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Chapter 4 Part 2- Genetics Since Mendel Life Science
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Question… If you crossed Purebred Red four- o’clock plants with Purebred White four-o’clock plants, what would the offspring look like?
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Remember… they were Pink !?!?!
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Incomplete Dominance- when two homozygous parents combine, the offspring results in a mixed (or blended) phenotype The evil Grey chicken!?!?!
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When neither allele for a trait is Dominant. The phenotype produced is a blending between the two homozygous parents. –The combining of Purebred Red & Purebred White produced PINK plants.
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Although Mendel studied peas that were controlled by two alleles, many traits can be controlled by more than two alleles…
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Multiple Alleles A trait that is controlled by Having more than two alleles is controlled by Multiple Alleles. Traits controlled by Multiple Alleles produce more than three phenotypes of that trait.
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Example of Multiple Alleles… Blood Types: A, B, AB, and O. –The O allele is recessive to both A and B
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Other Worksheet… Phenotype: Genotype: A - AA or Ao Genotype B – BB or Bo Genotype AB – AB Genotype O – oo Genotype
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A and B are _______________ alleles o is _________________ “ A Blood” you need _____ and _____ _____ and _____ “B Blood” you need _____ and _____ _____ and _____ “AB Blood” you need _____ and _____ shows______________ “o Blood” you need _____ and _____ Because it’s ___________
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Polygenic Inheritance Polygenic Inheritance- when a group of gene pairs acts together to produce one trait. –Which creates more variety in phenotypes
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What would be an example? Many traits such as…Eye Color, Hair Color, Skin tone, & Handspan are traits produced by a combination of genes.
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Human Genes & Mutations What are Mutations?!?!?
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Mutations Mutations - a permanent change in the DNA sequence A mutation can be harmful, beneficial, or cause no effect.
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Chromosome Disorder Chromosome disorders- caused by more or fewer chromosomes than normal –Downs Syndrome- caused by an extra chromosome (trisomy) at Chromosome 21
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Recessive Genetic Disorders Recessive Genetic Disorders are disorders passed through the Recessive alleles. Both parents contain the recessive allele (containing the disorder) that comes together in the offspring.
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When both parents are Heterozygous, they do not show any symptoms –(Called “carriers” for the trait.) Example- Cystic Fibrosis is a homozygous recessive disorder.
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Sex-Linked Disorders An allele inherited on a sex chromosomes ( X or Y ) is called a sex-linked gene. Inherited conditions are linked with the X and Y chromosomes.
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Example- Color Blindness and Hemophilia
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Pedigree- used to follow or trace traits through generations of a family.
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Section 3 III. Advances in Genetics A. Genetic Engineering- experimentations that changes the arrangement of DNA that makes up a gene.
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Types: 1. Recombinant DNA Inserting a useful section of DNA into a bacteria Example- Creating Insulin (Page 143)
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2. Gene Therapy- When a “normal allele” is placed into a virus, the virus then delivers the normal allele when it infects a specific cell. (Figure 13 Page 144) May be used to control Cystic Fibrosis and other disorders.
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3. Genetically Engineering Plants- Plants are created by genetically inserting the desired genes of one plant into another plant you want to show those genes. Also genetically engineered: ANIMALS “Cloning”
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