Lesson 5-Punnett Squares and Pedigrees
How can a pedigree trace a trait through generations?
-A pedigree is another tool used to study patterns of inheritance. -Pedigrees can be created to trace any inherited trait. -Pedigrees can be useful in tracing a special class of inherited disorders known as sex linked disorders. -Sex linked disorders are associated with an allele on a sex chromosome (23rd). -Many sexlinked disorders are caused by an allele on the X chromosome. -Woman can be carriers for a certain trait without showing it if she is heterozygous, but since men have only one X chromosome, they can never be carriers unless they have it and show it themselves.
How can Punnett squares be used to make predictions about offspring?
-A punnett square doesn't tell you the exact result of a cross will be, only helps you find the probability that a certain genotype will occur. -This probability can be expressed in the form of a ratio. A ratio would be written as 1:4, but sometimes it would be like 1:16.
How are Punnett squares used to predict patterns of heredity?
-Gregor mendel noticed that traits are inherited in patterns. -One tool to understand the patterns is a Punnet square. -A punnett square shows all of the possible allele combinations in the offspring. -The top of a Punnett square shows one parent's alleles for a trait and the left of the square shows the other parents. -Each compartment within the punnett square shows an allele combination in potential offspring.
