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DO NOW: Quietly…….. Take a poll of how many of you have the following traits: - brown hair -blonde hair -red hair - black hair - blue/green eyes -brown eyes GENETICS MAIN IDEA………… Parent Traits Parent Traits Offsprings Traits ALIEN ACTIVITY http://www2.edc.org/weblabs/BabyBoom/babyBoo m.html WHAT IS GENETICS??? Genetics is the scientific study of heredity. Heredity is what makes each species unique. KEY VOCABULARY Dominant: inherited characteristic that appear in an organism Represented with capital letter. Ex: B, X, R Recessive: inherited characteristics often masked Represented with lowercase letter. Ex: b, x, r EXAMPLE: Dominate Brown Eyes: B Recessive Blue Eyes: b Phenotype: physical traits that appear in an individual as a result of its genetic make-up How to remember……. Phenotype= Physical Ex: brown eyes, blonde hair Genotype: genetic Make Up of an individual How to remember…. GENotype= GENEtic Ex: B- brown eyes b- blue eyes Homozygous Heterozygous having two identical alleles having two different alleles for a trait Ex: BB or bb Ex: Bb PHENOTYPE VS. GENOTYPE A little girl has blue eyes Genotype bb Phenotype Blue Eyes Allele different forms of a gene for a specific trait 2 for each trait CHROMOSOME FOR FLOWER COLOR ALLELE Could code for a PURPLE flower Could code for a WHITE flower MAIN IDEA………… Parent Traits Parent Traits Offsprings Traits HISTORY FATHER OF GENETICS: MENDEL HISTORY GREGOR MENDEL Austrian Monk Famous for his work with pea plants He is known as the father of genetics WHY did he work with pea plants? They weren’t messy Rapid results Many generation MENDEL MENDEL’S WORK Mendel used true-breeding plants True Breeding: When bred with themselves they would produce identical offsprings. He studied 7 different traits in pea plants. Trait: is a specific characteristic that can vary from one individual to another. MORE ON MENDEL’S WORK Hybrids are offspring from parents with different traits. Genes are the chemical factors that determine a trait. MENDEL’S EXPERIMENTS: 3 PRINCIPLES 1. 2. 3. Principle of Dominance Segregation Independent Assortment PRINCIPLE 1: THE PRINCIPLE OF DOMINANCE States that some alleles are dominant and others are recessive. Dominant alleles are always expressed. Recessive alleles are only expressed if both alleles are recessive. PRINCIPLE 2: SEGREGATION The two alleles for a trait separate HELP…… Segregate means to separate Happens during meiosis form gametes (sex cells) PRINCIPLE 3: INDEPENDENT ASSORTMENT states that genes for different traits separate independently during the formation of gametes. EX: the color of the flower has nothing to do with the length They separate INDEPENDENTLY LAWS OF INHERITANCE SUMMARIZE MENDEL’S PRINCIPLES The inheritance of biological characteristics are determined by genes. For two or more forms of a gene, dominance and recessive forms may exist Most sexually reproductive organisms have two sets of genes that separate during gamete formation (Principle #1). (Principle #2). Alleles segregate independently (Principle #3). MAIN IDEA………… Parent Traits Parent Traits Offsprings Traits PROBABILITY AND PUNNETT SQUARES PROBABILITY & GENETICS Probability is the likelihood that an event will happen. The principle of probability can be used to predict the outcomes of genetic crosses. PUNNETT SQUARES Diagram used to predict genetic crosses. REVIEW: Homozygous individuals with identical alleles Heterozygous individuals with different alleles are called Phenotype physical characteristic Genotype genetic makeup HOW TO USE PUNNETT SQUARES…… 1. 2. 3. 4. 5. 