Basics of Genetics and Inheritance
Math of
Genetics
Mary Simpson
MATH 150
Objectives
Understanding how to find the probability of genetic
outcomes for situations involving:
Multiple Traits
Linkage
Incomplete Dominance
Codominance
Multiple Allelism
Understanding Hardy Weinberg Equations in relation
to population genetics
Flashback to High School
Biology!
Genetics: the study of the inheritance of traits
Gene: a section of DNA that influences the heredity
of a trait
Flashback to High School
Biology!
Genetics: the study of the inheritance of traits
Gene: a section of DNA that influences the heredity
of a trait
Chromosome: dense coils of DNA that contain
multiple genes
Allele: denotes different versions of the same gene
Flashback to High School
Biology!
Genetics: the study of the inheritance of traits
Gene: a section of DNA that influences the heredity
of a trait
Chromosome: dense coils of DNA that contain
multiple genes
Allele: denotes different versions of the same gene
Gregor Mendel was a pioneer in genetics
Mendelian Genetics
Gregor Mendel (1822-
1884)
Studied the inheritance
of traits in pea plants
Mendelian Genetics
Gregor Mendel (1822-
1884)
Studied the inheritance
of traits in pea plants
Mendel looked for
patterns in the
inheritance traits from
parents with specified
traits
How Genes Are Inherited
The average human had 46 chromosomes (2 sets of
23)
How Genes Are Inherited
The average human had 46 chromosomes (2 sets of
23)
Half of these chromosomes come from the mother
and half from the father (1 set from each parent)
How Genes Are Inherited
The average human had 46 chromosomes (2 sets of
23)
Half of these chromosomes come from the mother
and half from the father (1 set from each parent)
Because there are two sets of chromosomes, a person
inherits two copies of each gene
How Genes Are Inherited
The average human had 46 chromosomes (2 sets of
23)
Half of these chromosomes come from the mother
and half from the father (1 set from each parent)
Because there are two sets of chromosomes, a person
inherits two copies of each gene
A person has two alleles for each trait that interact,
resulting in the expressed trait
Inheritance of Single Traits
Dominant Trait: if a gene for the dominant trait
(called a dominant allele) is present, it will be
expressed
Usually expressed with an uppercase letter (ex. A)
Recessive Trait: this trait will only be expressed in the
absence of a dominant allele
Usually expressed with a lowercase letter (ex. a)
Inheritance of Single Traits
Dominant Trait: if a gene for the dominant trait
(called a dominant allele) is present, it will be
expressed
Usually expressed with an uppercase letter (ex. A)
Recessive Trait: this trait will only be expressed in the
absence of a dominant allele
Usually expressed with a lowercase letter (ex. a)
Genotype: the combination of two alleles (ex. Aa)
Phenotype: the trait expression that results from a
genotype
Inheritance of Single Traits
Dominant Trait: if a gene for the dominant trait (called a dominant allele) is
present, it will be expressed
Usually expressed with an uppercase letter (ex. A)
Recessive Trait: this trait will only be expressed in the absence of a dominant
allele
Usually expressed with a lowercase letter (ex. a)
Genotype: the combination of two alleles (ex. Aa)
Phenotype: the trait expression that results from a genotype
Homozygous: genotype with two copies of the same allele (ex. AA, aa)
Heterozygous: genotype with one dominant allele and one recessive allele
(ex. Aa)
Punnett Squares
To form a punnett square, form a grid with the
paternal genotype on the top and the maternal
genotype down the left side
Punnett Squares
To form a punnett square, form a grid with the
paternal genotype on the top and the maternal
genotype down the left side
In the center sections of the table, combine the
paternal and maternal alleles to create all possible
genotypes for the offspring
Punnett Square Example
If we have a mother with genotype aa and a father
with genotype Aa
The punnett square would look as follows:
Punnett Square Example
If we have a mother with genotype aa and a father
with genotype Aa
The punnett square would look as follows:
Punnett Square Example
If we have a mother with genotype aa and a father
with genotype Aa
The punnett square would look as follows:
Punnett Square Example
If we have a mother with genotype aa and a father
with genotype Aa
The punnett square would look as follows:
Genotypic Ratio
: a ratio
of the number of
possible outcomes of
each genotype (in this
example
1:1
)
Phenotypic Ratio
: ratio
of the number of
outcomes that will result
in different phenotypes
(in this example
1:1
)
Practice Problem
The allele for dark hair (B) is dominant and the allele
for light hair (b) is recessive
If a female with genotype Bb and a male with
genotype Bb mate, what are the chances that they will
have a light haired offspring?
