proteins

Question 1

what are the monomers of proteins ?

Answer 1

amino acids

Question 2

what happens when 2 amino acids join together ?

Answer 2

a dipeptide is formed

Question 3

what happens when more than 2 amino acids join together ?

Answer 3

a polypeptide is formed

Question 4

what are proteins made up of ?

Answer 4

one or more polypeptides

Question 5

Do amino acids have the same or different structure ?

Answer 5

same

Question 6

what is the structure of amino acids?

Answer 6

a carboxyl group (-COOH),
an amine or amino group (-NH2
) and an R group (also known as a variable side group) attached to a carbon atom.

Question 7

what do R groups contain ?

Answer 7

R groups generally contain carbon.The only exception to this rule is glycine — its R group consists of just one hydrogen atom

Question 8

how many amino acids are their in living things ?

Answer 8

20

Question 9

what joins amino acids together ?

Answer 9

a condensation reaction between the carboxyl and amine group

Question 10

what happens when amino acids join ?

Answer 10

a molecule of water is released

Question 11

what are the bonds between amino acids called ?

Answer 11

peptide bonds

Question 12

what happens when dipeptide and polypeptides are broken down ?

Answer 12

hydrolysis reaction

Question 13

what is the primary structure of proteins ?

Answer 13

the sequence of amino acids in the polypeptide chain.

Question 14

what is the secondary structure of proteins ?

Answer 14

Hydrogen bonds form between
the amino acids in the chain. This makes it automatically coil into an alpha (a) helix or
fold into a beta (b) pleated sheet

Question 15

what bonds are formed in the tertiary structure of proteins ?

Answer 15

hydrogen bonds ,disulfide bridges and ionic bonds .

Question 16

when do disulfide bridges form in tertiary structure of proteins ?

Answer 16

whenever two molecules of the amino acid cysteine come close
together — the sulfur atom in one cysteine bonds to the sulfur atom in the other.their stronger than ionic or hydrogen bonds

Question 17

what i the Tertiary structure of proteins ?

Answer 17

when the secondary structure is coiled and folded further to form a 3D structure. For proteins made from a single polypeptide chain, the tertiary
structure forms their final 3D structure.

Question 18

what is the Quaternary structure in proteins ?

Answer 18

Some proteins are made of several different polypeptide chains held together by bonds.The Quaternary structure is the way these polypeptide chains are assembled together. Final 3D structure for these proteins .

Question 19

give examples of proteins formed from more than one polypeptides chain ?

Answer 19

haemoglobin,insulin, collagen

Question 20

what determines a protein function ?

Answer 20

it’s shape

Question 21

how does haemoglobin shape relate to it’s function ?

Answer 21

haemoglobin is a compact,
soluble protein, which makes it easy to transport. This makes it great for carrying oxygen around the body

Question 22

how is an enzymes shape related to its function ?

Answer 22

They’re usually roughly spherical in shape due to the tight folding of the polypeptide chains. They’re soluble and often
have roles in metabolism, e.g. some enzymes break down large food molecules (digestive enzymes,) and other enzymes help to synthesise (make) large molecules.

Question 23

How is an antibodies shape related to it’s function ?

Answer 23

An antibody is a Y shaped protein which has a constant region and a variable region.
The variable region of an antibody is of a complementary shape to a specific pathogenic antigen and this allows the antibody to bind to the antigen and neutralize the pathogen. The shape of the variable region varies between different antibodies therefore different antibodies can bind different antigens. The constant region of the antibody is the same for all antibodies. The constant region allows phagocytes to bind to the antibody. This allows the antibodies to act as opsonins which means they help the pathogens to be phagocytosed by phagocytes. Antibodies also have a hinge region which increases their flexibility and allows them to bind multiple pathogens at once - this is called agglutination.

Question 24

how are transport proteins suitable to their function ?

Answer 24

channel proteins are present in cell membranes . Channel proteins contain hydrophobic
(water hating) and hydrophilic (water loving) amino acids, which cause the protein to fold up and form a channel .
These proteins transport molecules and ions across membranes.

Question 25

How are structural proteins related to their function ?

Answer 25

Structural proteins are physically strong.They consist of long polypeptide chains lying parallel to each other with cross-links between them.

Question 26

Give 2 examples of structural proteins ?

Answer 26

Keratin and Collagen

Question 27

How is the structure of Collagen related to it’s function ?

Answer 27

Collagen has three polypeptide chains tightly coiled together, which makes it strong. This makes it a great supportive tissue in animals.

Question 28

Explain the test for protein -give the results

Answer 28

1. The test solution needs to be alkaline, so first you add a few drops of sodium hydroxide solution.
2. Then you add some copper(II) sulfate solution.
   If protein is present, the solution turns purple. If there’s no protein,the solution will stay blue