Transcript Chapter 11
CHAPTER 11
11-1 BASIC PATTERNS IN HUMAN INHERITANCE
Objectives 1. Analyze genetic patterns to determine dominant or recessive inheritance patterns 2. Summarize examples of dominant and recessive disorders 3. Construct human pedigrees from genetic information
Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Recessive Genetic Disorders A recessive trait is expressed when the individual is homozygous recessive for the trait.
Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance
Cystic Fibrosis
Affects the mucus-producing glands, digestive enzymes, and sweat glands Chloride ions are not absorbed into the cells of a person with cystic fibrosis but are excreted in the sweat. Without sufficient chloride ions in the cells, a thick mucus is secreted.
Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance
Albinism
Caused by altered genes, resulting in the absence of the skin pigment melanin in hair and eyes White hair Very pale skin Pink pupils
Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance
Tay-Sachs Disease
Caused by the absence of the enzymes responsible for breaking down fatty acids called gangliosides Gangliosides accumulate in the brain, inflating brain nerve cells and causing mental deterioration.
Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance
Galactosemia
Recessive genetic disorder characterized by the inability of the body to digest galactose.
Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance
Dominant Genetic Disorders
Huntington’s disease affects the nervous system. Achondroplasia is a genetic condition that causes small body size and limbs that are comparatively short.
Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance
Chapter 11 Complex Inheritance and Human Heredity
Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance Pedigrees A diagram that traces the inheritance of a particular trait through several generations
Chapter 11 Complex Inheritance and Human Heredity 11.1 Basic Patterns of Human Inheritance
Inferring Genotypes
Knowing physical traits can determine what genes an individual is most likely to have. Record keeping helps scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and ascertain genotypes.
11-2 COMPLEX PATTERNS OF INHERITANCE
Objectives 1. Distinguish between various complex inheritance patterns 2. Analyze sex-linked and sex-limited inheritance patterns 3. Explain how the environment can influence the phenotype of an organism
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance Incomplete Dominance The heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes.
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance Codominance Both alleles are expressed in the heterozygous condition.
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance
Sickle-cell Disease
Changes in hemoglobin cause red blood cells to change to a sickle shape. People who are heterozygous for the trait have both normal and sickle-shaped cells. Sickle cell Normal red blood cell 7766x
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance Multiple Alleles Blood groups in humans ABO blood groups have three forms of alleles.
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance
Coat Color of Rabbits
Multiple alleles can demonstrate a hierarchy of dominance.
In rabbits, four alleles code for coat color: C , c ch , c h , and c .
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance
Coat Color of Rabbits
Chinchilla Light gray Albino Dark gray Himalayan
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance Epistasis Variety is the result of one allele hiding the effects of another allele. eebb eeB_ No dark pigment present in fur E_bb E_B_ Dark pigment present in fur
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance
Sex Determination
Sex chromosomes determine an individual’s gender.
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance
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
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance Sex-Linked Traits Genes located on the X chromosome Red-green color blindness Hemophilia Sex-Linked Traits
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance
Polygenic Traits
Polygenic traits arise from the interaction of multiple pairs of genes.
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance
Environmental Influences
Environmental factors Diet and exercise Sunlight and water Temperature
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance
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.
Chapter 11 Complex Inheritance and Human Heredity 11.3 Chromosomes and Human Heredity
Karyotype Studies
Karyotype — micrograph in which the pairs of homologous chromosomes are arranged in decreasing size.
Images of chromosomes stained during metaphase Chromosomes are arranged in decreasing size to produce a micrograph.
Chapter 11 Complex Inheritance and Human Heredity 11.3 Chromosomes and Human Heredity Telomeres Telomere caps consist of DNA associated with proteins. Serves a protective function for the structure of the chromosome
Chapter 11 Complex Inheritance and Human Heredity 11.3 Chromosomes and Human Heredity Nondisjunction Cell division during which sister chromatids fail to separate properly Down syndrome Visualizing Nondisjunction
Chapter 11 Complex Inheritance and Human Heredity