1. The structure and function of Macromolecules
Chapter 5 notes
The structure and function of Macromolecules

2. Concept 5.1
Polymer: a long molecule consisting of similar or identical building blocks
- like a train with many cars
- monomers: repeating units that are the building blocks
Diversity of life is based around 40 or 50 polymers

3. Concept 5.1
Monomers are connected together by dehydration synthesis (anabolic)
- covalent bond w/ the loss of H2O
Polymers are broken down by hydrolysis (catabolic)
- reverse rxn. of dehydration synthesis
- “break with water”

4. Concept 5.1 1 2 3 H HO H HO Unlinked monomer Short polymer
Dehydration removes a water
molecule, forming a new bond
H2O HO 1 2 3 4 H
Longer polymer
(a)
Dehydration reaction in the synthesis of a polymer

5. Concept 5.1 HO H2O H 3 2 1 4 Hydrolysis adds a water
molecule, breaking a bond HO
H2O H 3 2 1 4

6. Concept 5.2 Carbohydrates: include sugars and polymers
Monosaccharides (monos = single; sacchar = sugar)
- molecular formula is CH2O
- ex. Glucose (C6H12O6)
- most sugars are rings when aqueous

7. Concept 5.2
(a) Linear and ring forms
(b) Abbreviated ring structure

8. Concept 5.2
Disaccharide: two monosaccharides joined by a glycosidic linkage
- formed by dehydration synthesis
- glucose + glucose = maltose + H2O
- glucose + fructose = sucrose + H2O

9. Concept 5.2 (b) Dehydration reaction in the synthesis of sucrose
Glucose
Fructose
Sucrose
Maltose
(a) Dehydration reaction in the synthesis of maltose

10. Concept 5.2
Polysaccharides: polymers w/ few hundred to a few thousand monomers
-fcn. of a polysaccharide is determined by monomers and positions of glycosidic linkages

11. Concept 5.2 Storage polysaccharides
- starch: found in plants; consists only of glucose monomers (1-4 linkage); how plants store glucose (chloroplasts)
- glycogen: polymer of glucose found in animals; stored in liver and muscle cells

12. Concept 5.2 Structural polysaccharides
- cellulose: major component of plant cell walls
- note: 2 ring structures of glucose (alpha (a) and beta (b))
- cellulose is composed of all b glucose
- cellulose = “insoluble fiber”

13. Concept 5.2
 Glucose
 Glucose
(a)  and  glucose ring structures

14. Concept 5.2

15. Concept 5.2 Cell walls microfibrils in a plant cell wall Microfibril
Glucose
monomer
Cellulose
molecules
Microfibril
microfibrils
in a plant
cell wall
0.5 µm
10 µm
Cell walls

16. Carbohydrates Structural polysaccharides (cntd.)
- chitin: carbohydrate used by arthropods to build exoskeletons
- also used to make decomposable surgical thread

17. Concept 5.2 The structure of the chitin monomer. (a) (b) (c)
Chitin forms the
exoskeleton of
arthropods.
Chitin is used to make
a strong and flexible
surgical thread.

18. Concept 5.3
Lipids: little or no affinity for water; consist mostly of hydrocarbons
- 3 families: fats, phospholipids, steroids
Fat: composed of 2 parts
- glycerol: 3 carbon alcohol w/ hydroxyl
- fatty acids: long carbon skeletons w/ carboxyl groups

19. Concept 5.3 Fatty acid (palmitic acid) Glycerol (a)
Dehydration reaction in the synthesis of a fat

20. Concept 5.3
Fatty acids can vary in length and in the number and location of double bonds
- “saturated”: no double bonds; most animal fats; solid at room temp.
- “unsaturated”: has one or more double bonds which removes H atoms; plants and fish; liquid at room temp.

21. Concept 5.3 Structural formula of a saturated fat molecule
Stearic acid, a
saturated fatty
acid

22. Concept 5.3 unsaturated fatty acid Oleic acid, an cis double
Structural formula
of an unsaturated
fat molecule
Oleic acid, an
unsaturated
fatty acid
cis double
bond causes
bending

23. Concept 5.3 The major fcn. of fats is energy storage.
- 1g of fat stores more than twice as much energy as 1g of a polysaccharide
- mammals stock food reserves in adipose cells

24. Concept 5.3
Phospholipids: similar to fats but have only 2 fatty acid tails; 3rd hydroxyl group joins to a phosphate group
- show ambivalent behavior to water
- head= polar (hydrophilic); tail= nonpolar (hydrophobic)
- arranged in a bilayer, or double layer

