Biology Chapter 3

Glycogen is all of the following except a form of energy storage. composed of glucose monomers. highly branched. insoluble in water. a base from which cellulose is made.

a base from which cellulose is made.

A question was raised during a class discussion about whether it was possible for two isomers to have different biological properties. A student from the class responded, stating that only optical isomers met this requirement. Which statement provides the best evaluation of this student's assertion? -It is only partially correct, because structural isomers can also meet the requirement. -It is completely correct. -It is only partially correct, because structural isomers and cis-trans isomers can also meet the requirement. -It is incorrect, because no isomers meet the requirement. -It is only partially correct, because cis-trans isomers can also meet the requirement.

-It is only partially correct, because structural isomers and cis-trans isomers can also meet the requirement.

A scientist isolates a previously undiscovered protein from a fruit fly and determines the sequence of amino acids making up the protein. Upon comparing the sequence to a database, he finds another protein isolated from a lizard with the same sequence. The lizard protein is known to be involved in glucose metabolism. The scientist predicts that the fruit fly protein must also be involved in glucose metabolism. How can his prediction be justified? -Two proteins with the same amino acid composition have the same mass, which allows the two molecules to function in the same way. -Two proteins made up of the same number and types of amino acids have the same composition, which allows the two molecules to function in the same way. -Two proteins with the same distribution of amino acids have the same size, which allows the two molecules to function in the same way. -Two proteins with the same amino acid sequence have the same structure, which allows the two molecules to function in the same way. -Two proteins isolated from modern terrestrial animals such as fruit flies and lizards should be closely related, which implies that the two molecules will function in the same way.

-Two proteins with the same amino acid sequence have the same structure, which allows the two molecules to function in the same way.

Phospholipids form a bilayer that -dissolves in a liquid environment. -has a hydrophobic core. -is impermeable to other molecules. -is held together by covalent interactions. -is broken down by hydrolysis.

-has a hydrophobic core.

The three-dimensional structure of protein -is determined by the sequence of amino acids in the polypeptide chain. -always contains multiple polypeptide chains. -cannot be altered once folded by chaperone proteins. -will be different in different organisms, even when the amino acid sequence is the same. -is not related to its function.

-is determined by the sequence of amino acids in the polypeptide chain.

How many unique polypeptide chains are there of 40 amino acids in length? 2^20 2^40 20^20 20^40 40^20

20^40

A carbohydrate with 24 carbon atoms can be expected to have how many hydrogen and oxygen atoms? 24 H and 24 O 48 H and 24 O 48 H and 48 O 48 H and 64 O 64 H and 48 O

48 H and 24 O

Which interaction is not involved in the formation of a protein's tertiary structure? Salt bridges Disulfide bridges Peptide bonds van der Waals interactions Hydrogen bonds

Peptide bonds

If hydrogen gas is bubbled through lard, which property of the lard will change? Physical state Color Solubility in water Triglyceride content Carbon content

Physical state

Phospholipids are saturated. rigid. a functional group. amphipathic. nonpolar.

amphipathic.

Carbohydrates are a store of genetic information.are the main structure of the plasma membrane. aid in the folding of proteins. are a base from which other molecules can be made. cannot be chemically modified.

are a base from which other molecules can be made. Carbohydrates have four major biochemical roles: They are a source of stored energy that can be released in a form usable by organisms. They are used to transport stored energy within complex organisms. They serve as carbon skeletons that can be rearranged to form new molecules. They form extracellular assemblies such as cell walls that provide structure to organisms.

The functional group written as -COOH is called the _______ group. amino carbonyl sulfhydryl carboxyl keto

carboxyl

All of the following are examples of lipids except chlorophylls. glucosamine. steroids. wax. oil.

glucosamine.

Triglycerides are composed of steroids and saturated fats. aggregates of glycerol. carotenoids and palmitic acid. phosphatidylcholine and linoleic acid. glycerol and fatty acids.

glycerol and fatty acids. Fats and oils are triglycerides Triglycerides that are solid at room temperature (around 20°C) are called fats; those that are liquid at room temperature are called oils. Triglycerides are composed of two types of building blocks: fatty acids and glycerol. Glycerol is a small molecule with three hydroxyl (—OH) groups (thus it is an alcohol). A fatty acid is made up of a long nonpolar hydrocarbon chain and an acidic polar carboxyl group (—COOH). These chains are very hydrophobic because of their abundant C—H and C—C bonds, which have similar electronegativity values and are therefore nonpolar.

