Quiz 2 Flashcards
All of the following are polysaccharides except:
a) chitin
b) amylopectin
c) glycogen
d) lactose
e) cellulose
d) lactose
What aspects of protein structure are stabilized or assisted by hydrogen bonds?
secondary, tertiary and quaternary statutes, but not primary structure
Which of the four classes of biological molecule is not a polymer? (Lipid, carb, protein, nucleic acid)
Lipid
If cells are grown in a medium containing radioactive 35S, which these molecules will be labelled?
a) amylose
b) proteins
c) nucleic acids
d) phospholipids
e) both proteins and nucleic acids
b) proteins
Why are sex hormones considered to be lipids?
They are not soluble in water.
One of the primary functions of RNA molecules is to?
Function in the synthesis of proteins
Dehydration rxns are used in forming which of the following compounds?
triglycerides, polysaccharides and proteins
The bonding of two amino acid molecules to form a larger molecule requires which of the following?
a) formation of hydrogen bond
b) removal of H2O
c) addition of H2O
b) removal of H2O
Polysaccharides, triglycerides and proteins are similar in that they..?
Are synthesized from subunits by dehydration rxns
Which of the following is an example of hydrolysis?
a) synthesis of two amino acids, forming a peptide with H2O release
b) the rxn of fat, forming glycerol and fatty acids with H2O release
c) synthesis of a nucleotide from a phosphate, pentose sugar, and nitrogenous base with production of H2O molecule
d) the rxn of a fat, forming glycerol and fatty acids with consumption of H2O
d) the rxn of a fat, forming glycerol and fatty acids with consumption of H2O
What type of covalent bond between amino acid side chains (R groups) functions in maintaining a polypeptides specific 3D shape?
Disulphide bond
At which level of protein structure are interactions between side chains (R groups) most important?
a) tertiary
b) quaternary
c) secondary
d) primary
a) tertiary
What is the structural feature that allows DNA to replicate?
Complimentary pairing of nitrogenous bases
The bonding of two amino acid molecules to form a larger molecule requires..?
a) release of NO
b) release of H2O
c) addition of H2O
d) addition of N
e) release of CO2
b) release of H2O
What maintains the secondary structure of a protein?
a) hydrogen bonds between the R groups
b) hydrogen bonds between the amino group of one peptide bond and the carboxyl of another peptide bond
c) peptide bonds
d) disulphide bonds
b) hydrogen bonds between the amino group of one peptide bond and the carboxyl of another peptide bond
Humans can digest starch but not cellulose because..?
(hint: enzymes)
Humans have enzymes that can hydrolyze the alpha glycosidic linkages of starch but not the beta glycosidic linkages of cellulose
Which of the following is true of both starch and cellulose?
a) they are cis-trans isomers of each other
b) they are both structural components of the plant cell wall
c) they are both polymers of glucose
c) they are both polymers of glucose
All of the following are amino acids except:
a) insulin
b) cholesterol
c) antibodies
d) enzymes
e) hemoglobin
b) cholesterol
Which class of biological molecules are grouped together because they are hydrophobic?
a) carbs
b) lipids
c) proteins
d) nucleic acids
b) lipids
Which of the following statements is true for the class of biological molecules known as lipids?
a) They are insoluble in water.
b) They contain less energy than proteins and carbohydrates.
c) They are made from glycerol, fatty acids, and phosphate.
d) They contain nitrogen.
e) They are made by dehydration reactions.
a) They are insoluble in water.
Which modifications of fatty acids will best keep triglycerides solid at warmer temperatures?
a) adding cis double bonds and trans double bonds to the fatty acids
b) creating cis double bonds to the fatty acids
c) creating trans double bonds to the fatty acids
d) adding hydrogens or trans double bonds to the fatty acids
e) adding hydrogens to the fatty acids
d) adding hydrogens or trans double bonds to the fatty acids
Molecules with which functional groups may form polymers via dehydration reactions?
a) carbonyl groups
b) carboxyl groups
c) hydroxyl groups
d) either hydroxyl or carboxyl groups
e) either carbonyl or carboxyl groups
d) either hydroxyl or carboxyl groups
Which of the following best summarizes the relationship between dehydration reactions and hydrolysis?
a) Dehydration reactions form polymers, and hydrolysis reactions break down polymers.
b) Dehydration reactions break down polymers, and hydrolysis reactions form polymers.
c) Dehydration reactions can occur only after hydrolysis.
d) Hydrolysis forms monomers, and dehydration reactions break down polymers.
a) Dehydration reactions form polymers, and hydrolysis reactions break down polymers.
Which of the following statements best summarizes the differences between DNA and RNA?
a) DNA encodes hereditary information, whereas RNA does not.
b) The bases in DNA form base-paired duplexes, whereas the bases in RNA do not.
c) DNA nucleotides contain a different sugar than RNA nucleotides.
d) DNA contains the base uracil, whereas RNA contains the base thymine.
c) DNA nucleotides contain a different sugar than RNA nucleotides.
The label on a container of margarine lists “hydrogenated vegetable oil” as the major ingredient. What is the result of adding hydrogens to vegetable oil?
a) The hydrogenated vegetable oil has a lower melting point.
b) The hydrogenated vegetable oil has fewer trans fatty acids.
c) The hydrogenated vegetable oil stays solid at room temperature.
d) The hydrogenated vegetable oil has more “kinks” in the fatty acid chains.
c) The hydrogenated vegetable oil stays solid at room temperature.
