of adenosine triphosphate (ATP), to name a few examples.
biological structure, as lipid bilayers, folded proteins, and macromolecular assemblies are all stabilized by the hydrophobic effect derived from the exclusion of water from nonpolar surfaces
Polypeptides range widely in length. Small peptide hormones, such as oxytocin, consist of as few as nine residues, while the giant structural protein titin has more than 25,000 residues
Enzymes modify many amino acids after their incorporation into polypeptides. These posttranslational modifications have both structural and regulatory functions
This repertoire of amino acids is sufficient to construct millions of different proteins, each with different capacities for interacting with other cellular constituents. This is possible because each protein has a unique three-dimensional structure
While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides very often end in the suffix -ose, as in the monosaccharides fructose (fruit sugar) and glucose (starch sugar) and the disaccharides sucrose (cane or beet sugar) and lactose (milk sugar).
Carbohydrates perform numerous roles in living organisms. Polysaccharides serve for the storage of energy (e.g. starch and glycogen) and as structural components (e.g. cellulose in plants and chitin in arthropods).
