Bio 109 Macromolecules Essay

Submitted By neonbecky
Words: 2023
Pages: 9

Biological Macromolecules: Four Classes
Carbohydrates
Lipids
Proteins
Nucleic acids
1

Polymers
• Most large biological molecules are polymers • An immense diversity of polymers can be built from just a small set of monomer building blocks
• Simple parts build complex structures
2

Principles of Polymers
• Polymer: a large molecule consisting of many identical or similar subunits connected together
• Polymer: poly=many; mer=unit or part
• Most biological macromolecules are polymers
• Monomer: unit or building block molecule
• A limitless variety of polymers can be built from a small set of monomers

3

Unity and Diversity of Life
• Unity in life: only about 40­50 common monomers used to synthesize the macromolecules of all living organisms
• Diversity in life: different properties emerge in the various organisms when the monomers are arranged in different ways
4

Dehydration Synthesis (1)
• Also called condensation synthesis
• A type of polymerization reaction­­2 or more small molecules are linked to form a larger molecule with repeating structural units
• Monomers are linked covalently & 1 H2O is removed for each linkage. One monomer loses a hydroxyl (OH); the other loses a hydrogen (H)
• REQUIRES ENERGY
• REQUIRES ENZYMES
5

Dehydration Synthesis (2)

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Hydrolysis (1)
• Covalent bonds between monomers are broken by the addition of H2O
• H from the H2O bonds to one monomer;
OH bonds to the adjacent monomer
• ENERGY IS OFTEN RELEASED
• REQUIRES ENZYMES
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Hydrolysis (2)

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Dehydration Synthesis and Hydrolysis Compared

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Carbohydrates
• Organic molecules composed of sugars and their polymers • Carbohydrates serve as fuel and building materials
• Sugars serve as fuel and carbon sources
• Polysaccharides, the polymers of sugars, have storage and structural roles
• Polymers are formed by condensation synthesis reactions 10

Monosaccharides (1)
• Simple sugar: contains C, H, and O (CH 2O)
• Major nutrients for cells
• Glucose is the most common and can be produced by photosynthetic organisms
• Store energy in their chemical bonds which is harvested by cellular respiration
• Carbon skeletons are raw material for other organic molecules • Building blocks for disaccharides and polysaccharides
• Functional groups: OH attached to all but one C, which is double bonded to O (carbonyl)
11

Monosaccharides (2)

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Monosaccharides (3)
• Glucose
– straight chain and ring forms

13

Disaccharides (1)
• 2 monosaccharides joined by a glycosidic linkage (covalent bond formed during condensation synthesis)
• Maltose: glucose + glucose
• Lactose: glucose + galactose
• Sucrose: glucose + fructose
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Disaccharides (2)

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Polysaccharides (1)
• Macromolecules: polymers of a few 100’s to 1000’s of monosaccharides
• Formed by enzyme­mediated condensation synthesis • Functions:
– Energy storage (starch & glycogen)
– Structural support (cellulose & chitin)
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Polysaccharides (2)
• Storage polysaccharides: starch







Plant storage molecule
Polymer of glucose: helical with  1­4 linkages
Stored within organelles called plastids
Amylose: simplest, unbranched polymer
Amylopectin: branched polymer
Most animals have digestive enzymes to hydrolyze starch – Major dietary sources: grains, potatoes
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Polysaccharides (3)
• Starch Granules
– Figure 5.6
– Transmission electron micrograph – Bright white material

18

Polysaccharides (4)
• Storage polysaccharides: glycogen
– Animal storage molecule
– Large polymer: highly branched with  1­4 and
4­6 linkages
– Stored in muscle and liver of humans and other vertebrates – Sometimes called animal starch
19

Polysaccharides (5)
• Glycogen: tem, dark stained granular material

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Polysaccharides (6)
• Storage polysaccharides – Structural models

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Polysaccharides (7)
• Structural polysaccharides: cellulose
– Linear, unbranched polymer of glucose in  1­4 linkages – Major structural component of plant cell walls
– Hydrogen bonds hold parallel…