Genetics part 1

Gregor Mendel

1822 Austrian monk University of

Vienna In charge of

the Garden

Parts of the plant Female part-carpel (egg) Male part-stamen-pollen (sperm)

Fertilization Produces new cell which develops into an embryo and is enclosed by

a seed Self-pollinating

Contain male and female parts Sperm cell in pollen fertilizes egg cells in flower Offspring inherit all traits of parent

True breeding Allowed to self pollinate Tall plant Green seeds

Cross Pollination Cut off male parts of one plant so it only had eggs Dusted it with pollen from a different plant

Cross Pollination

Produces seeds that had two different parents

Mendel could now cross bred plants with different parents

Terms Gene: chemical factors (sections of DNA) that

determine specific traits Trait: a specific characteristic that varies from one

individual to another. Allelle: different forms of a gene (trait)

Genotype: genetic make-up of an organism (the two alleles an

organism has inherited from each parent for a trait) Phenotype:

physical characteristics or the OBSERVABLE version of the trait

Dominant Allele for trait that will be expressed no matter what

the other allele is (A) Recessive

Allele for a trait that can only be expressed if dominant allele is ABSENT (a)

Heterozygous Dominant Organism that has two different alleles for a trait Aa

Homozygous (Dominant or Recessive) Organism that has two IDENTICAL alleles for a trait aa or AA

Punnett Square

Diagram that shows possible genotypes and phenotypes

Probablity

Punnet Square Hybrids

Offspring of crossing two parents with different versions of a trait

Ex. Tall with Short; Purple with White

Parents are the “P generation” Offspring are the “F1 generation” When two of the F1 plants are

crossed, the offspring are referred to as the “F2 generation”

Ratios What is a ratio?

A comparison between multiple objects Phenotypic ratios

Compares the number of different phenotypes for a cross

# of Dominant Phenotype : # of Recessive Phenotype

Genotypic ratios Compares the number of different genotypes for a cross 3 possibilities # of DD : # of Dd : # of dd Homozygous dominant DD Heterozygous dominant Dd Homozygous recessive dd

What are the phenotypes of the F1 generation? Probability of having a green pod? Probability of having a yellow pod?

What are the genotypes for the F1 generation?

What are the phenotypes of the F2 generation? Probability of having a green pod? Probability of having a yellow pod?

What are the genotypes for the F2 generation?

Probability Def: The likelihood of an event happening It’s a way to predict the average outcome of a

large number of events CANNOT predict the precise outcome of an event

only the LIKELIHOOD of the event Flip a coin

What is the probability of getting heads? What is the probability of getting tails? If you flip a coin 3 times…

What is the probability of getting heads? What is the probability of getting tails?

• If you flip a coin two times, does the first flip effect what you are going to get in the second flip?• No…• One event does not effect another

event’s probability

• If there is a ¼ chance of having a white plant…the chances of having another white plant when crossing the plants again is still ¼

• What are the chances of having 2 white plants after two fertilizations?

• ¼ x ¼ = 1/16

Things to keep in mind… Probability predicts the

AVERAGE outcome of a LARGE number of events

Cannot predict a precise outcome

The larger the number of events the closer you will be to getting the expected results