Complex Inhertiance
Recessive Genetic Disorders: a recessive trait is expressed when the individual is homozygous recessive for the trait. This is true for other species besides humans
Carriers: Individuals with at least one dominant allele who do NOT express the disorder Ex. If rr represents a genetic disorder, a person with the genotype Rr is a carrier for the disorder, but does not express it him/herself
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 Recessive Genetic Disorders
Dominant Gene Disorders: Organisms who have the disorder are homozygous dominant or heterozygous dominant for the genetic disorder
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 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. Predicting Disorders Record keeping helps scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and genotypes.
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. Normal red blood cell People who are heterozygous for the trait have both normal and sickle-shaped cells. Sickle cell 7766x
Multiple Alleles: genotype/phenotype that is determined by more than two alleles Ex. Blood type is determined by 3 alleles A, B, O 3 genes produce 4 blood types
I A = type A I B = type B i = type O I A and I B are codominant i is recessive to I A and I B
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.
AB is a universal recipient OO is a universal donor
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 of fur color is the result of one allele hiding the effects of another allele. eebb eeb_ E_bb E_B_ No dark pigment present in fur Dark pigment present in fur
Two sets of alleles control fur color E: dark pigment, B darkness of pigment EEBB: eebb:
Humans have 23 pairs of chromosomes 22 pairs of autosomes 1 pair of sex chromosomes
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance Sex Determination Sex chromosomes determine an individual s gender.
XX = female genotype XY = male genotype It is the male that determines the gender of the offspring
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.
The X chromosome carries some traits that are not carried on the Y chromosome Because males only have one X chromosome, they will inherit any X- chromosome trait; recessive or not
Chromosome inactivation: because females have 2 X chromosomes, one of them stops working so the organism will not have too many X related chromosomes Barr bodies: stain darker than activated chromosomes
Chapter 11 Complex Inheritance and Human Heredity 11.2 Complex Patterns of Inheritance Sex-Linked Traits Genes located on the X chromosome Genes located on the X chromosome Recessive trait on the X chromosome 10% of all males (only 1 out of 100 females)
!
Always use X and Y for genotype and put the letter for the disorder as a superscript Female normal: X C X C or X C X c (carrier) Male colorblind: X c Y Male normal: X C Y
"! Hemophilia: Organisms cannot produce clotting protein in blood Recessive on the X chromosome Approximately 1 in 10,000 males (1 in 1,000,000 females)
Muscular Dystrophy: sudden deterioration of muscles Recessive on the X chromosome 1 in 3,000 males
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 11.3 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
#$$
Allows geneticists to find autosomal disorders, human chromosome number disorders, and sex-linked disorders
%& Turner Syndrome: Individual is female with only one X chromosome Only 45 chromosomes total Female is sterile Caused by non-disjunction
Kleinfelter Syndrome: Male with an extra X chromosome (XXY) 47 Chromosomes Sterile May cause mental retardation Caused by non-disjunction
Down Syndrome: Individual has an extra #21 chromosome (trisomy) Causes mental retardation Heart and circulatory problems Caused by non-disjunction
% '
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
(