1. Aim: How can we describe carbohydrates and how they are associated with life? Do Now: Draw an animal cell membrane in as much detail as possible and describe. Homework: Review notes.

2. Carbon and the Molecular Diversity of Life
Chapter 3
Carbon and the Molecular Diversity of Life

3. Macromolecules
Are large, complex molecules composed of smaller molecules.
Figure 5.1

4. Macromolecules Most macromolecules are polymers, built from monomers
Four classes of life’s organic molecules are polymers:
Carbohydrates
Lipids
Proteins
Nucleic Acids

5. Specific monomers make up each macromolecule.
A polymer
Is a long molecule consisting of many similar building blocks called monomers.
Specific monomers make up each macromolecule.
Ex: amino acids are the monomers make up proteins

6. The Synthesis and Breakdown of Polymers
Monomers form larger molecules by condensation reactions called dehydration synthesis.
(a) Dehydration reaction in the synthesis of a polymer HO H 1 2 3 4
H2O
Short polymer
Unlinked monomer
Longer polymer
Dehydration removes a water molecule, forming a new bond
Figure 5.2A

7. The Synthesis and Breakdown of Polymers
Polymers can disassemble by:
Hydrolysis (addition of water molecules)
(b) Hydrolysis of a polymer HO 1 2 3 H 4
H2O
Hydrolysis adds a water molecule, breaking a bond
Figure 5.2B

8. Although organisms share the same limited number of monomer types, each organism is unique based on the arrangement of monomers into polymers
An immense variety of polymers can be built from a small set of monomers

9. 1. Carbohydrates First source of energy
Serve as fuel and building material
Include both sugars and their polymers (starch, cellulose, etc.)

10. Sugars Monosaccharides Are the simplest sugars Can be used for fuel
Can be converted into other organic molecules
Can be combined into polymers

11. Examples of monosaccharides:
Triose sugars (C3H6O3)
Pentose sugars (C5H10O5)
Hexose sugars (C6H12O6)
H C OH
H C OH
HO C H
H C OH
C O
HO C H H C O
Aldoses
Glyceraldehyde
Ribose
Glucose
Galactose
Dihydroxyacetone
Ribulose
Ketoses
Fructose
Figure 5.3

12. Monosaccharides May be linear Can form rings 4C 3 2 OH Figure 5.4
H C OH
HO C H
H C O C 1 2 3 4 5 6 OH 4C
6CH2OH 5C
H OH
2 C 1C
3 C 2C
1 C
CH2OH HO
(a) Linear and ring forms. Chemical equilibrium between the linear and ring
structures greatly favors the formation of rings. To form the glucose ring,
carbon 1 bonds to the oxygen attached to carbon 5.
Figure 5.4

13. Disaccharides
Consist of two monosaccharides
Are joined by a glycosidic linkage

14. Figure 5.5 CH2OH O H H OH HO OH H2O
Dehydration reaction in the synthesis of maltose. The bonding of two glucose units forms maltose. The glycosidic link joins the number 1 carbon of one glucose to the number 4 carbon of the second glucose. Joining the glucose monomers in a different way would result in a different disaccharide.
Dehydration reaction in the synthesis of sucrose. Sucrose is a disaccharide formed from glucose and fructose. Notice that fructose, though a hexose like glucose, forms a five-sided ring.
(a)
(b) H HO
H OH OH O
CH2OH
H2O 1 2 4
1– 4 glycosidic linkage
1–2 glycosidic linkage
Glucose
Fructose
Maltose
Sucrose
Figure 5.5

15. Polysaccharides Polysaccharides Are polymers of sugars
Serve many roles in organisms

16. Storage Polysaccharides
Chloroplast
Starch
Amylose
Amylopectin
1 m
(a) Starch: a plant polysaccharide
Figure 5.6
Starch
Is a polymer consisting entirely of glucose monomers
Is the major storage form of glucose in plants

