Question

A. Describe why a C-H bond represents a more reduced form of carbon than a C-O bond.

B. What is the role of the phosphorylated intermediate in energy coupling? Why must cells create phosphorylated intermediates when using ATP as a source of energy?  

C. Protein folding is a spontaneous process, but what information is used to guide this process of protein folding (i.e. how do proteins obtain the correct shape when they reach their tertiary structure)?

D. Describe the difference between an unstructured domain and a denatured protein

Answer 1

Answer-

(A) The C–H bond or carbon hydrogen bond is a bond formed between the carbon and hydrogen atoms , covalent bond i.e. carbon shares its outer electrons with four hydrogens and  making them stable.

•   bond length =  1.09 Å
• bond energy =  413 kJ/mol
• Electronegativity difference between C (2.55) and H (2.2)= 0.35
• due to less electronegativity valve of C−H bond it is considered as non-polar.

While  C– O  bond or carbon–oxygen bond is a bond formed between carbon and oxygen. the Oxygen has 6 valence outer electrons and only share two electrons during the  bonding with carbon, and have 4 nonbonding electrons which is present as in the form of 2 lone pairs :O:.

• polar covalent bond..

• Electronegativity difference of C(2.55)–O(3.44) bond = 0.89.

• Due to more Electronegativity difference value it is considered as polar.

due to these difference the C- H bond are more stable than the C-O bond.

(B)-role of the phosphorylated intermediate in energy coupling - these are the those molecule which receives a phosphate group from ATP (Adenosine triphosphate) leads to change in conformation and making the molecule more reactive than the reactivity of original molecule.

• phosphorylated intermediate changes the activation energy of the subsequent reaction step.
• Phosphorylated intermediates helps in maintaining the metabolic regulations by conserving the energy.

(C) Protein folding- it is a process in which a protein chain comes in its native functional 3-dimensional structure.   protein folding i.e. protein to adopt its native  correct three-dimensional conformation is present in their amino acid sequence.  Protein folding is a self assembly and spontaneous process. but some Proteins helps in protein folding are called molecular chaperones.chaperones catalyze protein folding during whole pathway by binding to the intermediate and stabilizing the partially unfolded or partially folded polypeptides to a native ,final correctly folded form. chaperones prevent incorrect folding and aggregation of unfolded or partially protein and helps in polypeptide chain to fold into its native conformation.. chaperone bind with the amino-terminal in partially folded and in unfolded conformation to complete polypeptide chain synthesis at the carboxy terminal followed by folding of  completed protein. Chaperones helps to  facilitate transfer of polypeptide chain across the mitochondrial membrane as well as proper folding in the organelle.  chaperones are also responsible for protein assembly and  in the regulation of protein degradation.  Proteins folding is also stabilized by several interaction including hydrophobic interactions,  hydrogen bonding and Van der Waals forces between amino acids responsible for polypeptide synthesis.  

(D) Difference between an unstructured domain and a denatured protein -

When a protein loses its native tertiary or quaternary structure but does not come in the form of amino acid sequence and become non functional  it is called denatured protein.

unstructured formed of structure is found when the protein if denatured and after some times it start to folded themselves are called unstructured domain. these domain have the required information for proper and correct folding.