AP Biology 2006-2007

Life Substances

The Role of Carbon

AP Biology

Cells Composed of 70-95% water the rest is

made up of CARBON based compounds Molecules that contain CARBON are

said to be ORGANIC Examples: methane, carbon dioxide,

proteins

AP Biology

Carbon’s Reactivity Carbon (C) appears in the 2nd row of the

periodic table and has 4 bonding electrons in its valence shell. Can form 4 bonds with other atoms

(each bond consisting of one of the carbon’s electrons and one of the bonding atom’s electrons)

These bonds form a tetrahedron A pyramid with a spike at the top and

angles of 109°

AP Biology

Hydrocarbons Simplest organic compound Gets its name because it only contains

hydrogen and carbon atoms Examples:

Methane Ethane Hexane Isohexane Cyclohexane

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Carbon Bonds

Single bonding Double bonding

Triple bonding

There appears to be no limit to the number of different structures carbon can form…

Keep in mind carbon can form 4 bonds. So, as the number of bonds between carbon atoms increases, the number of

hydrogen atoms decreases

AP Biology

Simple Hydrocarbons Alkanes carbon-carbon (single bond)

Chemical formula: CnH2n+2

All enter combustion reactions with oxygen to produce CO2 and water vapor

They are flammable!

Alkenes carbon = carbon (double bond) Chemical formula: CnH2n

Alkynes carbon carbon=carbon (triple bond) Chemical formula: CnH2n-2

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Isomers Structures that have identical chemical

formulas but their structural formulas are different Different chemical properties too

Because carbon can bond in so many ways, a single molecule can have different bonding configurations

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Structural Isomers two substances

having the same molecular formula but different physical and chemical properties because the arrangement of their component atoms is different.

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Geometric Isomers A chemical compound

having the same molecular formula as another but a different geometric configuration, as when atoms or groups of atoms are attached in different spatial arrangements on either side of a bond or a ring.

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Enantiomers Two substances

having the same molecular formula but they are mirror images of one another.

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What type of isomer are these?

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Functional Groups Hydroxyl – OH

These are referred to as alcohols

The existence of a functional group completely changes the chemical properties of a molecule

Example: Ethane (2C alkane): gas at room temp Ethanol (2C alcohol): liquid at room temp

Common drinking alcohol active ingredient in “alcoholic” beverages such as beer and wine

AP Biology 2006-2007

OH

OH

H

H

HO

CH2OH

HH

H

OH

O

Carbohydratesenergy

molecules

AP Biology

Carbohydrates

AP Biology

Carbohydrates Carbohydrates are composed of C, H, O

carbo - hydr - ate

General formula: CH2O

(CH2O)x C6H12O6

Function: energy energy storage raw materials structural materials

Monomer (building block): sugars

ex: sugars, starches, cellulose

sugar sugar sugar sugar sugar sugar sugarsugar

AP Biology

Sugars Most names for sugars end in -ose Classified by number of carbons

6C = hexose (glucose) 5C = pentose (ribose) 3C = triose (glyceraldehyde)

OH

OH

H

H

HO

CH2OH

HH

H

OH

O

Glucose

H

OH

HO

O H

HHO

H

Ribose

CH2OH

Glyceraldehyde

H

H

H

H

OH

OH

O

C

C

C6 5 3

AP Biology

Sugar structure5C & 6C sugars form rings in solution

Carbons are numberedCarbons are numbered

Where do you find solutions?

In cells!

AP Biology

Numbered carbons

C

CC

C

CC

1'

2'3'

4'

5'

6'

O

energy stored in C-C bondsenergy stored in C-C bonds

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Simple & complex sugars Monosaccharides

simple 1 monomer sugars glucose

Disaccharides 2 monomers sucrose

Polysaccharides large polymers starch

OH

OH

H

H

HO

CH2OH

H

H

H

OH

O

Glucose

AP Biology

Dehydration Synthesis=Dehydration Synthesis=PolymerizationPolymerization

Remove H2O2 Monomers Bond=

Polymer

Anabolic reactionAnabolic reactionProduces polymerProduces polymerMonomer + Monomer Monomer + Monomer Polymer + Water Polymer + Water

AP Biology

Building sugars Dehydration synthesis

glycosidic linkage

|glucose

|glucose

monosaccharides disaccharide

|maltose

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Building sugars Synthesis

|fructose

|glucose

monosaccharides

|sucrose

(table sugar)

disaccharide

Let’s go to the videotape!

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Catabolic reactionCatabolic reactionProduces monomersProduces monomers

Ex) PolysaccharidesEx) Polysaccharides monosaccharides monosaccharides

Polymer + Water Polymer + Water Monomer + Monomer Monomer + Monomer

HydrolysisHydrolysis

Add H2OSeparate polymer into:

2 monomers

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Polysaccharides Polymers of sugars

costs little energy to build easily reversible = release energy

Function: energy storage

starch (plants) glycogen (animals)

structure = building materials cellulose (plants) chitin (arthropods & fungi)

AP Biology

Linear vs. branched polysaccharides

starch(plant)

glycogen(animal)

energystorage

What doesbranching do?

Let’s go to the videotape!

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Polysaccharide diversity Molecular structure determines function

isomers of glucose structure determines function…

in starch in cellulose

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Digesting starch vs. cellulose

starcheasy todigest

starcheasy todigest

enzyme

enzyme

cellulosehard todigest

cellulosehard todigest

AP Biology

Cellulose Most abundant organic

compound on Earth herbivores can digest cellulose most carnivores cannot digest cellulose

that’s why they eat meat to get their energy & nutrients

cellulose = roughage

BIG DEAL!Who can live

on this stuff?!

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Cowcan digest cellulose well; no need to eat other sugars

Gorillacan’t digest cellulose well; must add another sugar source, like fruit to diet

AP Biology

Helpful bacteria How can cows digest cellulose?

bacteria live in their gut & help digest cellulose-rich (grass) meals

AP Biology 2006-2007

Let’s build some

Carbohydrates!