Question

Question 6 (1 point)

Relative to non-cooperative DNA binding, cooperative DNA binding of proteins leads to which of the following?

Question 6 options:

	lower binding affinity
	increased binding to nonspecific sequences
	a sigmoidal binding curve
	a slower transition between unbound and completely bound protein as concentration increases
	tighter binding to nucleosomes

Answer 1

• Relative to non-cooperative DNA binding, cooperative DNA binding of proteins leads to which of the following -

Correct ans is - Increased binding to nonspecific sequence

because in non cooperative DNA binding ,substrate binding decreses affinity for subsequent substrate.and in cooperative binding,substrate binding increses affinity for subsequent substrate and also increased binding to nonspecific sequences.

• other options are worng like,Lower binding affinity,as we know hemoglobin has two alpha and two beta chain .hemoglobin is a protein found in red blood cells that binds oxygen and carbon dioxide. in hemoglobin, the binding of the ligand or targets to the first subunit(protiens) affects the second subunit(proteins) in a way that increases the binding affinity for the ligand or target.this indicates a cooperative binding.but in noncoperative DNA binding,binding of one ligand that doesn't have an effect on the binding of another ligand for any subunits that might be present.so there is lower binding affinity.
• a sigmoidal binding curve ,in cooperative binding there is high or incresed affinity for ligand or targets.in hemoglobin after binding of oxygen to the first subunit of hemoglobin, the second subunit has an increased affinity for oxygen and when this bound that also increases the affinity for the third subunit.This increased affinity for the ligand causes a sigmoidal or an S shaped binding curve and its seen in cooperative binding.but In non-cooperative binding, we see a logarithmic curve since the binding of one ligand doesn't have an effect on the binding of another ligand for any subunits that might be present.
• a slower transition between unbound and completely bound protein as concentration increases,it does not depends on concentration.it depends on affinity that bound ligand or specific targets .so this option is wrong.
• tighter binding to nucleosomes ,in cooperative binding there is tighter binding to nucleosome as seen in hemoglobin protein.but in relative to non cooperative binding that is not the correct ans.