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11.2 Complex Patterns of Inheritance
Complex Inheritance and Human Heredity
Incomplete Dominance
The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes.
Chapter 11
Complex Inheritance and Human Heredity
Codominance
Both alleles are expressed in the heterozygous condition.
11.2 Complex Patterns of Inheritance
Chapter 11
Complex Inheritance and Human Heredity
Multiple Alleles
Blood groups in humans
ABO blood groups have three forms of alleles.
11.2 Complex Patterns of Inheritance
Chapter 11
Complex Inheritance and Human Heredity
Coat Color of Rabbits
Multiple alleles can demonstrate a hierarchy of dominance.
In rabbits, four alleles code for coat color: C, cch, ch, and c.
11.2 Complex Patterns of Inheritance
Chapter 11
Complex Inheritance and Human Heredity
Coat Color of Rabbits
Light gray
Dark gray Himalayan
Albino
Chinchilla
11.2 Complex Patterns of Inheritance
Chapter 11
Complex Inheritance and Human Heredity
Sex Determination
Sex chromosomes determine an individual’s gender.
11.2 Complex Patterns of Inheritance
Chapter 11
Complex Inheritance and Human Heredity
Dosage Compensation
The X chromosome carries a variety of genes that are necessary for the development of both females and males.
The Y chromosome mainly has genes that relate to the development of male characteristics.
Chromosome inactivation
Barr bodies
11.2 Complex Patterns of Inheritance
Chapter 11
Complex Inheritance and Human Heredity
Polygenic Traits
Polygenic traits arise from the interaction of multiple pairs of genes.
11.2 Complex Patterns of Inheritance
Chapter 11
Complex Inheritance and Human Heredity
Environmental Influences
Environmental factors
Diet and exercise
Sunlight and water
Temperature
11.2 Complex Patterns of Inheritance
Chapter 11
Complex Inheritance and Human Heredity
Twin Studies
Helps scientists separate genetic contributions from environmental contributions
Traits that appear frequently in identical twins are at least partially controlled by heredity.
Traits expressed differently in identical twins are strongly influenced by environment.
11.2 Complex Patterns of Inheritance
Chapter 11
Complex Inheritance and Human Heredity
Telomeres
Telomere caps consist of DNA associated with proteins.
Serves a protective function for the structure of the chromosome
11.3 Chromosomes and Human Heredity
Chapter 11
Complex Inheritance and Human Heredity
Inferring Genotypes
Knowing physical traits can determine what genes an individual is most likely to have.
Predicting Disorders
Record keeping helps scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and ascertain genotypes.
11.1 Basic Patterns of Human Inheritance
Chapter 11
Karyotype—micrograph in which the pairs of homologous chromosomes are arranged in decreasing size.
11.3 Chromosomes and Human Heredity
Complex Inheritance and Human Heredity
Karyotype Studies
Images of chromosomes stained during metaphase
Chromosomes are arranged in decreasing size to produce a micrograph.
Chapter 11
Pedigree
Key: = Males
= Females
Shading = Have trait
No Shading = Do not have trait
(Attached Earlobes = f )
(Free Earlobes = F)
1 2
1 2 3
I
II
4 5
1 2 3
3 41 2
1 2 36
I
II
What are the Genotypes of the people shown below?
ff
ff
ff
F F F
F F
F
F
F F F
f f f
? ?
?
f f f
f
- - - - - -
- - -
What Does Each One Show?
Divorce
Adoption
Not Married but Biological mom and dad
Divorce and Death
