chapter 14
mendel scientific research
a heritable featurethat varies among individuals -charachter
used peas to study inheritance, due to large number of offspring and short generation time
each variant for character is called a trait
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chose varieties with true breeding - over many generations of offspring, they only produce the same variety as the parent plant
the crossing of two true breeding varieties is called hybridization
true breeding parents referred to as P generation, and offspring the F1 generation (first generation) and then onto the F2 generastion (second geeneration)
the dominant trait, and recessive trait, the resultant offspring approximate a 3:1 ratio. this showed inmendels experiment with the purple and white flowers with purple being dominant an whitie recessive
alternative versions of genes are called allels
if two allels at a locus differ, then one dominant allell determines the appearance, the recessive has no effect on the organisms appearance
law of segregation-two allels for a for a heritable charachter segregate during gamete formation and end up in different gametes
punnette square can predict the allele composition
an organism that has a pair of identical allelles for a gene encoding a character is called a homozygote, it is said to be homozygous for that gene
an organisms that has two different allels for a gene is called heterozygote and is said to be heterozygous for that gene
an organisms distinguishable traits are called a phenotype, and its genetic makeup a genotype
monohybrids -heterozygous for one particular charachter.
cross between two heterozygotes is monohybrid cross
dihybrids-individuals heterozygous for the two charachters being followed in the cross
dihybrid cross, cross between f1 dihybrids
LAW OF INDEPENDENT ASSORTMENT-two or more genes assort independently during gamete formation.
This law applies only to genes (allele pairs) located on different chromosomes or to genes that are very far apart on the same chromosome
multiplication rule- multiply the probability of one event, by the probability of another event
addition rule- probability any the or more mutually events will occur
allels can show different
co dominance- two allels each affect the phenotype in separate distinguisable ways
complete dominance- phenotypes of a hetrerozygote and the dominant homozygote are indistinguishable
incomplete dominance-when neither allele is completely dominant
codominance- two alleles each affect the phenotype in separate, distinguishable ways