Ch. 3 Key Terms

Question 1

alpha-helix structure (α-helix)

Answer 1

type of secondary protein structure formed by folding the polypeptide into a helix shape with hydrogen bonds stabilizing the structure

Question 2

amino acid

Answer 2

a protein’s monomer; has a central carbon or alpha carbon to which an amino group, a carboxyl group, a hydrogen, and an R group or side chain is attached; the R group is different for all 20 common amino acids

Question 3

beta-pleated sheet (β-pleated)

Answer 3

secondary structure in proteins in which hydrogen bonding forms “pleats” between atoms on the polypeptide chain’s backbone

Question 4

biological macromolecule

Answer 4

large molecule necessary for life that is built from smaller organic molecules

Question 5

carbohydrate

Answer 5

biological macromolecule in which the ratio of carbon to hydrogen and to oxygen is 1:2:1; serves as energy sources and structural support in cells and form arthropods’ cellular exoskeleton

Question 6

cellulose

Answer 6

polysaccharide that comprises the plants’ cell wall; provides structural support to the cell

Question 7

chaperone

Answer 7

protein that helps nascent protein in the folding process

Question 8

dehydration synthesis

Answer 8

(also, condensation) reaction that links monomer molecules, releasing a water molecule for each bond formed

Question 9

denaturation

Answer 9

loss of shape in a protein as a result of changes in temperature, pH, or chemical exposure

Question 10

deoxyribonucleic acid (DNA)

Answer 10

double-helical molecule that carries the cell’s hereditary information

Question 11

disaccharide

Answer 11

two sugar monomers that a glycosidic bond links

Question 12

enzyme

Answer 12

catalyst in a biochemical reaction that usually a complex or conjugated protein

Question 13

glycogen

Answer 13

storage carbohydrate in animals

Question 14

glycosidic bond

Answer 14

bond formed by a dehydration reaction between two monosaccharides with eliminating a water molecule

Question 15

horomone

Answer 15

chemical signaling molecule, usually protein or steroid, secreted by endocrine cells that act to control or regulate specific physiological processes

Question 16

hydrolysis

Answer 16

reaction that causes breakdown of larger molecules into smaller molecules by utilizing water

Question 17

lipid

Answer 17

macromolecule that is nonpolar and insoluable in water

Question 18

messenger RNA (mRNA)

Answer 18

RNA that carries information from DNA to ribosomes during protein synthesis

Question 19

monomer

Answer 19

smallest unit of larger molecules that are polymers

Question 20

monosaccharide

Answer 20

single unit or monomer of carbohydrates

Question 21

nucleic acid

Answer 21

biological macromolecule that carries the cell’s genetic blueprint and carries instructions for the cell’s functioning

Question 22

nucleotide

Answer 22

monomer of nucleic acids; contains a pentose sugar, one or more phosphate groups, and a nitrogenous base

Question 23

omega fat

Answer 23

type of polyunsaturated fat that the body requires; numbering the carbon omega starts from the methyl end or the end that is farthest from the carboxylic end

Question 24

peptide bond

Answer 24

bond formed between two amino acids by a dehydration synthesis

Question 25

phosphodiester

Answer 25

linkage covalent chemical bond that holds together the polynucleotide chains with a phosphate group linking neighboring nucleotides' two pentose sugars

Question 26

phospholipid

Answer 26

membranes' major constituent; comprised of two fatty acids and a phosphate-containing group attached to a glycerol backbone

Question 27

polymer

Answer 27

chain of monomers

Question 28

polynucleotide

Answer 28

long chain of amino acids that peptide bonds link

Question 29

primary structure

Answer 29

linear sequence of amino acids in a protein

Question 30

protein

Answer 30

biological macromolecule comprised of one of more amino acid chains

Question 31

purine

Answer 31

type of nitrogenous base in DNA and RNA; for example adenine and guanine

Question 32

pyrimidine

Answer 32

type of nitrogenous base in DNA and RNA; for example cytosine, thymine, and uracil

Question 33

quaternary structure

Answer 33

association of discrete polypeptide subunits in a protein

Question 34

ribonucleic acid (RNA)

Answer 34

single-stranded, often internally base paired, molecule that is involved in protein synthesis

Question 35

ribosomal RNA (rRNA)

Answer 35

RNA that ensures the proper alignment of the mRNA and the ribosomes during protein synthesis and catalyzes forming the peptide linkage

Question 36

saturated fatty acid

Answer 36

long-chain hydrocarbon with single covalent bonds in the carbon chain; the number of hydrogen atoms attached to the carbon skeleton is maximized

Question 37

secondary structure

Answer 37

regular structure that proteins form by intramolecular hydrogen bonding between the oxygen atom of one amino acid residue and the hydrogen attached to the nitrogen atom of another amino acid residue (local bending)

Question 38

starch

Answer 38

storage carbohydrate in plants

Question 39

steroid

Answer 39

type of lipid comprised of four fused hydrocarbon rings forming a planar structure

Question 40

tertiary structure

Answer 40

a protein's three-dimensional conformation, including interactions between secondary structural elements; formed from interactions between amino acid side chains

Question 41

trans fat

Answer 41

fat formed artificially by hydrogenating oils, leading to a different arrangement of double bond(s) than those in naturally occurring lipids

Question 42

transcription

Answer 42

process through which mRNA forms on a template of DNA

Question 43

tRNA

Answer 43

RNA that carries activated amino acids to the site of the protein synthesis on the ribosome

Question 44

translation

Answer 44

process through which RNA directs the proteins formation

Question 45

triacylglycerol (also, triglyceride)

Answer 45

fat molecule, consists of three fatty acids linked to a glycerol molecule

Question 46

unsaturated fatty acid

Answer 46

long-chained hydrocarbon that has one of more double bonds in the hydrocarbon chain

Question 47

wax

Answer 47

lipid comprised of a long-chain fatty acid that is esterified to a long-chain alcohol; serves as a protective coating on some feathers, aquatic mammal fur, and leaves