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Genetics and Heredity

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genetics
study of heredity
Gregor Mendel
a monk who bred pea plant to study inheritance, he discovered the basic principals of heredity; Father of Genetics
gene
location of a specific trait on a chromosome
allele
alternate forms of gene with a slight difference in base sequence
dominant
masks, one allele is stronger than the other
recessive
gets masked, weaker allele
genotype
genetic makeup of an individual (think gene)
phenotype
the expression of the genotype or the physical characteristics that you can see (think physical)
homozygous
when both alleles in a pair are the same (homo=same)
heterozygous
when the alleles in a pair are different from each other (hetero=different)
monohybrid cross
cross between two individuals that differ by one trait
law of segregation
two alleles for each trait separate when gametes form
law of dominance
in pair of alleles where one is expressed and one is not expressed, the expressed allele is dominant and unepressed is not dominant
P1
parental generation or the original generation that you observe
F1
the offspring of the P generation
F2
the offspring of the F1 generation
single allele traits
traits that are controlled by a single dominant allele or homozygous recessive alleles
multiple alleles
traits controlled by more than two alleles for the same gene
incomplete dominance
traits which have a heterozygous genotype that is intermediate between the dominant and recessive allele
codominant trait
traits which have a heterozygous genotype where both alleles have equal expression
sex-linked traits
traits that appear in the 23rd pair of chromosomes (the chromosomes that determine gender) and are normally found on the x chromosome
polygenic traits
traits controlled by two or more genes
single allele traits
example: height in pea plants is controlled by a dominant tall allele or two recessive short alleles
multiple alleles
example: there are three alleles for blood type ( A, B, O) which results in four blood types
incomplete dominance
example: some varieties of flowering plants will produce a pink flowering version when a homozygous red and homozygous white are crossed
sex-linked traits
examples: colorblindness and hemophilia
polygenic traits
example: skin color is controlled by 4-7 genes
traits
passed from parents to offspring
dominant, recessive
example: allele for tall pea plant is (T) ______ over short pea plant (t) _______
genotype
example: the ______for a pure tall pea plant would be TT
phenotype
example: if the genotype for height in the pea plant is tt, then you will see a short pea plant
homozygous
example: a pure tall pea plant is _____ dominant, genotype=TT
heterozygous
example: a tall pea plant with genotype Tt is ______