MYTUTOR SUBJECT ANSWERS

442 views

How are single-gene disorders inherited?

Most of our characteristics are encoded by a pair of alleles. These are different forms of the same gene, one inherited from the father and one from the mother. Inheriting a mutated allele can lead to disease in one of two ways. In 'dominant' diseases, such as Huntington's chorea, only one mutant allele need be inherited for the disease to develop. In 'recessive' diseases, such as cystic fibrosis, a person must inherit two mutant alleles, one from each parent, to be affected. Genetic counsellors commonly use Punnett squares to determine the probability that a given pregnancy will result in a child with a single-gene disorder. This involves drawing up all the possible combinations of the parents' alleles, and calculating the percentage or ratio of children which would be affected. A subset of single-gene disorders are said to be X-linked, as the alleles responsible are encoded on the X-chromosome. An interesting consequence of this is that although an X-linked disease may be classed as recessive, a boy can inherit only one mutant allele and still develop disease, as he has no second X-chromosome containing a healthy allele to offset the effects of the mutant one.

Kilda C. GCSE Chemistry tutor, GCSE Biology tutor, GCSE Maths tutor, ...

11 months ago

Answered by Kilda, a GCSE Biology tutor with MyTutor


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

259 SUBJECT SPECIALISTS

£22 /hr

Teresa B.

Degree: Anatomy (Bachelors) - Glasgow University

Subjects offered:Biology, Spanish+ 3 more

Biology
Spanish
French
Chemistry
-Personal Statements-

“Since the dawn of time, I've been talking to people about things I love and enjoy. How cliché, I know. But don't roll your eyes at me yet. Hear me out: ...”

£18 /hr

Abhinav T.

Degree: Medicine (Other) - University College London University

Subjects offered:Biology, Physics+ 2 more

Biology
Physics
Maths
Chemistry

“Confirming understanding by verbal confirmation and communication so as to ensure clarity and confidence during the learning process and progression.”

MyTutor guarantee

Sahil M. A Level Biology tutor, GCSE Biology tutor, A Level Chemistry...
£20 /hr

Sahil M.

Degree: Medicine (Bachelors) - Manchester University

Subjects offered:Biology, Spanish+ 3 more

Biology
Spanish
Maths
Chemistry
-Medical School Preparation-

“Hello! My name is Sahil and I am currently a medical student at the University of Manchester. I am really looking forward to tutoring you in Spanish, Chemistry, Biology or Maths as well as trying to help you during the difficult proce...”

About the author

Kilda C.

Currently unavailable: for regular students

Degree: Medicine (Bachelors) - Oxford, New College University

Subjects offered:Biology, Physics+ 2 more

Biology
Physics
Maths
Chemistry

“Hello! I'm Kilda, I come from Belgium and I'm about to start my third year readingMedicine at the University of Oxford. I have been tutoring Science, Maths, Piano and Music Theory since 2011. When I am tutoring, or trying to learn som...”

You may also like...

Posts by Kilda

How are action potentials transmitted?

How are single-gene disorders inherited?

Other GCSE Biology questions

What is the difference between an artery and a vein?

How does antibiotic resistance relate to evolution?

Explain how bacteria can become resistant to antibiotics.

How are action potentials transmitted?

View GCSE 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