Think about Topic for your Final Paper 60 Points

1

• Think about Topic for your Final Paper (60
  Points)
• Your suggestion of topic is due by Thursday,
  Nov.13.
• FINAL PAPER is due Thursday, Dec. 11 (our last
  lecture)
• (Late Papers are NOT accepted.
• No electronic submissions)
• See back of syllabus and our class website
• for more details about Final paper
• Quiz 5 on 11/4 Quiz 6 on 12/2.
• Quiz 7 on Dec. 18, 810 am (Final Exam day)
• Your six best quiz grades count (plus miniquizzes
  and final paper)

2

• Final Paper on a plant-chemistry topic
• Length of paper About 5 pages double spaced.
• Typed preferred, but very neat, well-legible
  handwriting is accepted.
• Do include some relevant chemical structures.
• Your paper must include
• Your name, date, title
• Introduction (background to the topic), including
  relevant chemical structures
• Main body which should include your own thoughts
• A conclusion
• Sources (literature, websites etc.) with copies
  of at least one title page

3

• Today
• Discussion of Quiz 4
• Brief review of Plant Pigments
• Begin of Chemical Defense in Plants (pp. 40
  48)

4
Quiz 4. High 20 Low 0 Average 14

• Which functional group is always found in
  carbohydrates? (Write structure and name)
• OH alcohol group
• Name (just name) two sugars found in flower
  nectars.
• Glucose fructose sucrose
• Name two differences between fats and of oils
• Fats are solid at room temperature, and oils are
  liquid at room temperature
• Fats have mostly saturated hydrocarbon rests
• and oils have unsaturated (often poylunsaturated)
  hydrocarbon rests

5
Which part of a fat molecule is responsible for
its water-repelling (hydrophobic)
character? The long hydrocarbon rest What is
the meaning of unsaturated fat? There are
double bonds in the hydrocarbon rest What is
always found in the structure of fat or oil
molecules? The ester group The long hydrocarbon
rest
6
What is typical of molecules that have a smell?
(Name at least two characteristics.) They are
relatively small on a molecule scale (up to about
12 Cs They are mostly organic and mostly
hydrophobic
7
Which of the following two compounds would you
expect to have a (good or bad) smell? Give a
brief explanation.
This one. Its not too large and its a terpene
(2 isoprene units), nice smell!
CH3CH2CH2CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2
CH2 CH2 CH2 CH3?
This has no smell. It is too large (17 Cs!) to
have molecules in the gas phase at room
temperature
8
Plant Pigments

• Carotenoids water-insoluble terpenes with 40Cs
• Anthocyanins water-soluble
• Betalains water-soluble alkaloids with N in
  their structure chemically not related to
  anthocyanins
• Flavonoids water-soluble
• Tannins water-soluble
• Tannins, flavonoids and anthocyanins are
  chemically related

9
Anthocyanins

10
Betalains
in plants of the order Caryophyllales Cacti,
Portulacaceae, Chenopodiaceae, Nyctaginaceae ..
11
Flavonoids
Luteoline
12
Tannins
13
Plants Need Defenses!

• from animals snails, insects, deer
• Chemical defense?
• from fungal infections, microorganisms
• Chemical defense?
• from other plants Chemical defense?
• from temperature extremes
• Chemical defense?

14
Chemical Plant DefensesReader pp. (pp. 40 48)

• Strong odors terpenes, sulfurous compounds
• Sticky resins terpenes, carbohydrates,
• Irritants phenolics, enzymes, ...
• Defensive tastes tannins, acids,
• Toxins alkaloids, cyanogenic glycosides,
  cardenolides,

15

• Chemical principles we keep practicing while
  learning about chemical plant defenses
• Structures of organic compounds in general
• Functional groups
• Compounds with chiral carbons
• Volatile or not?
• Solubility
• Glycosides

16
Toxins
A great website http//www.ansci.cornell.edu/plan
ts/toxicagents/
17
Strong Odors
Strong odors monoterpenes, sulfurous compounds
18
Glucosinolates in plants of the Mustard (or
Cabbage) family (Brassicaceae)
a glycoside!
Insect resistance
19
Allicin from Garlic
volatile, smell..
20
Sticky Resins

• are nonvolatile, water-insoluble
• 20-carbon diterpenes and 30-carbon triterpenes.

Chiral carbons?
21
Sticky Gums
Gums polysaccharides composed of many sugar
subunits.
?-D-glucose a monosaccharide
22
Next time

• More plant defenses .