What is the chemical reaction mechanism by which cells make polymers from monomers?
a) phosphodiester linkages
b) the formation of disulphide bridges between monomers
c) ionic bonding of monomers
d) hydrolysis
e) dehydration reactions
e) dehydration reactions
Which bonds are created during the formation of the primary structure of a protein?
a) phosphodiester bonds
b) peptide bonds
c) hydrogen bonds
d) disulphide bonds
e) peptide bonds, hydrogen bonds, and disulphide bonds
b) peptide bonds
If one strand of a DNA molecule has the sequence of bases 5’ATTGCA3’, the other complementary strand would have the sequence..?
a) 5’TGCAAT3’
b) 5’UAACGU3’.
c) 5’UGCAAU3’.
d) 3’UAACGU5’.
a) 5’TGCAAT3’
The basis for diversity, both within a species and among species, is a result of the
a) fact that some individuals have mutations.
b) infinite number of base molecules to build from.
c) ratio of lipid to protein.
d) shared structures of polymers and lipids.
e) arrangement of a few base molecules into many different macromolecular combinations.
e) arrangement of a few base molecules into many different macromolecular combinations.
Which of the following polymers contain nitrogen?
a) starch
b) amylopectin
c) chitin
d) glycogen
e) cellulose
c) chitin
The amino acids of the protein keratin are arranged predominantly in an α helix. This secondary structure is stabilized by…?
a) ionic bonds
b) covalent bonds.
c) hydrogen bonds.
d) polar bonds.
e) peptide bonds.
c) hydrogen bonds.
What maintains the secondary structure of a protein?
a) hydrogen bonds between the R groups
b) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond
c) peptide bonds
d) hydrophobic interactions
b) hydrogen bonds between the amino group of one peptide bond and the carboxyl group of another peptide bond
If a DNA sample were composed of 10% thymine, what would be the percentage of guanine?
a) 10
b) 20
c) 80
d) 40
d) 40
Which of the following statements about the 5’ end of a polynucleotide strand of DNA is correct?
a) The 5’ end has a phosphate group attached to the number 5 carbon of deoxyribose.
b) The 5’ end is the fifth position on one of the nitrogenous bases.
c) The 5’ end has a carboxyl group attached to the number 5 carbon of deoxyribose.
d) The 5’ end has a hydroxyl group attached to the number 5 carbon of deoxyribose.
e) The 5’ end has phosphate attached to the number 5 carbon of the nitrogenous base.
a) The 5’ end has a phosphate group attached to the number 5 carbon of deoxyribose.
A molecule with the chemical formula C6H12O6 is probably a
a) carbohydrate and lipid only.
b) carbohydrate.
c) carbohydrate and monosaccharide only.
d) lipid.
e) monosaccharide
c) carbohydrate and monosaccharide only.
Which of the following is not a polymer?
a) cellulose
b) chitin
c) DNA
d) starch
e) glucose
e) glucose
Which of the following descriptions best fits the class of molecules known as nucleotides?
a) a nitrogenous base and a pentose sugar
b) a pentose sugar and a purine or pyrimidine
c) a nitrogenous base, a phosphate group, and a pentose sugar
d) a phosphate group and an adenine or uracil
e) a nitrogenous base and a phosphate group
c) a nitrogenous base, a phosphate group, and a pentose sugar
There are 20 different amino acids. What makes one amino acid different from another?
a) different side chains (R groups) attached to an α/alpha carbon
b) different side chains (R groups) attached to the amino groups
c) different side chains (R groups) attached to a carboxyl carbon
d) different asymmetric carbons
e) different structural and optical isomers
a) different side chains (R groups) attached to an α/alpha carbon
Which of the following statements concerning saturated fats is not true?
a) They have multiple double bonds in the carbon chains of their fatty acids.
b) They are more common in animals than in plants.
c) They generally solidify at room temperature.
d) They contain more hydrogen than unsaturated fats having the same number of carbon atoms.
e) They are one of several factors that contribute to atherosclerosis.
a) They have multiple double bonds in the carbon chains of their fatty acids.
Which of the following is not a monomer/polymer pairing?
a) amino acid/protein
b) triglyceride/phospholipid bilayer
c) ribonucleotide/RNA
d) deoxyribonucleotide/DNA
e) monosaccharide/polysaccharide
b) triglyceride/phospholipid bilayer
Which of the following is true of cellulose?
a) It is a polymer composed of enantiomers of glucose.
b) It is a storage polysaccharide for energy in plant cells.
c) It is a major structural component of plant cell walls.
d) It is a polymer composed of enantiomers of glucose, it is a storage polysaccharide for energy in plant cells, it is digestible by bacteria in the human gut, and it is a major structural component of plant cell walls.
e) It is digestible by bacteria in the human gut.
c) It is a major structural component of plant cell walls.
What type of covalent bond between amino acid side chains (R groups) functions in maintaining a polypeptide’s specific three-dimensional shape?
a) ionic bond
b) hydrogen bond
c) hydrophobic interaction
d) van der Waals interaction
e) disulphide bond
e) disulphide bond
Which of these molecules is not formed by dehydration reactions?
a) DNA
b) amylose
c) disaccharides
d) fatty acids
e) protein
d) fatty acids
Which of the following is a reasonable explanation for why unsaturated fatty acids help keep any membrane more fluid at lower temperatures?
a) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
b) Unsaturated fatty acids are more polar than saturated fatty acids.
c) The double bonds result in shorter fatty acid tails and thinner membranes.
d) Unsaturated fatty acids have a higher cholesterol content and therefore more cholesterol in membranes.
e) The double bonds block interaction among the hydrophilic head groups of the lipids.
a) The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
Distinguish between the glycosidic linkage found in starch and cellulose. Explain why the difference is biologically important.
Starch has alpha glycosidic linkages and cellulose has beta glycosidic linkage. Is important because we have an enzyme that breaks down the alpha but not the beta.
How do different stimuli lead to different signals?
different shape = different binding affinity
stronger binding = stronger signal = sweeter
