proteins<3

Question 1

name the 4 structural levels in proteins

Answer 1

PRIMARY -> sequence of amino acids
SECONDARY -> alpha helicase and beta pleated sheets
TERTIARY -> bonding between alpha helices and beta sheets
QUATERNATARY -> further internal and external bonding

Question 2

describe primary structure

Answer 2

simple sequence of amino acids in chain.
the most simple description of protein structure
N terminus and C terminus

Question 3

describe secondary structure ALPHA HELICASE!

Answer 3

can be R or L handed - usually R
proteins vary in alpha heliacse length and content
ampiphathic helicase -hydrphillic outward hydrophobic inward

Question 4

describe secondary structure BETA STRANDS AND SHEETS

Answer 4

almost fully extended sections of polypeptide
not as compact as helicase
strands can be parallel or antiparallel
parallel is less stable

Question 5

how are beta sheets stabalised?

Answer 5

by H bonds between carbonyl oxygen and amide hydrogen on adjacent strand

Question 6

describe tertiary protein structure

Answer 6

Amino acids come closer together in tertiary level
resulting side chain interactions
stabilised by non covalent interactions between side chains covalent disulphide bridges also present

Question 7

describe tertiary structure SUPER SECONDARY

Answer 7

also called MOTIFS - combination of alpha helices and beta strands + loops
motifs can be linked to specific protein functions
examples- coiled-coiled, hairpin, greek key

Question 8

describe tertiary structure DOMAINS

Answer 8

compact units and indépendant of each other but joined at primary structures
each domain consist of several elements of secondary structures
can group proteins with simular sequences and domains
direct relationship between domain and structure

Question 9

describe quaternary structure

Answer 9

further level of structure seen in many proteins not all!
refers to subsist which have independent polypeptide chain
stabilised with weak non covalent bonds, hydrophobic interactions with electrostatic forces contributing

Question 10

where do salt bridges form in protein

Answer 10

deep inside hydrophobic part

Question 11

what is a denaturant required to do?

Answer 11

unfold Native (N) form of protein

Question 12

chemical, heat and pressure denaturant all work by?

Answer 12

causing disruption of bond interaction

Question 13

name three types of denaturant?

Answer 13

pressure
chemical
heat

Question 14

do denatured proteins still have a lot of internal structure

Answer 14

yes

Question 15

can all proteins renature spontaniously

Answer 15

NO

Question 16

does denaturation require more or less energy compared to renaturation?

Answer 16

LESS

Question 17

how do proteins fold?

Answer 17

spotaniously to achieve lowest energy state

Question 18

do enzymatic pathways have weak or strong interactions?

Answer 18

WEAK

Question 19

key features of WANDERWAAL forces

Answer 19

short range, small magnitude,
only when atoms in close proximity,
dipolar
clusters add strength

Question 20

what is Ka

Answer 20

association constant

Question 21

how do we work out Ka

Answer 21

Ka =1/Kd

Question 22

name 4 further side chain modifications

Answer 22

hydroxlation,
glycosylation,
phosphorolation,
collagen

Question 23

what do hydroxylation do?

Answer 23

add OH

Question 24

what does glycosylation do?

Answer 24

add sugar chains

Question 25

what does phosphorlation do?

Answer 25

add phosphate

Question 26

give key features of hydroxylation

Answer 26

occurs immediately after amino acid chain completed found in collagen requires vitamin C.

Question 27

key features of glycosylation

Answer 27

occurs immediately after amino acids chain completed found mainly in secreted proteins & in those located on surface of cells used for stabalisation of protein structure

Question 28

phophorolation key features

Answer 28

reversible occur many times in life of protein control of enzyme activity

Question 29

collagen key features

Answer 29

protein of connective tissue can take many forms depending on requirements eg, tendons-> like rope in skin-> loosely woven allowing expansion

Question 30

what are myoglobin and heamoglobyn?

Answer 30

globular proteins

Question 31

what structures does myoglobin have?

Answer 31

primary, secondary and tertiary

Question 32

what is myoglobyn

Answer 32

one polypeptide chain folded up into globule

Question 33

what does heamoglobyn comprise of?

Answer 33

the equivelent of 4 myoglobin molecules

Question 34

does haemoglobin have quaternary structures?

Answer 34

YES