Inheritance Flashcards
What did Kolventer discover in the 18th centuary?
Nicotiana (tobacco) reciprocal hybrids equivalent. Not all “information” came from one parent
What did Knight discover in 1799?
Pea stem & flower purple pigment Reciprocal hybrids equivalent F1 all pigmented F2 reappearance of non-pigmented form He made no attempt to explain these important results.
What did darwin discover ?
Scored Antirrhinum inheritance in individuals (instructed by his cousin Francis Galton). This data was later interpreted by Bateson to show Mendelian inheritance
When was Gregor Mendel paper presented and published?
Presented in 1865
Published in 1866
In 1875 who observed process of fertilisation
Hertwig
When did Hertwig and Strasburger suggested the cell nucleus was the location of the heredity function
1885
Define gene
unit of inheritance often responsible for one trait
Define allele
alternative states / mutations of a particular gene
Define homozygous and heterozygous
HOMO- identical alleles at the gene loci, producing identical gametes
Hetro- different alleles so different gametes
Define dominant and recessive
Dominant- allele trait always expressed
Recessive- allele trait only expressed if homozygous
Define phenotype
the expression of a character in an organism
Define genotype
the allelic hereditary constitution
P1 means?
parental generation
F1 means?
First filial generation, progeny from parents
F2 means?
Second filial generation, progeny resulting from F1 cross
How do we denote genes?
A (upper-case) = Dominant allele. a (lowercase) = recessive allele
In Drosophila: letter denotes the mutant allele “+” = wildtype allele
What are Mendel’s 4 postulates and laws of inheritance?
1) principles of paired factrors
2) principle of dominance
3) Law of Segregation/Law of purity of Gamtes (1st LAW)
4) Law of independent assortment (2nd LAW)
What are the 5 advantages of using peas for genetics?
1) A number of discrete traits that can be studied
2) Self fertilizing
3) Numerous viable and fertile progeny
4) Short generation time
5) Can carry out crosses between different individuals by emasculation of anthers before pollen ripe and transfer of pollen from alternate parent
Do a monohybrid cross for One tall and one short tree
TTxtt = all Tt
In the F2 cross of TT and tt plants. What is the ratio of the resulting plants?
Tt xTt =
- 25 TT
- 25 tt
- 5 Tt
What is the ratio usually seen in F2 generation from 2 homozygous ‘parents’
3:1
What is a dihybrid cross?
2 genes on different chromosomes each with 2 alleles
What is independent assortment?
When alleles are unlinked in dihybrid crosses
Do this dihybrid cross.
T is dominant to t
G is dominant to g
TG Tg tG tg x TG Tg tG tg
9:3:3:1
Tall green (T-G-) = TTGG, TTGg, TtGG, TtGg Tall yellow (T-gg) = TTgg, Ttgg Short green (ttG-) = ttGG, ttGg Short yellow (ttgg) = ttgg
What is the mathematical rules of complete dominance with gene loci on different chromosomes F2?
No of heterozygous gene pairs- n
No of diff. types of gametes form - 2^n
No of diff. genotypes produced- 3^n
No of diff. phenotypes produced- 2^n