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.

Today: Bellwork Part 2 Notes

Materials Unit Book

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

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

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

Unit VI: Mendelian Genetics

Part II: Monohybrid Crosses

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?

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…

Vocab Dominant – overpowering trait Recessive – weaker 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

Vocab Dominant – CAPITAL LETTER Recessive – lowercase letter

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

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

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

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

Think! Why would Mendel choose to study peas?

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

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

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

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)

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

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

Punnett Square Problem 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 Cross two guinea pigs Ff x ff F= short fur f=long fur Probability of long fur offspring?

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.

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