Introduction to Introduction to GeneticsGenetics

https://www.23andme.com/gen101/genes/

The work of The work of Gregor MendelGregor MendelAustrian monk Austrian monk

who is the father who is the father of Geneticsof GeneticsGenetics – the Genetics – the scientific study scientific study of heredityof heredity

Fertilization – when male and female Fertilization – when male and female reproductive cells joinreproductive cells joinMale – pollen or Male – pollen or spermsperm

Female – eggsFemale – eggsGameteGamete – the – the individual egg or individual egg or spermsperm

Seed/Zygote – Seed/Zygote – fertilized eggfertilized egg

True-breeding – if they True-breeding – if they were allowed to self-breed were allowed to self-breed they would have identical they would have identical offspringoffspringSelf-breeding – Sperm Self-breeding – Sperm and egg from the same and egg from the same flower fertilizeflower fertilize

Cross-pollinationCross-pollinationMendel took sperm Mendel took sperm from one true breeding from one true breeding plant and fertilized plant and fertilized eggs from other true eggs from other true breeding plantsbreeding plants

Genes and DominanceGenes and Dominance7 Traits7 Traits – a specific characteristic – a specific characteristic (examples: seed color, plant height, (examples: seed color, plant height, flower color, seed shape, etc…)flower color, seed shape, etc…)

GenesGenes – – chemical chemical factors that factors that determine determine traits (Hair traits (Hair color)color)

AllelesAlleles – – different forms different forms of traits of traits (Brown hair, (Brown hair, blue eyes)blue eyes)

SymbolsSymbols Dominant AllelesDominant Alleles

Capital LettersCapital Letters Recessive Recessive

AllelesAlleles Lower Case Lower Case

LettersLetters

HeterozygousHeterozygousHeterozygous (different)Heterozygous (different)

Gene pairs that carry one dominant and Gene pairs that carry one dominant and one recessive alleleone recessive allele

Aa, Bb, Cc, DdAa, Bb, Cc, Dd

HomozygousHomozygousHomozygous (same)Homozygous (same)

Gene pairs that carry 2 dominant OR 2 Gene pairs that carry 2 dominant OR 2 recessive allelesrecessive alleles

AA, aa, BB, bbAA, aa, BB, bb

PhenotypePhenotype Physical Physical characteristicscharacteristicsTall or shortTall or short

GenotypeGenotypeGenetic Genetic makeupmakeupGG, Gg, or GG, Gg, or gggg

Hybrids & PurebredsHybrids & PurebredsHybrids receive different alleles from Hybrids receive different alleles from

each parent (Hh, Bb, Zz)each parent (Hh, Bb, Zz)Purebreds receive the same alleles from Purebreds receive the same alleles from

each parent (HH, bb, ZZ)each parent (HH, bb, ZZ)

Law of DominanceLaw of Dominance – some – some alleles are dominant and alleles are dominant and other are recessiveother are recessiveDominant traits Dominant traits will always show will always show over recessive over recessive traitstraits

Law of Law of SegregationSegregationTwo alleles Two alleles separate separate when when gametes are gametes are formedformed

Did I get my genes from Grandpa or

Grandma?

Law of Law of Independent Independent AssortmentAssortmentGene pairs Gene pairs

separate randomly separate randomly and independently and independently from each other from each other during meiosisduring meiosis

Independent Independent assortment helps assortment helps account for the account for the many genetic many genetic variations observed variations observed in plants, animals, in plants, animals, and other and other organisms.organisms.

Probability and Probability and Punnett SquarePunnett Square

ProbabilityProbability – the – the likelihood that a likelihood that a particular event particular event will occurwill occur

Past outcomes do Past outcomes do not affect future not affect future outcomesoutcomes

Probabilities Probabilities predict predict averages, not averages, not exact outcomesexact outcomesProbability is Probability is more accurate more accurate when you have when you have more chancesmore chances