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11.1 Gregor Mendel
  • Mendel discovered certain laws of heredity after doing experiments with garden peas during mid-1800s.
  1. What was the concept of inheritance favored before Mendel's work and what did it say?
  2. What characteristics made the garden pea a good choice for Mendel's work.
Essential Study Partner Summaries of major points:
  1. Gregor Mendel
  2. Blending concept of inheritance
  3. Mendel's experimental procedure
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11.2 One-trait Inheritance
  • When Mendel did one-trait crosses he found that each organism contains two factors for each trait and the factors segregate during formation of gametes.
  • Today it is known that alleles located on chromosomes control the traits of individuals and homologous pairs of chromosomes separate during meiosis I.
  • A testcross can be used to determine the genotype of an individual with the dominant phenotype.
  1. What are the P, F1 and F2 generations?
  2. What is a reciprocal cross?
  3. State the four points of the Law of Segregation.
  4. What is a gene, an allele, and a gene locus?
  5. What is the difference between heterozygous and homozygous?
  6. The alleles present in an individual is referred to as the ______________. The physical expression of those alleles is called the _______________.
  7. What gametes are produced by an individual with a heterozygous genotype in which B is a dominant allele and b is the recessive?
  8. What are the genotypic and phenotypic ratios of the offspring of a cross between an individual homozygous recessive and an individual heterozygous for hair color. Assume white (R) is the dominant trait and red (r) is the recessive. Use a punnett square if necessary.
Essential Study Partner Summaries of major points:
  1. Cross-pollination monohybrid crosses
  2. Mendel's results
  3. As viewed by modern genetics
  4. Genotype versus phenotype
  5. Monohybrid genetics problems
  6. Laws of probability
  7. The Punnett square
  8. One-trait testcross
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11.3 Two-trait Inheritance
  • When Mendel did two-trait crosses he found that every possible combination of factors is present in the gametes.
  • Today it is known that homologous pairs of chromosomes separate independently during meiosis I and this produces all possible combinations of alleles in the gametes.
  • A testcross can also be used to determine the genotype of an individual that is dominant in two traits.
  1. Explain the Law of Independent Assortment.
  2. What are the possible gametes and proportions of each produced by an individual with the genotype Aabb?
  3. A fish breeder crossed two cichlids, both with long fins and red spots. The F1 generation had 52 long finned fish with red spots, 19 long finned fish with no spots, 18 short finned fish with red spots and 7 short finned fish with no spots. Can you determine the genotype of the parents? If so, what is it and how do you know? If not, why?
  4. What is involved in a test cross and why would you do it?
Essential Study Partner Summaries of major points:
  1. Dihybrid cross
  2. Law of independent assortment
  3. Dihybrid genetics problems
  4. Two-trait testcross
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11.4 Human Genetic Disorders
  • Many human genetic disorders are inherited according to Mendel's laws.
  • The pattern of inheritance indicates whether the disorder is a dominant or a recessive disorder.
  • Dominant disorders appear if a single dominant allele is inherited; recessive genetic disorders require the inheritance of two recessive alleles.
  1. What is any chromosome that is not a sex chromosome (X or Y) called?
  2. A _____________ can be used to illustrate the pattern of inheritance for a genetic disorder (or any other genetic trait) within a family.
  3. What is a carrier for a genetic disorder?
  4. What is the probability that two people who are carriers for a recessive genetic disorder will produce a child expressing the disorder?
Summaries of major points:
  1. Predicting offspring
  2. Autosomal dominant disorders
  3. Autosomal recessive disorders
  4. Beyond simple Mendelian inheritance
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11.5 Beyond Mendelian Genetics
  • The genotype must be considered an integrated whole of all the genes because genes often work together to control the phenotype.
  • There are forms of inheritance that involve degrees of dominance, interactions, multiple alleles, and polygenes.
  • Environmental conditions can influence gene expression.
  1. Genes are said to have ______________ when a heterozygote displays a phenotype that is intermediate to that of the parents.
  2. Human blood type is an example of a gene which has more than two possible alleles (though each individual only has 2). What is this type of trait called?
  3. When a heterozygous organism has portions of the phenotype of both alleles of a gene (i.e. a sorrel horse with a mixture of red and white hairs), the alleles are said to be what?
  4. What is happening when a population displays a continuous variation of phenotypes for a trait (i.e. some are very short, some very tall, but with a great number of different sizes in between)?
  5. Can the environment affect the expression of genes? If so, give an example. If not, why?
Essential Study Partner Summaries of major points:
  1. Incomplete dominance and codominance
  2. Genes that interact
  3. Pleiotropy
  4. Multiple alleles
  5. Polygenic inheritance
  6. Environment and the phenotype
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