1. The Chemicals of Life Part 1

2. Why study Carbon? All living things are made of cells Cells ~72% H2O
~3% salts (Na, Cl, K…)
~25% carbon compounds
carbohydrates
lipids
proteins
nucleic acids
Why do we study carbon -- is it the most abundant element in living organisms?
H & O most abundant
C is the next most abundant

3. Chemistry of Life
Organic chemistry is the study of carbon compounds (in living things)
C atoms are versatile building blocks
bonding properties
4 stable covalent bonds
Carbon chemistry = organic chemistry
Why is it a foundational atom?
What makes it so important?
Can’t be a good building block if you only form 1 or 2 bonds.

4. Hydrocarbons Simplest C molecules = hydrocarbons
combinations of C & H
Simplest HC molecule = methane
1 carbon bound to 4 H atoms
non-polar
not soluble in H2O
hydrophobic
stable
very little attraction between molecules
a gas at room temperature

5. Hydrocarbons can grow adding C-C bonds straight line branching ring
methane
ethane
adding C-C bonds
straight line
ethane
hexane
branching
isohexane
ring
cyclohexane
hexane
isohexane
cyclohexane

6. Diversity of organic molecules

7. Isomers Molecules with same molecular formula but different structures
different chemical properties
Same formula but different structurally & therefore different functionally. Molecular shape determines biological properties.
Ex. Isomers may be ineffective as medicines

8. Structural isomers
Molecules differ in structural arrangement of atoms

9. Geometric isomers
Molecules differ in arrangement around C=C double bond
same covalent partnerships

10. Enantiomer (stereo) isomers
Molecules which are mirror images of each other
C bonded to 4 different atoms or groups
assymetric
left-handed & right-handed versions
“L” versions are
biologically active

11. Form affects function
Structural differences create important functional significance
amino acid alanine
L-alanine used in proteins
but not D-alanine
medicines
L-version active
but not D-version
sometimes with tragic results…

12. Form affects function Thalidomide
prescribed to pregnant women in 50’s & 60’s
reduced morning sickness, but…
stereoisomer caused severe birth defects

13. Diversity of molecules
Substitute other atoms or groups around the C
ethane vs. ethanol
H replaced by an hydroxyl group (–OH)
nonpolar vs. polar
gas vs. liquid
ethane
ethanol

14. Functional groups
Components of organic molecules that are involved in chemical reactions
give organic molecules distinctive properties
ex: male & female hormones…

15. Viva la difference!
Basic structure of male & female hormones is identical
identical C skeleton
attachment of different functional groups
interact with different targets in the body
For example the male and female hormones, testosterone and estradiol, differ from each other only by the attachment of different functional groups to an identical carbon skeleton.

16. Types of functional groups
6 functional groups most important to chemistry of life: (p.25)
hydroxyl u amino
carbonyl u sulfhydryl
carboxyl u phosphate
Affect reactivity
hydrophilic
increase solubility in water

17. Hydroxyl –OH (do not confuse this with (OH)-!!)
organic compounds with OH = alcohols
names typically end in -ol
ethanol

18. Carbonyl C=O O double bonded to C if C=O at end molecule = aldelhyde
if C=O in middle of molecule = ketone

19. Carboxyl –COOH C double bonded to O & single bonded to OH group
compounds with COOH = acids (e.g., acetic acid)
fatty acids
amino acids

20. Amino -NH2 N attached to 2 H compounds with NH2 = amines
amino acids
NH2 acts as base
ammonia picks up H+ from solution

21. Sulfhydryl –SH S bonded to H compounds with SH = thiols
SH groups stabilize the structure of proteins

22. Phosphate –PO4 P bound to 4 O connects to C through an O
PO4 are anions with 2 negative charges
function of PO4 is to transfer energy between organic molecules (ATP)

23. Why study Functional Groups?
These are the building blocks for biological molecules

24. HOMEWORK
Read and make notes 1.1
p. 17 #1-2, 4-7, 9, 11

25. Macromolecules
Smaller organic molecules join together to form larger molecules
macromolecules
4 major classes of macromolecules:
carbohydrates
lipids
proteins
nucleic acids

26. Polymers
Long molecules built by linking chain of repeating smaller units
polymers
monomers = repeated small units
covalent bonds
• great variety of polymers can be built from a small set of monomers
• monomers can be connected in many combinations like the 26 letters in the alphabet can be used to create a great diversity of words
• each cell has millions of different macromolecules

