MYTUTOR SUBJECT ANSWERS

1048 views

How does gel electrophoresis work to separate DNA fragments of different lengths and how may the lengths of the different strands then be determined?

The process of gel electrophoresis uses the fact that DNA fragments are negatively charged (due to the bulky, negative phosphate groups within the sugar-phosphate backbone) in order to pull the fragments through a gel (essentially a very thick liquid). To do this, the fragments are inserted by pipette into one end of the gel slab and a positive charge is generated at the opposite end. As opposite charges attract one another, this causes the DNA fragments to move towards the other end of the gel. Importantly, as larger (i.e. longer) molecules of DNA are heavier and take up more space, the resistive forces agaisnt their movements through the gel will be greater than for the smaller fragments, so the larger frgaments will not move as far as smaller ones. In this way, the frgaments will be separated according to their size, forming 'bands' a particular distance along the gel. Using standard known lengths of DNA as a kind of ruler (known as a size standard), the length of fragments in each band of the separated DNA can be compared to the location of the bands with the known lengths of DNA, which like a ruler, will give you the size of your fragments that you are testing

James P. A Level Biology tutor, GCSE Biology tutor, GCSE Chemistry tu...

11 months ago

Answered by James, an A Level Biology tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

190 SUBJECT SPECIALISTS

£22 /hr

Xanthe W.

Degree: Biological Sciences with a Year in Industry/Research (Bachelors) - Imperial College London University

Subjects offered:Biology, Maths+ 1 more

Biology
Maths
Chemistry

“Top tutor from the renowned Russell university group, ready to help you improve your grades.”

£20 /hr

Katie D.

Degree: Biomedical Science (Bachelors) - Durham University

Subjects offered:Biology

Biology

“Hello, I am just a genuine, patient, friendly person who wants to help other struggling students to understand, enjoy and hopefully succeed in biology.”

£26 /hr

Abigail M.

Degree: Plant Evolution and Ecology (Doctorate) - Oxford, Jesus College University

Subjects offered:Biology, Zoology+ 8 more

Biology
Zoology
Maths
Geography
Extended Project Qualification
Environmental Studies
English
Chemistry
-Personal Statements-
-Oxbridge Preparation-

“PhD (Biology) at the University of Oxford **Available this summer!** Compassionate, patient and experienced in helping students boost their confidence!”

About the author

James P.

Currently unavailable:

Degree: Medicine (Bachelors) - Oxford, St Catherine's College University

Subjects offered:Biology, Physics+ 5 more

Biology
Physics
Maths
Chemistry
.UKCAT.
.BMAT (BioMedical Admissions)
-Medical School Preparation-

“About me Hi guys, my name's James and I'm a medical student going into my second year at St Catherine's College, Oxford. I'll do my best to show you that learning doesn't have to be dull and to help you overcome any question or proble...”

MyTutor guarantee

You may also like...

Posts by James

How does gel electrophoresis work to separate DNA fragments of different lengths and how may the lengths of the different strands then be determined?

What kind of books should I read that would look good on a personal statement/when discussed in an interview?

Other A Level Biology questions

Describe the structure of DNA

What causes bacteria to become antibiotic resistant?

How does a plant respond to light?

Describe key structural differences between prokaryotic and eukaryotic cells.

View A Level Biology tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok