Ch. 3 Biologically Important Molecules

Question 1

amino acids

Answer 1

The building blocks (monomers) of proteins. There are 20 different ones.

Question 2

cholesterol

Answer 2

A large, ring-shaped lipid found in cell membranes. Is the precursor for steroid hormones, and is used to manufacture bile salts.

Question 3

lipoproteins

Answer 3

Large conglomerations of protein, fats, and cholesterol that transport lipids in the bloodstream.

Question 4

phospholipid

Answer 4

The primary membrane lipid. They consist of a glycerol molecule esterified to tow fatty acid chains and a phosphate molecule. Additional, highly hydrophilic groups are attached to the phosphate, making this moleucle extremely amphipathic.

Question 5

proteins

Answer 5

Biological macromolecules that act as enzymes, hormones, receptors, channels, transporters, antibodies, and support structures inside and outside cells

Question 6

peptide bonds

Answer 6

covalent bonds between amino acids in proteins, link amino acids into polypeptide chains

Question 7

disulfide bridges

Answer 7

covalent bonds between amino acids in proteins, link amino acids between cysteine R-groups

Question 8

backbone of the polypeptide

Answer 8

N-C-C-N-C-C

Question 9

residue

Answer 9

an individual amino acid when it is part of a polypeptide chain

Question 10

Proteolysis (proteolytic clevage)

Answer 10

hydrolysis of a protein by another protein

Question 11

Proteolytic enzyme (protease)

Answer 11

protein that does the cutting in hydrolysis of a protein

Question 12

denatured

Answer 12

improperly folded proteins, makes proteins non-functional

Question 13

Denaturation

Answer 13

disruption of a protein’s shape without breaking peptide bonds

Question 14

Primary Structure (sequence)

Answer 14

linear ordering of amino acid residues

Question 15

Secondary Structure (hydrogen bonds between backbone groups)

Answer 15

refers to the initial folding of a polypeptide chain into shapes stabilized by hydrogen bonds between NH and CO groups. 2 most common structures: alpha-helix and beta-pleated sheet

Question 16

Alpha Helix

Answer 16

secondary structure

Question 17

parallel beta-pleated sheet

Answer 17

secondary structure, adjacent polypeptide strands running in the same direction

Question 18

anti-parallel beta-pleated sheet

Answer 18

secondary structure, adjacent polypeptide strands run in the opposite directions

Question 19

Tertiary Structure (Hydrophobic/Hydrophilic Interactions)

Answer 19

interactions between amino acid residues located more distantly from each other in the polypeptide chain. Hydrophobic R-groups tend to fold into the interior of the protein, away from the solvent, and hydrophilic R-groups tend to be exposed to water on the surface of the protein.

Question 20

Quaternary Structure (Various Bonds Between Separate Chains)

Answer 20

Describes interactions betweens polypeptide subunits.

Question 21

Subunit

Answer 21

single polypeptide chain that is part of a large complex containing many subunits (a mulitsubunit complex)

Question 22

monosaccharide (simple sugar)

Answer 22

single carbohydrate molecule, general chemical formula: C(n)H(2n)O(n)

Question 23

glycosidic linkage

Answer 23

bond between 2 sugar molecules

Question 24

Glycogen

Answer 24

energy storage carbohydrate in animals and is composed of thousands of glucose units

Question 25

Starch

Answer 25

energy storage carbohydrate in plants

Question 26

Cellulose

Answer 26

polymer of cellobiose; cellobiose does not exist freely in nature, exists in polymerized, cellulose form

Question 27

Lipids

Answer 27

oily or fatty substances that play 3 physiological roles

Question 28

3 Roles of Lipids

Answer 28

1) In adipose cells, triglycerides (fats) store energy
2) In cellular membranes, phospholipids constitute a barrier between intracellular and extracellular environments
3) Cholesterol is a special lipid that serves as the building blocks for the hydrophobic steroid hormones

Question 29

Hydrophobic

Answer 29

water-fearing

Question 30

Hydrophilic

Answer 30

water-loving

Question 31

Lipophilic

Answer 31

lipid-loving

Question 32

Lipophobic

Answer 32

lipid-fearing

Question 33

saturated

Answer 33

when every carbon atom in the chain is covalently bound to the maximum number of hydrogens

Question 34

unsaturated

Answer 34

one or more double or triple bonds in carbon chain

Question 35

micelle

Answer 35

how free fatty acids interact in an aqueous solution, the force that drives the tails into the center of the micelle is called the hydrophobic interaction

Question 36

triacylglycerol (triglyceride)

Answer 36

technical name for fat, composed of three fatty acids esterified to ta glycerol molecule

Question 37

Lipases

Answer 37

enzymes that hydrolyze fats

Question 38

Terpenes

Answer 38

built from isoprene units (C5H8) wit ha general formula (C5C8)n

Question 39

testosterone

Answer 39

an androgen or male sex horomone

Question 40

estradiol

Answer 40

an estrogen or female sex hormone

Question 41

3 Reasons that phosphate anhydride bonds store so much energy

Answer 41

1) When phosphates are linked together, their negative charges repel each other strongly
2) Orthophosphate has more resonance forms and thus a lower free energy than linked phosphates
3) Orthophosphate has a more favorable interaction with the biological solvent (water) than linked phosphates

Question 42

Nucleotides

Answer 42

building blocks of nucleic acids (RNA and DNA), built of: ribose sugar group (deoxyribose), purine (pyrimidine base), and 1, 2, or 3 phosphate units, ex. ATP