Proteins/protein structure 1

Question 1

four levels of protein structure

Answer 1

primary
secondary
tertiary
quaternary

Question 2

protein classification by shape

Answer 2

globular vs fibrous

Question 3

protein classification by composition

Answer 3

simple vs conjugated

Question 4

contain only amino acids

Answer 4

simple proteins

Question 5

contain protein and ‘non protein’ components

Answer 5

conjugated proteins

Question 6

the specific amino acid sequence of a protein

Answer 6

primary structure

Question 7

similar sequence and arose from the same ancestor gene, and carry out similar fuctions

Answer 7

homologous proteins

Question 8

sickle cell anemia is caused by a substitution of _____ for a ____

Answer 8

valine for a glutamate

Question 9

polypeptide bond between nitrogen on amino group and alpha carbon

Answer 9

phi bond

Question 10

polypeptide bond between alpha carbon and carboxyl carbon

Answer 10

psi bond

Question 11

polypeptide bond between carboxyl carbon and nitrogen of amino group

Answer 11

omega bond

Question 12

structures stabilized by hydrogen bonding between carbonyl and the N-H groups of polypeptide’s backbone

Answer 12

secondary structure

Question 13

two most common secondary structures

Answer 13

alpha helix

beta pleated sheet

Question 14

a rigid, rod-like structure formed by a helical turn

Answer 14

alpha helix

Question 15

alpha helix are stabilized by hydrogen bonding between N-H and a carbonyl group ____

Answer 15

four amino acids away

Question 16

two amino acids that do foster alpha helix

Answer 16

glycine

proline

Question 17

why doesn’t glycine form alpha helix

Answer 17

its to small and flexible

Question 18

why doesn’t proline form alpha helix

Answer 18

too rigid, lacks a N-H group for hydrogen bonding

Question 19

which are more abundant in nature left or right handed secondary structures

Answer 19

right handed secondary structures

Question 20

three different types of right handed alpha helices

Answer 20

alpha helix
3-10 helix
pi helix

Question 21

form when two or more polypeptide chain segments line up, side by side

Answer 21

beta pleated sheets

Question 22

two types of beta pleated sheets

Answer 22

parallel

antiparallel

Question 23

which type of beta sheet is less stable

Answer 23

parallel sheets

Question 24

many proteins have supersecondary structures with patterns of alpha helix and beta sheets

Answer 24

motifs

Question 25

refers to unique three dimensional structures formed by globular proteins

Answer 25

tertiary structure

Question 26

four main chemical interactions help stabilize tertiary structure

Answer 26

hydrophobic interactions ionic interactions hydrogen bonds covalent bonds

Question 27

hydrophobic R groups are brought together as they exclude water or are excluded fro water

Answer 27

hydrophobic interactions

Question 28

occurs between R goups of amino acids

Answer 28

hydrogen bonding

Question 29

includes disulfide bridges

Answer 29

covalent bonds

Question 30

occurs especially between oppositely charged groups

Answer 30

ionic interactions

Question 31

structurally independent segments that have specific functions

Answer 31

domains

Question 32

core structural element of a domain is

Answer 32

fold

Question 33

proteins that consist of repeated domains

Answer 33

mosaic or modular proteins

Question 34

level of structure achieved when two or more folded polypeptides in tertiary structure associate to form a functional protein

Answer 34

quaternary structure

Question 35

individual polypeptides in quaternary structure are called

Answer 35

subunits

Question 36

three reasons for common occurrence of multiunit proteins

Answer 36

1. synthesis of subunits is more efficient 2. worn out subunits can be replaced more effectively 3. biological function requires interaction of subunits

Question 37

polypeptide subunits are held together by

Answer 37

linkages

Question 38

covalent cross links in collagen are initiated by

Answer 38

lysyl oxidase

Question 39

some proteins are partially or completely unstructured

Answer 39

unstructured proteins