Download Emily Irwin Biology B: Heredity Unit: Complete Dominance

Teacher’s Name: Emily Irwin
Biology B: Heredity
Unit: Complete Dominance - traits
Date: 1/4/10
Lesson Title/Topic: Inherited traits, phenotype,
genotype, dominant, recessive
Mentor: Heather Peterson
Objectives and Big Ideas
Phenotype is what is physically expressed and the sequences for these traits are found in the genotype. The
genotype is the specific sequence of genes. Two alleles for a trait are inherited from an individual’s parents, one
from mom and one from dad. A trait is dominant if only one allele is needed for the trait to be expressed. The
dominant trait also masks the recessive allele in complete dominance. A trait is recessive if two alleles are
needed for the trait to be expressed and can be covered by the dominant allele.
A trait that is homozygous has to alleles that are the same (BB or bb) and a trait that is heterozygous is (Bb).
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Students will be able to describe relationships, as well as differences, between genotype and phenotype
Students will practice identifying traits that are completely dominant among individuals in the classroom
Standards (http://www.michigan.gov/mde/0,1607,7-140-38924_41644_42814---,00.html)
B4.1B Explain that the information passed from parents to offspring is transmitted by means of genes that are coded in
DNA molecules.These genes contain the information for the production of proteins.
B4.1c Differentiate between dominant, recessive, codominant, polygenic, and sex-linked traits
Materials/Equipment-
Bikini bottom genetics WS
Single trait inheritance WS
Pictures of traits
Activities
Monday
Intro:
(~10 minutes) Journal questions: What did you do over winter break? What did you learn from the chocolate
kisses activities before break (use vocab)?
(~5 minutes) Go over test
(~10 minutes) go over the journal questions, what happened in the kisses activity? Make sure students remember
the difference between genotype and phenotype (practice examples of each). Students should get this worksheet
back out and we can add notes together as a class.
Middle:
(~10 minutes) Go over possible traits that can be inherited and show pictures of each example. Try and guide
students into brainstorming experiences that they are already familiar with (hair color, eye color, freckles, etc.)
(~10 minutes) In groups go to the back of the room and determine what traits they express and record the
genotype for each. Make sure students are including both of the alleles (from each parent) and can identify if it is
homozygous or heterozygous.
(~5 minutes) Discuss results, practice homozygous/heterozygous, practice individually at seat with examples put
on the whiteboard.
(~5 minutes) Go back and answer the alien question from before break again. What would the parents genotype
for number of eyes have to be in order to have a daughter and a son with one eye? (if each parent had three
eyes). Have students practice this individually on their own in their journal and then discuss different answers
after they have time to work alone.
End:
(~5 minutes) Ticket out the door journal question: Some aliens have the trait for antennae, which is a dominant
trait. Draw a picture of an alien that is heterozygous dominant. Discuss answer
(~5-10 minutes) Homework: Bikini bottom genetics worksheet for more practice and to introduce karyotyping
tomorrow.
Assessment
Students will be assessed throughout the lesson based on their answers to the various journal questions. I will
circulate around the room to read their answers and then use their different ideas, and misconcpetions, to
continue the lesson. This activity is a good review of vocabulary from before break as well as a transition into
future lessons.
Notes/Comments: