My Genetics/Baby Lab
All class populations shared the same gene pool, yet each team produced a unique baby with different combinations of traits expressed in the phenotype / appearance. Similarly, we each have a unique genetic heritage.
Variation occurs in Meiosis I of sexual reproduction by crossing over and independent assortment.
Crossing over is the random exchange of alleles between homologous pairs during prophase I, synapsis. This results in variation.
Independent assortment is the random line up of chromosome pairs (tetrads) during metaphase I. Tetrads line up at the equator and the two pairs of sister chromatids can be lined up in various ways. When the homologous pairs are pulled apart during anaphase I, different pairs of sister chromatids can go to different sides depending on how they randomly lined up.
When gametes are formed, random fertilization occurs. A random egg is fertilized by a random sperm.
When a genotype is heterozygous, the phenotype can be shown in a number of ways depending on the patter of inheritance. Heterozygous patterns of inheritance are Mendelian Dominance, Incomplete Dominance, and Co-Dominance. Only the dominant allele may be expressed in the phenotype, both alleles blend and are shown in the phenotype, or both alleles are fully expressed, respectively.
Polygenic traits are traits with three or more gene pairs that all contribute to the phenotype. It produces much variety in the population.
In Mendelian Dominance, the dominant allele always shows in phenotype. Recessive alleles only show when paired with another recessive allele. When this occurs, the genotype is homozygous recessive. Eye shape is determined by Mendelian Dominance. The R allele makes a round eye shape, and the r allele makes an almond eye shape. The baby had the genotype RR, so she has a round eye shape. Because the trait follows Mendelian Dominance, if the baby had alleles Rr, the eye shape would still be round.
Incomplete Dominance occurs when both alleles blend and are shown in phenotype. In Incomplete Dominance, the two alleles also may not blend equally. One allele may be more prominent than another. Eye brows are a trait that follows Incomplete Dominance (blending). The allele F represents full eye brows, and the allele f represents thin eye brows. The baby has alleles ff, so she has thin eye brows. If she had alleles Ff, the baby would have medium thickness eye brows. ---- Skin Color is a polygenetic trait that follows incomplete dominance, as well. The three allele pairs were Dd, dd, and dd. This meant that the baby has light skin. Dd does not mean dark; it means medium because of Incomplete Dominance. Both dd’s mean very light. A polygenetic trait is a trait with three or more gene pairs. The gene pairs combine to make a trait that represents all the gene pairs. The baby has relatively light skin. Another polygenetic trait is hair color. Polygenetic traits make much variety in the population.
Sex is determined by X and Y chromosomes. XX is the genotype for a female, and XY is the genotype for a male. The egg always has an X chromosome. The sperm has either an X or a Y, so it may contribute an X or Y. Therefore, the father determines gender of child. Possible combinations are XX, XX, XY, and YX. There is a 50:50 chance of male or female. In the baby lab, we flipped two coins. If the two coins were the same, the baby was female. If the two coins were different, the baby was male. The possible combinations were TH, HT, HH, and TT. We rolled TT, so the baby was female. The baby received an X chromosome from the mother, and an X chromosome from the father.
Co-Dominance is when both alleles are fully expressed in the phenotype. For instance, if a father had the genotype Ao and phenotype A, and a mother had the genotype BB and the phenotype B, it is possible for a child to have blood type AB. A sibling may have blood type B with genotype Bo. All the possible allele combinations are AB, AB, Bo, and Bo.
However, we are more than our genetic blueprint. We are largely defined by our life experiences and environmental influences. The choices someone makes in their life impacts who that person is.
Anything that affects a person's life besides their genetics is an environmental influence. Most people can control some of their environmental influences. For example, what a person eats, whether a person does drugs or not, and how much a person exercises has a direct influence on that person. If a person were to spend time with different people, they would not have been the same. The people and type of environment someone is surrounded by has a strong impact on how that person develops. The different situations a person has been through can nearly dictate how a person will react in another situation. Choices a person makes have consequence, and people learn from them. What a person knows also determines what a person might do in a certain situation, and what a person does in a situation affects themselves.
