Exam Four

Question 1

bronsted and lowry definitions of acids and bases

Answer 1

ACIDS: release a H+
BASES: accept H+

Question 2

keq/ the equilibrium constant

Answer 2

aA + bB = cC + dD
Keq = [C]c[D]d/ [A]a[B]b
products/reactants
- solids and solvents are omitted

keq > 1 (reactants are favored)
keq < 1 (products are favored)
keq = 1 (reactants = products)

Question 3

le chatelier’s principle

Answer 3

when a reversible reaction is pushed out of equilbrium, the reaction responds to reach a new equilibrium
- any changes in conc. pressure or temp can be a disruption
- RATE OF FORWARD REACTION INCREASES (addition to the reaction)
- RATE OF REVERSE REACTION INCREASES (removal from reaction)

Question 4

the equilibrium constant of water

Answer 4

Kw = 1.0 x 10^-14

Question 5

a solution with a higher H3O+ than OH- will be:

Answer 5

have a pH lower than 7, and be acidic

Question 6

pH scale

Answer 6

acidic pH < 7
neutral pH = 7
basic pH > 7

Question 7

acid and base strength

Answer 7

STRONGER THE ACID - more H3O+ PRODUCTION - LOWER PH
STRONGER THE BASE - more OH- - HIGHER PH

LARGER KA - STRONGER ACID
LOWER PKA - STRONGER ACID

Question 8

neutralization

Answer 8

• occurs when an acid and a base react to form a salt and water
• reaction seen when proper amounts of acid and base are added

Question 9

titration

Answer 9

• lab technique used to determine conc. of an acid and base solution
• acid solution (unknown), base of known conc. is ADDED to consume acid
• specific indicator added to find titration end point

Question 10

buffers

Answer 10

• solution that is resistant to a pH change when a small amount of acid or base is added
• created from weak acid and conjugate base; are within a 50:50 ratio
• most resistant to pH changes when the pH is equal to pKa of the acid

Question 11

carbohydrates

Answer 11

• can be seen through sugars and starches
• help provide energy
• used to store energy
• plants produce them through photosynthesis
• stored carbs can be broken down to produce energy

Question 12

monosaccharides

Answer 12

classified by their functional group
- aldoses - contains aldehyde
- ketoses - contains ketone

Question 13

chiral C atom

Answer 13

one that is attached to 4 different atoms or groups of atoms

Question 14

D or L sugars

Answer 14

D sugars: -OH attached to the chiral carbon FURTHEST FROM CARBONYL GROUP to the RIGHT
L sugars: -OH attached to the LEFT

Question 15

amino sugars

Answer 15

an -OH group of a monosaccharide has been replaced by an amino (-NH2) group

Question 16

benedict’s reagent

Answer 16

• used in the lab to oxidize aldehydes
• sugars that give a POSITIVE RESULT - looks for reducing sugars (in urine)
• sugar is being oxidized while Cu2+ is reduced
• helps monitor diabetes

Question 17

alpha and beta anomers

Answer 17

alpha anomer - has the C#1 -OH pointing down
beta anomer - has the C#1 -OH pointing up
*always gonna be the first carbon - anomeric carbon (typically on the right side of ether group)
- creates a GLYSODIC BOND with other saccharides

Question 18

cellulose

Answer 18

• example of a polysaccharide
• important to maintain the structure of plants
• humans lack the enzyme that hydrolyzes cellulose
• has many intra and inter chain H bonds
• composed of glucose

Question 19

starch

Answer 19

• example of a polysaccharide
• energy storage molecule for plants
• composed of glucose
• has alpha (1 to 4) glycosidic bond that makes starch coil

Question 20

amino acids

Answer 20

• contains 1 carboxyl group and 1 amino group
• there’s around 20 different AA’s found in proteins
• named as alpha-amino acids

Question 20

glycogen

Answer 20

• another polysaccharide
• composed of glucose
• energy storage compound
• animal starch

Question 20

nonpolar amino acids

Answer 20

only contain ALKYL GROUPS

Question 21

polar neutral amino acids

Answer 21

• has sulfur or oxygen atoms, sometimes alcohol

Question 22

acidic amino acids

Answer 22

have a CARBOXYLIC ACID ATTACHED and is negatively charged

Question 23

basic amino acids

Answer 23

have a couple of NITROGEN ATOMS attached and are POSITIVELY CHARGED

Question 24

pH charges

Answer 24

• peptide will change if the pH is changed
  pH 1 - net charge 2+
  pH 7 - net change 0
  pH 14 - net charge 2-

Question 24

fibrous proteins

Answer 24

• exist in long fibers or strings
• often seen in hair and skin
• typically tough and water insoluble

Question 25

globular proteins

Answer 25

• spherical in shape
• highly folded
• water-soluble
• also are known as enzymes
• has nonpolar amino acids in interior, has polar amino acids on surface

Question 26

primary structure

Answer 26

• order of amino acid residues/amino acid sequence
• listed from N-terminus to C-terminus

Question 27

the loss of the native conformation of a protein caused by heat

Answer 27

• denaturation

Question 28

quaternary structure in proteins occurs only in proteins composed of:

Answer 28

• more than one polypeptide chain
• maintained by non-covalent interactions
• regulates protein activity

Question 29

secondary structure

Answer 29

• how protein chain is folded, twisted, or bent
• has alpha-helix and beta-sheets
  (both stabilized by hydrogen bonds)

Question 30

tertiary structure

Answer 30

the overall 3D shape of a protein

Question 31

b sheets

Answer 31

• form when different segments of a polypeptide chain align side by side
• parallel sheets - same direction
• antiparallel sheets - opposite directions

Question 32

examples of non-amino acids compounds called prosthetic groups:

Answer 32

the heme group and several metal ions