AP Biology Review (Ch. 5)

Distinguish between a pyrimidine and a purine.

A pyrimidine is a six-membered ring of carbon and nitrogen atoms, while a purine is a six-membered ring connected to a five-member ring.

Distinguish between a saturated and unsaturated fat, and list some unique emergent properties that are a consequence of these structural differences.

A saturated fat is solid at room temp. and has no double bonds in any of its 3 fatty acids, while an unsaturated fat has at least 1 double bond in any of its 3 fatty acids, and is liquid at room temp.

Identify a peptide bond and explain how it is formed.

A peptide bond is how amino acids are linked to form polypeptides/proteins. A carboxyl and amino group bond through a dehydration reaction.

Identify a glycosidic linkage and describe how it is formed.

A glycosidic linkage is the bond between two monosaccharides, to form a disaccharide. This bond occurs through a dehydration reaction.

List the major components of a nucleotide (the monomer for nucleic acids), and describe how these monomers are linked together to form a nucleic acid.

A nucleotide is made of a nitrogenous base, a pentose sugar, and a phosphate group. These are joined by covalent bonds between a phosphate group on the 5' side and an OH/Hydroxyl group on the 3' side.

Explain how weak interactions & disulfide bonds contribute to tertiary protein structure.

Attractions between R groups contribute to bends in tertiary structure, and strong bonds called disulfide bridges reinforce the proteins conformation.

Describe the distinguishing characteristics of carbohydrates, and explain how they are classified. Describe the monomer for carbohydrates.

Carbohydrate sugars and sugar polymers serve as fuel for cells and raw material for molecules. The monomer for a carbohydrate is a single sugar/monosaccharide, which form rings in aqueous solutions. Made of Carbon, Hydrogen, and Oxygen.

List the four major classes of biomolecules.

Carbohydrates, lipids, proteins, and nucleic acids.

Briefly describe the three-dimensional structure of DNA.

DNA forms a double helix between 2 strands of a sugar-phosphate backbone and attracted Nitrogenous bases. In DNA, T and A, and G and C are attracted to each other. While in RNA, T is replaced by U.

Define denaturation and explain how proteins may be denatured.

Denaturation occurs when a portein becomes biologically inactive due to changes in pH, salt concentration, temperature, and other environmental factors.

Describe the unique properties, building block molecules and biological importance of the three important groups of lipids: fats, phospholipids, and steroids.

Fats: Made of glycerol and 3 fatty acids. Can form saturated or unsaturated fats. Serve as energy storage. Phospholipids: Made of glycerol and 2 fatty acids. Form bilayers and are found in cell membranes. Steroids: Made of a carbon skeleton with 4 fused rings. Make many hormones.

Identify an ester linkage and how it is formed.

Formed by a fatty acid bonding to a glycerol through a dehydration reaction. Between a hydroxyl and carboxyl group.

Describe how covalent linkages are formed (dehydration synthesis, condensation, building up of macromolecules) and broken (hydrolysis, breaking down of macromolecules) in organic polymers.

In organic molecules, covalent linkages are formed by dehydration reactions, in which H2O molecules are lost, and organic polymers are broken up when H2O molecules are added to covalent linkages.

Explain what distinguishes lipids from other major classes of macromolecules.

Lipids don't have polymers yet share the same little to no affinity for water, which groups them together.

Describe the characteristics that distinguish nucleic acids from other macromolecules.

Nucleic acids (DNA and RNA) store information relating to amino acid sequences of other proteins. Made of nucleotides, which consist of a nitrogenous base, a pentose sugar, and a phosphate group.

Summarize the functions of nucleic acids.

Nucleic acids contain information for all other cell functions and for their own replication.

Describe the important biological functions of polysaccharides.

Polysachharides can be used as fuel in the form of a storage polysachharide, or building material for cell structures as a structural polysaccharide.

Define primary structure and describe how ti may be deduced in the laboratory.

Primary structure is simply the sequence of amino acids in a polypeptide. Determined by inherited genetic information.

Describe the characteristics that distinguish proteins from the other major classes of macromolecules, and explain the biologically important functions of this group.

Proteins make up over 50% of dry mass of most cells, important in every aspect of an organism. Serve for structural support, storage, transport, cellular communications, movement, and defense against foreign substances.

Using collagen and hemoglobin as an example, describe quaternary protein structure.

Quaternary protein structure differs between proteins. In collagen, 3 polypeptides combine in a rope-like structure. Meanwhile, hemoglobin, made of 4 polypeptides, forms a globular structure.

Distinguish between the glycosidic linkages found in starch and cellulose, and explain why the difference is biologically important.

Since glucose is either made of alpha or beta monomers, starch is made of only alpha monomers while cellulose is made of both. In the end, starch molecules are helical, while cellulose molecules are straight, which results in tighter bonds, making cell walls in plants stronger. Also, because of its bonds, most living organisms can digest starch but not cellulose.

List the functions of nucleotides.

The function of a nucleotide is to contain information that, when connected to other nucleotides, provides genetic information to be produced in proteins and all other cells as well as its own replication.

Explain what determines protein conformation and why it is important.

The sequence of amino acids is what determines a proteins conformation. A protein's conformation gives it its function, and any small change can make the protein ineffective.

Describe the two types of secondary protein structure, and explain the role of hydrogen bonds in maintaining the structure.

The two types of secondary protein structures are the alpha helix, and the beta pleated sheets. Hydrogen bonds connect the R groups together, maintaining its shape.

Describe the principles relating to formation of macromolecules (polymers) from monomers, and the formation of monomers from polymers. Explain how organic polymers contribute to biological diversity.

To form polymers from monomers, a dehydration reaction must occur, in which an H2O molecule is lost. To form monomers from polymers, a hydrolysis reaction must occur in which an H2O molecule breaks up the chain of monomers to form separate monomers. Organic polymers contribute to biological diversity because, like an alphabet, only 50-60 monomers can make countless polymers.