Macromolecule AP bio

1. Macromolecules
Chapter 5

2. How are macromolecules built?
Most macromolecules are polymers; long
molecules consisting of building blocks called
monomers.
There are 4 categories:
❁ Carbohydrates
❁ Lipids (not technically)
❁ Proteins
❁ Nucleic Acids

3. Synthesis and Breakdown of Polymers:
Macromolecules differ based on their monomer
units but are assembled in a similar manner.
A Condensation (Dehydration) Reaction:
❁ monomers linked by covalent bonds
❁ water molecule is lost
❁ variety of monomer combinations increases
diversity

4. One monomer provides an H. Another
provides OH. An H2O molecule is formed.
Requires enzymes and energy.
***Also called Dehydration Synthesis!!!!

5. Hydrolysis:
❁ monomers disassembled
❁ water molecule is added
❁ H from water attaches to one monomer and
OH from water attaches to another.

6. “The Molecular Logic Of Life Is Simple
But Elegant: Small molecules common
to all organisms are ordered into unique
macromolecules.”

7. Carbohydrates

8. Characteristics of Carbohydrates
Carbohydrates = “Watered Carbon” consisting of
C, H, & O.
Categories:
❁ Monosaccharides = monomers (simple sugars)
❁ Disaccharides = 2 monomers (sugars)
❁ Polysaccharides = polymer (starches)

9. Function of carbohydrates:
❁ Energy
❁ Raw Materials
❁ Energy Storage
❁ Structural Support
The simplest carbohydrates have names that often
end in “-ose” and are named for the number of
carbon atoms.
❁ Trioses, Pentoses, and Hexoses

10. Notice Functional Groups:

11. Monosaccharides (monomers)
Generally follow formula: (CH2O)x
Contain carbonyl and hydroxl groups.
Function as major nutrients for cells, as well as
raw material, for other organic molecules.
Most Common Types: C6H12O6
❁ Glucose: most common to all carbs!
❁ Galactose: milk sugar (enantiomer)
❁ Fructose: fruit sugar (structural isomer)

12. In aqueous solutions, most
sugars form rings:

13. Disaccharides (sugars)
Two monosaccharides joined by a type of
covalent bond called a glycosidic linkage.
How does a disaccharide form?
Most Common Types:
❁ Maltose: glucose + glucose
❁ Lactose: glucose + galactose
❁ Sucrose: glucose + fructose

16. Polysaccharides (polymers)
Contain few hundred to a few thousand
monomer units!!
Function primarily in energy storage and for
structural materials.
Most Common Types:
❁ Starch: plant storage
❁ Glycogen: animal storage
❁ Cellulose: structural
❁ Chitin: structural

17. Starch:
Consists entirely of glucose molecules.
Helical in shape (bond angle); linear or branched.
Plants store starch as granules in specialized
structures called plastids (amyloplasts).
Stockpile of surplus glucose.

18. Glycogen:
Consists entirely of glucose molecules.
Helical in shape; more extensively branched.
Animals store glycogen in their muscle cells and
liver.
Stockpile of surplus glucose.

20. Cellulose:
Consists entirely of glucose molecules.
Glycosidic linkages differ from those in starch.
Straight molecules that never branch.
Provide support for cell wall in plants.
Most abundant organic compound on Earth.

22. Can we digest
cellulose?
What
organisms can?

23. Chitin:
Makes up exoskeleton
of arthropods.
It is tough and leathery
but hardens in the
presence of calcium
carbonate.
Fungi also use chitin as
building material for cell
walls.

24. Lipids

25. Characteristics of Lipids
Lipids are not considered polymers.
They are hydrophobic due to hydrocarbon
chains.
They contain mainly C, H, & O (also P).
Categories:
❁ Fats
❁ Phospholipids
❁ Steroids

26. Fat Molecules
Glycerol (3-carbon alcohol) + 3 Fatty Acids =
Triglyceride.
❁ Glycerol has 3 hydroxyl groups
❁ Fatty acids have hydrophobic C-H tails
and polar carboxyl heads
Each fatty acid molecule is connected to glycerol
by an ester linkage.

27. Synthesis of a Fat Molecule
The -OH groups on glycerol react with the -COOH
groups of the fatty acids and undergo dehydration
synthesis.

29. Fatty Acids
Fatty acids are responsible for the hydrophobic
nature of lipids (long H-C chain)
They can vary in their size and in their bonding
patterns; saturated versus unsaturated.

30. Unsaturated Fats
Liquid at room temperature due to kinks in the
fatty acid chain (cis-double bonds).
Mostly plant and fish fats.
(b) Unsaturated fat and fatty acid
cis double bond
causes bending
Oleic acid
Figure 5.12

31. (a) Saturated fat and fatty acid
Stearic acid
Figure 5.12
Saturated Fats
Solid at room temperature due to tightly packaged
molecules; mostly animal fats.
Excess can lead to a cardiovascular disease called
atherosclerosis (plaque build-up).
Hydrogenated oils may be worse. (trans fats)

32. Major Functions of Fats
Energy storage in adipose cells
(2X more than carbs!)
Protection and Cushioning
Insulation (blubber)

33. Phospholipids
Similar to fat molecules only with two fatty acids
and a phosphate group (negative charge)
Major component of cell membranes

34. Lipid Bi-layer
The cell membrane is composed of two
phospholipid layers.
Phospholipids arrange themselves so their
hydrophilic heads are in contact with water and
hydrophobic tails face away. Why is this good?