17. (b) Glycogen: an animal polysaccharide
Consists of glucose monomers
Is the major storage form of glucose in animals
Mitochondria
Giycogen granules
0.5 m
(b) Glycogen: an animal polysaccharide
Glycogen
Figure 5.6

18. Structural Polysaccharides
Cellulose
Is a polymer of glucose and is a structural polysaccharide.
Found in the cell wall of plants

19.  Figure 5.8 About 80 cellulose molecules associate
Plant cells
0.5 m
Cell walls
Cellulose microfibrils
in a plant cell wall 
Microfibril
CH2OH OH O
Glucose monomer
Parallel cellulose molecules are
held together by hydrogen
bonds between hydroxyl
groups attached to carbon
atoms 3 and 6.
About 80 cellulose
molecules associate
to form a microfibril, the
main architectural unit
of the plant cell wall.
A cellulose molecule
is an unbranched 
glucose polymer.
Cellulose
molecules
Figure 5.8

20. Cellulose is difficult to digest
Cows have microbes in their stomachs to facilitate this process, we however do not have these same microbes.
Figure 5.9

21. Chitin, another important structural polysaccharide
Is found in the exoskeleton of arthropods (invertebrate with an exoskeleton).
Can be used as surgical thread.
(a) The structure of the
chitin monomer. O
CH2OH OH H NH C
CH3
(b) Chitin forms the exoskeleton
of arthropods. This cicada
is molting, shedding its old
exoskeleton and emerging
in adult form.
(c) Chitin is used to make a
strong and flexible surgical
thread that decomposes after
the wound or incision heals.
Figure 5.10 A–C

22. Aim: How can we describe lipid and protein structure and function
Aim: How can we describe lipid and protein structure and function? Do Now: Do the number of fat cells increase, decrease, or remain the same as you age? Justify your response. Homework: Review notes.

23. 2. Lipids Lipids are a diverse group of hydrophobic molecules. Lipids:
Are the one class of large biological molecules that do not consist of polymers.
Share the common trait of being hydrophobic.

24. Are constructed from two types of smaller molecules, a single glycerol and usually three fatty acids.
Vary in the length and number and locations of double bonds they contain

25. (a) Saturated fat and fatty acid
Saturated fatty acids
Have the maximum number of hydrogen atoms possible.
Have NO double bonds.
(a) Saturated fat and fatty acid
Stearic acid
Figure 5.12
Why are saturated fats bad for us?

26. (b) Unsaturated fat and fatty acid
Unsaturated fatty acids
Have one or more double bonds
(b) Unsaturated fat and fatty acid
cis double bond
causes bending
Oleic acid
Figure 5.12
Why are unsaturated fats good for us?

27. Phospholipids Have only two fatty acids.
Have a phosphate group instead of a third fatty acid.

28. (a) Structural formula (b) Space-filling model
Phospholipid structure
Consists of a hydrophilic “head” and hydrophobic “tails”.
CH2 O P CH C
Phosphate
Glycerol
(a) Structural formula
(b) Space-filling model
Fatty acids
(c) Phospholipid
symbol
Hydrophobic tails
Hydrophilic
head
Hydrophobic
tails –
Hydrophilic head
Choline +
Figure 5.13
N(CH3)3

29. The structure of phospholipids:
Results in a bilayer arrangement found in cell membranes.
Hydrophilic
head
WATER
Hydrophobic
tail
Figure 5.14

30. Steroids
Steroids:
Are lipids characterized by a carbon skeleton consisting of four fused rings.
Steroids" has more than one meaning. Your body naturally produces some steroids, to help you fight stress and grow bigger during puberty. (But your body knows just the right amount that you need, so there's no need to take any extra.) There's also a type of medicine called steroids that people might take if they have pain, asthma, or a skin problem. But these aren't the kind of steroids getting attention in sports.
When people say steroids (say: STARE-oydz), they often mean illegal anabolic steroids. Anabolic steroids are artificially produced hormones that are the same as, or similar to, androgens, the male-type sex hormones in the body. The most powerful of these is testosterone (say: tes-TOSS-tuh-rone). Anabolic steroids can be taken in the form of pills, powders, or injections. Anabolic steroids are always illegal, meaning that you could get arrested for buying, selling, or taking them.

