Proteins Prt 2

Question 1

what does the amino acid sequence determine

Answer 1

Amino acid sequence determines protein structure

Question 2

what are proteins

Answer 2

Proteins are polymers of amino acid monomers

Question 3

what are amino acids linked by

Answer 3

Amino acids are linked by peptide bonds to form polypeptides

Question 4

what structure do amino acids have

Answer 4

Amino acids have the same basic structure, differing only in the R group present

Question 5

how are amino acids classified

Answer 5

Amino acids are classified according to their R groups: basic (positively charged); acidic (negatively charged); polar; hydrophobic

Question 6

what does the wide range of functions carried out by proteins result from

Answer 6

The wide range of functions carried out by proteins results from the diversity of R groups

Question 7

what is the primary structure

Answer 7

The primary structure is the sequence in which the amino acids are synthesised into the polypeptide

Question 8

what does hydrogen bonding along the backbone of the protein strand result in

Answer 8

hydrogen bonding along the backbone of the protein strand results in regions of secondary structure — alpha helices, parallel or anti-parallel beta-pleated sheets, or turns

Question 9

what bonds stabilize the interaction between r groups in a tertiary structure

Answer 9

The polypeptide folds into a tertiary structure

This conformation is stabilised by interactions between R groups: hydrophobic interactions; ionic bonds; London dispersion forces; hydrogen bonds; disulfide bridges

Question 10

where does a Quaternary structure exist

Answer 10

Quaternary structure exists in proteins with two or more connected polypeptide subunits

Question 11

what is a prosthetic group

Answer 11

A prosthetic group is a non-protein unit tightly bound to a protein and necessary for its function

Question 12

what can interactions of the R groups be influenced by

Answer 12

Interactions of the R groups can be influenced by temperature and pH

Question 13

what does ligand binding do

Answer 13

Ligand binding changes the conformation of a protein

Question 14

what is a ligand?

Answer 14

A ligand is a substance that can bind to a protein

Question 15

what are the R groups not involved in protein folding for

Answer 15

R groups not involved in protein folding can allow binding to ligands

Question 16

what do binding sites have

Answer 16

Binding sites will have complementary shapes and chemistry to the ligand

Question 17

what happens as a ligand binds to a protein-binding site

Answer 17

As a ligand binds to a protein-binding site the conformation of the protein changes. This change in conformation causes a functional change in the protein

Question 18

what do Allosteric interactions occur between

Answer 18

Allosteric interactions occur between spatially distinct sites

Question 19

what do many allosteric proteins consist of

Answer 19

Many allosteric proteins consist of multiple subunits (have quaternary structure)

Question 20

what do allosteric proteins with multiple subunits show

Answer 20

Allosteric proteins with multiple subunits show co-operativity in binding, in which changes in binding at one subunit alter the affinity of the remaining subunits

Question 21

what do allosteric enzymes contain

Answer 21

Allosteric enzymes contain a second type of site, called an allosteric site

Question 22

what do modulators regulate

Answer 22

Modulators regulate the activity of the enzyme when they bind to the allosteric site

Question 23

following the binding of a modulator what happens

Answer 23

Following binding of a modulator, the conformation of the enzyme changes and this alters the affinity of the active site for the substrate

Question 24

what does the binding and release of oxygen in haemoglobin show

Answer 24

The binding and release of oxygen in haemoglobin shows co-operativity

Answer 25

The influence and physiological importance of temperature and pH on the binding of oxygen

Question 26

what does the addition or removal of phosphate cause

Answer 26

The addition or removal of phosphate can cause reversible conformational change in proteins. This is a common form of post-translational modification

Question 27

what do protein kinases do

Answer 27

Protein kinases catalyse the transfer of a phosphate group to other proteins

Question 28

what happens to the terminal phosphate of ATP

Answer 28

The terminal phosphate of ATP is transferred to specific R groups

Question 29

what do protein phosphatases do

Answer 29

Protein phosphatases catalyse the reverse reaction

Question 30

what does phosphorylation bring about

Answer 30

Phosphorylation brings about conformational changes, which can affect a protein’s activity. The activity of many cellular proteins, such as enzymes and receptors, is regulated in this way

Question 31

what are some proteins activated by
?

Answer 31

Some proteins are activated by phosphorylation while others are inhibited