Practice Problem
The allele for dark hair (B) is dominant and the allele
for light hair (b) is recessive
If a female with genotype Bb and a male with
genotype Bb mate, what are the chances that they will
have a light haired offspring?
Practice Problem
The allele for dark hair (B) is dominant and the allele
for light hair (b) is recessive
If a female with genotype Bb and a male with
genotype Bb mate, what are the chances that they will
have a light haired offspring?
Practice Problem
The allele for dark hair (B) is dominant and the allele
for light hair (b) is recessive
If a female with genotype Bb and a male with
genotype Bb mate, what are the chances that they will
have a light haired offspring?
Practice Problem
The allele for dark hair (B) is dominant and the allele
for light hair (b) is recessive
If a female with genotype Bb and a male with
genotype Bb mate, what are the chances that they will
have a light haired offspring?
To have light hair the genotype
must be bb
There is only a 1/4 chance of
that, therefore the chance is
25%
Inheritance of Two Traits
Looking at the inheritance of two traits is called a
dihybrid cross
Inheritance of Two Traits
Looking at the inheritance of two traits is called a
dihybrid cross
To set up the punnett square you have to look at all
possible combinations of maternal and paternal DNA
Inheritance of Two Traits
Looking at the inheritance of two traits is called a
dihybrid cross
To set up the punnett square you have to look at all
possible combinations of maternal and paternal DNA
You use those 4 combinations from each parent to set
up the punnett square
Practice Problem
We will look at the inheritance of brown and black fur
and coarse and soft fur in hamsters
Brown fur (B) and soft fur (S) are dominant
Practice Problem
We will look at the inheritance of brown and black fur
and coarse and soft fur in hamsters
Brown fur (B) and soft fur (S) are dominant
Practice Problem
We will look at the inheritance of brown and black fur
and coarse and soft fur in hamsters
Brown fur (B) and soft fur (S) are dominant
If the mother has genotype
BBss
and the father has
genotype
BbSs
, what is the chance that an offspring
will have brown coarse fur?
Practice Problem Cont.
If the mother has genotype Bbss and the father has
genotype BbSs, what is the chance that an offspring
will have brown coarse fur?
Practice Problem Cont.
If the mother has genotype Bbss and the father has
genotype BbSs, what is the chance that an offspring
will have brown coarse fur?
Practice Problem Cont.
If the mother has genotype Bbss and the father has
genotype BbSs, what is the chance that an offspring
will have brown coarse fur?
Practice Problem Cont.
If the mother has genotype Bbss and the father has
genotype BbSs, what is the chance that an offspring
will have brown coarse fur?
Phenotypic Ratio 6:6:2:2
Practice Problem Cont.
If the mother has genotype Bbss and the father has
genotype BbSs, what is the chance that an offspring
will have brown coarse fur?
Phenotypic Ratio 6:6:2:2
Practice Problem Cont.
If the mother has genotype Bbss and the father has
genotype BbSs, what is the chance that an offspring
will have brown coarse fur?
