bio exam 2
In a nucleotide, the phosphate is attached to the ____________ carbon of the sugar, and the base is attached to the ____________ carbon of the sugar.
2'; 3' Correct Answer *5'; 1' You Answered 3'; 5' 1'; 5'
The complexity and variety of organic molecules is due to _____.
* the chemical versatility of carbon atoms the diverse bonding patterns of nitrogen their interaction with water the variety of rare elements in organic molecules
Enzymes that readily break starch apart cannot hydrolyze the glycosidic linkages found in cellulose. Why is this the case?
*The geometry of the bonds is different, and the shapes of enzyme active sites are highly specific. Cellulose molecules are highly branched, and enzymes are too bulky to fit. Starch is held together by peptide bonds, not glycosidic linkages. Starch is held together by hydrogen bonding, not covalent bonding.
How do the alpha and beta forms of glucose differ?
*Their ring structures differ in the location of a hydroxyl group. Their linear structures differ in the location of a hydroxyl group. The alpha form can be involved in 1,4 and 1,6 glycosidic linkages; the beta form can participate only in 1,4 linkages. The oxygen atom inside the ring is located in a different position.
The two strands of a DNA molecule
*are anti-parallel You Answered are exact copies of each other can not be separated contain ribose and deoxyribose in opposite strands
Which of the following is a FALSE statement concerning amino groups? Amino groups _____.
*are nonpolar are found in amino acids are basic with respect to pH contain nitrogen
In condensation reactions, the atoms that make up the water molecule come from
*both of the monomers. enzymes. only one of the monomers. oxygen.
A simple sugar composed of one monomer with six carbons can be classified as a
*hexose pentose disaccharide polysaccharide
The non-polar fatty acid tails of a phospholipid are considered to be
*hydrophobic proteins carbohydrates hydrophilic
The basic sequence (or order) of amino acids in any protein is call its ________ structure.
*primary quaternary secondary tertiary
Which of the following is not a macromolecule?
*salt RNA protein DNA
Which one of the following is not a component of an amino acid?
*triphosphate group carboxyl group amino group alpha carbon
The diversity found among DNA molecules is due to the sequence of _______.
base sequence
All amino acids have a hydrogen atom, a _______ group, an amino group, and a side chain attached to a central carbon atom.
carboxyl
When an insect is crushed, it creates a crunching sound. What carbohydrate is the most likely source of this sound?
cellulose glycogen peptidoglycan Correct! *chitin
Saturated fatty acids
have a bend in them. do not pack tightly together. do not have 2 hydrogen per carbon. Correct! *are straight.
Phospholipids and triglycerides both _____.
have a phosphate have three fatty acids Correct! * have a glycerol backbone contain serine or some other organic compound
Research indicates that ibuprofen, a drug used to relieve inflammation and pain, is a mixture of two enantiomers; that is, molecules that _____.
have identical chemical formulas but differ in the branching of their carbon skeletons differ in the arrangement of atoms around their double bonds differ in the location of their double bonds Correct! *are mirror images of each other
Lactose, or milk sugar, is composed of one glucose unit and one galactose unit. It can be classified as a
hexose monosaccharide Correct! *disaccharide
A carbon atom is most likely to form what kind of bond(s) with other atoms?
hydrogen ionic ionic bonds, covalent bonds, and hydrogen bonds Correct! *covalent
A __________ amino acid may be found in the watery fluid in the cell.
hydrophilic
Which one of the following does NOT contribute to a protein's tertiary structure?van der Waal's forcesAll of these choices are correct.
•male bonding hydrogen bonding covalent bonding ionic bonding
The side chain of leucine is hydrophobic. In a folded protein, where would you expect to find leucine?
Surrounded by water Outside of the cell Correct! *Tucked on the inside of the protein On the outside of a protein
The two strands of a DNA molecule
are exact copies of each other Correct Answer *are complementary and anti-parallel can never be separated contain both ribose and deoxyribose
How many electron pairs does carbon share to complete its valence shell?
8 3 2 Correct! *4
Which of the following is true of carbon?
It forms only polar molecules. It can form a maximum of three covalent bonds with other elements. It is highly electronegative. Correct! *It can form both polar and nonpolar bonds.
The two strands of a DNA molecule are said to be complementary. What does this mean?
The sugars and phosphate groups of the nucleotides form a backbone Correct Answer *The nucleotides on either strand pair with their complementary base The 5' and 3' ends of the strands are at opposite ends of the DNA molecule The 5' and 3' ends of the strands are at the same end of the DNA molecule
Why are hydrocarbons insoluble in water?
They are less dense than water. ) The majority of their bonds are polar covalent carbon-to-hydrogen linkages. Correct! *The majority of their bonds are nonpolar covalent carbon-to-hydrogen linkages. They exhibit considerable molecular complexity and diversity.
What do phospholipids and triglycerides have in common?
They both have a phosphate. They both have three fatty acids. They both contain serine or some other organic compound. Correct! *They both have a glycerol backbone.
The condensation reaction that joins two amino acids results in the formation of
a phosphodiester bond a hydrogen bond Correct! *a peptide bond an ionic bond
A nucleotide contains a pentose sugar, a phosphate, and a(n)
acid lipid Correct! *nitrogenous base glycerol
Which of the following is NOT a component of an amino acid?
amino group carboxyl *nitrogenous base You Answered R group
Testosterone and estradiol are male and female sex hormones, respectively, in many vertebrates. In what way(s) do these molecules differ from each other? Testosterone and estradiol _____.
are cis-trans isomers but have the same molecular formula are enantiomers of the same organic molecule Correct! * have different functional groups attached to the same carbon skeleton are structural isomers but have the same molecular formula
"DNA" stands for _______________.
deoxyribonucleic acid
A simple sugar composed of one monomer with five carbons can be classified as a
disaccharide polysaccharide Correct Answer *pentose hexose
Carbohydrates made up of two simple sugars are called _______.
disaccharides
A _______ amino acid will try to "hide" from the water in the cell.
hydrophobic
The bonds that form between the units of polymeric macromolecules are _______ bonds.
ionic Correct! *covalent disulfide hydrogen
Secondary structure is characterized by which one of the following types of interactions?
ionic bonding between an acidic side chain and a basic side chain a covalent bond between two cysteines Correct! *hydrogen bonding within the peptide backbone hydrogen bonding between side chains of amino acids
A compound contains hydroxyl groups as its predominant functional group. Therefore, this compound _____.
lacks an asymmetric carbon and is probably a fat or lipid will not form hydrogen bonds with water should dissolve in a nonpolar solvent Correct! *should dissolve in water
Starch is a polymer of glucose subunits. The subunits of any polymer are called _______.
monomers
A nucleotide contains a pentose sugar, a phosphate, and a(n) __________.
nitrogen base
__________ molecules are carbon containing molecules produced by biological processes.
organic
What type of chemical bond exists between the two different strands of DNA?
peptide Correct Answer *hydrogen You Answered covalent ionic
In starch, glucose monomers are linked together with ________ glycosidic linkages.
pi Correct! *alpha delta beta
Steroids are ________.
powered by ATP. a class of transmembrane transport proteins. Correct! *a class of lipid with four-ring structure. a portion of all phospholipids.
The three dimensional folding of a single protein is referred to as the
quaternary structure secondary structure. Correct Answer *tertiary structure primary structure.
The sugar found in DNA is
ribose tetrose Correct! *deoxyribose hexose
Two carbon atoms held together in a double covalent bond share _______ electron(s).
six two Correct Answer *four one
Glucose and fructose are _________ isomers.
structural
