Mendel: Single Gene Inheritance Flashcards
Who is the father of modern genetics?
Gregor Mendel
Mendel’s experiments
Studied pea traits with two distinct forms, one dominant and one recessive
Generation titles
P1- parental generation
F1- first filial generation
F2- Second filial generation
Pair of homologous chromosomes
an individual inherits one of each type of chromosome from each parents
Gene locus
the location of a particular gene on a chromosome
Pair of alleles
different versions of the same gene
Alleles are located…
at the same sight(locus) on a pair of homologous chromosomes
Examples of alleles?
Freckles and no freckles
Ear lobe and no ear lobe
Tall plants and short plans
ETC.
Dominant is the ______ trait.
observed
Recessive is the _______ trait.
masked
True breeding plants
Plants which consistently have offspring with the same traits as the parents
Genotype
Organisms alleles- the letter combinations in a Punnett square
Phenotypes
outward expression of an allele combination- ex. brown hair, blue eyes, etc.
Which traits are expressed in heterozygote or hybrid?
Dominant
Which traits are not expressed in the heterozygote?
Recessive- they are hidden and individuals are carriers
Monohybrid cross
Follows one trait
Ex. Tt x Tt results in 3/4 tall and 1/4 short
Mendel’s experiments with a monohybrid cross helped him conclude that…
among the hybrid parents the recessive trait was hidden but not absent
Mendel’s First Law: Segregation
Alleles from mom and dad separate and randomly join with other alleles. At the end of meiosis each gamete carries one copy of an allele
Modes of inheritance
rules that explain the common patterns of single-gene transmission
Autosomal inheritance can be….
dominant or recessive
Criteria for autosomal dominant
-male and female can be affected
- males and females transmit trait with equal frequency
- trait shows up in every generation
- transmission stops after a generation in which no one inherits mutation
Criteria for autosomal recessive
- males and females can be affected
- trait can skip generation
- parents of individual are hetero or have trait, but MUST be carriers
- most conditions appear unexpectedly in families because they are transmitted through carriers
Homozygous dominant
BB
Homozygous recessive
bb
Heterozygous
Bb
Autosomal dominant vs autosomal recessive
DOMINANT
AA- phenotype +
Aa- phenotype +
aa- “normal” trait(recessive)
RECESSIVE
AA- “normal” trait(dominant)
Aa- “normal”, but carrier
aa- phenotype +