Phenotypic Ratio 6:6:2:2
Out of the sixteen possible genetic combinations, 6 result
in brown, coarse fur
6/16= .375 = 37.5%
Linkage
Linked genes are those found on the same
chromosome
Linkage
Linked genes are those found on the same
chromosome
This means that these traits should not follow the
same pattern of inheritance because the traits cannot
be independently assorted into gametes
Linkage
Linked genes are those found on the same
chromosome
This means that these traits should not follow the
same pattern of inheritance because the traits cannot
be independently assorted into gametes
In terms of a punnett square, having two linked traits
would be treated like having a single trait
Linkage
Linked genes are those found on the same
chromosome
This means that these traits should not follow the
same pattern of inheritance because the traits cannot
be independently assorted into gametes
In terms of a punnett square, having two linked traits
would be treated like having a single trait
Mendel was lucky that each of the traits he studied
had genes that were not linked
Incomplete Dominance
Incomplete dominance means that the dominant allele
will not completely dominant the recessive allele
Incomplete Dominance
Incomplete dominance means that the dominant allele
will not completely dominant the recessive allele
In many cases this means that heterozygous
individuals will have intermediate phenotypes
Incomplete Dominance
Incomplete dominance means that the dominant allele
will not completely dominant the recessive allele
In many cases this means that heterozygous
individuals will have intermediate phenotypes
This will not alter genotypic ratios, but it will alter
phenotypic ratios
Practice Problem
The allele for white flowers (R) is dominant, but it’s
dominance incomplete
The allele for red flowers (r) is recessive
Practice Problem
The allele for white flowers (R) is dominant, but it’s
dominance incomplete
The allele for red flowers (r) is recessive
What are the possible phenotypes of the offspring of
two plants with genotypes Rr and Rr?
Practice Problem
The allele for white flowers (R) is dominant, but it’s
dominance incomplete
The allele for red flowers (r) is recessive
What are the possible phenotypes of the offspring of
two plants with genotypes Rr and Rr?
Practice Problem
The allele for white flowers (R) is dominant, but it’s
dominance incomplete
The allele for red flowers (r) is recessive
What are the possible phenotypes of the offspring of
two plants with genotypes Rr and Rr?
Practice Problem
The allele for white flowers (R) is dominant, but it’s
dominance incomplete
The allele for red flowers (r) is recessive
What are the possible phenotypes of the offspring of
two plants with genotypes Rr and Rr?
RR will have white
flowers
rr will have red flowers
Rr will have pink
flowers (intermediate
between white and red)
Practice Problem
If we mated two of that same type of flowers with the
genotypes, RR and Rr, what is the probability that the
offspring will have pink flowers?
Practice Problem
If we mated two of that same type of flowers with the
genotypes, RR and Rr, what is the probability that the
offspring will have pink flowers?
Practice Problem
If we mated two of that same type of flowers with the
genotypes, RR and Rr, what is the probability that the
offspring will have pink flowers?
Practice Problem
If we mated two of that same type of flowers with the
genotypes, RR and Rr, what is the probability that the
offspring will have pink flowers?
2/4 or 50%
chance
Codominance
Codominance: when heterozygotes have the
phenotypes associated with each allele (because both
alleles are dominant)
Codominance
Codominance: when heterozygotes have the
phenotypes associated with each allele (because both
alleles are dominant)
The best example is blood type
There are three alleles for blood type (I
A
, I
B
, i)
Codominance
Codominance: when heterozygotes have the
phenotypes associated with each allele (because both
alleles are dominant)
The best example is blood type
There are three alleles for blood type (I
A
, I
B
, i)
I
A
and I
B
are codominant, so if a person has genotype
I
A
I
B
, they will have type AB blood
I
A
i, results in type A, I
B
i in type B and ii in type O
Practice Problem
What are the possible blood types of offspring of
parents with genotypes I
A
i and I
B
I
B
Practice Problem
What are the possible blood types of offspring of
parents with genotypes I
A
i and I
B
I
B
Practice Problem
What are the possible blood types of offspring of
parents with genotypes I
A
i and I
B
I
B
Practice Problem
What are the possible blood types of offspring of
parents with genotypes I
A
i and I
B
I
B
I
A
I
B
will result in type AB
I
B
i will result in type B
Practice Problem
What is the chance that a mother with genotype I
B
i
and a father with genotype I
A
i will have a child with
type O blood?
Practice Problem
What is the chance that a mother with genotype I
B
i
and a father with genotype I
A
i will have a child with
type O blood?
Practice Problem
What is the chance that a mother with genotype I
B
i
and a father with genotype I
A
i will have a child with
type O blood?
Practice Problem
What is the chance that a mother with genotype I
B
i
and a father with genotype I
A
i will have a child with
type O blood?
