NAME ______________________________________________________
HOUR ____________
5-2 Guided Reading (pg 134-139)
INCOMPLETE DOMINANCE (Co-Dominance)
1. Many scientists repeated Mendel’s work. However when one crossed a red flower
with a white flower, he got a
flower!
___________________
2. Define “incomplete dominance” ________________________________________________________
________________________________________________________________________________________________
3. How does a horse get a palomino color? _______________________________________________
________________________________________________________________________________________________
MULTIPLE ALLELES
1. A trait that is controlled by more than 2 alleles is said to be controlled by
_________________________________
________________________________
2. Pretend 3 types of coins are made – Quarter (Q), Dime (D), and Nickel (N).
Pretend that you can only have 2 coins at a time. What are the 6 combinations of
coins you can have?
1. QQ 2. ___________ 3.___________
4.___________
5.___________
6.___________
3. What is an example of a human trait that is controlled by multiple alleles?
_________________________________________
4. What are the 3 alleles for this trait? ____________
_____________
_____________
5. Which allele is recessive? _____________
6. If humans carry only 2 of the 3 alleles, what are the 6 possible combinations for a
genotype?
1. _________
2. ___________ _3. __________ 4. ___________ 5. ___________ 6. ___________
POLYGENIC INHERITANCE
1. Define “polygenic inheritance.” __________________________________________________________
_________________________________________________________________________________________________
2. Give 3 examples of human traits that would be controlled by polygenic
inheritance.
______________________________
______________________________
______________________________
3. Polygenic traits are controlled by more than one gene pair. Sometimes ___________
pairs!
HUMAN GENES AND MUTATIONS
1. A mutation is: ____________________________________________________________________________
2. TRUE or FALSE Mutations can be helpful.
3. What can cause a mutation in human DNA? ________________________________________
4. Mistakes in the process of _______________________ can cause an organism to have
more or fewer chromosomes than normal.
5. People with Down Syndrome have ________ copies of chromosome # ___________.
RECESSIVE GENETIC DISORDERS
1. In order to inherit a recessive disorder, a person receives one allele from each
__________________________________.
2. ___________________ ____________________ is a homozygous recessive disorder. This
disorder makes it hard for the person to
____________________.
SEX-LINKED DISORDERS
1. Color blindness is a sex-linked disorder because the genes are carried on the
________ ______________________________.
2. Females carry ____________ copies of this trait because they have __________ X
chromosomes. Males carry only
gene.
__________
3. Color blindness is a _____________________ sex-linked disorder. Rickets, however, is a
sex-linked trait and more rare.
__________________________