Nucleic acids and chromatin
Nucleic acids and chromatin

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Nucleic acids and chromatin

‘Bulky’ agents

So far we have only considered damage caused by ‘small’ groups such as methyl groups. There is, however, a class of so-called ‘bulky’ DNA-damaging agents that have been widely studied. Many polyaromatic hydrocarbons (PAH) induce skin cancer in experimental systems and one such molecule benzo(a)pyrene, BaP), is found in tobacco smoke. BaP itself is an extremely stable and unreactive molecule, but it is metabolised within the cell to a highly reactive derivative that forms characteristic DNA modifications at the C2 amino group of guanine. The C2 amino group is normally ‘buried’ within the inner core of the DNA double helix, but the BaP metabolite is small enough to fit into the minor groove of DNA. Here it reacts with the guanine and intercalates between the stacked bases, thereby distorting the helix (Figure 21).

Figure 21
Figure 21 A reactive metabolite of BaP (space-filling) reacts with nine base-pair helical duplex DNA (tubes) through the minor groove, resulting in its intercalation and helix distortion. (Based upon pdb file 1dxa)
S377_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has over 40 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus