Download Mendelian Genetics - Deer Creek Schools

AP BIO
Please pick up the following papers on the counter by the door as you come into the room:
Genetics – Chapter 11 Reading Guide
Blood Type Worksheet
Pedigree Worksheet
Mendelian Genetics
CHAPTERS 11 & 12
WAKEFIELD 2015
Goals • Identify Mendel’s scientific approach to the laws of inheritance
and probability and its physical basis in the behavior of alleles and
chromosomes
• Communicate the complexity predicted by Mendelian genetics
• Relate the chromosomal basis of genetic disorders
Scales4) Using the concepts of Mendelian genetics, students will be able to predict heritable
factors from true-breeding, hybridization and mutations then apply these predictions to
populations and evolutionary processes.
3) Using the concepts of Mendelian genetics, students will be able to predict heritable
factors from true-breeding, hybridization and mutations then apply these predictions to
populations.
2) Using the concepts of Mendelian genetics, students will be able to predict heritable
factors from true-breeding, hybridization and mutations
1) Students may need assistance in using the concepts of Mendelian genetics to predict
heritable factors from true-breeding, hybridization and mutations
Gregor Mendel – 1860’s
Developed fundamental principals of inheritance & the
laws of segregation
Used garden peas
Many varieties
Fertilization is easily controlled
Offspring characteristics can be quantified
2 laws of inheritance
Law of Segregation
Law of Independent Assortment
Gregor Mendel – 1860’s
Studied 7 characters or heritable features we now call
alleles or traits
Used true-breeding (homozygous) plants
Performed hybridization by cross-pollinating to create
hybrids (heterozygous) plants
Quantified by their qualitative traits
P Generation – F1 Generation –F2 Generation
Law of Segregation
Alternate forms of alleles (genes) account for qualitative
variations in offspring
Organisms have 2 copies of each allele (gene) for each trait
When 2 different alleles occur together, one will be
dominant and one will be recessive
Allele pairs segregate during gamete formation (Mendel’s
Law of Segregation)
Punnett Square
Used to quantify the qualities
of offspring and to predict
future offspring
Dominant offspring
designated by capital letter
Recessive offspring designated
by small case letter
Monohybrid cross – complete the
Punnett Square for the following cross:
Parent 1 – Tall homozygous
pea plant
Parent 2 – Short homozygous
pea plant
Punnett Square
What is the phenotypic ratio?
What is the genotypic ratio?
What prediction can you
make based on this type of
cross?
Monohybrid cross – complete the
Punnett Square for the following cross:
Parent 1 – Tall heterozygous
pea plant
Parent 2 – Short pea plant
Punnett Square
What is the phenotypic ratio?
What is the genotypic ratio?
What prediction can you
make based on this type of
cross?
Monohybrid cross – complete the
Punnett Square for the following cross:
Parent 1 – Tall heterozygous
pea plant
Parent 2 – Tall heterozygous
pea plant
Punnett Square
What is the phenotypic ratio?
What is the genotypic ratio?
What prediction can you
make based on this type of
cross?
Explain how a test cross might be done
and what would it effectiveness be?
Law of Independent Assortment
Each pair of alleles segregates independently of every
other pair of alleles
Important in dihybrid crosses
Applies to genes located on different chromosomes or
close or far apart on the same chromosome
Parent 1
Homo – Tall
Hetero – Yellow
Parent 2
Hetero – Tall
Hetero - Yellow
Create a Punnett Square showing the parental alleles, their
potential allele combinations and the phenotypic and
genotypic ratios of the cross
Punnett Square
What is the phenotypic ratio?
What is the genotypic ratio?
What prediction can you
make based on this type of
cross?
Inheritance Patterns
Dominant / Recessive
One allele will mask the other allele in a pair
Dominant allele is evident in the phenotype
Inheritance Patterns
Incomplete Dominance
Neither allele is dominant
Phenotype will be a blend of the two alleles
Complete the following crosses & give phenotypes &
genotypes:
Homozygous red X homozygous white
Pink X Pink
Inheritance Patterns
Codominance – neither allele is dominant over the
other – both phenotypes will be present in the offspring
Complete the following crosses giving the phenotypes
and genotypes:
White chicken X black chicken
Cross 2 speckled chickens
Blood Types – Explain the inheritance pattern
Blood types –
Genotype
Blood Type (Phenotype)
Blood Proteins Present
Blood Antibodies Present
ii
Type O
None
Anti-A and Anti-B
IA IA
Type A
A
Anti-B
IA i
Type A
A
Anti-B
IB IB
Type B
B
Anti-A
IB i
Type B
B
Anti-A
IA IB
Type AB
A and B
None
Blood Types
Practice on the blood type scenario problems on your
hand out -
Hereditary Multiplication & Addition Rules
Applied to monohybrid crosses
States:
The probability that a certain combination of
independent events will occur together is equal to the
product of the separate probability of the independent
events
The probability of a particular genotype being formed by
fertilization is equal to the product of the probabilities of
forming each type of gamete needed to product that
genotype
Multiplication Rule
States:
The probability that 2 or more independent events will occur
together in some specific combination can be determined by
multiplying the probability of one event by the probability of
another event
½ x ½ =¼
Hardy-Weinberg Principle (1908)
States:
 Frequencies of alleles and genotypes in a population
remain constant from generation to generation, provided
that only Mendelian segregation and recombination of
alleles are at work
 Such a gene pool is called Hardy-Weinberg Equilibrium
Hardy-Weinberg Principle (1908)
p = frequency of the dominant allele in the population
q = frequency of the recessive allele in the population
p2 = percentage of the homozygous dominant individuals
q2 = percentage of the homozygous recessive individuals
2pq = percentage of heterozygous individuals
Hardy-Weinberg Principle
Pleiotropy
The ability of a
single gene to effect
other multiple genes
tryosine
Chickens and the Frizzle Trait
Epistasis
The expression of a
gene at one locus may
affect the expression of
another gene at
another locus – called
“modifier genes”
Will cause a variance in
the F2 ratio of 9:3:3:1
Chickens and the Frizzle Trait
Polygenic Traits
Called Quantitative Characters
Creates phenotypic gradiations
 Hair color
 Skin color
 Height
 Eye Color
Pedigrees – Humans follow Inheritance
Patterns
Chapter 12
Chromosomal Basis for Inheritance