Proteins: structure

Question 1

what are the 4 levels of protein structure?

Answer 1

1. primary
2. secondary
3. tertiary
4. quartnerary

Question 2

what is the primary structure of a protein?

Answer 2

the sequence of amino acids bonded together by peptide bonds

Question 3

what bond is formed between proteins?

Answer 3

peptide bonds

Question 4

what is the primary structure determined by?

Answer 4

DNA

Question 5

what does DNA determine in the primary structure of a protein?

Answer 5

1. structure
2. what amino acids have been added or removed
3. shape
4. function

Question 6

what is the secondary structure of a protein?

Answer 6

the structure of a protein when the weak, negatively charged nitrogen and oxygen atoms interact with weak positively charged hydrogen atoms to form hydrogen bonds.

Question 7

what atoms interact with each other to form the secondary structure?

Answer 7

weak negatively charged nitrogen and oxygen atoms, with weak positively charged hydrogen atoms

Question 8

what do the hydrogen bonds do to the protein shape?

Answer 8

can cause its shape to become either coiled or folded.

Question 9

what are the 2 different structures/shapes that can form from the secondary structure?

Answer 9

1. alpha helix
2. beta pleated

Question 10

how does the alpha helix shape form?

Answer 10

weak negative nitrogen/oxygen interacts with weak positive hydrogen, forming hydrogen bonds which form between every fourth peptide bond.

Question 11

how does the beta pleated sheet shape form?

Answer 11

forms when the proteins folds in a way that two parts of the polypeptide chain are parallel to each other. which enables hydrogen bonds to form between parallel peptide bonds.

Question 12

what kinds of proteins usually have a secondary structure?

Answer 12

fibrous proteins

Question 13

how can the hydrogen bonds be broken?

Answer 13

1. temperature
2. pH

Question 14

what is the tertiary structure of proteins?

Answer 14

the overall 3d shape of the polypeptide chain

Question 15

what is the tertiary structure determined by?

Answer 15

the interactions between amino acid side-chains (the R groups)

Question 16

what bond is between the R groups?

Answer 16

hydrogen bonds

Question 17

what bond is formed between cysteine amino acids?

Answer 17

disulphide bonds

Question 18

what is a cysteine amino acid?

Answer 18

a proteinogenic amino acid that contains a sulfur atom in its R group

Question 19

what bond is formed between charged R groups?

Answer 19

ionic

Question 20

what bond is formed between non-polar R groups?

Answer 20

weak hydrophobic interactions

Question 21

what kinds of proteins commonly have a tertiary structure?

Answer 21

globular

Question 22

when does a quaternary structure exist?

Answer 22

when a protein has more than one polypeptide chain working together as a functional macromolecule.

Question 23

what is an example of a quaternary structure?

Answer 23

haemoglobin

Question 24

what is each polypeptide chain in the quaternary structure called?

Answer 24

a subunit of the protein

Question 25

what bonds are in the primary protein level?

Answer 25

peptide bonds

Question 26

what bonds are in the secondary protein level?

Answer 26

peptide and hydrogen bonds

Question 27

where are the hydrogen bonds in the secondary protein level?

Answer 27

between the amino acid and the carboxyl group

Question 28

what bonds are in the tertiary protein level?

Answer 28

peptide, hydrogen, disulphide, and ionic bonds, also hydrophobic interactions

Question 29

where are the hydrogen bonds in the tertiary protein level?

Answer 29

R groups, amino acids, and carboxyl groups

Question 30

what bonds are in the quaternary protein level?

Answer 30

the same as the tertiary protein level.