Athena has an arranged marriage with Sonya's boy, Kai William Salgado-Tran. See here.
Variation occurs in Meiosis I of sexual reproduction by crossing over and independent assortment.
Crossing over is the random exchange of alleles between homologous pairs during prophase I, synapsis. This results in variation.
Independent assortment is the random line up of chromosome pairs (tetrads) during metaphase I. Tetrads line up at the equator and the two pairs of sister chromatids can be lined up in various ways. When the homologous pairs are pulled apart during anaphase I, different pairs of sister chromatids can go to different sides depending on how they randomly lined up.
When gametes are formed, random fertilization occurs. A random egg is fertilized by a random sperm.
When a genotype is heterozygous, the phenotype can be shown in a number of ways depending on the patter of inheritance. Heterozygous patterns of inheritance are Mendelian Dominance, Incomplete Dominance, and Co-Dominance. Only the dominant allele may be expressed in the phenotype, both alleles blend and are shown in the phenotype, or both alleles are fully expressed, respectively.
Polygenic traits are traits with three or more gene pairs that all contribute to the phenotype. It produces much variety in the population.
In Mendelian Dominance, the dominant allele always shows in phenotype. Recessive alleles only show when paired with another recessive allele. When this occurs, the genotype is homozygous recessive. Eye shape is determined by Mendelian Dominance. The R allele makes a round eye shape, and the r allele makes an almond eye shape. The baby had the genotype RR, so she has a round eye shape. Because the trait follows Mendelian Dominance, if the baby had alleles Rr, the eye shape would still be round.
Incomplete Dominance occurs when both alleles blend and are shown in phenotype. In Incomplete Dominance, the two alleles also may not blend equally. One allele may be more prominent than another. Eye brows are a trait that follows Incomplete Dominance (blending). The allele F represents full eye brows, and the allele f represents thin eye brows. The baby has alleles ff, so she has thin eye brows. If she had alleles Ff, the baby would have medium thickness eye brows. ---- Skin Color is a polygenetic trait that follows incomplete dominance, as well. The three allele pairs were Dd, dd, and dd. This meant that the baby has light skin. Dd does not mean dark; it means medium because of Incomplete Dominance. Both dd’s mean very light. A polygenetic trait is a trait with three or more gene pairs. The gene pairs combine to make a trait that represents all the gene pairs. The baby has relatively light skin. Another polygenetic trait is hair color. Polygenetic traits make much variety in the population.
Sex is determined by X and Y chromosomes. XX is the genotype for a female, and XY is the genotype for a male. The egg always has an X chromosome. The sperm has either an X or a Y, so it may contribute an X or Y. Therefore, the father determines gender of child. Possible combinations are XX, XX, XY, and YX. There is a 50:50 chance of male or female. In the baby lab, we flipped two coins. If the two coins were the same, the baby was female. If the two coins were different, the baby was male. The possible combinations were TH, HT, HH, and TT. We rolled TT, so the baby was female. The baby received an X chromosome from the mother, and an X chromosome from the father.
Co-Dominance is when both alleles are fully expressed in the phenotype. For instance, if a father had the genotype Ao and phenotype A, and a mother had the genotype BB and the phenotype B, it is possible for a child to have blood type AB. A sibling may have blood type B with genotype Bo. All the possible allele combinations are AB, AB, Bo, and Bo.
However, we are more than our genetic blueprint. We are largely defined by our life experiences and environmental influences. The choices someone makes in their life impacts who that person is.
Anything that affects a person's life besides their genetics is an environmental influence. Most people can control some of their environmental influences. For example, what a person eats, whether a person does drugs or not, and how much a person exercises has a direct influence on that person. If a person were to spend time with different people, they would not have been the same. The people and type of environment someone is surrounded by has a strong impact on how that person develops. The different situations a person has been through can nearly dictate how a person will react in another situation. Choices a person makes have consequence, and people learn from them. What a person knows also determines what a person might do in a certain situation, and what a person does in a situation affects themselves.
Athena has an arranged marriage with Sonya's boy, Kai William Salgado-Tran. See here.