Unit 4 Biology

Blending Inheritance Theory

The outcome will be predictable depdning on parent’s phenotype

• not reliable due to genotype, and the presence of recessive genes

Gregor Mendel

• looked at traits of flower petals- color

• made conclusions about genetics

• crossed seperate generations against themselves, and over again

  • crossed true breeders

  • when crossing those offspring, found differing results in phenotype, disproving the blending inheritance theory.

    • these purple flowers weren’t true breeders (F1)

True breeders

• homozygous organisms

• when crossed, while always produce the same phenotype and genotype

Segregation of Alternate Factors

Mendel’s First Law

alternate factors- genes

• summarizes meiosis, saying that fertilazitions added a genes to create pairs

• unparied genes- segregated in haploid

P generation

• crossing of true breeders

F1 generation

• crossed the heterozyous purple flower, a result of P

F2

the result of F1

• ratio of 3:1

• genotypic ration of 1:2:1

Factors

• genes, seperated in gametogenisis/reconnected in meiois

Phenotype

• characteristic that is physically represented in offspring

Allele

• different form of a gene

• dominant or recessive

Locus

the location of a gene on the chromosome

Dominant allele

• version of gene that is superior over the other

• only need one present in the gene pair to display its phenotype

• upper case

Recessive Allele

• version of a gene that is inferior

• need two instances of its allele in a gene to be phenotypically expressed

• lowercase

Heterozyous gene

• two alleles in a pair that are not the same

• expresses the dominant allele

Homozygous gene

• two versions of alleles that are identical

• either dominant or recessive

Probablity

• the frequency of a certain genotypic outcome during meiosis

• dependent on parent genes, and visualizes with the punnet square

Single Trait cross

• gametes that are crossed with one trait- two alleles x two alles

• analzye the ratio of possible resulting genotypes (out of 4)

Independent Assortment

Mendels 2nd Law

• looks at two different traits

• FOILing of genes

• Linked v. Unliked

  • Unliked genes, 4 chromosomes that don’t influence eacher in FOILING

  • 4×4 possibly genotypes

Double Cross Genes

P Reation 9:3:3:1

• genotypic hybrids

G Ratios:1:1:1:1:2;2:2:2:4

Test Crosses

• confirm genotypes

  • heterozygoud or homozygous?

Linked vs. Unlinked Genes

• dependent on location

• the closer a gene is to another, the higher the linakge

  • less likely to spit apart during crossing over

Genetic Maps

• used the concept of linked genes to map out different locus'

• if genes were harder to seperate, they were confirmed to be closer

• recombination and cytological

  • recomb. is relative, cytological is exact

• linked genes makes independent assortment disfunctional

  • have to be on two different types of chromosome pairs

    • should be the assumption