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Chapter 5 The Structure and Function of Macromolecules

Some believe…

¢ Primitive Earth provided inorganic precursors from which organic molecules could have been synthesized due to the free energy and absence of a significant quantity of oxygen

¢  In turn, these molecules served as building blocks for the formation of more complex molecules

Fig. 4-2

Water vapor

H2 NH3

“Atmosphere”

Electrode

Condenser

Cold water

Cooled water containing organic molecules

Sample for chemical analysis

H2O “sea”

EXPERIMENT

CH4

•  1953 – Miller set up a closed system to simulate conditions though to have existed on early Earth

•  These complex reaction sets could have occurred in solution (organic soup) or as reactions on solid reactive surfaces

Introductory Terms

¢  Macromolecule ¢  Monomer

l  Example: •  Lego block •  letters

¢  Polymer l  Example:

•  Lego castle •  words

Reaction Types

¢ Hydrolysis** ¢ Dehydration** ¢ Endergonic ¢ Exergonic ¢ Redox (OIL RIG)

Macromolecular Reactions J

¢  Dehydration Synthesis:

¢  Hydrolysis:

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4 Macromolecules (polymers) fall into 4 major groups

1.  Carbohydrates 2.  Lipids 3.  Proteins 4.  Nucleic Acids

Carbohydrates

¢ Structure: l C:H:O in a 1:2:1 Ratio l Example: C6H12O6

¢ Functions: l Short-term energy storage

•  Pasta dinner before the big race, game, etc.

l Structural Support

Carbohydrate Types

¢ Monosaccharide ¢ Disaccharide ¢ Polysaccharide ¢ Pentose ¢ Polysaccharide Structural molecules

Carbohydrates

¢  Monosaccharides: l  “one sugar” l  C:H:O Ratio =

1:2:1 l  Simple ring

sugars l  Examples:

•  Glucose and fructose

Carbohydrates

¢  Disaccharides: l  “double sugar” l  2 monosaccharides

joined together by dehydration synthesis

l  Example: •  Sucrose •  Lactose

Carbohydrates

¢  Polysaccharides l  Polymers – lots of

monosaccharides are linked together

l  Starch and glycogen are examples

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Pentose - carbs ¢  5 carbon sugars

Structural Carbohydrates

¢  Structural Polysaccharides l  Cellulose l  Chitin

Lipids - Fats ¢  Structure:

l  C, H, O l  Hydrophobic (insoluble)

¢  Functions: l  Insulation and long-term energy storage

¢  Types: l  Fats & Oils l  Waxes l  Phospholipids l  Steroids

Fats ¢ Structure:

dehydration synthesis

Lipids

¢ Examples l Glycerol l Triglycerol

Lipids – saturated vs. unsaturated

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Lipids - phospholipids Phospholipids in water

Lipids - steroids

2005-2006

From Cholesterol → Sex Hormones ¢  What a big difference a little atom can make!

Proteins

¢  Most of a cell is made up of proteins ¢  Instrumental in almost everything

organisms do ¢  Structure:

l All proteins are created from unique combinations

l C,H,O,N l Amino acids

•  Peptide bonds

Proteins - function ¢  Major Functions:

l  Structure (keratin in hair & nails) l  Motion (actin & myosin in muscles) l  Transport (hemoglobin transports oxygen) l  Signaling (hormones can signal cells to

respond) l  Defense (antibodies) l  Enzymes (speed up chemical reactions by

lowering activation energy)

l  **(Energy (last resort for humans) 4 Cal/g)**

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¢  A protein is one or more polypeptides precisely twisted, folded and coiled into a molecule of unique shape (3-D)

¢  4 shapes l Primary l Secondary l Tertiary l Quaternary

Protein structure Protein - structure

Proteins ¢  Denaturation:

l  When pH, salt concentration, extreme heat, and/or other environmental factors are altered, the protein may unravel and lose its shape

l  Biologically inactive l  Structure + function l  (A change in

structure alters function)

protein denatured video

Nucleic Acids

Informational polymers made of : l  Nucleotides:

1.  Sugar 2.  Phosphate 3.  Nitrogen base (A, T, G, C, U*)

l  CHNOPS

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Nucleic Acids Nucleic Acids - differences

¢  RNA is single stranded; DNA is double stranded

¢  RNA has uracil instead of thymine ¢  RNA has ribose sugar, & DNA has

deoxyribose sugar. Functions: DNA serves as the genetic code for production

of proteins. RNA- DNA’s helper