Building Blocks and Linear Biopolymers

Question 1

Macromolecules

Answer 1

A molecule containing a very large number of atoms; the three main types of biological macromolecules are proteins, nucleic acids, and polysaccharides

Question 2

Polymer

Answer 2

Any large molecule composed of multiple identical or similar units (monomers) linked by covalent bonds.

Question 3

Monomer

Answer 3

Any small molecule that can be linked chemically with others of the same type to form a polymer; like amino acids, nucleotides, and monosaccharides

Question 4

Protein

Answer 4

A macromolecule composed of one or more linear polypeptide chains and folded into characteristic three-dimensional shape (conformation) in its native, biologically active state

Question 5

Peptide Bond

Answer 5

The covalent amide linkage between amino acids formed between the amino group of one amino acid and the carboxyl group of another with the net release of a water molecule (dehydration)

Question 6

Nucleic Acid

Answer 6

A polymer of nucleotides linked by phosphodiester bonds; DNA and RNA are the primary nucleic acids in cells

Question 7

Phosphodiester Bond

Answer 7

Chemical linkage between adjacent nucleotides in DNA and RNA; consists of two phosphoester bonds, one on the 5’ side of the phosphate and the other on the 3’ side

Question 8

Polysaccharide

Answer 8

Linear or branched polymer of monosaccharides linked by glycosidic bonds and usually containing more than 15 residues

Question 9

Glycosidic Bond

Answer 9

The covalent linkage between two monosaccharide residues formed when a carbon atom in one sugar reacts with a hydroxyl group on a second sugar with the net release of a water molecule (dehydration)

Question 10

Amino Acid

Answer 10

An organic compound containing at least one amino group and one carboxyl group

Question 11

Amino Acid Structure

Answer 11

A central alpha carbon atom bonded to four different chemical groups:
- an amino (NH2) group
- carboxyl or carboxylic acid (COOH) group
- a hydrogen (H) atom
- one variable group, called a side chain or R group.

Question 12

Hydrophobic Amino Acid

Answer 12

Amino acid with non polar side chain; poorly soluble in water

Question 13

Hydrophilic Amino Acid

Answer 13

Amino acid with polar side chain; the most hydrophilic of these amino acids is the subset with side chains that are charged (ionized) at the pH typical of biological fluids

Question 14

Disulfide Bond

Answer 14

Bond that serves to cross-link regions within a single polypeptide chain or between two separate chains; help stabilize the folded structure of some proteins

Question 15

Acetylation

Answer 15

The addition of acetyl groups (CH3CO) to amino acids; may play important role in controlling the life span of proteins within cells

Question 16

Phosphorylation

Answer 16

The addition of a phosphate group (PO4) to hydroxyl groups in serine, threonine, and tyrosine residues

Question 17

glycosylation

Answer 17

The attachment of linear and branched carbohydrate chains

Question 18

DNA (deoxyribonucleic acid)

Answer 18

Long linear polymer, composed of four kinds of deoxyribose nucleotides, that is the carrier of genetic information

Question 19

RNA (ribonucleic acid)

Answer 19

Linear, single-stranded polymer, composed of ribose nucleotide

Question 20

Nucleotide

Answer 20

A nucleoside with one or more phosphate groups linked via an ester bond to the sugar moiety, generally to the 5’ carbon atom.

Question 21

Nucleotide Structure

Answer 21

Three-part structure: a phosphate group is linked by a phosphoester bond to a pentose (five-carbon) sugar, which is linked to a nitrogen- and carbon-containing ring structure (base)

Question 22

Purines

Answer 22

A class of nitrogenous compounds containing two fused heterocyclic rings (adenine and guanine)

Question 23

Pyrimidines

Answer 23

A class of nitrogenous compounds containing one heterocyclic ring (cytosine and thymine/uracil)

Question 24

Nucleoside

Answer 24

A small molecule composed of a purine or pyrimidine base linked to a pentose (ribose/deoxyribose)

Question 25

Ester Bond

Answer 25

A covalent bond linking an acid with an alcohol

Question 26

Esterification

Answer 26

The formation of an ester bond, accompanied by the release of a hydroxyl (–OH) group from the acid and a proton (–H) from the hydroxyl group on the alcohol, which form a water molecule

Question 27

Base Pair

Answer 27

Association of two complementary nucleotides in a DNA or RNA molecule stabilized by hydrogen bonding between their base components; adenine pairs with thymine or uracil and guanine pairs with cytosine

Question 28

Denaturation / Melting

Answer 28

Drastic Alteration in the conformation of a protein or nucleic acid due to disruption of various noncovalent interactions caused by heating or exposure to certain chemicals; usually results in loss of biological function

Question 29

Melting Temperature Factors

Answer 29

• # of G - C pairs: molecules that contain a greater proportion of G∙C pairs require higher temperatures to denature because the three hydrogen bonds are more stable than A∙T pairs, which have only two hydrogen bonds
• ion concentration of solution: negatively charged phosphate groups in the two strands are shielded by positively charged ions; when the ion concentration is low, this shielding is decreased, thus increasing the repulsive forces between the strands and reducing the Tm
• pH: at low (acid)
  pH, the bases become protonated and thus positively charged, repelling each other. At high (alkaline) pH, the bases lose protons and become negatively charged, again repelling each other because of their similar charges
• agents that destabilize hydrogen bonds lower Tm

Question 30

Hybridization

Answer 30

Association of two complementary nucleic acids strands to form double-stranded molecules, which can contain two DNA strands, two RNA strands, or one DNA and one RNA strand

Question 31

Topoisomerase I

Answer 31

Enzyme that binds to DNA at random sites and breaks a phosphodiester bond in one strand and joins the two ends of the broken strand

Question 32

Topoisomerase II

Answer 32

Enzyme that relieves torsional stress in DNA by making breaks in both strands of a double-stranded DNA and then relitigating them