1/4 or 25%
Multiple Gene Inheritance
Multiple Gene Inheritance: there is more than one
gene that controls the expression of a trait
Multiple Gene Inheritance
Multiple Gene Inheritance: there is more than one
gene that controls the expression of a trait
Example: Pepper Color
Pepper color is controlled by two different genes
The first gene controls the expression of red pigment
The dominant allele (R) indicates the presence of red
pigment
The recessive allele (r) indicates the absence of red
pigment
Multiple Gene Inheritance
Multiple Gene Inheritance: there is more than one
gene that controls the expression of a trait
Example: Pepper Color
Pepper color is controlled by two different genes
The first gene controls the expression of red pigment
The dominant allele (R) indicates the presence of red
pigment
The recessive allele (r) indicates the absence of red
pigment
The second gene controls the expression of either green
(G) or yellow (g) pigment
Multiple Gene Inheritance
If red pigment is expressed, the pepper will be red,
regardless of the second gene.
Multiple Gene Inheritance
If red pigment is expressed, the pepper will be read,
regardless of the second gene.
If the red pigment is absent, you must look to the
second gene to determine color
Multiple Gene Inheritance
If red pigment is expressed, the pepper will be red,
regardless of the second gene.
If the red pigment is absent, you must look to the
second gene to determine color
What would the color of a pepper with the genotype
Rrgg be?
Multiple Gene Inheritance
If red pigment is expressed, the pepper will be read,
regardless of the second gene.
If the red pigment is absent, you must look to the
second gene to determine color
What would the color of a pepper with the genotype
Rrgg be?
Red
Multiple Gene Inheritance
If red pigment is expressed, the pepper will be red,
regardless of the second gene.
If the red pigment is absent, you must look to the
second gene to determine color
What would the color of a pepper with the genotype
Rrgg be?
Red
What about rrGg
Multiple Gene Inheritance
If red pigment is expressed, the pepper will be read,
regardless of the second gene.
If the red pigment is absent, you must look to the
second gene to determine color
What would the color of a pepper with the genotype
Rrgg be?
Red
What about rrGg
Green
Hardy Weinberg Principle
Looks at the frequency of alleles in a population
The Principle makes several important assumptions:
There is not natural selection regarding the gene in
question
There is no genetic drift
There is no gene flow
There is no mutation
Random mating with respect to the gene in question is
occurring
Hardy Weinberg Principle
Hardy Weinberg Equation:
p
2
+ 2pq + q
2
= 1
p + q = 1
Hardy Weinberg Principle
Hardy Weinberg Equation:
p
2
+ 2pq + q
2
= 1
p + q = 1
p=allele frequency of the dominant allele
q=allele frequency of the recessive allele
Hardy Weinberg Principle
Hardy Weinberg Equation:
p
2
+ 2pq + q
2
= 1
p + q = 1
p=allele frequency of the dominant allele
q=decimal version of the recessive allele
p
2
is the frequency of the homozygous dominant
genotype
q
2
is the frequency of the homozygous recessive
genotype
2pq is the frequency of the heterozygous genotype
Genes that the Hardy Weinberg
Equilibrium Applies To
Tongue Rolling (dominant)
Genes that the Hardy Weinberg
Equilibrium Applies To
Tongue Rolling (dominant)
Free (dominant) v. Attached (recessive) Earlobes
Genes that the Hardy Weinberg
Equilibrium Applies To
Tongue Rolling (dominant)
Free (dominant) v. Attached (recessive) Earlobes
Hand Clasping
Left thumb over right (dominant)
Right thumb over left (recessive)
Genes that the Hardy Weinberg
Equilibrium Applies To
Tongue Rolling (dominant)
Free (dominant) v. Attached (recessive) Earlobes
Hand Clasping
Left thumb over right (dominant)
Right thumb over left (recessive)
Widow’s Peak (dominant)
Genes that the Hardy Weinberg
Equilibrium Applies To
Tongue Rolling (dominant)
Free (dominant) v. Attached (recessive) Earlobes
Hand Clasping
Left thumb over right (dominant)
Right thumb over left (recessive)
Widow’s Peak (dominant)
Mid-Digital Hair (dominant)
Using the Hardy Weinberg
Equations
If the frequency of the recessive allele for sickle cell
anemia is .4 in a population of 100,000
The dominant allele has a frequency of .6
Individuals that are heterozygous for this allele have a
higher resistance to malaria
How many members of the population would have the
increased resistance to malaria?
