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Chapter #26

Chapter #26. Inheritance of Traits. Chapter 26.1 Notes. Genetics is the study of how traits are passed from parents to offspring. Body cells have 2 of each chromosome. Sex cells have 1 of each chromosome (sperm and egg).

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Chapter #26

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  1. Chapter #26 Inheritance of Traits

  2. Chapter 26.1 Notes • Genetics is the study of how traits are passed from parents to offspring. • Body cells have 2 of each chromosome. • Sex cells have 1 of each chromosome (sperm and egg). • Gene is a small section of chromosome that determines a trait. Example eye color, hair color, ear shape.

  3. Human TraitsTongue rolling- dominantWidow’s peak- dominantFree ear lobe- dominantAttached ear lobe- recessiveHitch-hiker’s thumb- recessiveBent little finger- dominant

  4. Dominant genes that keep other genes from showing their traits. • Pure dominant or homozygous dominant (FF) has 2 dominant (BIG) genes. • Pure recessiveor homozygous recessive (ff) has 2 recessive (lower case) gene • Heterozygous (Ff) 1 dominant gene and 1 recessive gene.

  5. Chapter 26.2 Notes • Punnett square is a way to show which genes can combine. • Gregor Mendel- 1865 Austrian monk who studied the genetics of pea plants “The father of Genetics”.

  6. Genotype is the actual genetic make up of an organism…the letters (TT, Tt, tt) • Phenotype is what the organism look like (TT=tall, Tt=tall, tt= short) • Monohybrid cross only 1 trait at a time is crossed (4 squares)

  7. Example • In pea plants tall height is dominant to short height. If you cross a pure recessive short plant and a heterozygous tall plant what are the genotype and phenotype???

  8. In pea plants tall height is dominant to short height. If you cross a pure recessive short plant and a heterozygous tall plant what are the genotype and phenotype??? • Step #1, write the key for the letters. • T= tall • t= short

  9. In pea plants tall height is dominant to short height. If you cross a pure recessive short plant and a heterozygoustall plant what are the genotype and phenotype???Step #2, figure out each parents letters • T= tall • t= short • Parent #1 tt • Parent #2Tt

  10. In pea plants tall height is dominant to short height. If you cross a pure recessive short plant and a heterozygoustall plant what are the genotype and phenotype???Step #3, Draw the punnett square t t T= Tall t= short Tt T Tt t tt tt

  11. In pea plants tall height is dominant to short height. If you cross a pure recessive short plant and a heterozygoustall plant what are the genotype and phenotype???Step #4, Figure out the geno and phenotypes Genotype Tt=2 and tt=2 Phenotype Tall=2 and short =2 t t T= Tall t= short T Tt Tt t tt tt

  12. Dihybrid cross is when 2 traits are crossed at the same time (16 squares) • Example in pea plant round and yellow seeds are dominant over wrinkled and green seeds. If a pure dominant round, yellow seed plant is crossed with a pure recessive wrinkled, green seed plant are crossed what are the geno and phenotype?

  13. Work Cited “Mouse Genes”. April 18, 2007. http://www.uga.edu/srel/kidsdoscience/images/genetics-puppets.gif “Cartoon”. April 18, 2007. http://www.cartoonstock.com/newscartoons/cartoonists/bgr/lowres/bgrn968l.jpg “Mendel”. April 19, 2007. http://www.micro.utexas.edu/courses/levin/bio304/genetics/mendel.gif “Mendel Cartoon”. April 19, 2007. http://eebweb.arizona.edu/courses/ecol320/Mendel'sPeaSoupSmall.jpg “Punnett square”. April 19, 2007. http://www.usd.edu/med/som/genetics/curriculum/fig1-13.JPG

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