Proteins/protein structure 1 Flashcards Preview

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Flashcards in Proteins/protein structure 1 Deck (39):
1

four levels of protein structure

primary
secondary
tertiary
quaternary

2

protein classification by shape

globular vs fibrous

3

protein classification by composition

simple vs conjugated

4

contain only amino acids

simple proteins

5

contain protein and 'non protein' components

conjugated proteins

6

the specific amino acid sequence of a protein

primary structure

7

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

homologous proteins

8

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

valine for a glutamate

9

polypeptide bond between nitrogen on amino group and alpha carbon

phi bond

10

polypeptide bond between alpha carbon and carboxyl carbon

psi bond

11

polypeptide bond between carboxyl carbon and nitrogen of amino group

omega bond

12

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

secondary structure

13

two most common secondary structures

alpha helix
beta pleated sheet

14

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

alpha helix

15

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

four amino acids away

16

two amino acids that do foster alpha helix

glycine
proline

17

why doesn't glycine form alpha helix

its to small and flexible

18

why doesn't proline form alpha helix

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

19

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

right handed secondary structures

20

three different types of right handed alpha helices

alpha helix
3-10 helix
pi helix

21

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

beta pleated sheets

22

two types of beta pleated sheets

parallel
antiparallel

23

which type of beta sheet is less stable

parallel sheets

24

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

motifs

25

refers to unique three dimensional structures formed by globular proteins

tertiary structure

26

four main chemical interactions help stabilize tertiary structure

hydrophobic interactions
ionic interactions
hydrogen bonds
covalent bonds

27

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

hydrophobic interactions

28

occurs between R goups of amino acids

hydrogen bonding

29

includes disulfide bridges

covalent bonds

30

occurs especially between oppositely charged groups

ionic interactions

31

structurally independent segments that have specific functions

domains

32

core structural element of a domain is

fold

33

proteins that consist of repeated domains

mosaic or modular proteins

34

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

quaternary structure

35

individual polypeptides in quaternary structure are called

subunits

36

three reasons for common occurrence of multiunit proteins

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

37

polypeptide subunits are held together by

linkages

38

covalent cross links in collagen are initiated by

lysyl oxidase

39

some proteins are partially or completely unstructured

unstructured proteins