Genetics – The study of inheritance

Gregor Mendel, born 1822•a monk from Austria that studied math, science, and ran the monastery's garden. •founded the scientific study of inheritance.

Mendel studied how traits (specific characteristics) like flower color or plantheight passed from parent to offspring.

Each parent plant ispure for its color.

The offspring appearpink but are no longer pure for that color.

How did the second generation get a variety of offspring?

How did the second generation get a variety of offspring?

Mendel carefully bred pea plants to observepatterns of inheritance. How could he prevent uncontrolled pollination? (like we had with our bean plants)

By removing the stamens (they makethe pollen or malesex cells of plants)he was able to knowwhat characteristicsthe pea plant had thatfertilized the pea plantthat grew the peas.

Mendel concluded that traits are passed on as distinct units called genes.Gene- The chemical genetic code (DNA)passed from parent to offspring that codes for a specific trait.

Alleles- different variations of a gene. Example= blue eyes vs. brown eyes. alleles are represented as a letterExample = b – blue eyes, B- brown eyes

The principles of dominance are based on the idea that alleles occur in pairs. You get one from mom and one from dad. Dominant alleles are expressed if one or more are present. Example:someone with BB would have brown eyes, so would someone with Bb.

Recessive Alleles are only expressed if youhave 2. Example: someone with bb would have blue eyes.Someone with Bb would have brown eyesThese principles define simple dominance.

Genotype: the type of genes someone has. There are 3 basic types of genotypes. BB = homozygous dominant

Bb = heterozygous

bb = homozygous recessive

a zygote is a fertilized egg. It has genesfrom mom’s egg and dad’s sperm.

A phenotype is the physical trait that is expressed. (this is based on the genotype)

Brown eyes is the phenotypeexpressed by _____ or ____genotypes.

Blue eyes is the phenotypeexpressed by the_____ genotype

A genetic cross involves breeding twoindividuals.The P generation is the original parents.The F1 generation is the parents offspring.filius =son filia=daughter

A punnett square is used to predict the outcome of a genetic cross.

Fill in for a cross between BB X BB B = the brown allele b = the blue allele

Fill in a cross between two blue eyed parents. = __ __X__ __

Fill in a cross between two homozygous parents.

Fill in a cross between two heterozygous parents.

Fill in a cross between one heterozygousparent and one homozygous dominantparent.

Fill in a cross between one homozygous recessive parent and one heterozygous parent.

Applying Mendel’s Principles 11.2

Probability is what the average will probablybe. It is not a guarantee. Every time an egg is fertilized, it has the same probability of inheriting certain traits regardless of how many time the parents have reproduced.

Punnett squares are mathematical modelsused to predict the probability of genotypesand phenotypes.

Does everyone with blond hair have blueeyes? Does everyone with blue eyes haveblond hair?

Section 11-3

Figure 11-10 Independent Assortment in Peas

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