6. Choose a letter to represent the alleles in the cross. Write the genotypes of the parents. Enter the possible gamete at the top and side of the Punnett square. Complete the Punnett square by writing the alleles from the gametes in the appropriate boxes. Determine the phenotypes of the offspring. Using the results of step 4. write down the genotypic and phenotypic ratios. EXAMPLE PUNNETT SQUARE EXAMPLE: WHAT IS THE PROBABILITY THAT TWO HETEROZYGOUS PURPLE FLOWERS WILL PRODUCE A WHITE FLOWER? 1. Choose a letter to represent the alleles in the cross. 2. Write the genotypes of the parents. 3. Enter the possible gamete at the top and side of the Punnett square. WHAT IS THE PROBABILITY THAT TWO HETEROZYGOUS PURPLE FLOWERS WILL PRODUCE A WHITE FLOWER? 4. Complete the Punnett square by writing the alleles from the gametes in the appropriate boxes. 5. Determine the phenotypes of the offspring. 6. Using the results of step 4. write down the genotypic and phenotypic ratios REVIEW QUIZ ON PROBABLITY AND PUNNETT SQUARES http://anthro.palomar.edu/mendel/quizzes/mendq ui2.htm DO NOW: 1. Curly hair is dominant to straight hair. If a heterzygous curly haired woman marries a man with straight hair, what is the genotype and phenotype ratio? 2. In dogs, long eyelashes is dominant to short eyelashes. A short eyelashed dog is mated with a homozygous long eyelashed dog. What is the percentage their puppies will have short eyelashes? MAIN IDEA………… Parent Traits Parent Traits Offsprings Traits TEST CROSSES WHAT IS A TEST CROSS????? Test that is conducted to determine if the genotype of an organism HOMOZYGOUS DOMINANT for a trait HETEROZYGOUS for a trait 5 KEY POINTS…… 1. 2. The organism with the dominant trait is always crossed with an organism that is HOMOZYGOUS RECESSIVE If ANY offspring shows the recessive trait than the unknown genotype is heterozygous. 1. 3. If ALL offspring have the dominant trait, the unknown is homozygous dominant. 1. 4. 5. Recessive trait seen heterozygous Dominate trait homozygous Large numbers of offspring are needed for reliable results Start by making a key and writing down what you know. EXAMPLE: If fire breathing is dominant to not fire breathing in Gregorous Dragon, how can we determine if Mendelia is homozygous dominant or heterozygous????? SO WHAT DO WE KNOW…………. Let’s say F= fire breathing f= can’t fire breathe. Set up a two different Punnett squares Both with a homozygous recessive ff Then as the other parent place a: FF in one Punnett square Ff is another Essentially, your two Punnett squares will have: Ff crossed with ff FF crossed with ff INTERPRETATION If all of the Gregorous dragon babies can firebreathe we can assume that Mendelia is HOMOZYGOUS DOMINANT If any of the babies DO NOT fire breathe than Mendelia is HETEROZYGOUS DIFFERENT TYPES OF INHERITANCE DIHYBRID CROSSES DIHYBRID CROSSES Cross that involves two traits Gives 16 offsprings Example: Pea color and wrinkles STEPS FOR SOLVE FOR DIHYBRID CROSS 1. 2. 3. Make a key for the two traits that you are crossing Write out the different genotypes of the parents Figure out the possible gametes 1. 2. 3. 4. similar to FOIL there are four for each parent each gamete must have one allele from each trait Set up and Solve the Punnett Square EXAMPLE PROBLEM: A MOTHER IS HETEROZYGOUS BROWN HAIR AND BLUE EYES. THE FATHER HAS BLONDE HAIR AND IS HETEROZYGOUS FOR BROWN EYES. WHAT ARE THE POSSIBLE GENOTYPES AND PHENOTYPES OF THEIR OFFSPRINGS? Step 1 (assume brown hair & brown eyes are dominant) Make a key for the traits Brown Hair (B) vs Blonde Hair ( b) Brown Eyes (E) vs Blue eyes (e) Step 2 Genotypes of the parents Mother Bbee Father bbEe Step 3 Figure out the possible gamete Mother Gamete’s Be, Be, be, be Father’s Gamete’s bE, be, bE, be STEP 4 SET UP AND SOLVE PUNNET SQUARE Be bE be bE be Be be BbEe BbEe bbEe Bbee Bbee bbee BbEe Bbee BbEe Bbee bbEe bbee be bbEe bbee bbEe bbee COUNT UP THE POSSIBLE GENOTYPES AND PHENOTYPES THAT YOU HAVE FROM YOUR