31. One steroid, cholesterol
Is found in cell membranes
Is a precursor for some hormones HO
CH3
H3C
Figure 5.15

32. 3. Proteins
Proteins have many structures, resulting in a wide range of functions.
Proteins do most of the work in cells and act as enzymes.
Proteins are made of monomers called amino acids.

33. An overview of protein functions
Table 5.1

34. Enzymes
Are a type of protein that acts as a catalyst, speeding up chemical reactions.
Substrate
(sucrose)
Enzyme
(sucrase)
Glucose OH
H O
H2O
Fructose
3 Substrate is converted
to products.
1 Active site is available for
a molecule of substrate, the
reactant on which the enzyme acts.
Substrate binds to
enzyme. 2
4 Products are released.
Figure 5.16
All enzymes are proteins, but not all proteins are enzymes.

35. Polypeptides Polypeptides A protein
Are polymers (chains) of amino acids
A protein
Consists of one or more polypeptides

36. Amino acids
Are organic molecules possessing both carboxyl and amino groups
Differ in their properties due to differing side chains (variable groups), called R groups

37. Twenty Amino Acids 20 different amino acids make up proteinsH
H3N+ C
CH3 CH
CH2 NH
H2C
H2N
Nonpolar
Glycine (Gly)
Alanine (Ala)
Valine (Val)
Leucine (Leu)
Isoleucine (Ile)
Methionine (Met)
Phenylalanine (Phe)
Tryptophan (Trp)
Proline (Pro)
H3C
Figure 5.17 S
20 different amino acids make up proteins

38. Polar Electrically chargedOH
CH2 C H
H3N+ O
CH3 CH SH
NH2
Polar
Electrically
charged –O
NH3+
NH2+
NH+ NH
Serine (Ser)
Threonine (Thr)
Cysteine
(Cys)
Tyrosine
(Tyr)
Asparagine
(Asn)
Glutamine
(Gln)
Acidic
Basic
Aspartic acid
(Asp)
Glutamic acid
(Glu)
Lysine (Lys)
Arginine (Arg)
Histidine (His)

39. Amino Acid Polymers
Amino acids
Are linked by peptide bonds.

40. Protein Conformation and Function
A protein’s specific conformation (shape) determines how it functions.

41. Four Levels of Protein Structure
1. Primary structure:
Is the unique sequence of amino acids in a polypeptide.
Figure 5.20 –
Amino acid subunits
+H3N Amino end o
Carboxyl end c
Gly
Pro
Thr
Glu
Seu
Lys
Cys
Leu
Met
Val
Asp
Ala
Arg
Ser
lle
Phe
His
Asn
Tyr
Trp
Lle

42. 2. Secondary structure:
Is the folding or coiling of the polypeptide into a repeating configuration.
Includes the  helix and the  pleated sheet. O C
 helix
 pleated sheet
Amino acid subunits N H R H
Figure 5.20

43. Is the overall three-dimensional shape of a polypeptide.
3. Tertiary structure:
Is the overall three-dimensional shape of a polypeptide.
Results from interactions between amino acids and R groups.
CH2 CH
O H O C HO
NH3+ -O S
CH3
H3C
Hydrophobic interactions and van der Waals interactions
Polypeptide backbone
Hyrdogen bond
Ionic bond
Disulfide bridge

44. 4. Quaternary structure:
Is the overall protein structure that results from the aggregation of two or more polypeptide subunits.
Polypeptide chain
Collagen
 Chains
 Chains
Hemoglobin
Iron
Heme

45. Review of Protein Structure
+H3N
Amino end
Amino acid
subunits
helix

46. Sickle-Cell Disease: A Simple Change in Primary Structure
Results from a single amino acid substitution in the protein hemoglobin

