Chapter 17: Genetics Flashcards
who is Mendel and and what did he study, theory?
an Australian monk in 1860s
he studied inheritance patterns of simple traits=genes in the garden pea and these traits had distinguishable types or alleles
theory of inheritance
phenotype
visible type of trait, appearance
genotype
combination of alleles
monohybrid cross
Study the inheritance of one trait
use true breeding homozygous parents for cross- Mendel started with this
P1
F1
F2
parental
first filial- first gen children
second filial - second gen children
what kind of experiments did Mendel do?
controlled experiments and observed the results
PP x pp=
all Pp
Pp x Pp=
3 purple, 1 white
1 PP, 2 Pp, 1pp
the dihybrid crosses are based on
monohybrid cross ratios
law of segregation
each organism is diploid: has 2 copies/ alleles of each gene
during meiosis these alleles segregate so that each gamete contains only one allele for each gene
each trait is controlled by
2 alleles
dominant allele
can mask the expression of the recessive allele
needs only 1 dominant allele to see the dominant phenotype
alleles for a gene occur at the same
gene locus= position on homologous chromosomes
homozygous
organism has 2 of the same alleles
heterozygous
organism has 2 different alleles
visual appearance of organism
phenotype
genetic composition of an organism
Genotype
homozygous dominant
heterozygous dominant
homozygous recessive
PP
Pp
pp
since all Pp and PP individuals all have the dominant phenotype there is a difference between
phenotypic and genotypic ratio
which is the phenotypic ratio and which is genotypic?
1 PP: 2 Pp: 1 pp
3 purple: 1 white
genotype
phenotype
if mom is Tt, what gametes can she give?
T and t
how do you know the genotype of an organism if heterozygous and homozygous dominants look the same?
one trait test cross
test cross- cross an organism with the dominant phenotype with an organism with the recessive phenotype.
the ratio of dominant: recessive phenotype will tell you the genotype of the dominant parent
what kind of game yes can dominant parents make?
recessive?
T and?
t
if the dominant parent is a heterozygous the expected phenotype with a recessive is
homozygous
1 tall: 1 short
all tall