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Bellwork: 4/2

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  1. Bellwork: 4/2 Put your phone up  Week 4/1 - 4/5 Have you ever done Punnett squares before? What is a gene? Allele? Give an example of a gene & its possible alleles.

  2. Today: • Bellwork • Part 2 Notes

  3. Materials • Unit Book

  4. This Week: • Mon/Wed*: Meiosis Model & Video • Tuesday: Part 2 Notes • Thurs/Fri*: Mendelian Traits Activity & Video

  5. Next Week: • Monday: PS Practice & Assign Project • Tues/Wed: Quiz, Sample Project, Pt. 3 Notes • Thursday: Dihybrid Practice & Pt. 4 Notes • Friday: Blood Type Practice & Pt. 5 Notes

  6. Homework • Meiosis Poster due… • 4th & 6th – Thursday • 5th & 7th - Friday

  7. Unit VI: Mendelian Genetics

  8. Part II: Monohybrid Crosses

  9. Objective ?s • What patterns of inheritance are observed across generations? • How do the combination of chromosomes received from each of our parents affect our body’s appearance and function?

  10. Vocab • Gene– a nucleotide sequence of DNA that encodes a protein • Example: Height • Allele– alternative forms of a gene (each individual has two alleles) • Example: Tall, short…

  11. Vocab • Dominant– overpowering trait • when dominant alleles are present, the organism will always exhibit that trait • Recessive– weaker trait • organisms will only exhibit recessive traits when the dominant allele is NOT present

  12. Vocab • Dominant– CAPITAL LETTER • Recessive– lowercase letter

  13. Vocab • Homozygous – having identical alleles for the trait • Homozygous Dominant = TT • Homozygous Recessive = tt • Heterozygous – having two different alleles for the trait • Tt

  14. Vocab • Phenotype– an organism’s expressed physical traits – the one you observe • Example: tall • Genotype – an organisms genetic makeup; the combination of alleles in the homologous chromosomes • Example: height – TT, Tt, tt

  15. Heredity Pre- Mendelian • Blending theory – heredity material from each parent blends in the offspring • Once blended, it is inseparable (cannot return to traits of parents • Example: red flowers crossed with white flowers create pink flowers

  16. Gregor Mendel • Austrian Monk • Studied science & mathematics at University of Vienna • While doing his genetic research he was a substitute natural science teacher at a local high school • Developed 2 laws of inheritance • Biological organism: garden peas

  17. Think! Why would Mendel choose to study peas?

  18. Why Garden Peas? • Detectable traits • Mendel chose seven features to examine • Easy to grow • Short life cycle

  19. Why Garden Peas? • Mating easy to control • Flowers contain both male & female reproductive organs • Allowed for both… • Self-fertilization– pollen fertilizes egg from same plant • Cross-pollination– pollen fertilizes egg from different plant

  20. Think! What would the difference between the self-fertilized offspring & the cross-pollinated offspring be?

  21. Mendel’s Laws of Inheritance • Developed 2 laws of inheritance: • Law of Segregation • Followed single trait (monohybrid cross) • Law of Independent Assortment • Followed two traits (dihybrid cross)

  22. Law of Segregation • Each individual has two alleles for each trait that separate during the formation of gametes • Alleles reside on homologous chromosomes • Gametes (haploid) contain only one allele • Fertilization brings two gametes together returning the 2 alleles to the offspring

  23. Purpose of Punnett Square • Examines the probability of getting a particular phenotype based on combination of gametes • Each square in a monohybrid cross represents 25% chance or ¼ probability

  24. Punnett Square Problem • Cross two guinea pigs Ff x ff F= short fur f=long fur Probability of long fur offspring? • Monohybrid Crosses– looking at a single trait • Identify genotype of parents • Determine possible gametes for each parent • Set up Punnett Square • Fill in square by combining allele from sperm and egg • Address question the problem asked

  25. Sample Problem • A plant that is homozygous recessive for shortness is crossed with a heterozygous tall plant. Using a monohybrid Punnett square, show what the offspring will look like. • List the phenotypes & their probabilities. • List the genotypes & their probabilities.

  26. Sample Problem • Tim & Jan both have freckles, a dominant trait (F) but their son Michael does not. Use a punnett square to show how this is possible. • List the phenotypes & their probabilities • List the genotypes & their probabilities

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