1. Genetics

2. vocabulary
dominant – written as a capital letter, this trait will show in Mendelian genetics
recessive – written as a lower case letter; only will show if two recessive alleles are present
homozygous – SAME alleles; TT or tt
heterozygous – DIFFERENT alleles; Tt
genotype – letter combination that show the genes; TT, Tt, tt
phenotype – physical description; tall or short

3. 47
In a genetics laboratory, two heterozygous tall plants are crossed. If tall is dominant over short, what are the expected phenotypic results?
Tt x Tt T t T t
Phenotype:
75% TALL TT, Tt
25 % SHORT tt
3:1
 TT Tt tt

4. R Tt Tt tt tt x Tt t t T t 50% short 50% tall 1:1
If one homozygous short plant is crossed with a heterozygous tall plant, what percentage of the offspring will be short?
tt x Tt t t T t
50% short
50% tall
1:1
 Tt Tt tt

5. RRdd x RrDD
Rd Rd Rd Rd RD rD
RRDd
RrDd

6. Genotypes:
RRDd-50%
RrDd-50%
Phenotypes:
100% red eyes and dark fur

7. Incomplete dominance the two traits blend when both are present
RW x RW Two pink flowers are crossed R W R W
25% RED-RR
50% PINK-RW
25% WHITE-WW RR RW WW

8. Co-Dominance Both traits show up when both are present
A A A B
50% AA
IA IA
IA IB

9. Explain how it is possible for a man with type a blood and a woman with type b blood have a child with type o blood.
O (i) blood is recessive, so if the male is AO and the female is BO then a child could have OO

10. #51 Sex linked traits are carried on the sex chromosome X
Males have one X, females have two X’s
Therefore a male only needs one allele to have the trait, but females need 2 alleles to have the trait. This makes is more rare for a female to have a sex linked trait. But females can be carriers

11. #53
Sample Sex-linked trait Question: Color blindness is a sex-linked recessive trait. A mother with normal color vision and a color blind father have a color blind daughter. Which of the following statements is correct?
All of their daughters will be color blind.
The mother is a carrier of the color blindness gene.
All of their sons will have normal color vision.
All of their sons will be color blind.