Transcript Genetics
Genetic Disorders ESSENTIAL QUESTION: How does a mutation affect the life of an organism? What are some options that scientists have to predict the possibility of genetic diseases in infants? Do all mutations cause a change in the physical appearance of an organism? REVIEW Changes in the gene code change _______________ the protein that is made A change in the genetic code = ________________ mutation Many genetic ___________ result DISORDERS from changes in the DNA code so _________________ NON-FUNCTIONING proteins are produced. KINDS OF MUTATIONS Mutations that produce changes in a single gene = GENE MUTATIONS _________________ Mutations that produce changes in whole chromosomes = _____________________ CHROMOSOMAL MUTATIONS CHROMOSOMAL MUTATIONS ____________________________: Change in the ______________ or structure ____________ number of chromosomes Ex: Inversion of chromosome 12 Do you recognize this family? *Hint: They are from a TV show They are the Roloff family from TLC’s show Little People Big World How are the members of this family the same? How are they different? Same Different facial features, hair color etc. height Some family members (including the parents) exhibit the characteristic short stature of Achondroplasia, a dominant genetic disorder that results in a form of dwarfism. EXPLORATION ACTIVTIY: How is it possible for Matt and Amy (the parents) to have a child like Zach with Achondroplasia, dominant genetic disorder, and three children who do not have the disease? DID YOU QUICKLY THINK, Since some of the Roloff children do not exhibit dwarfism, what do we know about Matt and Amy’s genes for Achondroplasia? THAT’S RIGHT!!! Matt and Amy both have an Aa genotype. This would allow them to have children who exhibit dwarfism as well as children of normal height. Dwarfism: Aa or AA Normal height: aa DID YOU KNOW? 1. As the occurrence of infectious and nutritional diseases decreases in developed countries, genetic diseases have come to the forefront. 2. At least one-third of the children in pediatric hospitals are there because of hereditary disorders. 3. Chromosomal mutations account for about half of all firsttrimester miscarriages. 4. A total of about 7% of the population suffers from some type of genetic disorder. GENETIC DISEASES: inherited disorders reflecting gene mutations or abnormalities in chromosome structure or number, which result in a functional or anatomical change. Examples: -changes that cause deformities (cleft lip) -metabolic change (phenylketonuria “pku”) -structural changes (albinisim) How are genetic disorders transmitted or inherited? Genetic diseases can be inherited in a manner similar to that of normal traits. These diseases include single-gene disorders that are autosomal or sex-linked. Autosomal Sex-linked means that the gene is present in a chromosome pair other than the sex chromosomes means that the gene is located on a sex chromosome Types of Genetic Diseases Sex-linked Autosomal recessive Autosomal dominance Sex-Linked Genes Pattern of inheritance is located on the Xchromosome or the Y- chromosome Y is much smaller Therefore, there are more X-linked disorders/traits What numbers do you See? Ex. Colorblindness X-linked disorder Most common in ? Males (1/10) Females (1/100) AUTOSOMAL RECESSIVE DISORDER A mutation that causes a protein to be NONFUNCTIONAL would appear _________ Recessive to the normal working allele. • EXAMPLES: • Phenylketonuria (PKU) • Tay-Sachs Disease • Cystic Fibrosis The following is simply an example to assist with your understanding: Ex: Phenylketonuria (PKU) CAUSE: ENZYME breaks down an Mutation in gene for an ___________ that __________ amino acid ___________ called phenylalanine X X Build up causes ________________________ MENTAL RETARDATION Phenylketonuria (PKU) ALL babies are ________ tested ____ for PKU before they leave the hospital. Treatment: LOW in phenylalanine to Need a diet _____________________ extend life and ______________ mental PREVENT retardation amino acid If phenylalanine is an _____________, what type of foods should PKU patients avoid? PROTEINS ! __________________ Autosomal Dominant Disorders • A mutation that codes for a new protein whose action masks the normal allele appears as a dominant _____________ mutation. HENCE, • DOMINANT _________________________ GENETIC DISORDERS: • Examples: • Huntington’s Disease • Achondroplasia (Roloff family ) Analyzing Karyotypes What can you tell by this karyotype? Karyotype Organized profile of a human’s chromosomes Chromosomes are paired by centromere location banding pattern Size REVIEW Chromosomes that determine the sex of an organism = Sex chromosomes _________________ All other chromosomes = autosomes _________________ Humans have two sex chromosomes X Y 44 and _____ autosomes EXPLANATION ACTIVITY • Karyotyping Activity Analyzing Karyotypes What can you tell by analyzing this karyotype? Karyotype Analysis: Chromosomal Disorders Nondisjunction- occurs when either homologous chromosome fails to separate during meiosis Results abnormal # of chromosomes in gametes Trisomy = 1 extra homologous chromosome (3) Polysomy = more than 1 extra Monosomy = only 1 chromosome Examples: Down syndrome, Klinefelter syndrome, Turner Syndrome Find the chromosome that results from nondisjunction below That’s right, the sex chromosome has an extra Y. Trisomy, polysomy, or monosomy? ELABORATION ACTIVITY • Predict the genetic disorder by constructing a karyotype.