mendel’s laws of heredity 10.1. gregor mendel an austrian monk who studied heredity through pea...
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Mendel’s Laws of Heredity
10.1
Gregor Mendel
An Austrian monk who studied heredity through pea plants
“Father of Genetics”
HeredityThe passing on of characteristics from parents to offspringTraits Characteristics that are inherited
Genetics
The branch of biology that studies heredity
Gametes
Male and female sex cells (egg and sperm)
Fertilization
The process in which the male gamete unites with the female gamete
Zygote
The fertilized cell that develops into a seed, baby, etc.
Pollination
The transfer of pollen grains from a male reproductive organ to a female reproductive organ in plants
Hybrid
Offspring formed by parents having different forms of a trait
Ex tall and short height
Monohybrid Cross
Mendel crossed parent plants of different heights
(mono = single trait)
Original parents (true breeding plants) are the P1 generation
Offspring of the parent plants are known as the F1 generation (filial)
Cross two F1 plants with each other and their offspring are
known as F2
generation
Alleles
Different gene forms
Come in pairs
DominantThe observed trait of an organism that masks the Recessive form of a trait
Dominant = capital letter
Recessive = small case letter
Mendel’s 1st Law of Inheritance
Law of Segregation
Gametes receive only one allele for a trait from each parent
Phenotype
The expression of a gene (The way an organism looks/behaves)
Genotype
The actual genetic make-up of an organism (TT)
Genotypes…
TT=the plant has 2 alleles for tallness
Tt=1 allele for tallness and 1 allele for shortness
tt=2 alleles for shortness
Homozygous
If the two alleles for the trait are the same
TT = homozygous dominant (for height)
tt = homozygous recessive (for height)
Heterozygous
The 2 alleles for a trait are different
Tt=1 allele for tallness and 1 for shortness
(for height)
Dihybrid Cross
A cross where two different traits are used
Di means two
Mendel’s 2nd Law
Law of Independent Assortment
Distribution of alleles for 1 trait into the gamete doesn’t affect distribution of alleles for the other trait
Punnett Square
A shorthand way of finding the expected ratios of possible genotypes in the offspring cross
The gametes that each parent forms are listed on the top and left side of the square
Probability
The likelihood that something will occur
Punnett Squares aren’t exact results because genetics is by chance (like flipping a coin)