proteins

Question 1

thyrotropin is an example of what size peptide

Answer 1

a tiny peptide, has 3 amino acid residues

Question 2

cytochrome is an example of what size peptide

Answer 2

a medium peptide, 104 amino acid residues

Question 3

Tyrosine kinase is an example of what size peptide

Answer 3

a large peptide, 1200 amino acid residues

Question 4

RNA polymerase is an example of what size peptide

Answer 4

an Extra large peptide, has 4158 aa residues

Question 5

TRUE or FALSE proteins only contain one peptide chain

Answer 5

FALSE

Question 6

the bond that forms peptide bonds is known as

Answer 6

condensation reaction, when bonding it release H2O and when unbonding it gains this back

Question 7

when is a protein most thermodynamically stable?

Answer 7

when it has a spatial arrangement of atoms

Question 8

what type of favourable bonds does a native fold try to have as many of

Answer 8

multiple weak, non-covalent bonds and covalent (such as disulfide non-peptide)

Question 9

TRUE or FALSE: alpha-helices and beta-sheets are both held in place by hydrogen bonds, which form between the carbonyl O of one amino acid and the amino H of another

Answer 9

TRUE

Question 10

in an alpha-helix, the carbonyl (C=O) of one amino acid is ??? bonded to the amino H (N-H) of an amino acid that is ??? down the chain. (E.g., the carbonyl of amino acid 1 would form a hydrogen bond to the N-H of amino acid 5.)

Answer 10

hydrogen bonded to the amino H of an amino acid that is FOUR down the chain.

Question 11

in a Beta-sheet, +2 segments of a polypeptide chain line up ???, forming a sheet-like structure held together by ??? bonds. These bonds form between carbonyl and amino groups of ???, while the R groups extend above and below the plane of the sheet

Answer 11

line up next to each other to form a sheet-like structure held together by HYDROGEN bonds that form between carbonyl and amino groups of the BACKBONE

Question 12

an antiparallel beta-sheet the strands run in opposite directions, resulting in ??? bonds which provide strength—> N-terminus of one strand is positioned next to the C-terminus of the other, very strong

Answer 12

linear hydrogen bonds

Question 13

??? residues are buried in the protein interior. This occurs frequently

Answer 13

Hydrophobic residues

Question 14

number of hydrogen bonds and ??? interactions within protein are maximised to reduce unfavourable/ unsuitable pairing between H-bonding and ???-groups

Answer 14

ionic interactions
ionic-groups

Question 15

RESONANCE bond is an ??? sharing of electrons between carbonyl O and amide N. This causes peptide bonds to be less reactive than esters, and exhibit a large ??? moment in favoured ???-configuration

Answer 15

unequal sharing
large dipole moment
trans-configuration

Question 16

what causes primary structure of peptide bonds to be very rigid and nearly planar?

Answer 16

the resonance bond

Question 17

secondary structure of a peptide refers to the ??? arrangement of polypeptide backbone

Answer 17

local spatial arrangment

Question 18

irregular arrangement of secondary structure is also known as

Answer 18

random coil

Question 19

alpha-helix is a ??? helix with 3.6 amino acid residues per turn

Answer 19

right-handed helix

Question 20

what offers stability in alpha-helix secondary structure?

Answer 20

amino acid sequence

Question 21

TRUE or FALSE: how far apart amino acid residues are can determine if a helix can form or if beta-sheet occurs instead

Answer 21

TRUE

Question 22

strong helix formers include ??? and ??? because they are small, hydrophobic

Answer 22

alanine and leucine

Question 23

proline acts as a ??? breaker because rotation around its N-C bond is impossible (because of its ??? structure)

Answer 23

helix breaker
ring structure

Question 24

Glycine acts as a helix ??? because its tiny r-group gives ??? flexibility

Answer 24

breaker
too much flexibility

Question 25

parallel beta sheets have the ??? bonded strands running in the same direction = ???-bonds are bent, causing ???

Answer 25

H-bonded strands
H-bonds are bent, causing weakness

Question 26

TRUE or FALSE: an alpha-helix has covalent bonds between amino acids near each other

Answer 26

FALSE they have non-covalent bonds

Question 27

do many proteins require chaperones to assist them with their folding?

Answer 27

yes

Question 28

Fibrous proteins are polypeptide chains arranged in long ??? made from the same/single type of secondary structure

Answer 28

long strands/sheets

Question 29

fibrous proteins provide ???, shape, external protection

Answer 29

support

Question 30

Globular proteins often contain both ??? and ??? secondary structures as they can interact together. these proteins tend to be enzymes and regulatory proteins

Answer 30

alpha and beta secondary structures

Question 31

Globular proteins are water soluble and lipid-soluble ??? proteins

Answer 31

lipid soluble membrane proteins

Question 32

Proteome refers to:

Answer 32

the entire complement of proteins expressed by a cell, tissue, organ

Question 33

cation exchange chromatography refers to when buffer is ??? , it binds ??? / ??? charged ions and will elute anions (negatively charged ions)

Answer 33

acidic/anionic
cations/positively charged ions

Question 34

gel filtration column (size exclusion) will elute the ??? proteins first because these sized proteins cannot enter

Answer 34

larger

Question 35

salting out separation of proteins: proteins precipitate depending on their ??? and can then be isolated with centrifugation

Answer 35

solubility

Question 36

column chromatography: for anion exchange, column is positive and binds ???

Answer 36

anions

Question 37

2D gel electrophoresis combines isoelectric focusing and SDS-PAGE so that
1st dimension seperates proteins by ???
2nd dimension separates proteins by ???

Answer 37

pI

molecular weight