Term
| Who is Gregor Mendel and what did he contribute to genetics? |
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Definition
| Gregor Mendel was an Austrian monk in the 19th century (1800s) He is the father of genetics. He studied inheritance in pea plants. He came up with two laws, the law of segration, and the law of independent assortment. |
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Term
| Pea plants heterozygous for flower position and stem length (AaTt) are allowed to self-pollinate and 400 of the resulting seeds are planted. Draw a Punnett square for this cross. How many offspring would be predicted to have terminal flowers and be dwarf? |
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Definition
| According to the law of independent assortment, 25 plants (1/16 of the offspring) are predicted to be aatt, or recessive for both characters. The actual result is likely to differ slightly from this value |
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Term
| List all gametes that could be made by a pea plant heterozygous for seed color and pod shape (YyIi). How big of a Punnett square would you need to predict the offspring of a selfpollination of this trihybrid? |
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Definition
| The plant could make eight different gametes (YRI, YRi, YrI, Yri, yRI, yRi, yrI, and yri). To fit all the possible gametes in a self-pollination, a Punnett square would need 8 rows and 8 columns. It would have spaces for the 64 possible unions of gametes in the offspring. |
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Term
| In some pea plant crosses, the plants are self-pollinated. Refer back to Concept 13.1 and explain whether self-pollination is considered asexual or sexual reproduction. |
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Definition
| Self-pollination is sexual reproduction because meiosis is involved in forming gametes, which unite during fertilization. As a result, the offspring in self-pollination are genetically different from the parent. |
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Term
| If a man with type AB blood marries a woman with type O blood what blood types would you expect in their children? What fraction would you expect of each type? |
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Definition
| Half of the children would be expected to have type A blood and half type B blood |
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Term
| Incomplete dominance and epistasis are both terms that define genetic relationships. What is the most basic distinction between these terms? |
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Definition
| Incomplete dominance describes the relationship between two alleles of a single gene, whereas epistasis relates to the genetic relationship between two genes (and the respective alleles of each) |
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Term
| According to Mendel’s model, which allele will determine the organisms appearance? |
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Definition
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Term
| Explain the four components of Mendel’s Model including the law of segregation |
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Definition
| First, alternative versions of genes account for variations in inherited characters. Second, for each character, an organism inherits two copies of a gene, one from each parent. Third, if the two alleles at a locus differ then the DOMINANT ALLELE determines appearance and the other the RECESSIVE allele has no noticeable effect on appearance. Fourth, the law of segregation states what the two alleles for a heritable character segregate(seperate from each other) during gamete formation and end up in different gametes |
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Term
| If you have an organism that has a dominant phenotype for a particular trait how can you determine its genotype for that trait? |
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Definition
| By performing a testcross |
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Term
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Definition
| A lethal recessive disorder that is caused by a dysfunctional enzyme that fails to break down specific brain lipids.symptoms begin with seizures, blindness, and degeneration of motor and mental performance a few months after birth. Child dies after a few years. |
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Term
| Beth and Tom each have a sibling with cystic fibrosis but neither Beth nor Tom nor any of their parents have the disease. Is it possible for Beth and Tom to have a child with cystic fibrosis? If the tests indicate that Tom is a carrier but Beth is not is, how would that effect their probability of having a child with cystic fibrosis? |
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Definition
| 1/9. Since cystic fibrosis is caused by a recessive allele, Beth and Tom's siblings who have CF must be homozygous recessive. Therefore, each parent must be a carrier of the recessive allele. Since Beth and Tom dont have CF this means they have a 2/3 chance of being a carrier. If they are both carriers, there is a 1/4 chance they will have a child with CF. 2/3 times 2/3 times 1/4= 1/9. 0, both ben and tom would have to be carriers to produce a child with the disease |
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Term
| Joan was born with six toes on each foot(D), a dominant trait called polydactyly. Two of her five siblings and her mother, but not her father, also has extra digits. What is Joan’s genotype for the number-of-digits character? Explain your answer. |
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Definition
| Joan's genotype is Dd. Because the allele for polydactyly D is dominant to the allele for five digits per appendage d, the trait is expressed in people with DD or Dd genotype. But because Joan's father does not have the disorder, his genotype must be dd, which means that Joan inherited a d allele from him. Therefore Joan, who has the trait, must be heterozygous. |
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