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Complex Patterns of Heredity. Advanced Biology DNHS. Complex Inheritance Patterns. Sometimes the laws and principles of genetics established by Gregor Mendel do not always explain the inheritance patterns seen in an organism. Incomplete Dominance. - PowerPoint PPT Presentation
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Complex Patterns of Complex Patterns of HeredityHeredity
Advanced Biology Advanced Biology
DNHSDNHS
Complex Inheritance Complex Inheritance PatternsPatterns
Sometimes the laws and principles of Sometimes the laws and principles of genetics established by Gregor genetics established by Gregor Mendel do not always explain the Mendel do not always explain the inheritance patterns seen in an inheritance patterns seen in an organism.organism.
Incomplete DominanceIncomplete Dominance
The heterozygous or hybrid The heterozygous or hybrid individual will show an intermediate individual will show an intermediate phenotype between the two phenotype between the two homozygous individualshomozygous individuals
Example – Snap Dragons flower color Example – Snap Dragons flower color red crossed with white = red crossed with white = pinkpink
R = redR’ = white
R R
R’R’
R’ R
R’R
RR’
RR’RR’ RR’
RR’ RR RR’
R’R’
Genotype: Genotype:
Phenotype: Phenotype:
All RR’ hybrid
All pink
¼ RR; ½ RR’; ¼ R’R’¼ red; ½ pink; ¼ white
CodominanceCodominance The heterozygous individual will show the The heterozygous individual will show the
phenotypes of each of the homozygous phenotypes of each of the homozygous individualsindividuals
Example – chickens, Example – chickens, black+white=checkered (black and black+white=checkered (black and white)white)
Multiple AllelesMultiple Alleles Situation wherein there exists more Situation wherein there exists more
than two alleles for a specific trait.than two alleles for a specific trait. Example – Blood type in humans (A, Example – Blood type in humans (A,
B, O alleles)B, O alleles)
Sex Linked TraitsSex Linked Traits When a trait is seen in one sex more When a trait is seen in one sex more
often than another due to a gene often than another due to a gene that is carried on one of the sex that is carried on one of the sex chromosomeschromosomes
Examples – eye color in fruit flies and Examples – eye color in fruit flies and hemophilia and color blindness in hemophilia and color blindness in humanshumans
Polygenic InheritancePolygenic Inheritance
When a trait is influenced by many When a trait is influenced by many genesgenes
Tends to be a wide range of Tends to be a wide range of phenotypic variationphenotypic variation
Examples: skin color, hair color, Examples: skin color, hair color, height in humansheight in humans
A situation in which there is an A situation in which there is an individual of unknown genotype individual of unknown genotype
To determine the genotype you To determine the genotype you would cross it with a pure recessive would cross it with a pure recessive individualindividual
Test CrossesTest Crosses
PedigreePedigree A graphic A graphic
genetic genetic family tree family tree that follows that follows a trait a trait through through several several generationsgenerations
AneuploidyAneuploidy
A condition of having an abnormal A condition of having an abnormal chromosome numberchromosome number
Example – Down’s Syndrome, Sex Example – Down’s Syndrome, Sex Chromosome Aneuploidies (Turner Chromosome Aneuploidies (Turner Syndrome)Syndrome)