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Unformatted text preview: Mendel’s Laws of Heredity
Mendel’s Laws of Heredity
Why we look the way we look... What is heredity?
What is aThe passing on of characteristics (traits) from parents to offspring
aGenetics is the study of heredity Mendel used peas...
Mendel used peas...
aThey reproduce sexually aThey have two distinct, male and female, sex cells called gametes
aTheir traits are easy to isolate Mendel crossed them
Mendel aFertilization the uniting of male and female gametes
aCross combining gametes from parents with different traits Questions
a What did Mendel cross?
a What are traits? a What are gametes? a What is fertilization?
a What is heredity?
a What is genetics? What Did Mendel Find?
What Did Mendel Find?
aHe discovered different laws and rules that explain factors affecting heredity. Rule of Unit Factors
Rule of Unit Factors
aEach organism has two alleles for each trait –Alleles different forms of the same gene
–Genes located on chromosomes, they control how an organism develops Rule of Dominance
Rule of Dominance
aThe trait that is observed in the offspring is the dominant trait (uppercase)
aThe trait that disappears in the offspring is the recessive trait (lowercase) Law of Segregation
Law of Segregation
aThe two alleles for a trait must separate when gametes are formed
aA parent randomly passes only one allele for each trait to each offspring Law of Independent Law of Independent Assortment
aThe genes for different traits are inherited independently of each other. Questions...
aHow many alleles are there for each trait?
aWhat is an allele?
aHow many alleles does a parent pass on to each offspring for each trait Questions...
aWhat do we call the trait that is observed? aWhat case (upper or lower) is it written in?
aWhat about the one that disappears? aWhat case is it written in? Phenotype & Genotype
Phenotype & Genotype
a Phenotype the way an organism looks – red hair or brown hair a genotype the gene combination of an organism – AA or Aa or aa Heterozygous & Homozygous
Heterozygous & Homozygous
a Heterozygous if the two alleles for a trait are different (Aa) a Homozygous if the two alleles for a trait are the same (AA or aa) Dihybrid vs Monohybrid
Dihybrid vs Monohybrid
aDihybrid Cross crossing parents who differ in two traits (AAEE with aaee)
aMonohybrid Cross crossing parents who differ in only one trait (AA with aa) Questions...
aWhat is the phenotype?
aWhat is the genotype?
aWhat is homozygous? aWhat is heterozygous? aWhat is monohybrid crossing? ...
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- Winter '11