chapter 3

Question 1

core structure of an amino acid consists of a

Answer 1

central carbon atom / alpha carbon

Question 2

central carbon atom/alpha carbon is covalently bonded to

Answer 2

a hydrogen atom, amino functional group (NH2), carboxyl group (COOH), and a side chain/ r group

Question 3

proteins are derived from

Answer 3

20 different amino acids

Question 4

in our cells amino acids are

Answer 4

ionized

Question 5

ionized form is when

Answer 5

The amino group acts as a base + accepts a hydrogen atom….
The carboxyl group acts as an acid bc of the 2 electronegative oxygen atoms

Question 6

why are amino acids unique?

Answer 6

due to the different R groups and each of them affect chemical properties of an amino acid

Question 7

what are the 3 r group types

Answer 7

1. charged (basic or acidic)
2. polar (partial charge)
3. nonpolar (no charge)

Question 8

polar and charged r groups…

Answer 8

are hydrophilic (interact w water) bc their charges allow them to interact w. waters partial charges

Question 9

Charged Acidic amino acids

Answer 9

contains R group with negative charge

Question 10

Charged Basic amino acids

Answer 10

has R-group with positive charge

Question 11

Polar amino acids have

Answer 11

R group with partially negative oxygen atom

Question 12

nonpolar r groups

Answer 12

hydrophobic (dont interact w water) bc they lack a charge so they cant interact with partial charges of water

Question 13

nonpolar amino acids

Answer 13

lack r-group with any charge/ partially charged oxygen atom

Question 14

how do amino acids link to one another?

Answer 14

thru formation of a peptide bond

Question 15

how do peptide bonds form?

Answer 15

when a carboxyl functional group of one amino acid reacts (dehydration/condensation reaction) with the amino group of another amino acid

Question 16

where can you find a stable covalent bond between C and N

Answer 16

peptide bond
stable bc the formation of intermittent C N double bond

Question 17

peptide

Answer 17

when amino acids link tg in a chain of 50 amino acids

Question 18

polypeptides

Answer 18

50 + amino acids linked

Question 19

protein

Answer 19

any chain of amino acids

Question 20

3 things to know about peptide

Answer 20

1. r group of each amino acid is oriented away from amino acid backbone
2. directionality where amino group is at one end of chain + carboxyl group at opposite end
3. bonds neighboring peptide bonds can rotate giving it flexibility

Question 21

four levels of structures of protein

Answer 21

primary, secondary, tertiary, quaternary

Question 22

primary structure

Answer 22

represents the unique sequence of amino acids in a protein

Question 23

what does the sequence of amino acids determine?

Answer 23

the shape and function of a protein due to the unique r group properties that affect size, reactivity and solubility

Question 24

secondary structure

Answer 24

result of hydrogen bonding between oxygen atom of carbonyl functional group and hydrogen atom in amino group resulting in 2 possible secondary structures

Question 25

2 types of secondary structures

Answer 25

alpha helix- coiled polypeptide backbone

beta sheet / pleated- polypeptide chain bends 180 and folds in the same plane

whether peptide/polypeptide chain will form into these depends on sequence of amino acids (primary structure)

Question 26

why are some amino acids more/less likely to form alpha helix or b sheet pleated structures?

Answer 26

due to specific geomtry/properties of the R side chain

Question 27

tertiary structure

Answer 27

protein 3D shape which forms from primart and secondary structures/interactions between r groups of different amino acids orr between r groups of amino acids AND peptide backbone

Question 28

5 types of r group interactions

Answer 28

hydrogen bonding
hydrophobic interactions
van der waals interactions
covalent bonding
ionic bonding

Question 29

hydrogen bonding

Answer 29

form between polar side chains and opposite partial charges

Question 30

hydrophobic interactions

Answer 30

water forces hydrophobic side chains tg

Question 31

van der waals interactions

Answer 31

weak electrical interactions between hydrophobic side chains

Question 32

covalent bonding

Answer 32

covalent bonds between side chains of sulfhydryl groups (disulfide bonds)

Question 33

ionic bonding

Answer 33

form between groups with full and opposing charges

Question 34

quaternary structure

Answer 34

result of two or more individual polypeptides interacting w. one another to form a single functional protein

has subunits

includes polypeptides w. distinct primary, secondary, and or tertiary structures

Question 35

what do the individual polypeptides that make up quaternary structure interact by?

Answer 35

Interact via same chemical bonds + interactions found in tertiary structures

Question 36

dimers

Answer 36

proteins that consist of 2 individual polypeptides

Question 36

trimers

Answer 36

proteins that consist of 3 individual polypeptides

Question 36

tetramers

Answer 36

proteins that consist of 4 individual polypeptides

Question 36

polypeptides subunit names

Answer 36

same - homo…. homodimer etc
different- hetero../heterotrimer etc

Question 37

protein functions depends on what

Answer 37

correct folding

Question 38

enzymes

Answer 38

effective catalysts bc they hold reactants (substrates) in precise orientation so that chemical reaction is more likely to occur

Question 38

which structure of a protein contains all info required for the proper folding of the protein and in protein folding necessary for its function

Answer 38

primary

Question 38

what does the lock and key model illustrate

Answer 38

how enzymes and substrates interact

enzymes orient substrates in a way to bring a reaction to act on specific substrates (active site)

Question 39

active site

Answer 39

location where chemical reaction occurs