1. The Four Groups of Biomolecules
SGN 5
Carbohydrates
Lipids
Proteins
Nucleic
acids

2. Life uses only about 20 different elements (and in the cell 5 are predominate) to make many different carbon based molecules (organic) of various sizes
Four groups of biomolecules Carbohydrates are predominant Lipids
Nucleic acids
Proteins

3. Carbohydrates Several basic forms
Monosaccharides
smallest carbs
monomers for bigger carbs
Disaccharides
two monomers
Oligosaccharides – 15 monomers
Polysaccharides many monomers

4. Monosaccharides
3 to 7 carbons with multiple hydroxyl groups and a carbonyl group

5. Synthesized in linear form with a carbonyl group, which in molecules of 5 or more carbons is involved in bond that forms typical monosaccharide ring structure 1:2:1 ratio of C:H:O in monosaccharide ring structure Multiple hydroxyl groups give small saccharides polarity and solubility

6. Most common are hexoses and pentoses (6 or 5 sided ring structure) that form when the linear monosaccharide curls back and bonds with itself (intramolecular reaction)
Examples of hexoses are glucose and fructose, while a common pentose is ribose/deoxyribose

7. Often monosaccharides serve as monomers for larger carbs or building blocks for other types of molecules (such as DNA), or as immediate source of energy (broken down by cellular respiration and other processes)
Carbohydrate polymers
DNA monomer

8. Disaccharides Two monomers joined by a dehydration reaction
Often used to transport energy (sucrose and maltose within plants, lactose from maternal to infant mammal)
xylem vessels

9. Oligosaccharides Up to approximately 10 monomers
Typically attached to proteins (glycoproteins) or lipids (glycolipids) as cell surface markers, parts of antibodies and other uses

10. Polysaccharides
Long chains of monomers, typically hundreds or thousands ; often the same monomer repeated, or with very little variation
Starch, cellulose and glycogen are all long polymers of only glucose

11. Differing monomers, lengths, branching patterns and how the monomers are linked give polymers different chemical properties; for example structure of starch vs that of cellulose – different glycosidic linkages, means animals can digest starch but not cellulose

12. Uses of polysaccharides
Glycogen molecule
Uses of polysaccharides
Energy storage (starch in plants, glycogen in the mammalian liver)
Structural material, such as cell walls
Plants – cellulose Fungus – chitin Bacteria - peptidoglycan

13. Generally have hydrophobic /insoluble or amphipathic properties
Lipids
Structure
Contain carbon and hydrogen and many fewer oxygens
Example of an unsaturated fat triglyceride (C55H98O6)
Glycerol (3 carbon alcohol) attached to three hydrocarbon chains fatty acids in dehydration reactions
Generally have hydrophobic /insoluble or amphipathic properties

14. In more complex lipids one of the fatty acids is replaced by a charged group or the fatty acids are converted into rings (steroids)

15. Uses of lipids
Long term energy storage and insulation (fats), waterproofing (cell membranes and waxes); steroids used in cell membrane structure (cholesterol) and cell signaling (sex hormones - estrogen and testosterone)

16. Proteins
Functions – enzymes, structure, transport, cell signals and receptors, defense, movement

17. Protein structure
Composed of C, H, O, nitrogen, and sulfur; Protein structure is the key to protein function For example, globular enzymes have complex pockets into which fit the molecules they manipulate
Other proteins “walk” along protein fibers

18. Monomers are approximately 20 amino acids (also called peptides)
Composed of central carbon attached to a hydrogen, an amino group, a carboxyl group, and a versatile or R group

19. Amino and carboxyl groups involved in dehydration and hydrolysis reactions and in polypeptide folding
Variable group can give amino acid neutral, polar or charged characteristic; also instrumental in polypeptide formation

20. Protein polymers are called polypeptides, which often have complex 3-D shapes and often join in multimolecular complexes Monomers are joined together by peptide bonds (covalent) between amino and carboxyl groups; this gives polypeptide direction, with an N-terminus and a C-terminus

21. Proteins either form parts of structures (peptidoglycans of bacterial cell walls; collagen holding animal cells together), or are involved in some active function (transport of compounds across the cell membrane; catalytic activity of enzymes) Structural proteins tend to be long intertwined chains (fibrous, such as collagen, or keratin, which forms hair and nails), while enzymes, transport proteins and other “active” types have diverse shapes (globular)
Keratin
A motor protein

22. Four levels of organization are responsible for the protein’s final structure

23. Primary structure – considers only the sequence of amino acids joined by covalent bonds

24. Secondary structure Hydrogen bonds between elements of polypeptide backbone/peptide group (amino, central carbon, carboxyl groups), not R groups

25. H-bonds between close sections of single polypeptide forms helices; more distant H-bonds form pleated sheet

26. Tertiary structure
Interactions between R groups of distant amino acids; this often causes intricate folding of polypeptide
Numerous types of weak bond interactions: hydrophobic interactions, hydrophilic interactions (hydrogen bonds, ionic bonds)
Disulfide bridges are covalent bonds between sulfhydryl groups, giving polypeptide increased stability

28. Quaternary structure
More than one polypeptide joined together by noncovalent bonds (hydrophilic and hydrophobic)
Proteins that require several polypeptides will not function if all the parts are not joined properly
Other factors, such as proteins that assist in folding and specialized localized conditions (for example, pH or salinity) within regions of the cell where certain proteins are manufactured are also important in proper protein contortions

30. Certain conditions will result in polypeptide denaturation (unfolding)
Most proteins only operate under optimal conditions of pH, salinity and temperature; conditions outside of optimal range disrupt weak bonds giving protein its shape

31. Nucleic acids
Genetic material – stores, transports and in some instances manipulates genetic information; also monomers can be modified for other uses, such as energy transfer

32. Composed of C, H, O, phosphorous and nitrogen Monomers are called nucleotides, polymers called polynucleotides

33. Nucleotides are composed of a pentose monosaccharide ring, a nitrogenous base and a phosphate group Nucleotides vary only in their base (cytosine, thymine, uracil, adenine, guanine), and whether the monosaccharide is ribose or deoxyribose

34. A polynucleotide is a long strand of nucleotides; two strands are joined by hydrogen bonds between the nitrogenous bases to form the double helix of DNA RNA exists as a single strand

35. DNA and RNA – used in use, transfer and storage of genetic information
Examples
DNA and RNA – used in use, transfer and storage of genetic information
ATP – a modified nucleotide used in transferring energy
ATP
NAD+