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What is a monomer?
Repeating subunits used to build substances.
What is a polymer?
Large molecules consisting of many repeating subunits of monomers.
What does hydrolysis mean, and what does it define?
It is Greek for "break using water".  It describes a process in which a polymer is disassembled into monomers in the reverse of a dehydration reaction.
Describe a dehydration reaction.
The connecting of monomers via a reaction in which two molecules are covalently bonded to each other through loss of a water molecule.
How are dehydration reactions related to condensation reactions?
A dehydration reaction is a specific form of condensation reaction in which the loss of a water molecule is the cause of two molecules being covalently bonded.
What do you call the breaking down of a polymer into monomer via the adding of water?
This process is known as hydrolysis, it is the opposite of a dehydration reaction.
What is a carbohydrate?
Are sugars, usually polymers.
What is the empirical formula for a monosaccharide?
What is the most common monosaccharide and what is its molecular formula?
The most common monosaccharide is glucose, its molecular formula is C6H12O6.
What are disaccharides and what are they composed of?
It''s Greek for "double sugar", it consists of two monomers joined by glycosidic linkage.
What is glycosidic linkage?
It is a covalent bond formed between two monosaccharides by a dehydration reaction.
What is the storage polysaccharide found in plants?  What is it?
Starch.  It is a polymer of glucose monomers.
Where is starch found within a cell?
They are found within plastids, which include chloroplasts.
What is the storage polysaccharide found in animals?  What is it?
Glycogen.  It is a polymer of of glucose that is similar to amylopectin, but more extensively branched.
Where is glycogen found?
Within vertebrates it is stored in the liver and muscle cells.
How long can glycogen exist in the human body without the consumption of food?  Is this problematic, if so where?
About a day.  This is a concern in low-carbohydrate diets.
What is a storage polysaccharide?
It is a sugar that can be stored in animal and plant cells to be withdrawn when needed by hydrolysis.
What process breaks down polysaccharides and what does it break down to?
Hydrolysis breaks down storage polysaccharides into their component glucose monomers.
What is a structural polysaccharide?
A form of polymer used by organisms to make strong materials.
Name two structural polysaccharides, and where they are found.

  • Cellulose, it is a major component of the tough walls that enclose plant cells.

  • Chitin, the carbohydrate used by arthropods to build their exoskeletons.

What is the difference between cellulose and starch?

  • A cellulose molecule is a 1-4 linkage β glucose polymer

  • A starch molecule is a 1-4 linkage α glucose polymer.

What is the difference between α glucose and β glucose?

  • In α glucose the hydroxyl group on the 1-carbon is placed below the the plane of a glucose ring.

  • In β glucose the hydroxyl group on the 1-carbon is placed above the plane of a glucose ring.

Where as _____ molecule is mostly _____, a cellulose molecule is _____.

  • Starch

  • helical

  • straight

What is a microfibril?
Cable-like parallel cellulose molecules found in plant cell walls.
What causes microfibrils?
Cellulose molecules are never branched, some hydroxyl groups on the strand can hydrogen bond with cellulose molecules lying in parallel to it.
What is the defining characteristic of lipids.
They mix poorly, if at all, with water.
Are lipids polymers?
What are the three most biologically important lipids?

  • Fats

  • Phospholipids

  • Steroids

What are the two smaller kinds of molecules that construct fats?

  • Glycerol

  • Fatty Acids

What is a fatty acid?
A carboxyl group attached to one end of a carbon skeleton, typically 16 to 18 carbon atoms long.
Why are fats hydrophobic?
Because of the relatively non-polar C-H bonds in their hydrocarbon chains.
Why do fats separate from water?
Because water molecules hydrogen bond to one another and exclude fats.
What is an ester linkage?
A bond between a hydroxyl and a carboxyl group.
What is a triacylglycerol and how is it formed?
It is a fat made of three fatty acid molecules join to glycerol via an ester linkage.
What three aspects do fatty acids vary in?

  • Length

  • Number of double bonds

  • Locations of double bonds

What is a saturated fatty acid?
It is fatty acid in which there are no double bonds, allowing for the maximum number of hydrogens saturating the molecule.
What is an unsaturated fatty acid?
A fatty acid with one or more double bonds formed by a removal of hydrogen atoms from the carbon skeleton.
In a fatty acid with a double bond in the hydrocarbon chain, how does it affect the acid''s structure?
It forms a kink in the hydrocarbon chain forming a cis double bond.
What types of fats are found in animals?  What types of fats are found in plants?
Most animal fats are saturated, the fats of fish and plants are usually unsaturated.
What structural formation causes saturated fats to be solid at room temperature?
The tails of saturated fats lack double bonds making the molecule more flexible, allowing the fat molecules to pack together tightly.
What is a hydrogenated vegetable oil?
Unsaturated fats that have been synthetically converted to saturated fats by the addition of hydrogen.
What is tans fats?
Unsaturated fats with trans double bonds.
A gram of fat stores how much energy in relation to polysaccharides?
Twice as much.
What purpose does an adipose cell serve?  What secondary purpose does this cell serve?

  • It''s where humans and other mammals stock their long term food resources.

  • Adipose tissue also cushions vital organs such as the kidneys and the layer beneath the skin insulates the body.

Why can plants contain bulky energy storage in the form of starch?
Because they''re not going anywhere.
Why are phospholipids vital to cells?
They make up cell membranes.
What are the two structural differences between fatty acids and phospholipids?

  • Has two fatty acids attached to glycerol instead of three.

  • The third hydroxyl group of glycerol is attached to a phosphate group.

What affect does the phosphate group in phospholipids have on the molecule?
It allows additional small molecules, usually charged or polar, to be linked to the molecule.  The phosphate end is hydrophilic, whereas the hydrocarbon tails are hydrophobic.
What happens when phospholipids when they are added to water?
They self-assemble into double-layered aggregates-bilayers-that shield their hydrophobic portions from water.  This is what protect the interior of the cells from its external environment.
What are steroids?
Lipids characterized by a carbon skeleton consisting of four fused rings.
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