Today: • Quiz 3 Discussion • My office hours: Tu 10 -11, Th 1 - 2 in Science 106 C • Family Science Night, Wednesday, Oct. 22, 6 - 9pm at Oak Grove Middle School in Concord! • “Primary Metabolites”: • Carbohydrates • Fats and Oils • Amino acids and proteins
Quiz 3 Answers High: 22 Low: 8 Average: 18.2 Write the formula for: calcium hydroxide (OH-) Ca(OH)2 magnesium nitrate (NO3- ) Mg(NO3)2 calcium carbonate (CO32- ) CaCO3 potassium phosphate (PO43- ) K3PO4 sodium sulfate (SO42- )Na2SO4
Draw the structures for two (three?) isomers of C5H12/of C4H8 a) Name two signs that a chemical reaction must have occurred (anywhere, in a lab or in a living organism). b) What is special about chemical reactions in plants? Mention at least two aspects. a) Which two products are always formed in a complete combustion of hydrocarbons (i.e. in the presence of plenty of oxygen)? b) Which two products are always formed during a fermentation? b) Which two products are always formed as a result of photosynthesis?
Primary and Secondary Metabolites • Primary metabolites: Organic metabolites that are found in all plants (and all animals) • Sugars, carbohydrates Provide energy ( have other functions, too...) • Functional groups, more on isomers • Fats and oils Provide protection and energy • Amino acids Building blocks of proteins • (More about these when we address “Plants and Foods”.) • Secondary metabolites: unique to some plants • Plant odors. Pigments. Defensive compounds.
Primary Metabolites:Carbohydrates Cx(H2O)xglucose, sucrose, fructose, lactose, cellulose…. • Carbohydrates (“Sugars”) • are composed of C, H, O • are organic compounds with lots of O-H functional groups • Functional groups are attachments to the carbon skeleton. They have typical chemical reactions.
Glucose has other molecular shapes as well…
Molecules that can be left-handed or right-handed: Asymmetric Molecules “Chiral Molecules”Optical Isomers A CH CH 3 3 H H B C C C COOH OH OH HOOC D E a chiral molecule Lactic acid mirror image Enantiomers = Mirror images
Many Functions of Glucose in Plants! • can be broken down during aerobic respiration to provide energy and high–energy compounds, such as ATP, to do further chemical work.
Functions of Glucose • can be converted into starch for later use(bulbs in Mediterranean climate!)
Functions of Glucose: • Is needed to compose cellulose in plants
Functions of Glucose • Required for the biosynthesis • of other carbohydrates (like starch and cellulose) • of fats and oils • of amino acids (building blocks of proteins) • Involved in the biosynthesis of all organic compounds in plants!
Functions of Glucose • Molecules that are poorly soluble in water can become better soluble • if glucose is bonded to them • making them “Glycosides” Examples: Cardiac Glycosides in Milkweed, Digitalis In conclusion: Glucose has many functions in plants!
Summary of functions of carbohydrates in plants (glucose and others) • Required for biosynthesis of all other organic plant molecules • Storage of energy (starch, other sugars) • Provide structure (cellulose) • Make other molecules water-soluble (glycosides) • Sweeten ripe fruit • Freeze-protection • Sticky gums as defense • Attract pollinators with sweet nectar
Practice:Can you find any chiral carbons in the molecules below? Mark them with * CH4 OH H C - C - COOH 3 H Lactic acid
Next class: More on “Primary Metabolites”: “Lipids. Fats and Oils”