Chapter 2

Question 1

Functions of proteins

Answer 1

They act like enzymes, hormones, receptors, antibodies and support structures inside/outside the cell

Question 2

What are proteins composed of? What does their composition sequence determine?

Answer 2

Proteins are composed of 20 different amino acids. The composition and sequence determines the function.

Question 3

Polar Hydrophilic amino acids

Answer 3

“Polar-Bears Sometimes Carry Tyny Things Around Glaciers” Serine, cysteine, tyrosine, threonine, asparagine, glutamine. Polar Bear: Water loving

Question 4

Non-Polar Hydrophobic amino acids

Answer 4

Glycine, alanine, valine, leucine, isoleucine, phenylalanine, tryptophan, methionine, proline. “Giant Ants Vandalize Local Icecream Parlor To Meet Peppermint”

Question 5

Hydrophobic Amino Acid Properties

Answer 5

aliphatic (alkyl) or aromatic side chains. Found in the inside of the protein. larger side groups have > repelling forces. aliphatic = organic compounds whose carbon atoms are linked in open chains rather than in a benzene ring

Question 6

polar amino acids

Answer 6

amino acids that are polar enough to form hydrogen bonds, but not enough to act as an acid or base serine, threonine, tyrosine –> hydrophobic aromatic rings.

Question 7

basic amino acids

Answer 7

Hydrophilic; lysine (pKa~10), arginine (pKa~12), histidine (pKa~6.5): can act as an acid or base sine pKa is close to 7, can be proton accept/donor

Question 8

acidic amino acids

Answer 8

Hydrophilic [Glutamic acid & Aspartic acid] pKa~4, contain 3 groups that can act as acids or bases, the two backbone groups and the R-group.

Question 9

Amino acids that contain sulfur

Answer 9

Cysteine and Methionine

Question 10

Two bond types and location

Answer 10

peptide bonds: link amino acids together in a polypeptide chain disulfide bridge: formed between cysteine R-groups

Question 11

Where the peptide bond links

Answer 11

carbonyl and alpha amino group between two amino acids with the loss of water

Question 12

The disulfide bond forms where?

Answer 12

between the thiol of one cysteine and the thiol of another. can happen between two different chains or within one

Question 13

What proteins structure does the disulfide bond stabilize?

Answer 13

stabilizes tertiary protein structure

Question 14

protein folding is vital to

Answer 14

the function of the protein

Question 15

Denaturation occur in what structures?

Answer 15

occurs in 2,3,4 structures

Question 16

Denaturation is

Answer 16

disruption of a proteins shape without breaking peptide bonds. Usually by urea since it disrupts hydrogen bonding interactions

Question 17

causes of denaturation

Answer 17

extremes of pH, extremes of temperatures, changes in salt concentration (Tonicity)

Question 18

primary structure

Answer 18

amino acid sequence: order amino acids are bonded to each other in the polypeptide chain

Question 19

secondary structure

Answer 19

hydrogen bonds between backbone groups. initial folding of the polypeptide chain into shapes stabilized by hydrogen bonds between backbone NH and CO groups

Question 20

α- helix

Answer 20

2nd structure. always right handed. hormones receptors/ion channels are found within the α- helix membrane integrated into hydrophobic membranes proline residues are never found here because they kink the polypeptide chain

Question 21

β- pleated sheets

Answer 21

2nd structure. bonding occurs between residues distant from each other in the chain/ separate polypeptide chains. back bone is extended not coiled. there are two kinds (1) parallel β- pleated sheet (2) β- antiparallel β- pleated sheet

Question 22

Tertiary structure

Answer 22

hydrophobic/hydrophilic interactions. interactions between amino acid resides located more distantly from each other in the polypeptide chain disulfide bonds are considered this structure

Question 23

quaternary structure

Answer 23

various bonds between separate chains. interactions between polypeptide subunits.

Question 24

What kind of interactions are involved in a quaternary structure

Answer 24

interactions involved include hydrogen bond, hydrophobic interactions, van ser Waals and for this structure covalent bonding applies as well.

Question 25

What structure does peptide bonding not apply to

Answer 25

Quaternary structures

Question 26

carbohydrates

Answer 26

chains of hydrated carbon atoms (CnH2nOn). Begins with an aldehyde or ketone and continues as a polyalcohol in which each C has a hydroxyl substituent

Question 27

How are carbohydrates produced and what is their use

Answer 27

produced by photosynthesis/biochemical synthesis. Principal energy source for cellular metabolism

Question 28

Monosaccharide

Answer 28

simple sugar

Question 29

Disaccharide

Answer 29

two simples sugars bonded together through a glycosidic linkage

Question 30

oligosaccharide

Answer 30

a combination of a few disaccharides

Question 31

polysaccharide

Answer 31

a few oligosaccharides together

Question 32

Fatty acids

Answer 32

unsub alkenes that end in a carboxylic acid. 14-18 carbons long, only even numbered found in human cells.

Question 33

unsaturated fatty acids

Answer 33

contains double bonds. do not bind max # of H and lowers m.p.

Question 34

saturated fatty acids

Answer 34

no double bonds. bind max # of H

Question 35

micelle

Answer 35

when fatty acids are exposed to water they group together and expose carboxyl group to the aqueous environment

Question 36

phospholipids

Answer 36

form a barrier between intracellular and extracellular environments

Question 37

triacylglycerols (TG)

Answer 37

3 Fatty acids bonded to a glycerol molecule. adipose cells store energy. fat molecules store more energy than carbohydrates hydrophobicity allows fat to pack together closer

Question 38

cholesterol

Answer 38

serves as a building block for hydrophobic steroid hormones. obtains in diet/synthesized in liver

Question 39

How does cholesterol affect the bi-lipid membrane?

Answer 39

controls membrane fluidity. high temps= reduces, low temps= increase

Question 40

Detergents

Answer 40

phospholipids. effectively solubilize oils while remaining highly water soluble

Question 41

lipids minimize contact with water

Answer 41

forming a lipid bolster, once formed they are stabilized by van der Waals forces between the long tails

Question 42

membrane fluidity

Answer 42

degree of saturation, tail length and amount of cholesterol

Question 43

steroids

Answer 43

all have basic tetracyclic ring system.

Question 44

peptide hormones

Answer 44

insulin. exert their effects by binding to receptors at the cell-surface

Question 45

steroid hormones

Answer 45

estrogen. diffuse into cells to find their receptors. diffuse through the lipid bilayer because they are highly hydrophobic.

Question 46

phosphorus containing compounds

Answer 46

linked phosphates are like compressed springs, waiting to fly open and provide energy for an enzyme to catalyze a reaction.

Question 47

nucleotides

Answer 47

building blocks of nucleic acids (RNA and DNA). Each contains a ribose/deoxyribose sugar group, a purine/pyrimidine base joined to C #1 of the ribose ring and 3 phosphate units joined to C 5 of ring

Question 48

ATP

Answer 48

universal short term energy storage molecule