Gregor Mendel Principles unit 4

Monophonic crossing experiments

Gregor Mendel’s ____ ____ ____ produces the results that turned the principles of genetic science

He Developed The ____ ____ ____ To Investigate The Rules That Govern The Transmission Of One Trait From Parent To Offspring

• He Replicated Each Monohybrid

Crossing Experiments Many Times

• This Increased The Probability Of Detecting Significant Patterns In The Results

Monohybrid crossing experiment

Parents With One Different Trait Are Mated (Crossed)

• Each Parent Breeds True For The Trait Of Interest

• The Ratio Of The Two Traits In The F1 Offspring Is Determined

• The F1 Offspring Are Mated

With Each Other

• The Ratio Of The Two Traits

In The F2 Offspring Is Determined

Mix

The Two Different Traits Inherited From Each Parent Do Not ___ In Offspring

• each parent transmits one unit of heredity (allele) to their offspring

2 alleles

A diploid (2N) individual has ___ _____ for the gene that regulates the flower color trait

• Offspring Inherit One Allele From Each Parent

• This Explanation Accounts For The 3:1 Ratio Of Purple Flowers To White Flowers Mendel Observed In The F2 Generation Of Offspring

One

Each parent transmits ____ of the 2 alleles for each gene to their offspring

• Meiotic Cell Division Enables Diploid (2N) Individuals To Produce Haploid (1N) Gametes

• Each Haploid Gamete (1N) Has One Copy Of Each Chromosome And Consequently One Allele For Each Gene

Law of segregation

Gregor Mendel’s ____ ____ _____ :

• The 2 alleles that control a train separate during meiosis and each allele enters a different gamete

Gregor Mendel Documented The Existence Of Dominant Phenotypes & Recessive Phenotypes

• In Some Heterozygotes, Only One Of

The Two Alleles For A Gene Is

Expressed In The Phenotype

• The Expressed Allele Causes A

Dominant Phenotype (Dominant Trait)

• The Unexpressed (Hidden) Allele

Causes A Recessive Phenotype

(Recessive Trait)

This Conclusion Is Based On The

Observation That All Heterozygotes In The F1 Monohybrid (Pp) Generation Always Expressed The Purple Flower Phenotype

Recessive trait (read the pic)

A ____ ___ That Remains Hidden In The F1

Generation Can Reappear In The F2 Generation

Test cross experiment

• Determines the genotype of individuals with a dominant phenotype

• The ____ ____ mates the individual expressing the dominant phenotype with an individual expressing the recessive phenotype

• The parent with the homozygous recessive genotype (pp) always produces gametes with the recessive allele (p)

Achondroplasia

The genetics of _______: The “a” allele causes the recessive wild-type phenotype the mutated “A” allele causes it he dominant reduced height phenotype

Achondroplasia

______ is due to a mutation in the fibroblast growth factor receptor 3 gene that reduces bone growth

Homozygous lethal genotype

If there is a homozygous dominant genotype it will self destruct because that cannot exist in human populations

More on achondroplasia

• Some parents with The Homozygous Recessive Genotype (aa) Have A Child With Achondroplasia (Aa)

• This is caused from a mutation in the recessive genotype that turns it into a Heterozygous dominant genotype