Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download Genetics and Heredity
Document related concepts
no text concepts found
Transcript
Genetics and Heredity KEY VOCABULARY Gene Unit or section of a chromosome that determines a trait Passed on from parent to offspring Contains the DNA code for traits Allele One of two (or more) different forms of the same trait Specific version of a gene Gene is for eye color Allele is for blue or brown eyes Found at the same place on a chromosome Genotype and Phenotype You get one version of a gene from each parent One allele from mother, One allele from father The interaction between these two versions gives you your unique characteristics or traits Genotype – Alleles of a gene an organism contains “What Allele you get.” from mother and allele from father Phentotype – Form of a trait an organism displays “What you see.” Different Genotypes Dominant vs. Recessive Dominant alleles – an allele that masks/overpowers the effect of the other allele Written as an UPPER CASE letter (Example - “T”) Recessive alleles – an allele that is masked or overpowered by a dominant allele Written as a LOWER CASE letter (Example - “t”) Different Genotypes Homozygous – Genotype where both alleles are the same type “Homo” means “same” Homozygous Dominant – “TT”; Homozygous Recessive – “tt” Heterozygous – Genotype where alleles are different “Hetero” means “different” One dominant allele, one recessive allele – “Tt” How alleles interact Dominant allele matched with dominant allele – Genotype “TT” Dominant trait will be displayed/visible Dominant Phenotype Dominant allele matched with recessive allele – Genotype “Tt” Dominant trait will be displayed/visible **most of the time, some exceptions** Dominant Phenotype Recessive allele matched with recessive allele – Genotype “tt” Recessive trait will be displayed/visible Recessive Phenotype Question? There are always two alleles interacting for every trait. Why is that? Question? What is the only way a recessive trait can be visibly displayed by an organism (Recessive Phenotype)? Different types of Dominance Sometimes when a trait has a Heterozygous Genotype (“Tt”) the phenotype (what you see) isn’t completely dominant in presentation Three types of Dominance Complete Dominance – dominant allele is fully displayed No presence of the recessive allele Example – Red Flower (dominant); White Flower (recessive) Incomplete Dominance – dominant and recessive allele are displayed as a MIX Example – Pink Flower (MIX of Red and White) Codominance – dominant and recessive allele are BOTH displayed Example – Red and White Flower (BOTH Red and White displayed) Determining the Probability of a Trait Geneticists use Punnett Squares to determine the possible outcomes of a specific cross of two parent organisms For example: One parent is Homozygous Dominant for a trait: “TT” Other parent is Heterozygous for a trait: “Tt” T T T TT TT t Tt Tt One parent alleles go here One parent alleles go here Sections inside table show possible offspring genotypes: • TT = 50% probability • Tt = 50% probability
Related documents