Heredity Chapter 11

Transmission of characteristics from parent to offspring is called ___________________. The science that studies how those characteristics are passed on from one generation to the next is called ___________________ heredity Genetics

The Father of Genetics _________________ -a monk -studied traits in pea plants -the beginning of our understanding about how genes work Gregor Mendel

Mendel experimented using ___________ _______ part of flower makes ________ __________ part of flower makes _______ cells Pea plants MALE Pollen FEMALE egg

Pea plants are normally self-pollinating so seeds have one parent

MENDEL’S PEA EXPERIMENTS Mendel started his experiments with peas that were _________________ If allowed to _________________ they would produce ____________________ to themselves. true breeding self pollinate offspring identical

P1 generation (_________) generation MENDEL’S EXPERIMENTS P1 generation (_________) generation parental F1 F2

When Mendel crossed PLANTS with 2 contrasting traits: (EX: Tall crossed with short) He always found same pattern: 1. ONLY one trait showed in the F1 generation BUT . . . 2. Missing trait returned in the F2 generation in a 3:1 ratio

Two Conclusions…. 1) Must be a pair of factors controlling a trait…one can hide the other

The factors are GENES carried on the pair of homologous chromosomes Different gene choices for a trait are called alleles

2nd Conclusion… The Principle of dominance Some alleles are dominant and others are recessive

DOMINANT HIDES RECESSIVE is hidden by __________________ = An allele that ________ the presence of another allele __________________ = An allele that __________________ the presence of another allele HIDES RECESSIVE is hidden by

DOMINANT/RECESSIVE T t (not s for short) capital Dominant Recessive _____________ allele is represented by a ____________ letter. (usually the first letter of the trait) ____________ allele is represented by the SAME _________________ letter. EX: Tall = ______ Short =______ capital Recessive lower-case T t (not s for short)

HOMOZYGOUS HETEROZYGOUS When both alleles in the pair are the same, the organism is _______________ or __________ EX: ____ or ___ When both alleles in the pair are different, the organism is _________________ or _____________ Ex: ____ HOMOZYGOUS PURE TT tt HETEROZYGOUS HYBRID Tt

PHENOTYPE/GENOTYPE The ________________ of an organism is its _____________ The ____________of an organism is its _____________ genetic makeup GENOTYPE appearance PHENOTYPE

The pattern corresponds to the ____________ of ______________ during Why did the recessive trait disappear in the F1 generation and reappear in the F2? The pattern corresponds to the ____________ of ______________ during ____________________ movement chromosomes MEIOSIS

REMEMBER SEGREGATION _____________ chromosomes ________________ during ANAPHASE I = _________________ HOMOLOGOUS SEPARATE SEGREGATION

F1 received carrying shortness ____ offspring __________ an allele for tallness from their _______ parent and an allele for shortness from their ________ parent. The F1 plants ALL ___________ but are ___________ an allele for _____________ TALL SHORT LOOK TALL carrying shortness

make gametes reappears EXPLAINING the F1 CROSS LAW OF ___________________ SEGREGATION alleles are separated when the F1 plants ______________ When these gametes recombined to make the F2 generation, the _____________ trait _______________ in ¼ of the offspring make gametes recessive reappears

MAKING A CROSS for only a __________ trait = ____________________ ONE GENE MONOHYBRID CROSS

DIHYBRID CROSSES (2 traits)

MAKING A CROSS with ___________________= ____________________ TWO gene traits DIHYBRID CROSS

LAW OF __________________________ the factors are distributed to gametes independently of other factors INDEPENDENT ASSORTMENT