25. Concept 5.3 (b) Space-filling model (a) (c) Structural formula
Phospholipid symbol
Fatty acids
Hydrophilic
head
Hydrophobic
tails
Choline
Phosphate
Glycerol
Hydrophobic tails
Hydrophilic head

26. Concept 5.3
Steroids: lipids with a carbon skeleton consisting of 4 fused rings
- differ in functional groups attached to rings
- Cholesterol: found in animal cell membranes; precursor for other steroids

27. Concept 5.3

28. Concept 5.4
Proteins: account for more than 50% of the dry weight of most cells
- used for structural support, storage, transport, signaling, movement, and defense

29. Concept 5.4
Proteins are polymers constructed from the same set of 20 amino acids
- called polypeptides
- consist of one or more polypeptides folded and coiled into specific conformations

30. Concept 5.4 Amino acids are the building blocks of proteins
- a carbon is bonded to an animo group, a carboxyl group, a hydrogen atom, and a variable (R)
- grouped according to side chains (nonpolar, polar, acidic, basic)

31. Concept 5.4

32. Concept 5.4

33. Concept 5.4 Amino acids are bonded together by a peptide bond
- carboxyl group of one amino acid connects w/ the amino group of another (dehydration synthesis)

34. Concept 5.4

35. Concept 5.4 Four levels of protein structure
- primary structure: unique sequence of amino acids
- even a slight change can affect a proteins conformation and ability to function
- ex. Sickle-cell disease

36. Concept 5.4

37. Concept 5.4
- secondary structure: coils or folds that are a result of hydrogen bonds at regular intervals
- a helix: delicate coil held together by hydrogen bonding between every fourth amino acid
- b pleated sheets: two or more regions lie parallel to each other

38. Concept 5.4

39. Concept 5.4
- tertiary structure: irregular contortions from interactions between side chains (R groups)
- hydrophobic interactions: nonpolar side chains cluster in the core, away from water
- van der Waals interactions help hold them together

40. Concept 5.4
- disulfide bridges: covalent bond between two cysteine monomers (have sulfhydryl groups)
- ionic bonds and hydrogen bonds also contribute

41. Concept 5.4

42. Concept 5.4
- quaternary structure: overall protein structure resulting from combining of multiple subunits
The unique conformation endows each protein with a specific function

43. Concept 5.4

44. Concept 5.4

45. Concept 5.4
The unique conformation endows each protein with a specific function
- denaturation: protein unravels and losses its conformation
- pH, [salt], temperature

46. Concept 5.5
Compounds that are responsible for determining the amino acid sequence of a polypeptide.
Two types of nucleic acids
- deoxyribonucleic acid (DNA)
- ribonucleic acid (RNA)
Flow of genetic information: DNA  RNA  Protein

47. Concept 5.5 mRNA Synthesis of mRNA in the nucleus DNA NUCLEUS
CYTOPLASM
Movement of
mRNA into cytoplasm
via nuclear pore
Ribosome
Amino
acids
Polypeptide
Synthesis
of protein 1 2 3

48. Concept 5.5
Nucleotides are the monomers (building blocks) of nucleic acids
-nucleotide = nitrogenous base + pentose (5-carbon sugar) + phosphate

49. (a) Polynucleotide, or nucleic acid (c) Nucleoside components: sugars
Concept 5.5
5 end
Nucleoside
Nitrogenous
base
Phosphate
group
Sugar
(pentose)
(b) Nucleotide
(a) Polynucleotide, or nucleic acid
3 end
3C
5C
Nitrogenous bases
Pyrimidines
Cytosine (C)
Thymine (T, in DNA)
Uracil (U, in RNA)
Purines
Adenine (A)
Guanine (G)
Sugars
Deoxyribose (in DNA)
Ribose (in RNA)
(c) Nucleoside components: sugars

50. Concept 5.5 Two families of nitrogenous bases:
- pyrimidines: single ring; cytosine (C), thymine (T), and Uracil (U)
- purines: double ring; adenine (A), and guanine (G)

51. Concept 5.5
Difference between DNA and RNA is in the sugar. DNA lacks an oxygen atom attached to its number 2 carbon
Polynucleotide: nucleotides are joined by phosphodiester linkage

52. Concept 5.5
DNA molecules have two polynucleotides that form a double helix.
- Watson and Crick (1953)
- A binds to T; C binds to G; forms two complementary strands