Proteins - structure of proteins

Question 1

what is the primary structure of a protein

Answer 1

the specific sequence of amino acids in the polypeptide chains.

Question 2

what do the sequence of amino acids influence

Answer 2

how the polypeptide chains folds to give the proteins final shape.

Question 3

what do the shape of the proteins determine

Answer 3

the function

Question 4

how many amino acids are there

Answer 4

20

Question 5

what are the bonds involved in the primary structure

Answer 5

only peptide bonds

Question 6

are the peptide bonds strong

Answer 6

yes

Question 7

what is the secondary structure of a protein

Answer 7

the initial folding of the polypeptide chain due to hydrogen bonds

Question 8

is the chain of amino acids straight

Answer 8

nope it twists

Question 9

how does the secondary structure form

Answer 9

the oxygen, hydrogen, and nitrogen atoms of the basic repeating structure of the atoms interact

Question 10

what bonds may form in the secondary structure

Answer 10

hydrogen bonds

Question 11

where do the hydrogen bonds form in the secondary structure

Answer 11

between the -NH group of one amino acid and the -CO group of another

Question 12

what is the shape called when the hydrogen bonds cause the chain to coil

Answer 12

alpha helix

Question 13

what are beta pleated sheets

Answer 13

polypeptide chains can also lie parallel to one another joined by hydrogen bonds forming sheet like structures. the pattern formed by the individual amino acids causes the structure to appear pleated.

Question 14

how are the beta pleated sheets held down

Answer 14

hydrogen bonds between the -NH group of one amino acid and the -CO of another further down hold the sheet together

Question 15

how strong are the hydrogen bonds

Answer 15

they are relatively weak

Question 16

what makes the alpha helix and the beta pleated sheet stable structures at optimal pH and temperature

Answer 16

they have lots of hydrogen bonds.
some chains dont adopt a regular structure and some chains have more than one secondary structure at different ends of the chain

Question 17

what is the tertiary structure

Answer 17

the folding of the secondary protein structure into a specific 3D shape

Question 18

what does the tertiary structure often include

Answer 18

sections of secondary structure

Question 19

how do tertiary structures form

Answer 19

the coiling or folding of sections of proteins into their secondary structures brings R groups of different amino acids closer together so they are close enough to interact and further folding of these sections will occur.

Question 20

what are the two types of tertiary structure

Answer 20

fibrous and globular

Question 21

how are fibrous and globular proteins held in place

Answer 21

by bonding between R groups of amino acids

Question 22

what do proteins bonds do

Answer 22

they hold the secondary, tertiary and quaternary structure together

Question 23

what is the secondary structure held together by

Answer 23

hydrogen bonds

Question 24

what is the tertiary and quaternary structure held by

Answer 24

hydrogen bonds and many more

Question 25

what are hydrogen bonds

Answer 25

they form between hydrogen atoms with a slight positive charge and other atoms with a slightly negative charge,

Question 26

where do hydrogen bonds form in amino acids

Answer 26

form between the amino group of one amino acid and the carboxyl group of another. they may also form between polar areas of the R groups of different amino acids.

Question 27

what are the hydrogen bonds involved in

Answer 27

keeping the tertiary and quaternary structure of the protein in the correct shape.

Question 28

what does the presence of multiple hydrogen bonds do

Answer 28

gives protein molecules a lot of strength.

Question 29

how do ionic bonds form

Answer 29

between the carboxyl and amino groups that are part of R groups. these ionise into NH3+ and COO- groups. positive and negative groups are strongly attracted to eachother to form an ionic bond between oppositely charged R groups

Question 30

how do disulfide links form

Answer 30

the R group of the amino acid cysteine contain sulfur. disulfide bridges between the R groups of two cysteines. these are strong covalent bonds.

Question 31

how do hydrophobic and hydrophillic interactions occur

Answer 31

hydrophobic parts of the R groups tend to associate together in the centre of the polypeptide to avoid water. in the same way, hydrophillic parts are found at the edge of the water.

Question 32

what do hydrophobic and hydrophillic interactions cause

Answer 32

twisting of the amino acid chain which changes the shape of the protein

Question 33

why are hydrophobic and hydrophillic interactions an important influence

Answer 33

most proteins are found to be surrounded by water inside a living organism

Question 34

what is the quaternary structure of a protein

Answer 34

3D protein comprised of two or more tertiary subunits

Question 35

do all proteins have a quaternary structure

Answer 35

no

Question 36

how do quaternary structures form

Answer 36

many proteins are made up of one or more polypeptide chains. quaternary structures describe how multiple polypeptide chains are arranged to make the complete protein molecule.

Question 37

what can hold the quaternary structure together

Answer 37

the bonds from the tertiary structure

Question 38

what are subunits

Answer 38

individual proteins which can be identical or different