Chapter 11 Note-Taking WorksheetBiology I

Gregor Mendel• Mendel was one of the first scientists to study ___________, the scientific study

of heredity.• Mendel carried out his research with ordinary garden __________ plants.• Peas are ____________________________, which means that sperm cells in

pollen fertilize the egg cells in the same flower.• This process is called ____________________.• Mendel used _______________________ pea plants as the basis of his

experiments.• Mendel wanted to produce seeds by joining the sperm and egg from different

plants.• In order to prevent self-pollination, Mendel cut away the pollen bearing male

parts and dusted pollen from another plant onto the flower.• This process is called _________________________.• Mendel studied seven different pea plant traits.• A _______________ is a specific characteristic such as seed color or plant height.

Parental (P) Cross• Mendel crossed two plants with contrasting traits, a tall plant with a short plant.• This initial pair is called the Parental _______ generation. • The offspring produced are called the First Filial ________ generation. • The offspring of crosses between parents with different traits are called

________________.• The results of the cross produced all tall pea plants.

F1 Cross• Mendel drew 2 conclusions from the results.

1. Biological inheritance is determined by factors that are passed from one generation to the next.– These factors are _______________.

2. Mendel’s principle of ____________________ which states that some alleles are dominant and others are recessive.

• Mendel wanted to find out if the short gene disappeared or was it hidden. • Mendel self-pollinated the F1 generation to produce a F2 generation. • The results produced ______ tall plants for every _______ short plant.

Explanation of the F1 Cross• Mendel assumed the dominant allele masked the recessive allele.• The reappearance of the recessive allele in the F2 generation indicated the allele

for shortness separated, or segregated, from the tall allele.• Mendel assumed this happened during the formation of the gametes. • The alleles segregate and each gamete contains only one allele.

Genetic Terms ______________- prevents the expression of the recessive genes

o Represented by capital letters T ______________- masked by the dominant trait

o Represented by a lower case letter t ______________- two genes that are the same: TT, tt ______________- two genes that are different: Tt ______________- actual genes of an organism: TT, Tt, tt ______________- physical appearance of an organism: Tall, Short

_______________- the likelihood that an event will occur: 50:50 chance of getting heads or tails

Punnett Square• A diagram that can show the gene

combinations from a genetic cross.• Organisms that have identical alleles for a trait are called ___________________.• Organisms that have two different alleles for the same trait are _______________.• Physical characteristics are called ______________________.• Genetic characteristics are called _______________________.• ______________________ traits are represented by capital letters, while

______________________ traits are represented by lower case letters.

Probabilities Predict Averages• ________________________ can not predict the precise outcome of an

individual event. • However, they can predict the __________________ outcome of a large event. • The same holds true for genetics.• The larger the number of offspring, the closer the resulting numbers will get to the

predicted values.

Independent Assortment in Peas The principle of ______________ ______________ states that genes for different

traits can segregate independently during the formation of ____________. Independent assortment helps account for the many genetic ______________

observed in plants, animals and other organisms.

Incomplete Dominance

______________ ______________ occurs when one allele is not completely dominant over another. They both contribute to the phenotype ______________.

Codominance• A situation where both alleles contribute to the ______________________. • Example:

– Certain chickens with black feathers crossed with a chicken with white feathers produces an offspring with both black and white feathers.

Other Examples RR = red cow hairs RW = red and white cow hairs WW = white cow hairs

Multiple Alleles• Genes that have more than _______________ alleles for a trait.

Ex:- Human hair color- Animal fur- Blood types- Human eye color

Polygenic Traits• Traits that are controlled by __________ or more genes.• Example:

– Human skin colorsSex-Linked Genes

• Sex linked genes are found on the __________________ chromosomes (X or Y).• Example – Colorblindness

- Colorblindness is a gene that is found on the X chromosome