Ch 5 2 understanding inheritance (k)
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Ch. 5.2 Understanding Inheritance
Transcript of Ch 5 2 understanding inheritance (k)
Ch. 5.2 Understanding Inheritance
Lesson 2 Reading Guide
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?
Focus Questions
• 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.
Lesson 2
1. What determines the
expression of traits?
Lesson 2
• 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.
1. What determines the expression of
traits?
Lesson 2
Lesson 2
• Phenotype – how a trait physically appears
• Genotype – the 2 alleles (genes) that control the phenotype of a trait
1. What determines the expression of
traits?
A pea plant that is Yy
a. Genotype
b. Phenotype
45Genoty
pe
Phenotype
00
A pea plant that is green
a. Genotype
b. Phenotype
Genotype
Phenotype
00
45
The two alleles
a. Genotype
b. Phenotype
Genotype
Phenotype
00
45
Lesson 2
• Homozygous = same alleles (ex: RR, rr)
• Heterozygous = different alleles (ex: Rr)
1. What determines the expression of
traits?
What is the genotype? Rr
a. Homozygous
dominant
b. Homozygous
recessive
c. Heterozygous
45Homozy
gous dom
inant
Homozy
gous rece
ssiv
e
Hetero
zygous
0 00
What is the genotype? ww
a. Homozygous
dominant
b. Homozygous
recessive
c. Heterozygous
45Homozy
gous dom
inant
Homozy
gous rece
ssiv
e
Hetero
zygous
0 00
What is the genotype? CC
a. Homozygous
dominant
b. Homozygous
recessive
c. Heterozygous
45Homozy
gous dom
inant
Homozy
gous rece
ssiv
e
Hetero
zygous
0 00
What is the genotype? Yy
a. Homozygous
dominant
b. Homozygous
recessive
c. Heterozygous
45Homozy
gous dom
inant
Homozy
gous rece
ssiv
e
Hetero
zygous
0 00
Lesson 2
A Punnett square is a model used to predict possible genotypes and phenotypes of offspring.
2. How can inheritance be modeled?
Draw the following Punnett Squares
Yy x yy CC x cc
• Punnett Square Brain Pop
Lesson 2
A pedigree shows phenotypes of genetically related family members.
Male
female
Male
affected
Female
affected
2. How can inheritance be modeled?
Mrs. Calderon’s family Pedigree for Blue eyes (bb)
What color are Mrs. Calderon’s dad’s eyes?
Mrs.
Calderon
Mrs. Calderon’s family Pedigree for Blue eyes (bb)
a. Blue
b. Dark
c. Can’t tell from the
chart
Blue
Dark
Can’t te
ll fro
m th
e chart
17
13
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)
1 2 3 4 5 6 7 8 9 0
0
2
0
11
0
1
00
2
5
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 Pedigree for Blue eyes (bb)
YesNo
Can’t te
ll fro
m th
e chart
6
0
15
Does Mrs. Calderon’s mom carry the blue eye gene?
Mrs.
Calderon
a. Yes
b. No
c. Can’t tell from the
chart
Mrs. Calderon’s family Pedigree for Blue eyes (bb)
YesNo
Can’t te
ll fro
m th
e chart
11
0
10
Lesson 2 Complex
• Sometimes traits appear to be blends of alleles.
Complex Patterns of Inheritance
3. How do some patterns of inheritance differ from Mendel’s model?
Lesson 2 Complex
3. How do some patterns of inheritance differ from Mendel’s model?
Complex patterns of inheritance
Incomplete dominance
Codominance
Polygenic Inheritance
Multiple alleles
Lesson 2 Complex
• Incomplete Dominance:when the offspring’s phenotype is a blend of the parents’ phenotypes.
3. How do some patterns of inheritance differ from Mendel’s model?
Lesson 2 Complex
• Codominance occurs when both alleles can be observed in a phenotype.
3. How do some patterns of inheritance differ from Mendel’s model?
Lesson 2
Polygenic Inheritance:
occurs when multiple genes determine the phenotype of a trait (ex: skin color, eye color).
3. How do some patterns of inheritance differ from Mendel’s model?
Lesson 2
3. How do some patterns of inheritance differ from Mendel’s model?
Lesson 2
Multiple alleles: Some traits are determined by more than one allele;
ex: Human ABO blood types
3. How do some patterns of inheritance differ from Mendel’s model?
Lesson 2
• 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.
Genes and the Environment
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
45Inco
mple
te d
omin
ance
Codomin
ance
Multi
ple alle
les
Polyge
nic in
heritance
0 000
What type of inheritance occurs when multiple genes determine the phenotype?
A. Incomplete
dominance
B. Codominance
C. Multiple alleles
D. Polygenic
inheritance
45Inco
mple
te d
omin
ance
Codomin
ance
Multi
ple alle
les
Polyge
nic in
heritance
0 000
What occurs when both alleles can be
observed in a phenotype?
A. incomplete dominance
B. homozygous
C. polygenic
D. codominance
45A. inco
mple
te d
omin
ance
B. hom
ozygo
us
C. polygenic
D. codom
inance
0 000
3. All inherited traits follow Mendel’s patterns of inheritance.
a. True
b. False
45Tru
eFa
lse
00
4. Scientists have tools to predict the form of a trait an offspring might inherit.
a. True
b. False
45Tru
eFa
lse
00
