1. Define and distinguish between the following pairs of terms: genotype and phe
ID: 18713 • Letter: 1
Question
1. Define and distinguish between the following pairs of terms: genotype and phenotype, heterozygous and homozygous, and dominant and recessive2. Use a Punnett square to predict the results of a monohybrid cross and state the phenotypic and genotypic ratios of the F2 generation
3. Define the law of segregation and explain how it applies to reproduction.
4. Define a “carrier” and explain how carriers are revealed in human pedigrees.
5. Describe the differences in the following: dominance, incomplete dominance, and codominance.
6. Distinguis between pleiotrophy and polygenic inheritance.
7. Explain how chromosomes determine the sex of an individual.
8. Explain the general characteristics and inheritance patterns for colorblindness and hemophilia.
Explanation / Answer
If you were to look at a DNA sample, you wouldn't know which one's GENEOTYPE (key word gene) you were looking at. However, when you looked at them they might look drastically different because one of them lost all of his hair to leukemia, had a hand amputated because of gangrene, and dyed his hair red. Geneotype is how their DNA affects their appearance Phenotype is how those genes are actually expressed (and not a result of environmental factors). Homozygous means you carry two genes that are the same for each trait. Example: BB for brown eyes. Heterozygous means you carry two different genes for each trait. Example: Bb would also be brown eyes, though the small "b" would be the gene for blue eyes. It doesn't show up in the phenotype (outward appearance) because the gene for brown eyes is dominant. If someone had blue eyes they would be homozygous "bb". A dominant trait manifests if it is in ether allele. A recessive trait must be present in both alleles to be expressed. Reccessive traits require 2 of the same allele, dominant traits require only one allele for the charecteristic to show. What is Mendel's Law of Segregation? Mendel's law of segregation states: "The two members of a gene pair segregate from each other into the gametes, so that one-half of the gametes carry one member of the pair and the other one-half of the gametes carry the other member of the pair." This means that each individual has two copies of every gene, that one copy came from the father and the other from the mother, and when the individual reproduces, they will contribute only one of the two copies to their offspring (while the other parent contributes the other). Which copy ends up in any given offspring will be random. The law of segregation, also called Mendel's first law of inheritance, applies to all diploid organisms with meiosis and sexual reproduction. What's the difference between incomplete dominance and co-dominance? In both instances, both alleles are expressed. How they're expressed is different. In incomplete dominance, the phenotype resembles a sort of blending of the two alleles. That is, if you have an allele for red petals and and allele for white petals, you end up getting pink petals with incomplete dominance. Co-dominance is when both alleles are expressed separately. Human blood type is a good example of this. The A and B alleles are both expressed, so you get the AB blood type. In the petal color example above, you'd get a flower with white and red splotches.
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