Using the Hardy Weinberg
Equations
If the frequency of the recessive allele for sickle cell
anemia is .4 in a population of 100,000 people
The dominant allele has a frequency of .6
How many members of the population would have the
increased resistance to malaria?
Heterozygous Frequency = 2pq
Using the Hardy Weinberg
Equations
If the frequency of the recessive allele for sickle cell
anemia is .4 in a population of 100,000 people
The dominant allele has a frequency of .6
How many members of the population would have the
increased resistance to malaria?
Heterozygous Frequency = 2pq
2pq = 2 * 0.4 * 0.6 = .48
Using the Hardy Weinberg
Equations
If the frequency of the recessive allele for sickle cell
anemia is .4 in a population of 100,000 people
The dominant allele has a frequency of .6
How many members of the population would have the
increased resistance to malaria?
Heterozygous Frequency = 2pq
2pq = 2 * 0.4 * 0.6 = .48
48,000 people would have increased malaria resistance
Homework
1.
What is the probability that a father with genotype
Hhpp and a mother with genotype HHPp will have
offspring that have the dominant phenotype for both
traits?
2.
If the allele frequency for blue eyes in a population is
0.35 and that allele is recessive, what is the frequency
of heterozygous individuals in the population?
Understanding the fundamentals of genetics and inheritance, this content covers topics such as Mendelian genetics, gene inheritance, chromosomes, alleles, and Gregor Mendel's pioneering work. It delves into genetic outcomes related to multiple traits, linkage, dominance, Hardy-Weinberg equations, and more, providing a flashback to high school biology while exploring how genes are inherited through chromosomes.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
E N D
Presentation Transcript
Math of Genetics Mary Simpson MATH 150
Objectives Understanding how to find the probability of genetic outcomes for situations involving: Multiple Traits Linkage Incomplete Dominance Codominance Multiple Allelism Understanding Hardy Weinberg Equations in relation to population genetics
Flashback to High School Biology! Genetics: the study of the inheritance of traits Gene: a section of DNA that influences the heredity of a trait
Flashback to High School Biology! Genetics: the study of the inheritance of traits Gene: a section of DNA that influences the heredity of a trait Chromosome: dense coils of DNA that contain multiple genes Allele: denotes different versions of the same gene
Flashback to High School Biology! Genetics: the study of the inheritance of traits Gene: a section of DNA that influences the heredity of a trait Chromosome: dense coils of DNA that contain multiple genes Allele: denotes different versions of the same gene Gregor Mendel was a pioneer in genetics
Mendelian Genetics Gregor Mendel (1822- 1884) Studied the inheritance of traits in pea plants
Mendelian Genetics Gregor Mendel (1822- 1884) Studied the inheritance of traits in pea plants Mendel looked for patterns in the inheritance traits from parents with specified traits
How Genes Are Inherited The average human had 46 chromosomes (2 sets of 23)
How Genes Are Inherited The average human had 46 chromosomes (2 sets of 23) Half of these chromosomes come from the mother and half from the father (1 set from each parent)
How Genes Are Inherited The average human had 46 chromosomes (2 sets of 23) Half of these chromosomes come from the mother and half from the father (1 set from each parent) Because there are two sets of chromosomes, a person inherits two copies of each gene
How Genes Are Inherited The average human had 46 chromosomes (2 sets of 23) Half of these chromosomes come from the mother and half from the father (1 set from each parent) Because there are two sets of chromosomes, a person inherits two copies of each gene A person has two alleles for each trait that interact, resulting in the expressed trait
Inheritance of Single Traits Dominant Trait: if a gene for the dominant trait (called a dominant allele) is present, it will be expressed Usually expressed with an uppercase letter (ex. A) Recessive Trait: this trait will only be expressed in the absence of a dominant allele Usually expressed with a lowercase letter (ex. a)
Inheritance of Single Traits Dominant Trait: if a gene for the dominant trait (called a dominant allele) is present, it will be expressed Usually expressed with an uppercase letter (ex. A) Recessive Trait: this trait will only be expressed in the absence of a dominant allele Usually expressed with a lowercase letter (ex. a) Genotype: the combination of two alleles (ex. Aa) Phenotype: the trait expression that results from a genotype