Disaccharides are joined together by hydrolysis. glycosidic linkages. salt bridges. peptide bonds. hydrophobic reactions.

glycosidic linkages.

In an α helix, the coiling is stabilized by the hydrophobic nature of the R chains, which causes the chain to coil with the R groups inward. disulfide bond formation between cysteines that are regularly spaced along peptide chains. hydrogen bonding of the N-H groups on one amino acid and the C=O groups on another. repulsion of the R chains from each other, causing the coil to form with the R groups on the outside. the N-C-C repeat of the polypeptide chain, allowing for regularly spaced peptide bonds between chain segments.

hydrogen bonding of the N-H groups on one amino acid and the C=O groups on another. The α (alpha) helix is a right-handed coil that turns in the same clockwise direction as a standard wood screw (see Figure 3.8B and Figure 3.9). The R groups extend outward from the peptide backbone of the helix. The coiling results from hydrogen bonds that form between the δ+ hydrogen of the N—H of one amino acid and the δ− oxygen of the C=O of another. When this pattern of hydrogen bonding is established repeatedly over a segment of the protein, it stabilizes the coil.

When they need energy, cells break down glycogen and starch into glucose using hydrolysis. glycoproteins. salt bridges. combustion. condensation.

hydrolysis. *Polysaccharides store energy and provide structural materials Polysaccharides are large (sometimes gigantic) polymers of monosaccharides connected by glycosidic bonds In contrast to polypeptides, polysaccharides are not necessarily linear chains of monomers. Each monomer unit has several sites that are capable of forming glycosidic bonds, and thus branched molecules are possible.

Fats and proteins share the use of _______ in establishing their three-dimensional structures. hydrolysis reactions ionic interactions peptide bonds ester linkages hydrophobic interactions

hydrophobic interactions

Glucose has six hydrogens. is a disaccharide. is broken down for energy. is a polysaccharide. is a pentose.

is broken down for energy. *All living cells contain the monosaccharide glucose; it is the "blood sugar" used to store and transport energy in humans. Cells use glucose as an energy source, breaking it down through a series of reactions that convert stored energy to more usable chemical-bond energy and produce carbon dioxide; this is a cellular form of the combustion reaction you saw in

Cholesterol is hydrophilic. is a carotenoid. must be taken up in an animal's diet. is classified as a carbohydrate. is involved in membrane integrity.

is involved in membrane integrity. *Lipids include both hydrophobic and amphipathic molecules that are largely composed of carbon and hydrogen. They are important in energy storage, light absorption, intercellular communication, and biological structures. A phospholipid is composed of two hydrophobic fatty acids linked to glycerol and a hydrophilic phosphate group. Cell membranes contain phospholipid bilayers.

All lipids are hydrophilic. polar. triglycerides. more soluble in nonpolar solvents than in water. polymers of fatty acids.

more soluble in nonpolar solvents than in water.

The R groups of amino acids have certain properties and allow for amino acids to be organized into all of the following groups except uncharged hydrophilic. negatively charged and hydrophilic. nonpolar hydrophobic. positively charged and hydrophilic. positively charged and hydrophobic.

positively charged and hydrophobic. Monomers of proteins link together to make the macromolecule *Each amino acid has both a carboxyl functional group and an amino functional group (see Figure 3.1) attached to the same carbon atom, called the α (alpha) carbon. Also attached to the α carbon atom are a hydrogen atom and a side chain, or R group, designated by the letter R (Figure 3.5).

A condensation reaction removes water when linking together monomers. requires oxygen when forming glycosidic linkages. adds hydroxyl groups to nucleic acid linkages. gives off hydrogen during the formation of hydrogen bonds. uses carboxyl groups in beginning catabolism.

removes water when linking together monomers.

A condensation reaction uses carboxyl groups in beginning catabolism. gives off hydrogen during the formation of hydrogen bonds. adds hydroxyl groups to nucleic acid linkages. removes water when linking together monomers. requires oxygen when forming glycosidic linkages.

removes water when linking together monomers. *Most macromolecules are formed by condensation and broken down by hydrolysis *Polymers are formed from monomers by a series of condensation reactions (in this case called dehydration reactions; both terms refer to the loss of water). Condensation reactions result in the formation of covalent bonds between monomers. A molecule of water is released with each covalent bond formed