biochemistry

Question 1

amino acids have _ groups attached to a central carbon

Answer 1

four

Question 2

_ groups include:
1. amino group
2. carboxylic acid group
3. hydrogen atom
4. R group

Answer 2

amino acid

Question 3

determines chemistry and function of amino acid

Answer 3

what is the R group?

Question 4

there are _ amino acids that appear in proteins of eukaryotic organisms

Answer 4

20

Question 5

stereochemistry for central carbon in eukaryotes will always be

Answer 5

L

Question 6

_ amino acids can exist in prokaryotes

Answer 6

D

Question 7

all amino acids have S configuration except _

Answer 7

cysteine

Question 8

_ is the only achiral amino acid

Answer 8

glycine

Question 9

glycine has R group: _

Answer 9

H atom

Question 10

what do these amino acids have in common?
- glycine
- alanine
- valine
- leucine
- isoleucine
- methionine
- proline

Answer 10

these amino acids are nonpolar and nonaromatic

Question 11

what do these amino acids have in common?
- tryptophan
- phenylalanine
- tyrosine

Answer 11

these amino acids are aromatic

Question 12

what do these amino acids have in common?
- serine
- threonine
- asparagine
- glutamine
- cysteine

Answer 12

these amino acids are polar

Question 13

what do these amino acids have in common?
- aspartate
- glutamate

Answer 13

these amino acids are acidic and negatively charged

Question 14

what do these amino acids have in common?
- lysine
- arginine
- histidine

Answer 14

these amino acids are basic and positively charged

Question 15

amino acids with long alkyl chains are _ while amino acids with charges are _

Answer 15

hydrophobic; hydrophilic

Question 16

amino acids can both accept and donate protons, which means they are _

Answer 16

amphoteric

Question 17

pH at which half of the species is deprotonated

Answer 17

what is pKa?

Question 18

amino acids exist in _ forms at different pH values

Answer 18

different

Question 19

amino acids are fully protonated at _ pH

Answer 19

low/acidic

Question 20

amino acids are fully deprotonated at _ pH

Answer 20

high/alkaline

Question 21

when the pH is near the pI of an amino acid, it is called _

Answer 21

zwitterion

Question 22

isoelectric point (pI) can be calculated by averaging two pKa values for amino acids _ a charged side chain

Answer 22

without

Question 23

amino acids can be _ (method)

Answer 23

titrated

Question 24

titration curve is mostly _ at pKa value and _ at pI value (of amino acids)

Answer 24

flat; vertical

Question 25

isoelectric point (pI) can be calculated by averaging two pKa values (protonation and deprotonation) for amino acids _ a charged side chain

Answer 25

with

Question 26

pI of amino acids without charged side changes ...

Answer 26

= 6

Question 27

pI of ACIDIC amino acids ...

Answer 27

below 6

Question 28

pI of BASIC amino acids ...

Answer 28

above 6

Question 29

dipeptides have _ AA residues; tripeptides have _ residues

Answer 29

2; 3

Question 30

amino acid subunits

Answer 30

what are residues?

Question 31

oligopeptides have _ residues while polypeptides have _ residues

Answer 31

few (less than 20); many (over 20)

Question 32

the release of one water molecule

Answer 32

what is dehydration (condensation)?

Question 33

_ reaction forms the peptide bond

Answer 33

condensation (dehydration)

Question 34

amide bonds are rigid due to _

Answer 34

resonance

Question 35

nucleophilic amino group attacks _ of another amino acid

Answer 35

electrophilic carbonyl group

Question 36

breaking a peptide bond is a _ reaction

Answer 36

hydrolysis

Question 37

linear sequence of amino acids a in peptide

Answer 37

what is primary structure?

Question 38

primary structure is stabilized by _

Answer 38

peptide bonds

Question 39

local structure of neighboring amino acids

Answer 39

what is secondary structure?

Question 40

secondary structure is stabilized by _ between amino groups and nonadjacent carboxyl groups

Answer 40

hydrogen bonding

Question 41

clockwise coils around central axis

Answer 41

what are alpha helices?

Question 42

rippled strands that can be parallel or antiparallel

Answer 42

what are beta pleated sheets?

Question 43

_ can interrupt secondary structure due to rigid cyclic structure

Answer 43

proline

Question 44

3D shape of single polypeptide chain

Answer 44

what is tertiary structure?

Question 45

_ structure is stabilized by _ hydrophobic and acid-base interactions, hydrogen bonding, and disulfide bonds

Answer 45

tertiary

Question 46

push hydrophobic R groups to interior of a protein

Answer 46

what are hydrophobic interactions?

Question 47

hydrophobic interactions _ entropy and creates _ Gibbs free energy

Answer 47

increases; negative

Question 48

forms when 2 cysteine molecules are oxidized and forms cystine (covalent bond)

Answer 48

what are disulfide bonds?

Question 49

interaction between peptides in protein that contain multiple subunits

Answer 49

what is quaternary structure?

Question 50

proteins with covalently attached molecules

Answer 50

what are conjugated proteins?

Question 51

attached molecules that can include metal ions, vitamin, lipid, carbohydrate, nucleic acid

Answer 51

what are prosthetic groups?

Question 52

loss of a 3D protein structure due to heat and increasing solute concentration

Answer 52

what is denaturation?