New version page

MSU ZOL 141 - Mendel

This preview shows page 1 out of 3 pages.

View Full Document
View Full Document

End of preview. Want to read all 3 pages?

Upload your study docs or become a GradeBuddy member to access this document.

View Full Document
Unformatted text preview:

ZOL 141 1st Edition Lecture 9Outline of Last Lecture II. Meiosis: New Gene CombinationsA. Random assortmentB. Crossing overI.Formation of Gametesa.Malesb.FemalesOutline of Current Lecture III. Gregor Johann MendelA. Study of single traitsB. Experimental setupC. ConclusionsD. Mendel’s first lawCurrent LectureTransmission of Genes from Generation to Generation—Chapter 3Gregor Johann Mendel (1822-1884)- Grew up on family’s farm in Austria- Had aptitude for learning- Studied to be monk at St. Thomas Monestary in 1843- 1851 sent to University of Vienna to continue studying science, studied with Frans Unger, Christian Doppler- 1853 returned to Monastery and experimented with pea plants that have shaped modern understanding of trait inheritanceMendel’s Study of Single Traits- Does each parent contribute equally to traits of offspring?o Female gametes are often larger than male gametes- Do traits in offspring result from a blending of parental traits or are the inherited as discrete units?- Experimental setupo Selecting a model organism Distinct traits that can be studied Self-fertilizing Offspring should be fertileo Common pea plant: Many varieties with different traits available Self or artificially fertilized, fertile offspring Short life cycle and easily maintainedo Preparing for study: Chose 7 traits that had two variations True-breeding (two years) Large-scale experiments: >28000 pea plantso Mendel’s Study of Single traits: experiments and results P1: parental, smoothxwrinkled F1: filial, smooth Only one of the parental traits was present in the F1 plants Did not matter which trait was present in the plant that contributed the pollen, results were the same DIAGRAM Mendel’s conclusions- Traits are not blendedo They remain unchanged even though they may not be expressed- Each parent makes an equal contribution to genetic makeup of the offspring Self fertilized F1 plants (monohybrid cross) to determine if wrinkled trait was hidden in them still- F2: second filial generation, 3:1 ratiosmooth:wrinkled- Trait not present in F1 plants reappeared in 25% of F2 plants More conclusions- Traits are determined by genes (factors)o Alternative forms of genes are called alleles- Genes can be present but not expressedo Dominant trait is expressed in F1o Recessive trait not expressed in F1 but reappears in some F2 plants- Plants with smooth peas in P1 and F1 are genetically distincto Knew this because self cross of P1 was smootho Phenotype describes observable properties of an organismo Genotype describes specific genetic constitution of an organism- Each plant carries two genes for a given traito In case of F1 plant it must carry one allele for smooth pea shape and one allele for wrinkled shapeo Uppercase=dominanto Lowercase=recessiveo S=smooth, s=wrinkled- Members of gene pair must segregate during gamete formationo Principle of segregation: Mendel’s first law- Mendel’s first lawo Equal chance either allele, alleles reunite randomlyo Homozygous: having identical alleles for one or more geneso Heterozygous: having two different alleles for one or more geneso Punnett square: allows you to predict the genotypes of the offspring that result from a particular


View Full Document
Loading Unlocking...
Login

Join to view Mendel and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Mendel and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?