The promoter of the araBAD operon from E. coli is activated in the presence of arabinose and the absence of glucose and directs expression of genes encoding enzymes required for arabinose metabolism. Unlike the cases of lac and gal genes, where a repressor and an activator work together, here two activators work together: AraC and CAP

+ arabinose	AraC binds that sugar and adopts a configuration that allows it to bind DNA as a dimer to the adjacent half-sites, araI1 and araI2
– arabinose	the AraC dimer adopts a different conformation and binds to araO2 and araI1, there is no monomer at site araI2, and so the protein cannot activate the araBAD promoter (araPBAD). This promoter is also controlled by CAP.

TLS Online TPP Program

#Question id: 27387

#Unit 1. Molecules and their Interaction Relevant to Biology

Electron affinity depends on

TLS Online TPP Program

#Question id: 27388

#Unit 1. Molecules and their Interaction Relevant to Biology

Electron affinity is the

TLS Online TPP Program

#Question id: 27389

#Unit 1. Molecules and their Interaction Relevant to Biology

The of the tendency of an atom to attract a bonding pair of electrons is known as

TLS Online TPP Program

#Question id: 27390

#Unit 1. Molecules and their Interaction Relevant to Biology

Some elements exist naturally as molecules. Such as, hydrogen and oxygen exist as two-atom molecules, but Sulfur and phosphorus normally  exists as

TLS Online TPP Program

#Question id: 27391

#Unit 1. Molecules and their Interaction Relevant to Biology

Choose the correct statement

1.Transfer of electrons is the characteristic of ionic bond 

2.Sharing of electrons is the characteristic of ionic bond

3.Sharing of electron is the characteristics of covalent bond 

4.Transfer of electron is the characteristics of covalent bond

TLS Online TPP Program

#Question id: 27392

#Unit 1. Molecules and their Interaction Relevant to Biology

Match the following

Bond	Bond energy in KJ
I. C=C	a. 891
II. C ≡ O	b. 946
III. N≡N	c. 1080
IV. C≡N	d. 611