Inheritance of Single Traits Dominant Trait: if a gene for the dominant trait (called a dominant allele) is present, it will be expressed Usually expressed with an uppercase letter (ex. A) Recessive Trait: this trait will only be expressed in the absence of a dominant allele Usually expressed with a lowercase letter (ex. a) Genotype: the combination of two alleles (ex. Aa) Phenotype: the trait expression that results from a genotype Homozygous: genotype with two copies of the same allele (ex. AA, aa) Heterozygous: genotype with one dominant allele and one recessive allele (ex. Aa)
Punnett Squares To form a punnett square, form a grid with the paternal genotype on the top and the maternal genotype down the left side
Punnett Squares To form a punnett square, form a grid with the paternal genotype on the top and the maternal genotype down the left side In the center sections of the table, combine the paternal and maternal alleles to create all possible genotypes for the offspring
Punnett Square Example If we have a mother with genotype aa and a father with genotype Aa The punnett square would look as follows: a a A a
Punnett Square Example If we have a mother with genotype aa and a father with genotype Aa The punnett square would look as follows: a a A A A a a a
Punnett Square Example If we have a mother with genotype aa and a father with genotype Aa The punnett square would look as follows: a a A Aa Aa a aa aa
Punnett Square Example If we have a mother with genotype aa and a father with genotype Aa The punnett square would look as follows: Genotypic Ratio: a ratio of the number of possible outcomes of each genotype (in this example 1:1) Phenotypic Ratio: ratio of the number of outcomes that will result in different phenotypes (in this example 1:1) a a A Aa Aa a aa aa
Practice Problem The allele for dark hair (B) is dominant and the allele for light hair (b) is recessive If a female with genotype Bb and a male with genotype Bb mate, what are the chances that they will have a light haired offspring?
Practice Problem The allele for dark hair (B) is dominant and the allele for light hair (b) is recessive If a female with genotype Bb and a male with genotype Bb mate, what are the chances that they will have a light haired offspring? B b B b
Practice Problem The allele for dark hair (B) is dominant and the allele for light hair (b) is recessive If a female with genotype Bb and a male with genotype Bb mate, what are the chances that they will have a light haired offspring? B b B B B b b b
Practice Problem The allele for dark hair (B) is dominant and the allele for light hair (b) is recessive If a female with genotype Bb and a male with genotype Bb mate, what are the chances that they will have a light haired offspring? B b B BB Bb b Bb bb
Practice Problem The allele for dark hair (B) is dominant and the allele for light hair (b) is recessive If a female with genotype Bb and a male with genotype Bb mate, what are the chances that they will have a light haired offspring? To have light hair the genotype must be bb B b There is only a 1/4 chance of that, therefore the chance is 25% B BB Bb b Bb bb
Inheritance of Two Traits Looking at the inheritance of two traits is called a dihybrid cross
Inheritance of Two Traits Looking at the inheritance of two traits is called a dihybrid cross To set up the punnett square you have to look at all possible combinations of maternal and paternal DNA
Inheritance of Two Traits Looking at the inheritance of two traits is called a dihybrid cross To set up the punnett square you have to look at all possible combinations of maternal and paternal DNA You use those 4 combinations from each parent to set up the punnett square
Practice Problem We will look at the inheritance of brown and black fur and coarse and soft fur in hamsters Brown fur (B) and soft fur (S) are dominant
Practice Problem We will look at the inheritance of brown and black fur and coarse and soft fur in hamsters Brown fur (B) and soft fur (S) are dominant
Practice Problem We will look at the inheritance of brown and black fur and coarse and soft fur in hamsters Brown fur (B) and soft fur (S) are dominant If the mother has genotype BBss and the father has genotype BbSs, what is the chance that an offspring will have brown coarse fur?
