Nucleic acids and chromatin
Nucleic acids and chromatin

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

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 further371

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses372.

If you are new to university level study, we offer two introductory routes to our qualifications. Find out Where to take your learning next?373 You could either choose to start with an Access courses374or an open box module, which allows you to count your previous learning towards an Open University qualification.

Not ready for University study then browse over 1000 free courses on OpenLearn375 and sign up to our newsletter376 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 prospectus371