1. Probability of Inheritance Lesson 1
Mrs. Anna Ward
Seventh Grade Science
Ridge Road Middle School

2. Do Now!!!
Please write each of the following statements. Use the following word bank to complete each sentence:
We note dominant alleles by using _________________.
We note recessive alleles by using _________________.
The _____________ are the traits that can be observed or seen.
The _____________ are the actual genetic traits that an organism has.
UPPER CASE LETTERS
LOWER CASE LETTERS
PHENOTYPE
GENOTYPE

3. Agenda for today… Review vocabulary from Genetics
Phenotype, Genotype, Dominant, and Recessive
Check for Understanding
Add two new vocabulary terms
Homozygous
Heterozygous
Create Vocab Comparison Cards for our Genetics Terms
Attach into Science Notebook

4. Phenotype/Genotype REVIEW
Phenotype: The characteristics you can observe/see or the organism has
EXAMPLE: My phenotype is Brown Hair.
Genotype: The actual genetic make-up of the organism
EXAMPLE: My genotype is Bb.

5. Check for understanding…
Which of the following is a genotype?
Brown Hair Bb
Green Eyes
Huntington’s Disease Xx
White Flowers
Curly Hair cc Gg

6. Which of the following is a phenotype?
Blue Eyes ff
Tall Plant Gg
Wrinkled Peas
Dark Skin Aa RR
Attached Earlobes

7. Dominant & Recessive Traits can be either DOMINANT or RECESSIVE.
DOMINANT TRAITS ALWAYS COVER UP RECESSIVE TRAITS.
DOMINANT = Big Letter (B)
RECESSIVE = Little Letter (b)

8. Practice DOMINANT RECESSIVE DOMINANT RECESSIVE RECESSIVE DOMINANT
Mark which of the following are dominant: D d F f r G g y
DOMINANT
RECESSIVE
DOMINANT
RECESSIVE
RECESSIVE
DOMINANT
RECESSIVE
RECESSIVE

9. So, to practice…. Consider the if a person can have the Alleles…
B—Brown Hair or
b—Blonde Hair
What are the possible Genotypes and Phenotype…
BB – 2 DOMINANT Alleles
Phenotype--BROWN HAIR
Bb – 1 DOMINANT Allele & 1 RECESSIVE Allele
bb – 2 RECESSIVE Alleles
Phenotype--BLONDE HAIR
Because blonde is recessive, you can not have any dominant “B” traits to mask the trait

10. Your Turn… ROUND ROUND WRINKLED WW? Ww? ww?
There are TWO possible alleles for seed shape in pea plants, WRINKLED or ROUND.
Round Peas are Dominant -- W
Wrinkled peas are recessive – w
If a pea plant has the following genotype, would it have round or wrinkled peas?
WW?
Ww?
ww?
ROUND
ROUND
WRINKLED

11. SHORT TAIL LL? Ll? ll? LONG TAIL LONG TAIL One more try…
In cats, the allele for LONG tails (L) is dominant over the allele for SHORT tails (l). What would be the phenotype for the following genotypes?
LL?
Ll?
ll?
LONG TAIL
LONG TAIL
SHORT TAIL

12. Homozygous Means….
Homozygous means that the alleles in the genotype are the same, either both dominant (LARGE letters) or recessive (SMALL letters).
Examples:
RR—HOMOZYGOUS DOMINANT
rr—HOMOZYGOUS RECESSIVE
AA—HOMOZYGOUS DOMINANT
aa—HOMOZYGOUS RECESSIVE

13. Heterozygous means…
Heterozygous means that the alleles in the genotype are different, with both a dominant & recessive allele.
Examples:
Rr—HETEROZYGOUS
Aa—HETEROZYGOUS
Bb—HETEROZYGOUS

14. Check for Understanding…
In your notebook, write down whether each of the following is Homozygous (HO) or Heterozygous (HE). AA Ff rr Gg HH Bb HO HE HO HE HO HE

15. Vocabulary Comparison Cards
Vocabulary Term
Is:
The opposite would be:
How? (Sketch or explain)
Genotype
The actual genetic make-up of an organism
Phenotype
Write with two letters
Aa, Rr, RR, aa, BB, etc.
Dominant
Recessive
Homozygous
Heterozygous

16. After you have attached the Comparison Cards, Complete the Exit Ticket:
1. In a Goddess Flower Plant, White Flowers (P) are dominant to purple flowers (p). What would the phenotype be if the plant had the following genotypes?
Pp?
pp?
PP?
2. How do we write a heterozygous genotype?
3. Would a heterozygous genotype show characteristics of the recessive or dominant allele?