2. The Organic Molecules of Living Organisms
Carbon, the building block of living things
Comprises 18% of the body by weight
Forms four covalent bonds
Can form single or double bonds
Can build micro- or macromolecules

3. Macromolecules Are Synthesized and Broken Down within the Cell
Dehydration synthesis
Removes equivalent of a water molecule to link molecular units
Requires energy
Builds macromolecules from smaller subunits
Hydrolysis
Adds the equivalent of a water molecule to break apart macromolecules
Releases energy
Dehydration synthesis is the reverse of hydrolysis

4. Sugars
Energy
Energy
Dehydration synthesis
Hydrolysis
Carbohydrate
Figure 2.13

5. Monomers and Polymers

6. Carbohydrates: Used for Energy and Structural Support
General formula: Cn(H20)n
Monosaccharides: simple sugars
Glucose
Fructose
Galactose
Ribose
Deoxyribose

7. Oligosaccharides: More than One Monosaccharide Linked Together
Monosaccharides can be linked together via dehydration synthesis
Disaccharides: two monosaccharides linked together
Sucrose: glucose + fructose
Maltose: glucose + glucose
Lactose: glucose + galactose

8. a) The five-carbon monosaccharides ribose and deoxyribose.
Figure 2.14a

9. Glucose (a monosaccharide) Fructose (a monosaccharide)
Sucrose (a disaccharide)
b) Two 6-carbon monosaccharides (glucose and fructose) are
joined together by dehydration synthesis, forming sucrose.
Figure 2.14b

10. Polysaccharides Store Energy
Polysaccharides: thousands of monosaccharides joined in chains and branches
Starch: made in plants; stores energy
Glycogen: made in animals; stores energy
Cellulose: indigestible polysaccharide made in plants for structural support

11. a) Glycogen is formed by dehydration synthesis from glucose subunits.
Figure 2.15a

12. b) A representation of the highly branched nature of glycogen.
Figure 2.15b

13. Lipids: Insoluble in Water
Three important classes of lipids
Triglycerides: energy storage molecules
Phospholipids: cell membrane structure
Steroids: carbon-based ring structures

14. Triglycerides Also known as fats and oils
Composed of glycerol and three fatty acids
Fatty acids
Saturated (in fats)
Unsaturated (in oils)
Stored in adipose tissue
Energy storage molecules

15. a) Triglycerides (neutral fats) are synthesized from glycerol and
Saturated
fatty acid
a) Triglycerides (neutral fats) are
synthesized from glycerol and
three fatty acids by dehydration
synthesis.
Figure 2.16a

16. b) Triglycerides with saturated fatty acids have straight tails, allowing them to pack closely together.
Figure 2.16b

17. c) Triglycerides with unsaturated fatty acids have kinked tails, preventing them from packing closely together.
Figure 2.16c

18. Phospholipids Structure Function
Glycerol + two fatty acids and phosphate group
One end of molecule is water soluble (hydrophilic)
Other end of molecule is water insoluble (hydrophobic)
Function
Primary component of cell membranes

19. Membrane structure
Phosphate
Polar head
Glycerol
Fatty acid
Nonpolar tail
Figure 2.17

20. Steroids Structure Examples: Composed of four carbon rings Cholesterol
Hormones
Estrogen
Testosterone

21. a) Cholesterol:
A normal component of
the cell membrane.
Figure 2.18a

22. b) Estrogen (estradiol): Female sex hormone
synthesized from cholesterol.
Figure 2.18b

23. synthesized from cholesterol.
c) Testosterone:
Male sex hormone
synthesized from cholesterol.
Figure 2.18c

24. Lipid Structure and Function

25. Proteins Long chains (polymers) of subunits called amino acids
20 different types
Amino end, carboxyl end, R group
Amino acids are joined by peptide bonds, which are produced by dehydration synthesis reactions

26. Figure 2.19 Amino acids with nonpolar R groups
Amino acids with uncharged polar R groups
Alanine (Ala)
Asparagine (Asn)
Isoleucine (Ile)
Cysteine (Cys)
Leucine (Leu)
Glutamine (Gln)
Methionine (Met)
Glycine (Gly)
Phenylalanine (Phe)
Serine (Ser)
Proline (Pro)
Threonine (Thr)
Tryptophan (Trp)
Tyrosine (Tyr)
Amino acids with positively charged R groups
Arginine (Arg)
Valine (Val)
Amino acids with negatively charged R groups
Histidine (His)
Aspartic acid (Asp)
Lysine (Lys)
Glutamic acid (Glu)
Figure 2.19

27. Amino acids with nonpolar R groups
Alanine
(Ala)
Isoleucine
(Ile)
Leucine
(Leu)
Methionine
(Met)
Phenylalanine
(Phe)
Proline
(Pro)
Tryptophan
(Trp)
Valine
(Val)
Figure 2.19a

28. Amino acids with negatively charged R groups
Aspartic acid (Asp)
Glutamic acid (Glu)
Figure 2.19b

29. Amino acids with uncharged polar R groups
Asparagine (Asn)
Cysteine (Cys)
Glutamine (Gln)
Glycine (Gly)
Serine (Ser)
Threonine (Thr)
Tyrosine (Tyr)
Figure 2.19c

30. Amino acids with positively charged R groups
Arginine (Arg)
Histidine (His)
Lysine (Lys)
Figure 2.19d

31. Amino
acids
Isoleucine (Ile)
Alanine (Ala)
Valine (Val)
Polypeptide
Figure 2.20

32. Protein Function Depends on Structure
Primary structure
Amino acid sequence
Stabilized by peptide bonds
Secondary structure
Alpha helix
Beta pleated sheets
Stabilized by hydrogen bonds

33. Protein Function Depends on Structure
Tertiary structure
Three-dimensional shape
Stabilized by disulfide and hydrogen bonds
Creates polar and nonpolar areas in molecule
Quaternary structure
Two or more polypeptide chains are associated

34. Primary structure (sequence of amino acids)
Figure 2.21a

35. Hydrogen
bonds
Secondary
structure
(orientation in
space of chains
of amino acids)
Alpha helix
Beta sheet
Random coil
Figure 2.21b

36. Tertiary structure (three-dimensional shape)
Alpha helix
Tertiary
structure
(three-dimensional
shape)
Random
coil
Beta sheet
Figure 2.21c

37. (number of polypeptide
Quaternary
structure
(number of polypeptide
chains and their
association)
Figure 2.21d

38. Protein Function Depends on Structure
Denaturation
Permanent disruption of protein structure
Can be damaged by temperature or changes in pH
Leads to loss of biological function

39. Protein Structure

40. Enzymes Facilitate Biochemical Reactions
Are proteins
Function as biological catalysts
Speed up specific chemical reactions
Are not altered or consumed by the reaction
Without enzymes, many biochemical reactions would not proceed quickly enough to sustain life
Each enzyme is specific for a specific chemical reaction

41. Enzyme
Reactants
Product
Reactants
approach enzyme
Reactants
bind to enzyme
Enzyme
changes shape
Products
are released
Figure 2.22

42. Enzymes Facilitate Biochemical Reactions
The functional shape of an enzyme is dependent on
Temperature pH
Ion concentration
Presence of inhibitors

43. Nucleic Acids Store Genetic Information
Two types
DNA: deoxyribonucleic acid
RNA: ribonucleic acid
Functions
Store genetic information
Provide information used in making proteins
Nucleic acids are long chains containing subunits known as nucleotides

44. Nucleic Acids Store Genetic Information
Nucleotides: building blocks of nucleic acids
Each nucleotide contains
5 carbon sugar
DNA nucleotides: deoxyribose
RNA nucleotides: ribose
Nitrogenous base
Phosphate group

45. Adenine (A)
Cytosine (C)
Thymine (T)
Guanine (G)
Phosphate
Deoxyribose
Figure 2.23

46. Nucleic Acids Store Genetic Information
Structure of DNA (deoxyribonucleic acid)
Double–stranded
Nucleotides contain
Deoxyribose (sugar)
Nitrogenous bases
Adenine
Guanine
Cytosine
Thymine
Pairing
Adenine - Thymine
Guanine - Cytosine

47. Base pair
Phosphate
Sugar
Nucleotide
Figure 2.24

48. Nucleic Acids Store Genetic Information
Structure of RNA (ribonucleic acid)
Single–stranded
Nucleotides contain
Ribose
Nitrogenous bases
Adenine
Guanine
Cytosine
Uracil

49. Phosphate
Ribose
Uracil
Figure 2.25

50. Nucleic Acid Function --- Nucleic Acids Store Genetic Information
DNA: instructions for making RNA
RNA: instructions for making proteins
Proteins: direct most of life’s processes
DNA → RNA → Proteins

51. ATP Carries Energy
Structure and function of adenosine triphosphate (ATP)
Nucleotide – adenosine triphosphate
Universal energy source
Bonds between phosphate groups contain potential energy
Breaking the bonds releases energy
ATP → ADP + P + energy

52. Adenosine Adenine (A) Triphosphate Ribose a) The structure of ATP.
Figure 2.26a

53. produces useful energy for the cell
Hydrolysis of ATP
produces useful energy
for the cell
Adenosine
Adenosine
Energy for ATP synthesis
comes from food or body
stores of glycogen or fat
b) The breakdown and synthesis of ATP.
The breakdown (hydrolysis) of ATP yields
energy for the cell. The reaction is reversible,
meaning that ATP may be resynthesized
using energy from other sources.
Figure 2.26b