| Genetics Review Sheet
Chapters 10 & 11 Main ideas: � Genes are located on chromosomes. � Genes that are located on the same chromosome tend to be inherited together. � Gene linkages may be broken apart by crossing over during meiosis. � Many traits are inherited by the action of dominant and recessive genes. � Each human gamete (sperm or egg) contains 23 chromosomes. � During fertilization, sperm and egg unite and a zygote is produced that contains 46 chromosomes. � Of the 46 chromosomes found in the human diploid cell, 2 are the sex chromosomes (X & Y) and the remaining 44 are called autosomes. � Genes that are carried on either the X or Y are said to be sex-linked. � Many genetic disorders can now be diagnosed before births because of genetic screening techniques like amniocentesis. Key words: allele codominance dihybrid cross gene genotype phenotype heterozygous homozygous dominant recessive incomplete dominance monohybrid cross Punnett-Square independent assortment segregation test cross autosome genetic disorder nondisjunction sex-linkage pedigrees ABO blood typing crossing over zygote Punnett-Square Practices Use the warm-up questions and my worksheet for additional practice. 1. A woman is a carrier for the hemophilia gene (recessive) and she marries a healthy man. Could they produce a hemophiliac girl? 2. A black guinea pig is bred with a white guinea pig. All the offspring happen to be grey. What must the genotype of each of the parents? If two grey guinea pigs are bred, what phenotypic ratios would you expect? 3. A plant heterozygous for both stem length and for seed shape is crossed with a plant heterozygous for stem length and homozygous recessive for seed shape. Long stems and round seeds (genes) are dominant over short stems and wrinkled seeds. What is the possibility of these plants producing long stemmed, wrinkled seeds? What is the possibility of these plants producing short stemmed, wrinkled seeds? |