35. Steroids
Characterized by 4 inter-locking rings.
Properties differ due to attachment of various
functional or side groups.

36. Cholesterol
Precursor to all other steroids.
Major component of animal cell membranes
involved in temperature moderation.
Contributes to cardiovascular disease.

37. Proteins

38. Characteristics of Proteins
Most structurally and functionally diverse group
of molecules that are also instrumental in almost
everything an organism does.
Functions: Proteins comprise 50% of a cell!
❁ Enzymes (too important for today!)
❁ Transport (cell membrane)
❁ Defense (antibodies)
❁ Storage (albumin)
❁ Structure (collagen)
❁ Contractile (muscles)
❁ Hormonal (signaling)
❁ Receptor (cell stimuli)

41. Protein Structure
The monomer of a protein is an amino acid.
Polymers of amino acids are called polypeptides.
One or more polypeptides combine to form a large
3-D protein.
Proteins generally end with “-ine”.

42. Amino Acids
There are 20 amino acids utilized by organisms to
build proteins.
Structure:
❁ central (α) carbon
❁ amino group (-NH2)
❁ carboxyl group (-COOH)
❁ Hydrogen
❁ R group: variable group (unique properties)

44. Building a Polypeptide
Amino acids are linked by a peptide bond through
dehydration synthesis.
The -NH2 group of one amino acid interacts with
the -COOH group of another.

46. The polypeptide only grows in one direction!!

47. Protein Function
The function of a particular protein is determined
by its structure.
Functional proteins consist of polypeptide chains
folded and twisted into a molecule with a unique
shape.
A newly synthesized polypeptide chain
spontaneously folds due to the formation of bonds
between parts of the amino acid chain.

48. Levels of Protein Structure
It all begins with the order of amino acids in the
newly synthesized chain.

49. Primary 1° Structure
Amino acid sequence
determined by DNA
(gene).
The slightest change at
this level could have
drastic effects (sickle cell
anemia).

51. Secondary 2° Structure
Coils or folds form
due to H-bonds
between atoms of the
polypeptide backbone.
❁ α helix
❁ β pleated sheet

52. Tertiary 3° Structure
A result of extensive folding due to the interaction
of the R groups along the polypeptide.
Additional interactions:
❁ Hydrophobic & van der Waals interactions (weak)
❁ Hydrogen & Ionic bonds
❁ Disulfide bridges (covalent)
CH2
CH
O
H
O
C
HO
CH2
CH2 NH3
+ C
-O CH2
O
CH2
S
S
CH2
CH
CH3
CH3
H3C
H3C
Hydrophobic
interactions and
van der Waals
interactions
Polypeptide
backbone
Hyrdogen
bond
Ionic bond
CH2
Disulfide bridge

53. Quaternary 4° Structure
The joining together of one or more polypeptides.
Finally a functional protein!

54. Denatured Proteins
Disruption of the 2° & 3° structure due to
environment of the cell.
❁ pH, temperature, & [salt] changes
❁ bonds break and protein unravels
Denatured proteins cannot function properly.
Some proteins can return to their original form,
others cannot.

56. Chaperonins
Folding is everything, so it must be done right!
They shelter folding, and newly folded, proteins
from the chemical reactions of the cell.

57. What is a proteins structure?
X-ray Crystallography
NMR Spectroscopy
Bioinformatics

58. Nucleic Acids

59. Characteristics of Nucleic Acids
Two Examples:
❁ DNA: Deoxyribonucleic Acid
❁ RNA: Ribonucleic Acid
Functions:
❁ Store and transmit genetic information
❁ DNA can replicate
❁ DNA directs RNA synthesis
❁ DNA & RNA direct protein synthesis
❁ Evolutionary comparisons

60. Structure of Nucleic Acids
Polynucleotide macromolecules consisting of
many monomer units called nucleotides:
❁ Nitrogenous base
❁ Pentose sugar:
DNA (deoxyribose) or RNA (ribose)
❁ Phosphate group
How does deoxyribose differ from ribose?

62. Nitrogenous Bases
Two Types:
❁ Purines: Adenine and Guanine
❁ Pyrimidines: Cytosine, Uracil, and Thymine
A,G, & C are
in both RNA
& DNA
T-only DNA
U-only RNA

63. Nucleotide Polymers
Nucleotides are linked by phosphodiester bonds
between the sugar and phosphate groups.
(Specifically, the 3’ -OH of one nucleotide and the 5’ -PO4 of
another)
A sugar phosphate backbone elongates in one
direction.
Nitrogenous bases extend from the backbone. The
order of these bases reflects genetic information.

64. One end is
always the 5’ and
the other is the 3’.

65. The DNA Double Helix
While RNA is usually a single strand of
nucleotides, DNA has two that spiral into a helix.
The two strands run in opposite directions and are
considered anti-parallel.
They are held together by H-bonds between
inward facing nitrogenous bases.
(van der Waals interactions between stacked bases help)

66. Note: A-T is held by two H-bonds and G-C is
held by 3 H-bonds.

67. Base Pairing Rules: Purine with Pyrimidine
A-T (DNA), A-U (RNA), & G-C (always)
Complimentary Base Pairing

68. DNA: A Template for Replication
When a cell divides, it requires identical genetic
information to be passed on to the new cells.