PUNNETT SQUARE Genotypes BbEe Bbee 4/16 bbEe 4/16 4/16 Phenotypes Brown Hair; Brown eyes Brown Hair; Blue eyes Blonde Hair; Brown eyes Blonde Hair; Blue eyes bbee 4/16 DO NOW: With the person sitting next to you…go through the DO NOW. Things to discuss: How do you begin a dihybrid cross? What are gametes and how do you solve for them? How do you interpret the punnett square? Try to figure out genotypic ratios if time allows MAIN IDEA………… Parent Traits Parent Traits Offsprings Traits SEX LINKED SEX LINKED sex is determined by the X and Y chromosomes. Females XX Males XY SEX DETERMINATION Sons: get their X chromosome from their mothers only. Get Their Y chromosome for their fathers Daughters: fathers must pass their X chromosomes SEX LINKED TRAITS Traits found on the SEX chromosomes Genes that are found on the X chromosome follow a have a special pattern of inheritance: X linked traits are only passed to sons from the mother Males are much more likely to be affected than females If trait is recessive, daughters have a second X chromosome so they can be heterozygous. Sons only have one X chromosome therefore more likely to express the trait Females can be carriers and pass the trait onto their son. Example: Baldness Colorbindness COLORBLINDNESS TRY THIS…… A woman is not colorblind but her husband is. Construct a punnett square to determine what is the chance that their children will be colorblind. What is the percentage of children with colorblindness? A woman who is a carrier for hemophilia marries an unaffected male. What is the % chance that their children will be affected? EXIT TICKET: A female who is a carrier for baldness marries a man who is bald. What percentage of the females will be carriers for baldness? What percentage of the males will be bald? What percentage of the offspring will NOT be bald? How does this relate to the big idea of the unit? DO NOW: Read the instructions on your DO NOW and work in the following groups: Group A- Taylor, Alyza, Jason, Sami, Jessie Group B- Hannah, Megan, Jess, Montana, Bryce Group C- Ashley, Vanessa, Juliann, Clare, Mark Group D- Emma, Rebecca, Kyle, Pierce, Taj MAIN IDEA………… Parent Traits Parent Traits Offsprings Traits INCOMPLETE DOMINANCE INCOMPLETE DOMINANCE when one trait is not completely dominant over another Results heterozygous form being blended together Example: Pink flower SOLVING INCOMPLETE DOMINANCE: Same as performing a regular monohybrid Punnett square Only difference Since both traits are equally dominant- you can use two DIFFERENT letters to symbolize the trait: Example: Red (R) and white (W) heterozygous offspring will be mixture of two trait Ex: red + white = PINK Example Problem: Black fur color are not completely dominant to white white fur color. The mother is a homozgygous for black fur color and the father is homozygous for white fur color. Perform a punnett square. B W W B BW BW BW BW CODOMINANCE CODOMINANCE Two different alleles are present and both are expressed Basically…….. Both alleles contribute to the phenotype. Example: Red cow X White Cow = Roan Cow Blood types BLOOD TYPES: Red blood cells are coated with different protein markers. Person can have either A B A and B neither protein. Blood Types are: A B AB O Genotype Genotype Phenotype AA or AO IAIA A Blood IAIO IBIB BB or BO B Blood IBIO AB IAIB AB Blood OO IOIO O Blood EXAMPLE PROBLEM #1 Melissa has type AB blood. Joe has type AB blood as well. If Melissa and Joe have a baby girl, what are the possible blood types the baby can have? HINT: Draw a Punnet Square!!!!!! EXAMPLE PROBLEM #2 David has blood type AB. Jessica has blood type O. They have a son that has blood type A? Since neither David nor Jessica have this blood type, was there a mistake in the hospital? HINT: Draw a Punnett Square to help!!!!!!!!!