* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 1 - G9Biology
Biology and consumer behaviour wikipedia , lookup
Human genetic variation wikipedia , lookup
Transgenerational epigenetic inheritance wikipedia , lookup
Gene expression programming wikipedia , lookup
Heritability of IQ wikipedia , lookup
Epigenetics of human development wikipedia , lookup
Designer baby wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Behavioural genetics wikipedia , lookup
Medical genetics wikipedia , lookup
Genome-wide association study wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
Genomic imprinting wikipedia , lookup
Genome (book) wikipedia , lookup
Population genetics wikipedia , lookup
Human leukocyte antigen wikipedia , lookup
Skewed X-inactivation wikipedia , lookup
Neocentromere wikipedia , lookup
Y chromosome wikipedia , lookup
Genetic drift wikipedia , lookup
Microevolution wikipedia , lookup
X-inactivation wikipedia , lookup
Hardy–Weinberg principle wikipedia , lookup
Name: Class: Date: # ___ Notes – Patterns of Heredity and Human Genetics (Chapter 12) Section 12.1 Pedigree – a family tree that shows patterns of inheritance. Refer to p 309-310 to complete this key. male/female known heterozygous (carrier) male/female male/female known heterozygous (carrier) male/female affected male (shows the trait in his phenotype/genotype) affected female (shows the trait in her phenotype/genotype) parents (the line between them represents _________________, the line going down represents ________________) siblings (both are male/female in this case) Section 12.3 Human Genetics. Previously, we learned about genetics in peas, guinea pigs, and other organisms. Now we’ll learn more about human genetics. A person may be homozygous dominant, heterozygous, or homozygous ___________________ for a certain trait. Given the allele f for earlobe attachment, a homozygous dominant individual will have the genotype . A heterozygous individual will have the genotype and a homozygous recessive individual will have the genotype . While genotype will influence phenotype, remember that environmental factors can also influence how/whether a gene is expressed. (See pp. 321-322.) Remember that humans have chromosomes in every cell. Of these, pairs are autosomes. An autosome is any chromosome except the sex chromosomes. Each person has one pair of sex chromosomes. Females have 2 X chromosomes while males have . Autosomal heredity just means that the allele for the trait being discussed is located on an autosome. If a trait is autosomal , this means that an individual will only need one dominant allele for the trait to be expressed in its phenotype. If a trait is autosomal , a person must have both recessive alleles before this trait is expressed. This is exactly the same as the genetic rules we were following in Chapter 10. A trait is considered sex-linked if its allele is located on a sex chromosome (usually the chromosome). We’ll learn more about this later. Punnett Problems (Part 1): 1. The allele for thick lips is dominant to the allele for thin lips. If a woman with thick lips marries a man with thin lips, how likely are they to have a child with thin lips? Page 1 of 4 2. Two people with thin lips get married. How likely are they to have a child with thick lips? _____ 3. Polydactyly is an autosomal dominant disorder. A woman who is heterozygous for polydactyly marries a man without polydactyly. a. What is the woman’s phenotype? b. What is the man’s phenotype? c. How likely are they to have a child with polydactyly? Section 12.2 1. complete dominance – what we learned earlier in Chapter 10. If one dominant allele is present in the genotype, it shows in the 2. incomplete dominance – - example – flower color in snapdragon plants (3 phenotypes: red, white and pink); pink is the phenotype of heterozygote - heterozygous phenotype shows 3. codominance - examples - - heterozygous phenotype shows 4. polygenic inheritance – a trait that is controlled by the inheritance of - in these cases, remember that a capital letter does not represent a dominant allele. All heterozygotes are intermediate in phenotype. What does this mean? (Read page 320 for a more thorough explanation.) - examples - 5. multiple phenotypes from multiple alleles – more than one allele contributes to the phenotypes of these traits - examples are color in pigeons (see Figure 12.9), HLA (human leukocyte antigen) system that recognizes foreign tissue in humans – because many alleles contribute to the phenotypes, there are many possible phenotypes (30 million for the HLA system!). Keep on reading for another example in humans. Traits Controlled by Multiple Alleles (pp. 324--325) You are probably used to seeing just two options for alleles, the dominant and the recessive (capital letter and small letter), right? However, some traits are determined by more than two alleles. One classic example is blood type. Blood type has different alleles, often written as , and Page 2 of 4 , which results in 4 different phenotypes (from 6 genotypes). Note: Blood type is not just multipleallelic. The A and B alleles are codominant and the O allele is recessive. (What does this mean?) Blood Type Possible genotypes Can accept what blood type? Can donate to what blood type? A B AB O Is it possible for a type A mother and a type B father have a type O child? Explain your answer. Can a type AB mother and a type B father have a type O child? Explain your answer. Problem-Solving Lab 12.2: Read the introduction on page 318 for another example of multiple alleles. Coat Color in Rabbits Phenotype Dark grey coat C Chinchilla Himalayan White Allele C cch ch c Pattern of Inheritance Dominant to all other alleles Dominant to Himalayan and to white Dominant to white Recessive 1. Complete the chart below. Phenotype All Possible Genotypes Dark grey-coated rabbit 4 possible: Chinchilla 3 possible: Himalayan 2 possible: White 1 possible: 2. Can a white rabbit and a chinchilla rabbit have white offspring? Explain your answer. 3. Can a Himalayan rabbit and a white rabbit have chinchilla offspring? Explain your answer. X-Linked Inheritance A trait is considered sex-linked if its allele is located on a sex chromosome (usually the chromosome). The sex chromosomes contain different genes. Genes found on the X chromosome are called -l genes. Genes on the Y chromosome are called -l g . Sex-linked traits are not autosomal. (Of course not. Why?) Examples of human traits/conditions that are sex-linked are and . Page 3 of 4 Punnett Problems (Part 2): Write the allele as a subscript on the sex chromosome. 1. Hemophilia is an X-linked recessive trait. If a man with hemophilia marries a carrier, how likely (% probability) are they to have a son with hemophilia? Phenotype of mother: not affected with hemophilia (because the allele is recessive) Genotype of mother: XHXh Phenotype of father: affected (and NOT homozygous recessive, because only the X chromosome carries the allele) Genotype of father: XhY Likelihood of having an affected son? 2. Colorblindness is also an X-linked recessive trait. Can a colorblind man who marries a non-colorblind woman have a son who is colorblind? Why/Why not? 3. Can a colorblind man have a colorblind daughter? Why/Why not? Common genetic conditions: Name of condition What is the defect (at the cellular or molecular level) Tay-Sachs disease Missing _________________ that breaks down _____________ in the central nervous system Cystic fibrosis A defective _________________ in cell membranes cannot remove _______________ in the digestive tract and lungs Sickle-cell anemia _________________________ are shaped like crescents - can slow blood flow, block _______________ ______________, and damage tissues; causes pain Huntington’s disease Parts of the ______________ break down Phenylketonuria Can’t change the amino acid ______ ______________ to ____________, which damages the central nervous system What is the phenotype? Male-pattern baldness What is this condition’s pattern of inheritance? Is it more common in some ethnic groups? If so, which one(s)? Page 4 of 4