Introduction to Genetics (BIOL0003) Notes - Modifications to Mendel
9 views 0 purchase
Course
Introduction to Genetics (BIOL0003)
Institution
University College London (UCL)
Embark on a nuanced exploration of genetic principles with these focused notes crafted for Year 1 students in the Introduction to Genetics (BIOL0003) module at University College London. Specifically delving into the modifications to Mendel's laws, this document offers a concise examination of Mend...
Modifications to Mendel’s Second Law
Deviations from Mendel’s Second Law – Gene Interaction
Mendel’s second law
o Law of independent assortment
During gamete formation – the segregation of alleles of one allelic pair is independent of the
segregation of the alleles of another allelic pair
o Dihybrid cross
P1 = SSYY x WWGG
F1 = all SWYG
All smooth yellow heterozygous
F2 = 9:3:3:1 ratio
o Inheritance of shape and colour is independent – giving the 9:3:3:1 ratio
o Mouse genome
Agouti mouse
Brown-black coat
o Strand has yellow band
Black mouse
Homozygous recessive aa for non-agouti
o Removes yellow band
Brown mouse
Pigment mutation – makes brown mouse bb
Cross agouti and brown mouse
AABB = agouti
aabb = brown
P1 = AABB x aabb
F1 = all AaBb = all agouti
F2 = 9:3:3:1 ratio of agouti: cinnamon: black: brown
o
Cinnamon = brown hair with yellow band
Albino mouse
, Modifications to Mendel’s Second Law
C locus – mouse can make no pigment
Cross black and albino mouse
BBCC = black
o B = dominant pigment
o C = ability to make pigment
bbcc = albino
o b = recessive pigment
o c = inability to make pigment
P1 = BBCC x bbcc
F1 = All BbCc = all black
F2 = genotype 9:3:3:1
o Phenotype 9:3:4 ratio of black: brown: albino
Last two classes have the same
phenotype – as they have the epistatic
albino allele at the C locus that masks
the phenotype at the B locus
Epistatic interaction
Expression of one gene locus hides the expression of another
o Mouse coat colour genes in horses
o Albino tiger
o Humans
Secretor – phenotype that has two parts
Secretor red
Non-secretor blue
Secretor phenotype = you express your ABO blood groups in your body fluids
Non-secretor phenotype = you don’t express your ABO blood groups in your body fluids
o Haemoglobins in pregnancy
Before birth – fetus has a different haemoglobin mix
As haemoglobin has to be better at absorbing oxygen
HbF (fetal) may persist – protects against sickle cell symptoms
o Purple and white foxgloves – complementation
Purple is dominant to white
P1 – white line 1 x white line 2
Two distinct ways of plant being white
o Making purple pigment – takes a number of steps
If any one of the steps are blocked = purple pigment not produced
o 2 lines with mutant allele at two different loci – plants are both white but for
different reasons
White line 1 = w1w1W2W2
White line 2 = W1W1w2w2
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller sujansathiendran. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $8.63. You're not tied to anything after your purchase.
