NON-MENDELIAN GENETICS: CODOMINANCE || GRADE 9 SCIENCE _ BIOLOGY

Ma'am Mica
19 Sept 202304:26

Summary

TLDRIn this educational video, we explore co-dominance, a non-Mendelian inheritance pattern where both alleles are equally expressed. Using speckled chickens and blood group antigens as examples, we demonstrate how traits are visible in heterozygotes. A practical problem-solving session follows, where we predict offspring genotypes and phenotypes from crosses between white and red cattle. The lesson concludes with a Punnett Square exercise, illustrating the genotypic and phenotypic outcomes of these crosses, providing a clear understanding of co-dominance in genetics.

Takeaways

  • 🔬 The lesson discusses co-dominance, a non-Mendelian pattern of inheritance where both alleles are expressed equally in the phenotype.
  • 🐓 A speckled chicken is given as an example of co-dominance, where black and white feathers are both visible, illustrating the expression of both alleles.
  • 🩸 Another example of co-dominance is in blood groups, specifically with the A and B antigens, where the presence of both results in an AB blood type.
  • 📊 The lesson uses a Punnett Square to predict the genotypes and phenotypes of offspring from a genetic cross.
  • 🐄 The first example problem involves crossing a white cow (ww) with a red bull (RR), resulting in heterozygous offspring (RW) with a phenotype of rowdy.
  • 🐃 When two heterozygous rowdy cows (RW) are crossed, the offspring can be homozygous red (RR), heterozygous rowdy (RW), or homozygous white (ww), with a genotypic ratio of 1:2:1.
  • 🌟 The phenotypes from the cross of two heterozygous rowdy cows are one red bull, two rowdy cows, and one white cow.
  • 📝 The lesson emphasizes the importance of understanding and applying genetic principles to predict outcomes of genetic crosses.
  • 👩‍🏫 The script is educational, aimed at learners interested in genetics, and encourages subscription for more content.
  • 🔔 The channel invites viewers to subscribe and enable notifications to stay updated with new educational videos.

Q & A

  • What is the law of co-dominance in genetics?

    -The law of co-dominance states that both alleles are expressed equally in the phenotype of a heterozygote, meaning both traits are observed.

  • Can you provide an example of co-dominance from the script?

    -A speckled chicken is an example of co-dominance, resulting from a cross between a black and a white chicken, producing a chicken with both black and white feathers.

  • What is another example of co-dominance mentioned in the script?

    -The blood group AB is an example of co-dominance, where the A and B alleles are co-dominant, and a person with both antigen A and B will have the blood type AB.

  • What is the genotype of the white cow and red bull used in the example problem?

    -The genotypes of the white cow and red bull are ww and RR, respectively, indicating they are homozygous for their respective traits.

  • How is the genotype of the offspring determined in the example of crossing a white cow and a red bull?

    -The genotype of the offspring is determined using a Punnett Square, resulting in four heterozygous Rr offspring.

  • What is the genotypic ratio of the offspring when a white cow and a red bull are crossed?

    -The genotypic ratio of the offspring is 4 Rr (heterozygous) to 0, indicating all offspring will have the genotype Rr.

  • What is the phenotype of the offspring when a white cow and a red bull are crossed?

    -The phenotype of the offspring is all row one, which means they will all have a red and white mixed coat.

  • What happens when two heterozygous Rr cows are crossed according to the script?

    -When two heterozygous Rr cows are crossed, the offspring can have genotypes RR (homozygous red), Rr (heterozygous), and rr (homozygous white).

  • What is the genotypic ratio of the offspring when two heterozygous Rr cows are crossed?

    -The genotypic ratio of the offspring is 1 RR : 2 Rr : 1 rr, indicating one homozygous red, two heterozygous, and one homozygous white.

  • What is the phenotype of the offspring when two heterozygous Rr cows are crossed?

    -The phenotype of the offspring is one red bull, two row one (red and white mixed coat), and one white cow.

  • What is the significance of the Punnett Square in determining the offspring's genotype and phenotype in the script?

    -The Punnett Square is used to predict the genotypes and phenotypes of the offspring by illustrating the possible combinations of alleles from each parent.

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Related Tags
GeneticsCo-dominanceSpeckled ChickenBlood GroupsPunnett SquareInheritance PatternsMendelian GeneticsEducational VideoBiological TraitsGenotype Phenotype