47. Sickle-cell hemoglobin
Primary structure
Secondary and tertiary structures
Quaternary structure
Function
Red blood cell shape
Hemoglobin A
Molecules do not associate with one another, each carries oxygen.
Normal cells are full of individual hemoglobin molecules, each carrying oxygen  
10 m
Hemoglobin S
Molecules interact with one another to crystallize into a fiber, capacity to carry oxygen is greatly reduced.
 subunit 1 2 3 4 5 6 7
Normal hemoglobin
Sickle-cell hemoglobin
. . .
Figure 5.21
Exposed hydrophobic region
Val
Thr
His
Leu
Pro
Glul
Glu
Fibers of abnormal hemoglobin deform cell into sickle shape.

48. What Determines Protein Conformation?
Protein conformation Depends on the physical and chemical conditions of the protein’s environment.
Temperature, pH, etc. affect protein structure.

49. Denaturation is when a protein unravels and loses its native conformation (shape).
Renaturation
Denatured protein
Normal protein
Figure 5.22

50. The Protein-Folding Problem
Most proteins:
Probably go through several intermediate states on their way to a stable conformation.
Denatured proteins no longer work in their unfolded condition.
Proteins may be denatured by extreme changes in pH or temperature.

51. Chaperonins:
Are protein molecules that assist in the proper folding of other proteins
Hollow cylinder
Cap
Chaperonin (fully assembled)
Steps of Chaperonin Action: An unfolded poly- peptide enters the cylinder from one end.
The cap attaches, causing the cylinder to change shape in such a way that it creates a hydrophilic environment for the folding of the polypeptide.
The cap comes off, and the properly folded protein is released.
Correctly folded protein
Polypeptide 2 1 3
Figure 5.23

52. Aim: How can we describe Nucleic acids and their association with life
Aim: How can we describe Nucleic acids and their association with life? Do Now: Is it good to have a very high fever? Why or why not? Homework: Review notes. Short Quiz on FRIDAY Chapters 2 and 3

53. 4. Nucleic Acids
Nucleic acids store and transmit hereditary information.
Genes:
Are the units of inheritance.
Program the amino acid sequence of polypeptides.
Are made of nucleotide sequences on DNA.

54. The Roles of Nucleic Acids
There are two types of nucleic acids:
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)

55. Deoxyribonucleic Acid DNA:
Stores information for the synthesis of specific proteins.
Found in the nucleus of cells.
Directs RNA synthesis (transcription)
Directs protein synthesis through RNA (translation)

56. The Structure of Nucleic Acids
5’ end
5’C
3’ end OH
Figure 5.26 O
Nucleic acids
Exist as polymers called polynucleotides
(a) Polynucleotide,
or nucleic acid

57. Each polynucleotide Consists of monomers called nucleotides
Sugar + phosphate + nitrogen base
Nitrogenous
base
Nucleoside O O O P
CH2
5’C
3’C
Phosphate
group
Pentose
sugar
(b) Nucleotide
Figure 5.26

58. Nucleotide Polymers Nucleotide polymers
Are made up of nucleotides linked by the–OH group on the 3´ carbon of one nucleotide and the phosphate on the 5´ carbon on the next

59. The DNA Double Helix Cellular DNA molecules:
Have two polynucleotides that spiral around an imaginary axis.
Form a double helix.

60. The DNA double helix Consists of two antiparallel nucleotide strands
3’ end
Sugar-phosphate backbone
Base pair (joined by hydrogen bonding)
Old strands
Nucleotide about to be added to a new strand A
5’ end
New strands
Figure 5.27

61. A,T,C,G The nitrogenous bases in DNA
Form hydrogen bonds in a complementary fashion (A with T only, and C with G only)

62. DNA and Proteins are Tape Measures of Evolution
Molecular comparisons
Help biologists sort out the evolutionary connections among species