27. How to build a polymer Condensation reaction Aka dehydration synthesis
joins monomers by “taking” H2O out
1 monomer provides OH
the other monomer provides H
together these form H2O
requires energy & enzymes

28. How to break down a polymer
Hydrolysis
use H2O to break apart monomers
reverse of condensation reaction
H2O is split into H and OH
H & OH group attach where the covalent bond used to be
This process releases energy
ex: digestion is hydrolysis
Most macromolecules are polymers
• build:
condensation (dehydration) reaction
• breakdown:
hydrolysis
An immense variety of polymers can be built from a small set of monomers

29. Carbohydrates

30. Carbohydrates Carbohydrates are composed of C, H, O carbo - hydr - ate
CH2O (empirical formula)
(CH2O)x  C6H12O6
Function:
energy u energy storage
raw materials u structural materials
Monomer: simple sugars (e.g., glucose)
ex: sugars & starches
carb = caron
hydr = hydrogen
ate = oxygen compound

31. Sugars
All monosaccharides can be distinguished by the carbonyl group they possess (aldehyde or ketone) along with the # of C in the backbone
6C = hexose (glucose)
5C = pentose (fructose, ribose)
3C = triose (glyceraldehyde)

32. What functional groups?
carbonyl
aldehyde
ketone
hydroxyl

33. Sugar structure 5C & 6C sugars form rings in aqueous solutions
in cells!
Carbons are numbered

34. Sugar Structure cont’d
When glucose becomes aqueous, there is a 50% chance that the –OH group at C1 will end up below the plane of the ring. If so, it is called α-glucose.
If the –OH group at C1 ends up above the plane of the ring, then it becomes β-glucose.

35. Numbered carbons C 6' C O 5' C C 4' 1' C C 3' 2'

36. Simple & complex sugars
Monosaccharides
simple 1 monomer sugars
glucose
Disaccharides
2 monomers
sucrose
Polysaccharides
large polymers
starch

37. Complex Sugars
All sugars are made up of monosaccharides held together by glycosidic linkages.
Glycosidic linkages are the covalent bonds that hold 2 monosaccharides together and are formed by condensation reactions in which the H atom of the hydroxyl group comes from one sugar and the –OH group comes from the hydroxyl group of the other.

38. Building sugars Dehydration synthesis monosaccharides disaccharide |
maltose |
glucose |
glucose |
maltose
glycosidic linkage

39. Building sugars Dehydration synthesis monosaccharides disaccharide |
sucrose = table sugar |
glucose |
fructose |
sucrose
structural isomers
glycosidic linkage

40. Polysaccharides Polymers of sugars Function:
costs little energy to build
easily reversible = release energy
Function:
energy storage
starch (plants)
glycogen (animals)
building materials = structural support
cellulose (plants)
chitin (arthropods & fungi)
Humans and other organisms use plants’ stockpile of energy as a food source for themselves.
Polysaccharides are polymers of hundreds to thousands of monosaccharides

41. Branched vs linear polysaccharides
Can you see the difference between starch & glycogen?
Which is easier to digest?
Glycogen = many branches = many ends
Enzyme can digest at multiple ends. Animals use glycogen for energy storage == want rapid release.
Form follows function.

42. Polysaccharide diversity
Molecular structure determines function
isomers of glucose
How does structure influence function…

43. Digesting starch vs. cellulose
Starch = all the glycosidic linkage are on same side = molecule lies flat
Cellulose = cross linking between OH (H bonds) = rigid structure

44. Cow
can digest cellulose well; no need to eat supplemental sugars. Have symbiotic bacteria that produce enzymes.
Gorilla
can’t digest cellulose well; must supplement with sugar source, like fruit

45. Cellulose
Most abundant organic compound on Earth (polymer of β-glucose)
Used by plants to create the cell wall
Humans are not able to break the glycosidic linkages in cellulose and therefore we cannot digest it.
Cross-linking between polysaccharide chains:
= rigid & hard to digest
The digestion of cellulose governs the life strategy of herbivores.
Either you do it really well and you’re a cow or an elephant (spend a long time digesting a lot of food with a little help from some microbes & have to walk around slowly for a long time carrying a lot of food in your stomach)
Or you do it inefficiently and have to supplement your diet with simple sugars, like fruit and nectar, and you’re a gorilla.

46. Homework
Read and make notes 1.2
p.21 #7-9, 11, 12