MYTUTOR SUBJECT ANSWERS

411 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...

7 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

147 SUBJECT SPECIALISTS

£20 /hr

Charlotte N.

Degree: Medicine (Other) - Durham University

Subjects offered: Biology, Chemistry+ 2 more

Biology
Chemistry
-Personal Statements-
-Medical School Preparation-

“Hi, I'm Charlotte, I'm 20 and I'm currently studying medicine at Durham university. I have a lot of experience teaching- I worked as a teaching assistant during my gap year and I have 3 younger siblings, so I'm always helping someone!...”

MyTutor guarantee

£20 /hr

Tom L.

Degree: BSc Clinical Sciences (Molecular Medicine) (Bachelors) - Leeds University

Subjects offered: Biology, French+ 3 more

Biology
French
Chemistry
-Personal Statements-
-Medical School Preparation-

“Hi, my name's Tom and I'm a fifth year Medical Student at the University of Birmingham. I am currently taking a year out to study an intercalated research year in Clinical Sciences at the University of Leeds focusing on research in ma...”

MyTutor guarantee

£22 /hr

Rachael O.

Degree: Medicine (Other) - Bristol University

Subjects offered: Biology, Science+ 6 more

Biology
Science
Maths
Human Biology
Chemistry
.UKCAT.
-Personal Statements-
-Medical School Preparation-

“Hi, my name's Rachael and I'm 21. I am a 3rd year medical student studying at Bristol University.  Availability: Mon-Fri 7pm-9pm (excluding Wednesdays). Weekends negotiable.  My aim is to help students enjoy learning and feel confid...”

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 cardiac cycle

What is an enzyme?

What are the main differences between eukaryotes and prokaryotes?

How does an invading pathogen cause disease?

View A Level Biology tutors

Cookies:

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

mtw:mercury1:status:ok