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 is _________________, a monk whose study of genetic traits was 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 Pollen MALE FEMALE egg

In pea plants, the pollen normally joins with an egg from the same plant (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

MENDEL’S PEA EXPERIMENTS Mendel removed pollen – making parts and added pollen from another plant. This allowed him to _____________ plants with ______________ characteristics and study the results different cross-breed

A specific characteristic is called a ________ trait

MENDEL’S EXPERIMENTS P 1 generation (_________) generation generation F1F1 F2F2 parental

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 F 1 generation BUT Missing trait returned in the F 2 generation in a 3:1 ratio

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

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

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 lower-case T t NOT S for short Dominant Recessive

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

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

Why did the recessive trait disappear in the F 1 generation and reappear in the F 2 ? Image modified from: The pattern corresponds to the ____________ of ______________ during ____________________ MEIOSIS movement chromosomes

REMEMBER _____________ chromosomes ________________ during ANAPHASE I = _________________ SEGREGATION Image modified from: HOMOLOGOUS SEPARATE

____ offspring __________ an allele for tallness from their _______ parent and an allele for shortness from their ________ parent. The F 1 plants ALL ___________ but are ___________ an allele for _____________ TALL Images from: BIOLOGY by Miller & Levine; Prentice Hall Publishing ©2006 SHORT LOOK TALL F 1 received carrying shortness

alleles are separated when the F 1 plants ______________ When these gametes recombined to make the F 2 generation, the _____________ trait _______________ in ¼ of the offspring EXPLAINING the F 1 CROSS LAW OF ___________________ SEGREGATION Image from: BIOLOGY by Miller & Levine; Prentice Hall Publishing ©2006 recessive made gametes reappears

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

DIHYBRID CROSSES ( 2 traits)

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

LAW OF __________________________ the factors are distributed to gametes independently of other factors INDEPENDENT ASSORTMENT Image modified from: