Mendelian Genetics Flashcards
Mendelian Genetics started with observation that there were:
Tiny humans, or homunculus!
From the homunculus, this was concluded.
Inheritance
Mendel’s original hypothesis?
Factors in parents. Get one from each!
Depending on what factors, would influence appearance.
P =
Parental generation - always true breeding
F1 =
First Filial - All offspring of PxP
F2 =
Second Filial - All offspring of F1xF1
Mendel’s 2 Laws of Inheritence?
Law of Segregation - Each parent has 2 copies of gene, 1 copy only in gamete.
Law of Independent Assortment - How those genes line up is random
F2 generation phenotypic ratio?
3:1
An organisms characteristic (Color/Position)
Trait
Specific characteristic expression of trait (Purple/Wrinkled)
Phenotype
A segment of DNA that encodes for a protein.
Gene
First Concept related to above was:
Variations of inherited traits (different forms of gene)
Second Concept of Mendel?
Always have 2 genes, but form of genes may be different!
Diploid =
Two copies of every gene, existing in homologous chromosomes
Locus =
Where the gene exists on the chromosome
Allele =
Form of a gene, two copies. One from each parent
Third concept of Mendel?
Some alleles are DOMINANT!
T/F Dominant allele can mask the presence of another
True
PP or pp
Homozygous Dominant or Recessive
Pp or pP
Heterozygous
Heterozygous are also known as “______”
Carriers
Fourth Concept of Mendel?
Law of Segregation! Alleles separate in meiosis into different gametes
How do alleles split?
In Anaphase I - each daughter has one, in Anaphase II - four gametes, each with their own chromatid. Therefore, gametes only have ONE allele. Always in a 50/50 Split!
Cross involving one trait?
Monohybrid Cross
Cross involving two traits?
Dihybrid Cross
In a monohybrid cross of purple & white flowers genotypes would be? And gametes?
PP x pp (Genotype)
PP or pp
Phenotypic ratio in F2 generation of Monohybrid cross?
3:1
Genotypic ratio of F2 in Monohybrid cross?
1:2:1
In probability when we say ‘and’ we ______ and when we say ‘or’ we ______ the probabilities.
Multiply - And
Add - Or
The testcross is a tool to determine an _______ _________.
Uknown Genotype - what the possible parent types were.
The Law of Independent Assortment looks @
2 Character Traits
To look at 2 character traits we use a:
Dihybrid cross
Phenotypic ration of dihybrid cross?
9:3:3:1 YR Yr yR yr YR Yr yR yr
Trihybrid phenotypic ratio?
1:6:15:20:15:6:1
