Biology Chapter 5

Book Notes
The structure and Function of Large Biomolecule Molecules
4 major groups carbohydrates lipids (not made of polymers) proteins nucleic acids
Carbs, Proteins, & Nucleic Acid are huge- known as macromolecules
The architecture of a large biomolecule plays a vital role in the function

5.1 Macromolecules are polymers, built from monomers

Polymer- long molecule constituting of many similar or identical building blocks linked by covalent bonds
Made up of monomers
The synthesis and breakdown of polymers
Processes are facilitated by enzymes; specialized macromolecules that help speed up chemical reactions
Monomers are connected by a reaction which occurs when they are covalently bonded together & release a water molecule; this is known as dehydration synthesis
Polymers are disassembled into monomers by hydrolysis
The bond between the monomers is broken by the addition of a water molecule
One monomer takes a H ion and one monomer takes a OH ion
The Diversity of Polymers
The key is the arrangement, the particular sequence that the units follow

5.2 Carbohydrates Serve as Fuel and Building Material

Carbohydrates include sugars
Simplest sugars are referred to as monosaccharide’s
Disaccharides are double sugar, consisting of two monosaccharides joined by a covalent bond
Sugars
Monosaccharides generally have a molecular formula that are multiples of CH2O
Glucose = most common monosaccharide (C6H12O6)
Glucose
Contains one carboxyl group and multiple hydroxyl groups
Sugar is usually an aldose or a ketone
Placement of carboxyl group
Most names for sugars end in –ose
Classifying sugars also includes the size of the carbon skeleton,
3 to 7 carbons long
Six carbons = hexose
5 carbons = pentose
3 carbons = triose
Another source for diversity is the spatial arrangement of their parts around asymmetric carbons
Disaccharide
Two monosaccharides joined by a glycoside linkage, a covalent bond formed between two monosaccharides by a dehydration reaction
Polysaccharides
Macromolecules with a few hundred to a few thousand monosaccharide joined by glycosidic links
Storage Polysaccharides
Plants store starch
Simpliest form of startch is the amylose
It is not branched
Amylopectin is more complex starch that slightly branched
Animals store polysaccharides called glycogen
A more extensively branched version of amylopectin
Hydrolysis of glycogen in these cells release glucose when the sugar level is too low
Structural Polysaccharides
Cellulose is the most abundant organic compound on Earth
Polymer of glucose
Two ring forms
Alpha ()
Right-side uo
Beta (B)
Upside down
Cellulose is never branched
Chitin is used in surgery stitches because it is able to dissolve and let wounds heal

5.3 Lipids are a diverse group of hydrophobic molecules
Lipids are the one class that doesn’t fall under polymers
Lipids are grouped with each other because they all don’t mix well with water
Fats
Although fats are not polymers, they are large molecules assembled from smaller molecules by dehydration reaction
Fatty Acids & Glycerol
One end is a carboxyl group and the other end is a fatty acid with hydrocarbon chains in the center
C-H bonds in the middle are the reason they are hydrophobic
3 fatty acid molecules are joined to a glycerol molecule by ester linkage; a bond formed by dehydration reaction between a hydroxyl group & a carboxyl group the resulting fat is called a triacylglycerol
The fatty acids can all be the same or they can be of two or three different kinds
Saturated
No double bonds between carbon atoms then as many hydrogen atoms as possible are bonded to the carbon skeleton
Saturated with hydrogen
Fatty acid is referred to as a saturated fatty acid
Mostly animal fats
Lack double bonds so allows them to pack tightly close together
Unsaturated
One or more double bonds with one fewer hydrogen atom on each double bond carbon
All double bonds are cis bonds and therefore put kinks in the chain
Mostly plant fats
Hydrogenating vegetable