Practice Problem Cont. If the mother has genotype Bbss and the father has genotype BbSs, what is the chance that an offspring will have brown coarse fur? BS Bs bS bs Bs Bs bs bs
Practice Problem Cont. If the mother has genotype Bbss and the father has genotype BbSs, what is the chance that an offspring will have brown coarse fur? BS Bs bS bs Bs Bs Bs Bs Bs Bs Bs Bs Bs Bs bs bs bs bs bs bs bs bs bs bs
Practice Problem Cont. If the mother has genotype Bbss and the father has genotype BbSs, what is the chance that an offspring will have brown coarse fur? BS Bs bS bs Bs BBSs BBss BbSs Bbss Bs BBSs BBss BbSs Bbss bs bBSs bBss bbSs bbss bs bBSs bBss bbSs bbss
Practice Problem Cont. If the mother has genotype Bbss and the father has genotype BbSs, what is the chance that an offspring will have brown coarse fur? BS Bs bS bs Bs BBSs BBss BbSs Bbss Bs BBSs BBss BbSs Bbss bs bBSs bBss bbSs bbss bs bBSs bBss bbSs bbss Phenotypic Ratio 6:6:2:2
Practice Problem Cont. If the mother has genotype Bbss and the father has genotype BbSs, what is the chance that an offspring will have brown coarse fur? BS Bs bS bs Bs BBSs BBss BbSs Bbss Bs BBSs BBss BbSs Bbss bs bBSs bBss bbSs bbss bs bBSs bBss bbSs bbss Phenotypic Ratio 6:6:2:2
Practice Problem Cont. If the mother has genotype Bbss and the father has genotype BbSs, what is the chance that an offspring will have brown coarse fur? BS Bs bS bs Bs BBSs BBss BbSs Bbss Bs BBSs BBss BbSs Bbss bs bBSs bBss bbSs bbss bs bBSs bBss bbSs bbss Phenotypic Ratio 6:6:2:2 Out of the sixteen possible genetic combinations, 6 result in brown, coarse fur 6/16= .375 = 37.5%
Linkage Linked genes are those found on the same chromosome
Linkage Linked genes are those found on the same chromosome This means that these traits should not follow the same pattern of inheritance because the traits cannot be independently assorted into gametes
Linkage Linked genes are those found on the same chromosome This means that these traits should not follow the same pattern of inheritance because the traits cannot be independently assorted into gametes In terms of a punnett square, having two linked traits would be treated like having a single trait
Linkage Linked genes are those found on the same chromosome This means that these traits should not follow the same pattern of inheritance because the traits cannot be independently assorted into gametes In terms of a punnett square, having two linked traits would be treated like having a single trait Mendel was lucky that each of the traits he studied had genes that were not linked
Incomplete Dominance Incomplete dominance means that the dominant allele will not completely dominant the recessive allele
Incomplete Dominance Incomplete dominance means that the dominant allele will not completely dominant the recessive allele In many cases this means that heterozygous individuals will have intermediate phenotypes
Incomplete Dominance Incomplete dominance means that the dominant allele will not completely dominant the recessive allele In many cases this means that heterozygous individuals will have intermediate phenotypes This will not alter genotypic ratios, but it will alter phenotypic ratios
Practice Problem The allele for white flowers (R) is dominant, but it s dominance incomplete The allele for red flowers (r) is recessive
Practice Problem The allele for white flowers (R) is dominant, but it s dominance incomplete The allele for red flowers (r) is recessive What are the possible phenotypes of the offspring of two plants with genotypes Rr and Rr?
Practice Problem The allele for white flowers (R) is dominant, but it s dominance incomplete The allele for red flowers (r) is recessive What are the possible phenotypes of the offspring of two plants with genotypes Rr and Rr? R r R r
Practice Problem The allele for white flowers (R) is dominant, but it s dominance incomplete The allele for red flowers (r) is recessive What are the possible phenotypes of the offspring of two plants with genotypes Rr and Rr? R RR r Rr R r Rr rr
Practice Problem The allele for white flowers (R) is dominant, but it s dominance incomplete The allele for red flowers (r) is recessive What are the possible phenotypes of the offspring of two plants with genotypes Rr and Rr? RR will have white flowers rr will have red flowers Rr will have pink flowers (intermediate between white and red) R RR r Rr R r Rr rr
Practice Problem If we mated two of that same type of flowers with the genotypes, RR and Rr, what is the probability that the offspring will have pink flowers?
