Chapter 5 Flashcards
What is a macromolecule?
When small organic molecules are joined inside cells, forming larger larger molecules. The four main classes are carbohydrates, lipids, proteins, and nucleic acids
Distinguish between monomers and polymers.
Polymer is a long molecule consisting of many similar or identical building blocks linked by covalent bonds.
Monomer is the repeating unit that serve as the building blocks of a polymer.
Describe dehydration reactions.
Monomers are connected by a reaction in which two molecules are covalently bonded to each other through loss of a water molecule. A condensation or specifically dehydration reaction.
Describe hydrolysis.
Polymers are disassembled to monomers by hydrolysis. A process that is essentially the reverse of the dehydration reaction. It means to break with water. Bonds between monomers are broken by the addition of water molecules.
What are carbohydrates? What are they composed of?
Carbohydrates include both sugars and polymers of sugars.
Distinguish among monosaccharides, disaccharides and polysaccharides.
Monosaccharides-generally have molecular formulas that are some multiple of the unit CH20. Glucose is the most common. Sugar is either an aldose ore a ketose depending on the location of the carbonyl group.
Disaccharides consist of two monosaccharides joined by a glycosidic linkage, a covalent bond formed between two monosaccharides by a dehydration reaction. Maltose, Sucrose (Table Sugar) are disaccharides.
Polysaccharides are macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages. Some serve as storage others as building material for structures that protect the cell or the whole organism
What are the functions of starch, glycogen and cellulose?
Starch is a storage polysaccharides of plants. It is a polymer consisting entirely of glucose monomers. Stored energy.
Glycogen is a polysaccharide stored in animals. It is a polymer of glucose that is more extensively branched that amyplopectin. Stored mainly in the liver and muscles. Stored fuel but easily depleted without more food consumption.
Cellulose is a polysaccharide that is a major component of the tough cell walls that enclose plant cells. It is produced by plants and is the most abundant organic compound on earth.
What are fats? What are they composed of? Are they polymers?
Fats are not polymers but they are large molecules assembled from smaller molecules by dehydration reaction.They are constructed from two smaller molecules glycerol and fatty Acids.
Distinguish between saturated and unsaturated fatty acids.
Saturated Fatty Acids have no double bonds between carbon atoms composing the chain, then as many hydrogen bonds as possible are bonded to the carbon skeleton, They are saturated with hydrogen.
Unsaturated Fatty Acids has one or more double bonds, formed by the removal of hydrogen atoms from the carbon skeleton. The fatty acid will have a kink in its hydrocarbon chain. Most animal fats are saturated. The hydrocarbon chains of their fatty acids-the tails of the fat molecules lack double bonds so the molecules can pack tightly. They become solid at room temperature.
What is a phospholipid?
A Phospholipid is similar to a fat but only has two fatty acids attached to glycerol rather than three. The third hydroxyl group is is joined to a phosphate group which has a negative electrical charge.
What is a steroid? What is cholesterol?
A steroid is a lipid characterized by a carbon skeleton consisting of four fused rings. Vary in function by different groups attached to the rings.
Cholesterol is a steroid and a common component of animal cell membranes.Precursor from which other steroids are synthesized. Hormones are steroids produced from cholesterol.
What is a protein? What are they composed of?
Proteins account for more than 50% of the dry mass of most cells and are instrumental in almost everything that organisms do. Some speed up chemical reactions while others play a role in structural support, storage, transport, cellular communications movement and defense against foreign objects.
Proteins are polymers constructed from the same set of 20 amino acids.
What is an enzyme?
The most important type of protein. Enzymes regulate metabolism by acting as catalysts, chemical agents that selectively speed up chemical reactions in the cell without being consumed by the reaction.
What type of bond holds amino acids together?
A covalent bond called a peptide bond.
What are nucleic acids? What are they composed of?
There are two types deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). These are the molecules that enable living organisms to reproduce their complex components from one generation to the next. Nucleic acids are macromolecules that exist as polymers called polynucleotides which consist of monomers called nucleotides. A nucleotide is composed of of three parts, a nitrogenous base, a pentose (FIVE CARBON SUGAR), and a phosphate group.
