Which polymers are composed of amino acids?
Which of the following is not attached to the central carbon atom in an amino acid?
An oxygen. The central carbon atom in an amino acid is bonded to an amino functional group, a carboxyl functional group, a side chain, and hydrogen.
Which part of an amino acid is always acidic?
Carboxyl functional group. The carboxyl group (COOH) contains two oxygen atoms that tend to pull electrons away from the hydrogen atom, so this group tends to lose a proton and is acidic.
Which monomers make up RNA?
Which of the following statements about the formation of polypeptides from amino acids is true?
A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid. A hydroxyl group is removed from the carboxyl group of one amino acid and hydrogen is removed from the amino group of the other amino acid, allowing a bond to form between the two groups.
True or false? Enzymes in the digestive tract catalyze hydrolysis reactions.
Which molecule is not a carbohydrate?
Which of the following statements about monosaccharide structure is true?
Monosaccharides can be classified according to the spatial arrangement of their atoms.
True or false? Peptidoglycan is a polysaccharide found only in bacteria.
Which complex carbohydrate contains only a-1,4-glycosidic linkages?
Which of the following complex carbohydrates is listed with its correct function?
Cellulose: structural component of plant cell walls
Which polysaccharide contains a modified monosaccharide?
Peptidoglycan. The N-acetylglucosamine and N-acetylmuramic acid units that make up peptidoglycan are composed of modified glucose monomers.
Which of these is NOT a lipid?
Saturated fat
Fatty acids lack double bonds
Phospholipid structure
Phospholipids are composed of a phosphate group, a glycerol, and fatty acids.
Which of these is rich in unsaturated fats?
olive oil
A function of cholesterol that does not harm health is its role
as a component of animal cell membranes
What do fats, steroids, and waxes have in common?
Low solubility in water
Dr. Haxton told one of his students, “To move in the bloodstream, fats need the help of phospholipids.” What would a good student say?
Yes. Nonpolar molecules aren’t compatible with water. Water rejects nonpolar molecules such as fats, so fats travel inside particles that are coated with polar parts of phospholipids and proteins.
Proteins are polymers of
amino acids
What type of bond joins the monomers in a protein’s primary structure?
Which of these illustrates the secondary structure of a protein?
Alpha helices and beta pleated sheets are characteristic of a protein’s secondary structure.
The secondary structure of a protein results from
Hydrogen bonds. Electronegative oxygen and nitrogen atoms leave hydrogen atoms with partial positive charges.
Tertiary structure is NOT directly dependent on
peptide bonds
Which of the following statements is an accurate description of proteins?
The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene.
Identify the level(s) of protein structure present in this molecule.
This protein illustrates all four levels of protein structure.
primary: the order of amino acids in the polypeptide chain

secondary: localized regions of alpha helices and beta pleated sheets

tertiary: the overall three-dimensional shape of a polypeptide, stabilized by interactions between R groups

quaternary: the association of more than one polypeptide subunit into a functional protein.

What could happen if a mutation in a gene caused a hydrophobic amino acid in a polypeptide to be replaced by a hydrophilic amino acid?
The new amino acid would not form the same interactions with hydrophobic R groups, and the protein’s shape would likely be affected.
If a strand of DNA has the nitrogen base sequence 5′-ATTTGC-3′, what will be the sequence of the matching strand?
3′-TAAACG-5; Adenine pairs with thymine and guanine pairs with cytosine.
If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain?
75; 100 nucleotide pairs are a total of 200 nucleotides. Because of base pairing, if there are 25 adenine there must also be 25 thymine. This leaves 200-50 = 150 nucleotides to be divided evenly between guanine and cytosine.
The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.
hydrogen bonds
A nucleotide is composed of a(n)
phosphate group, a nitrogen-containing base, and a five-carbon sugar
RNA nucleotides contain __________ than DNA nucleotides.
more oxygen
The orange unit with two linked rings in this diagram represents
A purine. Purines have two linked rings.
How likely is it that the next base, out of sight at the top of this polymer, is uracil?
Not a chance, since this is a DNA molecule, not an RNA molecule.
Which statement helps to explain how DNA stores hereditary information?
DNA contains four kinds of nitrogenous bases.
DNA and mRNA differ with respect to
the kind of sugar they contain

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