BIo 111 Chpt 3 Hw2-em

a dehydration reaction.

triglycerides

lipids

fatty acids.

phospholipids

uracil

1. The 2 types of nucleic acids found in living organisms are ribose and deoxyribose. false 2. The replication of DNA allows living organisms to pass on the code for making proteins from one generation to the next. true 3. DNA differs from RNA because it contains the sugar deoxyribose instead of ribose, it has the base uracil instead of thymine, and it is double-stranded rather than single stranded. false 4. Nucleic acids are long polymers of repeating subunits called nucleotides. true 5. Each nucleotide consists of three components: a pentose sugar, a phosphate group, and a nitrogenous base. true 6. When 2 nucleotides join by a condensation reaction, the phosphate group of one nucleotide binds to the nitrogenous base of the second nucleotide, forming a phosphodiester bond. false 7. A polynucleotide chain has a phosphate group at the 3´ end and a hydroxyl group at the 5´ end. false 8. During protein synthesis, the sequence of bases in RNA controls the sequence of bases in DNA which, in turn, controls the sequence of amino acids in a polypeptide. false 9. In DNA, adenine always pairs with thymine and guanine always pairs with cytosine. true 10. DNA is used to store the information needed to make all proteins required by an organism and to pass that information on to the next generation. true 11. In order to make a protein, information stored in RNA must be transcribed into molecules of DNA which directs the synthesis of proteins. false

Hydrogen bonding occurs between the amides of adjacent chains in the sheets instead of between the amides in different parts of the helices.

1. A triacylglycerol is composed of 3 glycerol molecules joined to a fatty acid. false 2. The fatty acids of a triglyceride need not be identical, and often they are very different from one another. true 3. Glycerol is a three-carbon alcohol, in which each carbon bears a carboxyl group. false 4. A fatty acid consists of a hydrocarbon chain joined to a hydroxyl group. false 5. The hydrocarbon chains of fatty acids vary in length as well as in the number and location of double bonds between the carbon atoms. true 6. Fatty acids with one double bond in their hydrocarbon chain are called monounsaturated, while those with more than one double bond are called polyunsaturated. true 7. A saturated fatty acid has the maximum number of oxygen atoms bonded to its hydrocarbon chain. false 8. Fats containing unsaturated fatty acids have high melting points because their fatty acid chains bend at the double bonds, preventing them from packing closely together. false 9. Most plant fats contain saturated fatty acids and are therefore liquid at room temperature. false 10. Additional hydrogen atoms can be added to saturated fats, a process called hydrogenation. false 11. When unsaturated fats are partially hydrogenated industrially, this can produce trans fats which have been linked to elevated levels of low-density lipoprotein (LDL) "bad cholesterol" and lowered levels of high-density lipoprotein (HDL) "good cholesterol." true

They contain a glycerol backbone. The phosphate head group is polar. The molecule is an important part of cell membranes.

1. A distinctive and recurrent sequence of structural elements within a protein, such as helix-turn-helix, is called a domain. false 2. Many proteins are composed of several different regions that are specialized to carry out specific functions. true 3. Specific functional regions within a protein are called motifs. false 4. As a polypeptide chain folds, each domain takes its proper shape more or less independently of the others. true 5. If we replace one domain of a protein with a domain from a different protein using molecular biology techniques, then the entire protein will become inactive. false

26%

monosaccharides.

72

20 carbon chain with no double bonds

The misfolded beta-amyloid proteins could not be refolded by chaperone proteins

1. Polysaccharides are long polymers made of many nucleotides that have been joined through dehydration synthesis. false 2. Cellulose is the main storage polysaccharide in plants while glycogen is an important storage polysaccharide in many animals. false 3. Both starch and glycogen are composed of α-glucose subunits. true 4. Starch is composed of amylose and amylopectin, which are unbranched and branched chains of α-glucose subunits, respectively. true 5. Like amylopectin, glycogen is insoluble in water, but it has a longer average chain length and fewer branches. false 6. Although some polysaccharides are used to store energy, others serve as structural material for cells. true 7. The principal structural polysaccharide in plants is starch. false 8. Cellulose is composed of a long, branched chain of β-glucose subunits. false 9. The starch-hydrolyzing enzymes produced by most organisms cannot break the bond between two α -glucose subunits because they only recognize β linkages. false 10. Chitin is a structural polysaccharide found in the exoskeleton of arthropods and the cell wall of many fungi. true

In a membrane because it has a hydrophobic tail and a polar head.

functional groups

1. starch 2. fructose 3. glycogen 4. glucose

nucleic acids.

glucose.

140

DNA molecules.

hydrolysis reactions

they have a relatively high ratio of energy storing C—H bonds.

nitrogen

carboxyl hydroxyl amino

monosaccharides : carbohydrates nucleotides : DNA fatty acids, glycerol : triglycerides 4 carbon rings : steroids

Valine

Nonpolar, hydrophobic, found in hydrocarbon chains.Correct: 5 Polar, soluble, forms H bonds, forms alcohols+=3 Polar, soluble, protons can dissociate from this group and it has acidic properties.=2 Polar, soluble, can act as a weak base and can accept a proton.=4 Polar, soluble, can participate in bonds that are important in energy storage, can be acidic if it loses protons.=1 Stabilizes proteins.=6

1. If a protein's environment is altered, the protein may change its shape or even unfold completely, a process called dissociation. false 2. Proteins can denature when the pH, temperature, or ionic concentration of the surrounding solution changes. true 3. Denatured proteins are usually biologically active. false 4. When normal environmental conditions are reestablished after protein denaturation, almost all proteins can spontaneously refold back into their natural shape. false 5. If the 3-D structure of a protein depends only on its primary structure and the surrounding environmental conditions, then when the protein is denatured and subsequently returned to its native conditions it will spontaneously refold back into its native structure. true 6. Proteins have a narrow range of conditions in which they fold properly; outside that range, proteins tend to renature. false 7. Some proteins require other proteins called chaperones in order to correctly fold into their normal 3-D shape. true 8. Cells use chaperones both to accomplish the original folding of some proteins and to restore the structure of incorrectly folded ones. true 9. Some diseases may occur because a protein with the correct amino acid sequence fails to correctly fold into its final functional form. true 10. During a process called dissociation, the polypeptides of a protein with quaternary structure separate and unfold, losing their individual tertiary structure. false 11. The final 3-D shape of a protein is determined entirely by its primary structure. false

Carbon has four valance electrons. Carbon forms the backbone of all organic molecules. Carbon can form bonds with four different atoms. Carbon can from four covalent bonds with another carbon atom.

polypeptide.

1. DNA Contain genes that can be transcribed 2. mRNA Translated into proteins 3. ATP Provide energy for cell activities 4. NAD+ and FAD Transport electron

secondary tertiary quaternary

nucleic acids