Genetics Unit

• On one page of your notebook, create a vocabulary sheet. Throughout these notes, write any red vocabulary words and their definitions on this page.

Vocabulary Word Definition:1.

2.

Gregor Mendel

• Austrian Monk• Studied pea plants

Mendel’s Crossbreeding

Trait DominantAllele

Recessive Allele

Seed Shape Round WrinkledSeed Color Yellow GreenSeed Coat Color

Gray White

Pod Shape Smooth ConstrictedPod Color Green YellowFlower Position Axial TerminalPlant Height Tall Short

Trait DominantAllele

Recessive Allele

Traits Alleles

InheritanceGregor Mendel – “Father of Genetics”

• Experimented with pea plants in 1850’s to show basic patterns of inheritance Seed Shape (round or wrinkled) Seed Color (yellow or green) Seed Coat color (gray or white) Pod Shape (smooth or constricted) Pod Color (green or yellow) Flower Position (axial or terminal) Plant Height (tall or short)

InheritanceGregor Mendel – “Father of Genetics”

• Did experiments with pea plants in mid-late 1800’s to show basic patterns of inheritance Seed Shape (round or wrinkled) Seed Color (yellow or green) Seed Coat color (gray or white) Pod Shape (smooth or constricted) Pod Color (green or yellow) Flower Position (axial or terminal) Plant Height (tall or short)

Found that when two plants with different alleles are crossed, the offspring look like one of the parents, rather than a blending of both parents.

Principle of DominanceSome alleles are dominant and others are recessive

Dominant Alleles

Recessive Alleles

Traits Alleles

InheritanceGregor Mendel – “Father of Genetics”

• Did experiments with pea plants in mid-late 1800’s to show basic patterns of inheritance Seed Shape (round or wrinkled) Seed Color (yellow or green) Seed Coat color (gray or white) Pod Shape (smooth or constricted) Pod Color (green or yellow) Flower Position (axial or terminal) Plant Height (tall or short)

Found that when two plants with different alleles are crossed, the offspring look like one of the parents, rather than a blending of both parents.

Principle of DominanceSome alleles are dominant and others are recessive

Dominant Alleles

Recessive Alleles

Inheritance: the passing of traitsfrom parents to offspring

Gregor Mendel – “Father of Genetics”• Phenotype - The observable physical characteristic of a trait• Genotype - The genetic combination of alleles for a trait• Punnett Square – tool used to predict probability of phenotype

Notice that letters are used to represent the alleles (usually correspond to the dominant phenotype – e.g. “P” for purple)

Upper Case Letters = Dominant Allele

Lower Case Letters = Recessive Allele

Phenotype: WhiteGenotype: pp

Phenotype: PurpleGenotype: PP

Practice

• Overview of genes to traits video• Copy the 3 questions below:• What do they mean when the say “you have

your father’s hair”?• How many chromosomes do organisms

have?• How much DNA do we have in common

with other animals?

• Complete the Phenotype Survey and write the results in your notebook.

InheritanceGregor Mendel – “Father of Genetics”

• Found that alleles show up in predictable patterns and that some alleles show up more often than others

• Homozygous (Pure-Breeds) - both alleles are the same• Heterozygous (Hybrids) - both alleles are different• Carriers – heterozygotes for a recessive trait

Pure-Breed Crosses result in: 100% chance dominant phenotype

Hybrid Crosses result in: 75% chance dominant phenotype25% chance recessive phenotype

InheritanceGregor Mendel – “Father of Genetics”

• Found that alleles show up in predictable patterns and that some alleles show up more often than others

• Alleles can be tracked through multiple generations and probabilities determined

First Generation: First Filial (F1)100% chance dominant phenotype

Second Generation: Second Filial (F2)75% chance dominant phenotype

Third Generation: Third Filial (F3)63% chance dominant phenotype

100% chance 75% chance 75% chance 0% chance

Parents: P1 generation

Practice

• Video on making punnett squares• In your notebook complete the Probability

(Long vs Short Big Toe) Lab.

Linked genes (genes that occur very close to one another on a chromosome) are the exception

Write these 4 ideas from Mendel in your notebook

Summary of Mendel’s PrinciplesGregor Mendel’s work forms the basis of modern genetics:• Genes are passed from parent to offspring• Some forms of genes (alleles) are dominant while others are recessive• Genes randomly segregate (independent assortment) when gametes are formed• The alleles for different genes usually segregate independently of one another