Genetics: design a species (dragon) http://biologycorner Create a baby http://www.biologycorner.com/worksheets/variations_on_a_human_face.html Lots of lesson plans http://www.biologycorner.com/lesson-plans/genetics/ Mouse cloning lab http://learn.genetics.utah.edu/content/cloning/clickandclone/

Welcome Back!!  TEACHER DESK FRONT DOOR

GENETICS: WHAT MAKES YOU, YOU? BIOLOGY

GENETICS?

Genetics Heredity/Inheritance: Characteristics are passed from parent to offspring Trait: A specific, observable characteristic of an individual Hybrids: Offspring of crosses between parents with different traits Where did YOU get your looks? Use definitions to prompt definitions before you show the sentence

Gregor Mendel Austrian monk, took care of garden Worked with pea plants (Why?) Fertilization (sexual reproduction to create a new cell) Wanted to see why some pea plants were tall, short, purple, white, etc. Pea plants are small, easy to grow, reproduce quickly

Gregor Mendel To learn how these traits were determined, Mendel “crossed” diff. pure-bred plants Made hybrids 7 different traits

Aa (gene) A (allele)=black hair a (allele)=blonde hair Genes & Alleles Gene: Parts of DNA that get passed from parent to offspring Alleles: A different form of a gene Example: The gene for hair color has two alleles: Blonde and black. Aa (gene) A (allele)=black hair a (allele)=blonde hair Allele = option

Principal of Dominance Principal of Dominance: Some alleles are dominant and others are recessive Someone with at least ONE dominant allele for a particular form of a trait will exhibit that form of the trait. An organism with a recessive allele for a particular form of a trait will only exhibit that form when the dominant allele for the trait is not present. In Mendel’s exp, the allele for tall was dominant, the allele for yellow was dominant over recessive.

An Inventory of My Traits! How unique is a person’s combinations of alleles?

Why are some people left handed??

https://www.youtube.com/watch?v=TGLYcYCm2FM What determines handedness?

Take out your definitions outline Notebook for warm up

Warm Up What is the difference between a trait and a gene? Gene versus allele? Dominant versus recessive?

Homozygous versus Heterozygous Organisms that have identical alleles for a particular gene: Homozygous (ex. TT) Organisms that have different alleles for a particular gene: Heterozygous (ex. Tt)

Phenotype VS Genotype! Phenotype: physical traits Genotype: genetic make up Plants: TT, Tt, tt. How many phenotypes? How many genotypes? Two phenotypes, 3 genotypes Tt, or TT tt

Alleles for each gene segregate from each other so that each gamete only cares one allele for each gene. Alleles separate during gamete formation and then pair up again in the F2 generation. Reccessive trait for height reappears later.

Segregation Alleles for each gene segregate from each other so that each gamete only carries one allele for each gene Alleles separate during gamete formation and then pair up again in the F2 generation. **Recessive traits can reappear in F2** The trait controlled by the recessive allele showed up in some of the F2 plants. So at some point the allele for shortness had separated from the allele for tallness. Alleles for tallness and shortness in the F1 plants must have segregated from each other during the formation of sex cells (gametes).

Using Probability If you crossed a TT plant with a Tt plant, would its offspring be tall or short? If you crossed a Tt plant with a tt plant, what percentage of offspring would be tall? What percentage would be short?

Predictions: Using Punnett Squares Punnett squares use probability to predict genotype & phenotype combinations in genetic crosses. You begin with a square. Then following the principle of segregation, all possible combinations of alleles in the gametes produced by one parent are written along the top edge of the square. The other parent’s alleles are then segregated along the left edge. Then write genotype possibilities for the F2 generation in the boxes.

Practice An F1 rabbit that is homozygous for long ears is crossed with a heterozygous rabbit. What is the probability that the cross will produce a rabbit with long ears? Use a punnett square to explain! 100%

Independent Assortment How do alleles segregate when more than one gene is involved? Dihybrid vs monohybrid cross Two different genes? Dihybrid. Single gene? Monohybrid. He wanted to see whether genes segregate independently. In F2, he found that some seeds had a combination of phenotypes not found in parents, so alleles for seed shape segregated independently from seed color. 9:3:3:1. Determine what alleles can be found in all of the possible gametes that each parent can produce.

Practice Let’s cross two pea plants that are heterozygous for size (tall & short alleles) and pea color (green & yellow alleles). The genotypes of the two parents are: TtGg and TtGg What is the ratio of tall to short phenotypes? Green to yellow phenotypes?

Review… In dragons, the allele for red scales is dominant over the allele for green scales. The male dragon has red scales. How can you determine the genotype of the red dragon?

Practice In a certain breed of dogs, yellow fur is dominant over brown fur. A heterozygous male has offspring with a homozygous recessive female. What percentage of offspring will be heterozygous? What percentage of offspring will be yellow? Brown?

Calculating Probabilities The ratio of dominant to recessive phenotypes in a monohybrid cross is 3:1 3/4 chance of showing dominant phenotype 1/4 chance of showing recessive phenotype

Welcome Back! 1. Take out your Monster Genetics assignment 2. Take out notebook for warm up

Warm Up -Assume big size in dogs is dominant and small is recessive. Two dogs are crossed; one is heterozygous for size, and the other is homozygous recessive for size. -What fraction of the offspring are big? What fraction are small?

Warm Up Brown eyes (B) are dominant over blue (b). A brown-eyed man and a blue-eyed woman have 3 children: two of whom have brown eyes, and one of whom has blue eyes. Draw the Punnett square. What is the man’s genotype? What are the genotypes of the children?

Is it possible for a red flower and a white flower to reproduce pink flowers?

Other Patterns of Inheritance Incomplete Dominance: When one allele is not completely dominant over another. Codominance: When phenotypes produced by both alleles are clearly expressed. Can red plus white = pink??

Incomplete Dominance / Codominance

Examples?? Heterozygous is in-between for incomplete dominance

What’s Due Punnett Square Practice due NEXT CLASS Bring ipads/laptops Bring colored pencils or any sketching pens

https://www.youtube.com/watch?v=Mehz7tCxjSE