CHAPTER 5: MORE DETAILED
All living things contain four main classes of large molecules know as carbohydrates, lipids, proteins, and nucleic acids.
Polymer: a long molecule consisting of many similar and identical building blocks linked by covalent bonds.
Monomers: building blocks that form polymers. In other to synthesis and break down these polymers two processes are required:
Condensation/dehydration reaction: involves a removal of a water molecule to form a bond between two or more monomers. (Facilitated by enzymes)
Hydrolysis: process that involves the addition of water to polymers in other to break the linkages between two or more monomers. Carbohydrates/sugars: made up of monosaccharides (one sugar), disaccharides (two sugars), and polysaccharides (many sugars). Main function of a carbohydrate is short-term energy storage—this is why people crash after going on a sugar run. They also help a great deal in cellular respiration. They also serve as structure components in living cells.
Ketone sugars/ ketoses: defines sugars whose carbonyl groups are found on the inside of a sugar molecule (Fructose).
Aldehyde sugars/ aldoses: defines sugars whose carbonyl groups are found on the outside of a sugar molecule (Glucose).
Glycosidic linkage: linkages found in all disaccharides and polysaccharides.
Triose: three-carbon sugars.
Pentose: five-carbon sugars.
Hexose: six-carbon sugars.
Starch: a polymer of glucose monomers of alpha configuration that function as granules within the cell structures of plants. Two forms of starch are amylose (unbranched) and amylopectin (branched).
Glycogen: a polymer of glucose found in animal muscle and liver cells.
Why are low carb diets bad?
Cellulose: major component of the cell walls in plants; most abundant organic molecule on earth; Cellulose cannot be digested by human beings because it’s made of beta configuration of glucose monomers— the enzymes in our body that breaks down sugar are all of alpha configuration; however fungi, bacteria can.(Cows can break down cellulose because they have bacteria that have enzymes that could break down cellulose. The difference in configuration explains the reason why starch is mostly helical and cellulose is straight.
Chitin:
Carbohydrate used by arthropods to build their exoskeletons, also used as surgical threads that decomposes after the wound or incision heals. Also found in the cell walls of fungi.
Lipids: biological molecules made up of compounds that are hydrophobic, and non-polar. They’re not to be considered macromolecules because the can only expand to three linkages. See fig. 5.11.
Fats:
Constructed from two kinds of smaller molecules: glycerol and fatty acids.
Fatty acids: contain a long carbon skeleton usually 16 to 18 carbon atoms in length. They are hydrophobic because of the non-polar C—H bonds in the hydrocarbon chains of fatty acids.
Ester linkage: defines a linkage that joins fatty acid to glycerol. It’s a bond between hydroxyl and carboxyl groups. Triacylglycerol: Formed by three fatty acids linked to one glycerol molecule.
Saturated Fat: no double bonds in hydrocarbon chain therefore solid. (Butter)
Unsaturated Fat: double bond(s) exist in hydrocarbon chain therefore liquid. (Vegetable oil)
Tran-saturated Fat: Unsaturated fat converted to saturated fat by the addition of hydrogen to the hydrocarbon chain. (Peanut butter)
Fats are good for long-term energy storage. A gram of fat stores twice as much energy as a gram of a polysaccharide.
Fat in humans and other mammals is stored in the adipose cells.
What is sexual dimorphism?
Phospholipids: Essential for cells because they make up the cell membrane; Phospholipids are made from adding a phosphate group to the fatty-acid molecule. The phosphate group makes a lipid hydrophilic.
Steroids: Lipids known by their four fused rings that serve as important hormones in the human body. (Cholesterol, testosterone, and estrogen)
Protein: Protein means