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Part 3: The Continuity of Life Foundations of Genetics Review
  1. Gregor Mendel studied inheritance by examining seven characteristics, or , using the garden .
     
     
     
     
  2. In Mendel's experiments, the F1 generation plants all expressed the trait. In the F2 generation, 3/4 of the offspring were dominant trait and 1/4 were .
     
     
     
     
  3. Mendel's theory of explains these observations.
    • Characteristics are inherited from parent to offspring as "factors" now known as that can be of different versions called , one allele inherited from each parent.
       
       
       
       
    • If both of the alleles are the same, the individual is for the trait, otherwise the individual is and exhibits the trait.
       
       
       
       
    • An individual's alleles are referred to as its and the expression of those alleles result in observable traits called its .
     
     
     
     
  4. A Punnett can be used to predict the distribution of and of offspring of a cross.
     
     
     
     
  5. A with a homozygous individual can be used to determine the of a individual.
     
     
     
     
  6. Mendel derived two laws from his experiments, including crosses involving two traits.
    • Law of independent : genes located on different are inherited independently of each other.
       
       
       
       
    • Law of : alleles are distributed into that combine to produce offspring.
     
     
     
     
  7. Alternative forms of a gene (alleles) result from .
     
     
     
     
    Review
     
     
     
     
  8. Many traits exhibit non-Mendelian inheritance.
    • dominance results when alternative alleles are not fully dominant or fully recessive; the heterozygote phenotype is between that of the homozygotes.
       
       
       
       
    • occurs when both alleles are expressed resulting in phenotypic expression of both. The human ABO blood group is controlled by alleles.
       
       
       
       
    • Some traits are and exhibit variation which results from the action of multiple genes.
       
       
       
       
    • The expression of some genes is also influenced by factors, such as photoperiod.
       
       
       
       
    • effects result when one gene influences more than one trait.
       
       
       
       
    • occurs when two or more genes interact to produce a phenotype.
     
     
     
     
  9. Morgan showed that traits like eye color in fruit flies are - linked; in this case the eye-color gene resides on the chromosome.
     
     
     
     
  10. Human somatic cells have chromosomes consisting of 22 homologous pairs of and one pair of chromosomes.
     
     
     
     
  11. Homologous pairs or sister may fail to separate during meiosis, resulting in , gametes with incorrect number of chromosomes, or .
     
     
     
     
  12. Nondisjunction abnormalities include trisomy 21, which causes syndrome, and sex chromosome aneuploidies.
     
     
     
     
  13. Mutations can result in alleles that cause disorders, most of which tend to be : only the recessive individuals are affected, heterozygotes are .
     
     
     
     
  14. can be used to track the inheritance of genetic disorders, such as sickle-cell and Huntington's disease, and other traits.
     
     
     
     
  15. Some genetic disorders can be detected during pregnancy using methods such as and , usually performed in the fourth month of pregnancy. 
     
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
    
 
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