Lecture 3: Mendelian Genetics Flashcards
Mendels background:
1822: Born in Austria (now part of Czech republic). Parent were farmers.
1843: Entered a monastery
1851-53: University of Vienna (maths&botany)
1856-63: Breeding peas
1866: published his experiments in a journal
1884: Died
1900: rediscovery of his work
The garden pea name;
Pisum sativum
Why did he use the garden pea?
- Comes in a wide variety of phenotypes (shapes and colours); single gene
- Readily available, short generation time, large number of progeny
- usually breeds by self-pollination (true breeding). Easy to manipulate (cross)
Cross pollination in peas:
Plant 1
1) Anthers (male part) removed before they shed pollen.
Plant 2:
Collect pollen arm anther using brush.
Brush pollen onto stigma of other plant.
Mendel first cross:
Cross one purple and white pea plant.
All F1 generation were purple.
Testcross to prove the second law:
WwGg x wwgg.
Ratios: 1:1:1:1.
Mendel published his work in 1865, what was it called?
“The Natural History Society of Brunn”
Who was mendels worked rediscovered by in 1900?
Hugo de Vries
Carl Torrens
Erich von Tshermack.
All investigated mechanisms off inheritance and realised they were beaten to it.
20 years of Mendelians Vs Biometricians was reconciled by
R. A. Fisher in 1918
The Mendel-Fisher controversy is arguing? And what year?
Was Mendel a cheat????
1936
Reasons to think Mendel was a cheat
- Mendels ratios were always very close to the theoretical expectations
- The probability of getting such a high degree of congruence is 7X10^-5
- were they ‘too good to be true’?
- was the data fabricated?
- Fisher attributed the alleged forgery to an ‘unknown assistant’
Natural Selection works because:
- Individuals vary genetically
- Some variants are fitter than others
- Variation is heritable
Genetic variation is caused by different ____
Alleles
One allele may be ______ to others
dominant
An individual has two alleles and may be ____ or _____
homozygous heterozygous
