How To Make Biological Molecules(Ch. 5)

Macromolecules• Smaller organic molecules join together to

form larger molecules– macromolecules

• 4 major classes of macromolecules:– carbohydrates– lipids– proteins– nucleic acids

H2O

HO

HO H

H HHO

Polymers• Long molecules built by linking repeating

building blocks in a chain – monomers

• building blocks• repeated small units

– covalent bonds

Dehydration synthesis

H2O

HO

HO H

H HHO

How to build a polymer• Synthesis

– joins monomers by “taking” H2O out• one monomer donates OH–

• other monomer donates H+ • together these form H2O

– requires energy & enzymes

enzymeDehydration synthesisCondensation reaction

You gotta be open to“bonding!

H2O

HO H

HO H HO H

How to break down a polymer• Digestion

– use H2O to breakdown polymers • reverse of dehydration synthesis• cleave off one monomer at a time• H2O is split into H+ and OH–

– H+ & OH– attach to ends

– requires enzymes– releases energy

Breaking upis hard to do!

HydrolysisDigestion

enzyme

2007-2008

Any Questions??

OH

OH

H

H

HO

CH2OH

HH

H

OH

O

Carbohydratesenergy

molecules

Carbohydrates• Carbohydrates are composed of C, H, O

carbo - hydr - ateCH2O

• Function:– energy – energy storage– raw materials – structural materials

• Monomer: sugars• ex: sugars, starches, cellulose

sugar sugar sugar sugar sugar sugar sugarsugar

C6H12O6(CH2O)x

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

HOH

O

Glucose

H

OH

HO

O H

HHO

H

Ribose

CH2OH

Glyceraldehyde

H

H

H

H

OH

OH

OC

C

C6 5 3

Functional groups determine function

carbonyl

ketone

aldehyde

carbonyl

Sugar structure5C & 6C sugars form rings in solution

Carbons are numbered

Where do you find solutions

in biology?In cells!

Numbered carbons

C

CC

C

CC

1'

2'3'

4'

5'6'

O

energy stored in C-C bonds

Simple & complex sugars• Monosaccharides

– simple 1 monomer sugars– glucose

• Disaccharides– 2 monomers– sucrose

• Polysaccharides – large polymers– starch

OH

OH

H

H

HO

CH2OH

HH

H

OH

O

Glucose

Building sugars• Dehydration synthesis

glycosidic linkage

|glucose

|glucose

monosaccharides disaccharide

|maltose

H2O

Building sugars• Dehydration synthesis

|fructose

|glucose

monosaccharides

|sucrose

(table sugar)

disaccharide

Let’s go to the videotape!

H2O

Polysaccharides • Polymers of sugars

– costs little energy to build– easily reversible = release energy

• Function:– energy storage

• starch (plants)• glycogen (animals)

– in liver & muscles

– structure• cellulose (plants)• chitin (arthropods & fungi)

Linear vs. branched polysaccharides

starch(plant)

glycogen(animal)

energystorag

e

What doesbranching do?

Let’s go to the videotape!

slow release

fast release

Polysaccharide diversity

• Molecular structure determines function

isomers of glucose structure determines function…

in starch in cellulose

Digesting starch vs. cellulose

starcheasy todigest enzyme

enzyme

cellulosehard todigest

Cellulose • Most abundant organic

compound on Earth– herbivores have evolved a mechanism to digest

cellulose– most carnivores have not

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

• cellulose = undigestible roughage

But it tasteslike hay!

Who can liveon this stuff?!

Chitin, a different structural polysaccharide

(a) The structure of the chitin monomer.

OCH2OH

OHH

H OH

H

NH

C

CH3

O

H

H

(b) Chitin forms the exo- skeleton of arthropods. This

cicada is molting, shedding its old exoskeleton and emergingin adult form. It is also found in

Fungal Cell Walls.

(c) Chitin is used to make a strong and flexible surgical

thread that decomposes after the wound or incision heals.

OH

Cowcan digest cellulose well; no need to eat other sugars

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

Helpful bacteria• How can herbivores digest cellulose so well?

– BACTERIA live in their digestive systems & help digest cellulose-rich (grass) meals

RuminantsTell me aboutthe rabbits,

again, George!

I eatWHAT!

Caprophage

2006-2007

Let’s build some

Carbohydrates!

EATX

Review Questions

1. Polymers of glucose units are used as temporary food storage in both plant and animal cells. Glucose units are connected to one another by 1, 4-linkages to make a linear polymer and by 1, 6-linkages to make branch points.

• (cont.) Polysaccharides of glucose unitsvary in size. The three most commonly encountered are:

Type of Starch

Cell Type Polymer Size

Average Number of 1,4-Bonds Between Branches

Amylopectin Plant 100,000,000 24 to 30

Amylos Plant 500,000 Linear Glycogen Animal 3,000,000 8 to 12

• (cont.) When each polymer bond is made, a water molecule is released and becomes part of the cell water. How many water molecules were released during formation of each of the Glycogen?A. 1,000,000B. 2,000,000C. 2,666,666D. 3,000,000E. 3,300,000

2. Which of the following is a polymer?

A. Simple sugar (aka monosaccharide)B. Carbon atomsC. GlucoseD. CelluloseE. deoxyribose

3. Starch and Glycogen bothI. Serve as energy storage for

organismsII. Provide structure and supportIII. Are structural isomers of glucose

A. I onlyB. II onlyC. I and II onlyD. I and III onlyE. I, II, and III