Mendel Flashcards
Who was Gregor mendel
Austrian monk, naturalist, known as father of genetics
Used pea plants to demonstrate hereditary
No knowledge of chromosomes at the time
5 reasons why mendel was successful
Repeated crosses many times
Used rules of Probability
Controlled pollination
Could study many generations
Pea plants have many traits that appear in 2 different forms (tall vs short)
Trait
A specific characteristic or feature exhibited by an organism
What was Mendels expierement
Studied self fertilizing plants to produce offspring with consistent traits generation after generation
He performed crosses, crossed true breeding plant w one form of a trait
Called these P generation (parents, generation)
True breeding organisms
Pass on same traits generation after gen
Cross
Fertilization of a female gamete with a male gamete
P generation:
Organisms initially being crossed
Monohybrid cross
Only 1 trait being looked at eg only seed colour
Alleles
Different versions of a gene
Law of dominance
Dominant Allele will always express itself when present in genotype
Ressesckve will only express when 2 copies of ressesive allele is present in genotype (rr)
Why is mendel the father of genetics?
Established true breeding
Crossed true breedin*lines
Obvserved patterns in offsprings
Identified dominant and ressesive
Identified mathematical ratios
Came up w laws of inheritance
Law of segregation
Pair of alleles for a given trait are segregated when gametes are formed
Eg Tt = gametes t and T
Each gamete contains only one of the alleles
Test cross/back cross
Used when organism has dominant phenotype, and we don’t know if it is homozygous dom (FF) or hetero (Ff)
To find out, cross dominant phenotype w homozygous recessive organism (rr)
Dihybrid cross
Crossing involving 2 traits, eg round and tall or wrinkled and short
What is the dihybrid phenotypic ratio (homo dom and homo rec)
9:3:3:1
9 is dominant forms of both traits (YyRr)
3 is offspring of one recessive form of a trait and one dominant form of the second traits (yyRR)
3 offspring displaying opposite combo of ressesicvd and dom forms (YYrr)
1 offspring with recessive forms of both (yyrr)
