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Chapter 4: Heredity Section1- Genetics Life Science Lesson Plan
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Inheriting Traits Create a short list of characteristics about yourself… What is another name for these characteristics? TRAITS
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Heredity Heredity is the passing of traits from parents to offspring. Inherited Traits- Traits that are passed from parents to their offspring (through fertilization)
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Genes are passed… but what are genes? Genes are sections of DNA on a chromosome. These genes on chromosomes control the traits that show up in an organism. –There are thousands of genes on a chromosome
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Alleles are different forms of a trait that a gene may contain. –There are 2 alleles for each gene –1 from mom and 1 from dad Example: Height –1 allele is tall –1 allele is small
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Alleles alleles a gene
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B. Genetics- is the study of inherited traits. 1. Gregor Mendel- The Father of Genetics “The Man”
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Mendel’s Experiment Mendel studied the traits of Pea Plants –Look Page 105 Crossed 2 Plants with different expressions of the trait –Example- Tall (T)& Short (t) –Round R & Wrinkled r
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Mendel’s Experiment When the plants were crossed he discovered that the new plant formed looked like one of the two parents. Take a look… Mendel’s Tall vs. Short Plants
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VOCABULARY 3. Purebreds- offspring receives the two same alleles for a trait (TT or tt)
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VOCABULARY 4. Hybrids- offspring receives two different alleles for a trait (Tt)
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2 Types of Alleles a.Dominant allele- covers up or dominates the other trait Represented by a Capital Letter b. Recessive allele- the trait seems to disappear Represented by a lower-case letter
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“Homo”zygous – an organism with 2 alleles for one trait that are the same (written TT) “Hetero”zygous – an organism with 2 alleles for one trait that are different (written Tt)
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Genotype- the genetic- makeup of an organism (types of letters used)
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Phenotype- the way an organism physically looks/behaves as a result of its genotype. Types of Words used: Tall, Short, Blonde, Brown, etc.
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The Use of Punnett Squares A Punnett Square can help you predict what an offspring will look like. “What’s the Probability of the baby’s gender?”
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A Punnett Square can help you predict what an offspring will look like 1. Monohybrid: Offspring of parents that differ in only one genetic characteristic
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Monohybrid Cross: GG x gg
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DYHIBRID CROSSES 2. Dyhybrid: Offspring of parents that differ in TWO genetic characteristic ***USE FOIL to separate the combinations F – FIRST O – OUTSIDE I – INSIDE L – LAST
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DIHYBRID EXAMPLE Tall & Green TtGg x TtGg
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DIHYBRID EXAMPLE #2 Brown hair vs Blonde hair AaBb x aaBb
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Chapter 4 Part 2- Genetics Since Mendel Life Science
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Question… If you crossed Purebred Red four- o’clock flower with Purebred White four-o’clock flower, what would the offspring look like?
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Actually… they were PINK!?!?!
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Incomplete Dominance- when two homozygous parents combine, the offspring results in a blended phenotype Combining Purebred Red & White and produced Pink
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Neither allele for a trait is Dominant. The phenotype produced is mixed between the two homozygous parents. –The combining of Purebred Red & Purebred White produced PINK plants.
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What would happen if you crossed a Red horse and a White horse?
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PINK!?!?!
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Just kidding… ROAN
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Although Mendel studied peas that were controlled by two alleles, many traits can be controlled by more than two alleles…
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Multiple Alleles A trait that is controlled by Having more than two alleles is controlled by Multiple Alleles. Traits controlled by Multiple Alleles produce more than three phenotypes of that trait.
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Example (Flip to Page) Example of Multiple Alleles… Blood Types: A, B, AB, and O. –The O allele is recessive to both A and B
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Other Worksheet… Phenotype A - AA or AO Genotype Phenotype B – BB or BO Genotype Phenotype AB – AB Genotype Phenotype O – OO Genotype
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Polygenic Inheritance Polygenic Inheritance- when a group of gene pairs acts together to produce one trait. –Which creates more variety in phenotypes
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What would be an example? Many traits such as…Skin Color, Eye Color, Hair Color, and Handspan are traits produced by a combination of genes.
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Human Genes & Mutations Mutations : a permanent change in the DNA sequence A mutation can be helpful, harmful, or cause no effect.
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Mutations Chromosome disorders- caused by more or fewer chromosomes than normal Downs Syndrome- caused by an extra copy of chromosome 21
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Recessive Genetic Disorders There are human genetic disorders that are caused by Recessive Genes. How could this occur? Both parents contain the recessive allele
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Because parents are Heterozygous, they do not show any symptoms –(Called “carriers” for the trait.) Cystic Fibrosis is a homozygous recessive disorder.
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Sex-Linked Disorders An allele inherited on a sex chromosomes ( X or Y ) is called a sex-linked gene. Inherited conditions are linked with the X and Y chromosomes.
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Example- Color Blindness is a sex- linked disorder caused by recessive allele on the X chromosome.
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Where did you get your genes from?
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Pedigrees Pedigree- used to follow or trace traits through generations of a family.
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No… not the dog food…
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Section 3 III. Advances in Genetics A. Genetic Engineering- experimentations that changes the arrangement of DNA that makes up a gene.
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Types: 1. Recombinant DNA Inserting a useful section of DNA into a bacteria Example- Creating Insulin (Page 143)
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2. Gene Therapy- When a “normal allele” is placed into a virus, the virus then delivers the normal allele when it infects a specific cell. (Figure 13 Page 144) May be used to control Cystic Fibrosis and other disorders.
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3. Genetically Engineering Plants- Plants are created by genetically inserting the desired genes of one plant into another plant you want to show those genes. Also genetically engineered: ANIMALS “Cloning”
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Works Cited www.coolclips.com www.coolclips.com http://kentsimmons.uwinnipeg.ca/cm15 04/mendel.htm http://kentsimmons.uwinnipeg.ca/cm15 04/mendel.htm www.classzone.com www.classzone.com www.dkimages.com www.dkimages.com www.virtualsciencefair.org www.virtualsciencefair.org www.scienceray.com
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