punnett

1. Ch. 5.2 Understanding Inheritance

2. Focus Questions
1. What determines the expression of
traits?
2. How can inheritance be modeled?
3. How do some patterns of inheritance
differ from Mendel’s model?

3. 1. What determines the
expression of traits?
• Mendel concluded that
two factors—one from
each parent—control
each trait (called
chromosomes).
• Chromosomes are
made of coiled up DNA
• Genes are segments of
DNA for 1 trait.

4. 1. What determines the expression of
traits?
• Remember that DNA stores genetic info.
• Alleles – different forms of a gene
– Each chromosome has 1 allele for every
gene on it.
– Ex: Color of pea plant is found in 1 gene,
alleles are purple and white
• The two chromosomes in an offspring cell may
have the same or different alleles.

6. 1. What determines the expression of
traits?
• Phenotype – how a
trait physically
appears
• Genotype – the 2
alleles (genes) that
control the
phenotype of a trait

7. A pea plant that is Yy
a. Genotype
b. Phenotype
45
Genotype
0 0
Phenotype

8. A pea plant that is green
a. Genotype
b. Phenotype
Genotype
0 0
Phenotype
45

9. The two alleles
a. Genotype
b. Phenotype
Genotype
0 0
Phenotype
45

10. 1. What determines the expression of
traits?
• Homozygous =
same alleles
(ex: RR, rr)
• Heterozygous =
different alleles
(ex: Rr)

11. What is the genotype? Rr
a. Homozygous
dominant
b. Homozygous
recessive
c. Heterozygous
45
0 0 0
Homozygous recessive
Homozygous dominant
Heterozygous

12. What is the genotype? ww
a. Homozygous
dominant
b. Homozygous
recessive
c. Heterozygous
45
0 0 0
Homozygous recessive
Homozygous dominant
Heterozygous

13. What is the genotype? CC
a. Homozygous
dominant
b. Homozygous
recessive
c. Heterozygous
45
0 0 0
Homozygous recessive
Homozygous dominant
Heterozygous

14. What is the genotype? Yy
a. Homozygous
dominant
b. Homozygous
recessive
c. Heterozygous
45
0 0 0
Homozygous recessive
Homozygous dominant
Heterozygous

15. 2. How can inheritance be modeled?
A Punnett square is a model used to
predict possible genotypes and
phenotypes of offspring.

16. Draw the following Punnett Squares
Yy x yy CC x cc

17. • Punnett Square Brain Pop

18. 2. How can inheritance be modeled?
A pedigree shows phenotypes of
genetically related family members.
Male
female
Male
affected
Female
affected

19. Mrs. Calderon’s family Pedigree for Blue eyes (bb)

20. What color are Mrs. Calderon’s dad’s eyes?
Mrs.
Calderon
Mrs. Calderon’s family
0 0 0
Pedigree for Blue eyes (bb)
a. Blue
b. Dark
c. Can’t tell from the
chart
60
Blue
Dark
Can’t tell from the chart

21. How many brothers does Mrs. Calderon’s dad have?
Mrs.
Calderon
a. 1
b. 2
c. 3
d. 4
e. 5
f. 6
g. 7
h. 8
i. 9
j. 0
Mrs. Calderon’s family
Pedigree for Blue eyes (bb)
0 0 0 0 0 0 0 0 0 0
60
1
2
3
4
5
6
7
8
9
0

22. Does Mrs. Calderon carry the blue eye gene?
Mrs.
Calderon
a. Yes
b. No
c. Can’t tell from the
chart
Mrs. Calderon’s family
0 0 0
Pedigree for Blue eyes (bb)
60
Yes
No
Can’t tell from the chart

23. Does Mrs. Calderon’s mom carry the blue eye
gene?
Mrs.
Calderon
a. Yes
b. No
c. Can’t tell from the
chart
0 0 0
Mrs. Calderon’s family
Pedigree for Blue eyes (bb)
60
Yes
No
Can’t tell from the chart

24. 3. How do some patterns of inheritance
differ from Mendel’s model?
Complex Patterns of Inheritance
• Sometimes traits appear
to be blends of alleles.

25. 3. How do some patterns of inheritance
differ from Mendel’s model?
Complex
patterns of
inheritance
Incomplete
dominance
Codominance
Polygenic
Inheritance
Multiple
alleles

26. 3. How do some patterns of inheritance
differ from Mendel’s model?
• Incomplete Dominance:
when the offspring’s
phenotype is a blend of
the parents’ phenotypes.

28. 3. How do some patterns of inheritance
differ from Mendel’s model?
• Codominance occurs
when both alleles can be
observed in a phenotype.

30. 3. How do some patterns of
inheritance differ from
Mendel’s model?
Polygenic
Inheritance:
occurs when
multiple genes
determine the
phenotype of a trait
(ex: skin color, eye
color).

31. 3. How do some patterns of inheritance differ from
Mendel’s model?

32. • Eye Color

33. 3. How do some patterns of inheritance
differ from Mendel’s model?
Multiple alleles: Some traits are
determined by more than one allele;
ex: Human ABO blood types

34. Genes and the Environment
• An organism’s environment can affect its
phenotype.
• Some examples of environmental factors
that affect phenotype are soil type that a
flower is growing in or time of year that a
butterfly develops.

36. What type of inheritance is it when the
offspring’s phenotype is a blend of the parents’
phenotypes?
A. Incomplete
dominance
B. Codominance
C. Multiple alleles
D. Polygenic
inheritance
45
Incomplete dominance
0 0 0 0
Multiple alleles
Polygenic inheritance
Codominance

37. What type of inheritance occurs when multiple
genes determine the phenotype?
A. Incomplete
dominance
B. Codominance
C. Multiple alleles
D. Polygenic
inheritance
45
Incomplete dominance
0 0 0 0
Multiple alleles
Polygenic inheritance
Codominance

38. What occurs when both alleles can be
observed in a phenotype?
A. incomplete dominance
B. homozygous
C. polygenic
D. codominance
45
0 0 0 0
B. homozygous
A. incomplete dominance
C. polygenic
D. codominance

39. 3. All inherited traits follow Mendel’s
patterns of inheritance.
a. True
b. False
45
True
0 0
False

40. 4. Scientists have tools to predict the
form of a trait an offspring might
inherit.
a. True
b. False
45
True
0 0
False