1. Explain how the traits of an organism are related to the genes in DNA. 2. Describe how an organism’s genotype determines its phenotype (include the role of dominant and recessive alleles).

Genes in DNA or responsible for the traits an organism has. This is caused by Dominant and Recessive Traits. Remember that Genotypes are the genetic letters such as RR, Rr, and rr. Phenotype is physical traits.

Dominant Traits are more likely or always show in the offspring. The Dominant Genotype uses Capital letters such as RR.

Recessive Traits are less likely to show up. Their Genotype use lower case such as rr. Now genotypes of Rr have one dominant trait and one recessive trait. If the dominant trait was black fur and the recessive white fur, the offspring will be black fur because dominant traits overpower the other.

To understand how to know if an organism will have Dominant or Recessive Genes, you have to use something called a Punnet Square. Lets imagine 2 parents both have the genotype Rr. R is Black fur and r is white fur. As you can see from the chart, 3 of 4 boxes have Rr and 1 rr. Since there is a Dominant Trait with a Recessive, they will show a Dominant Phenotype, or Black fur. This has 3/4 chance and a 1/4 chance for white fur in the offspring.

| R. r

R | Rr. Rr

r | Rr. rr

a. suckling by young

b. hypothalamus

c. dopamine

d. trh

e. anterior pituitary

f. mammary glands

g. milk production