Inheritance Conceptual Biology Chapter

Vocabulary 1. genetics 2. heredity 3. self-fertilize 4. trait 5. gene 6. allele 7. hybrid 8. dominant 9.recessive 10.segregation 11.probability 12.Punnett square 13.homozygous 14.heterozygous 15.phenotype 16.genotype 17.multiple alleles 18.polygenic traits 19.gene linkage 20.gene map

I. Mendel & Genetics A.How do characteristics pass from parents to offspring? 1.heredity = how characteristics are passed from parent to offspring 2.genetics = scientific study of heredity

B.Gregor Mendel – father of genetics 1.Mendel worked with pea plants that self-fertilize. a.self-fertilize = sperm and egg from the same plant that go through fertilization b.self-fertilizing plants produce offspring identical to themselves 2.Mendel decided to cross- fertilize these peas and study the results

C. Genes and Dominance 1. gene = section of DNA that has instructions for making a protein, each protein causes a characteristic 2. trait = a specific characteristic, ex: seed color or plant height 3. Mendel studied pea plants that had different traits, ex: green or yellow seeds DRAW

Seed Shape Flower Position Seed Coat Color Seed Color Pod Color Plant Height Pod Shape Round Wrinkled Round Yellow Green Gray White Smooth Constricted Green Yellow Axial Terminal Tall Short YellowGraySmoothGreenAxialTall

4.Mendel learned some forms of genes are dominant and others are recessive. a. dominant = trait that covers up another trait b. recessive = trait that is covered over and seems to disappear c. alleles = different forms of a gene that can be dominant or recessive, ex: tall and short

P Generation F 1 Generation F 2 Generation TallShortTall Short DRAW - Mendel’s Pea Experiment

Gene Location and Dominance Genes are parts of DNA that code for one protein. Genes are parts of DNA that code for one protein. Genes have two forms called alleles. Genes have two forms called alleles. Alleles can be dominant or recessive. Alleles can be dominant or recessive. Use a capital letter for the dominant allele, lower case for recessive allele. Use a capital letter for the dominant allele, lower case for recessive allele.

D. Segregation 1.Mendel crossed a tall plant with a short plant to make plant children. a. All the children were all tall. He called these plants hybrids b. hybrid = offspring of parents with different traits 2.Mendel crossed the plant children with themselves to make plant grandchildren a. The grandchildren were 3:1, tall to short plants! b. The short trait came back ¼ of the time (in 1 out of 4 plants)

3.Alleles for a trait separate when sex cells are made a.Each sex cell carries one copy of each gene as an allele DRAW Figure 2 in Chapter 5 Children Grandchildren

concluded that which is called Gregor Mendel DominanceSegregation Pea plants Genes determine traits Some alleles are dominant, and some alleles are recessive Alleles are separated when making sex cells experimented with E. Gregor Mendel graphic organizer

Although Mendel did most of his genetics work on pea plants, his ideas about genetics also apply to all other organisms…

Probability Practice If you toss a coin, what is the probability of getting heads? Tails? If you toss a coin, what is the probability of getting heads? Tails? 1 chance in 2. This is ½ or 50%. 1 chance in 2. This is ½ or 50%. If you toss a coin 10 times, how many heads and how many tails would you expect to get? If you toss a coin 10 times, how many heads and how many tails would you expect to get? 5 heads and 5 tails = ½ of the time heads or tails 5 heads and 5 tails = ½ of the time heads or tails Working with a partner, have one person toss a coin ten times while the other person tallies the results on a sheet of paper. Then, switch tasks to produce a separate tally of the second set of 10 tosses. Working with a partner, have one person toss a coin ten times while the other person tallies the results on a sheet of paper. Then, switch tasks to produce a separate tally of the second set of 10 tosses.

II. Probability and Punnett Squares A. Genetics & Probability 1.Probability = the chance that a particular event will happen 2.Probability is used to predict the traits of offspring B. Punnett squares 1.Punnett square = a tool used to predict the traits in offspring 2.Homozygous = organisms that have two identical alleles for a trait (TT or tt) 3.Heterozygous = organisms that have two different alleles for a trait (Tt)

4. Phenotype = physical characteristics (ex: tall or yellow) 5. Genotype = genetic makeup, alleles (ex: Tt or tt) DRAW Punnett square (for only one trait)

C.Probabilities Predict Averages 1.Probability does not predict exact outcomes 2.larger # of events  more accurate the probability 3.larger # of offspring  closer the resulting offspring will be to what was predicted 4.Ex: When we breed two fruit flies and get thousands of offspring, the babies ’ characteristics are very close to our prediction. If you breed horses and only get two offspring, their characteristics may not match the prediction because there are too few offspring.

A.Beyond Dominant & Recessive Alleles 1.Some alleles are neither dominant or recessive 2.Incomplete Dominance - heterozygous phenotype somewhere in between the two homozygous phenotypes a.ex: snapdragon flowers b.use two different letters for the alleles when doing a Punnett square IncompleteDominance III. Advanced Genetics DRAW

3.Codominance - both alleles contribute to the phenotype separately a. ex: Appaloosa horses b. use two different letters for the alleles in a Punnett square Codominance

4.Multiple Alleles - more than two alleles for a gene existing in a population a.ex: rabbit coat color 1)alleles for where & how much color expressed: C, c ch, c h, c b.ex: human blood type 1)alleles: A, B, and O Human Blood Rabbit Coat Color Alleles

5.Polygenic traits - traits controlled by two or more genes a.ex: skin color in humans is controlled by 4 different genes b.there are many genes for human eye color, 2 we know well: 1 for a brown and 1 for a green pigment, ex: BbGg Polygenic Trait - Eye Color, 2 different genes Predicting Your Children’s Eye Color: children-have children-have children-have

Location on chromosomesChromosome # 2

IV. Gene Linkage and Mapping A. Gene Linking 1.Some genes seem to be “ linked ” since they are often inherited together 2.These genes are located close together on the same chromosome B. Gene Maps 1.Gene maps show the location of genes on a particular chromosome