Chapter 11 Genetics. STATE FRAMEWORKS 3. Genetics

Transcription

1 STATE FRAMEWORKS 3. Genetics Chapter 11 Genetics Central Concepts: Genes allow for the storage and transmission of genetic information. They are a set of instructions encoded in the nucleotide sequence of each organism. Genes code for the specific sequences of amino acids that comprise the proteins characteristic to that organism. 3.1 Describe the basic structure (double helix, sugar/phosphate backbone, linked by complementary nucleotide pairs) of DNA, and describe its function in genetic inheritance. 3.2 Describe the basic process of DNA replication and how it relates to the transmission and conservation of the genetic code. Explain the basic processes of transcription and translation, and how they result in the expression of genes. Distinguish among the end products of replication, transcription, and translation. 3.3 Explain how mutations in the DNA sequence of a gene may or may not result in phenotypic change in an organism. Explain how mutations in gametes may result in phenotypic changes in offspring. 3.4 Distinguish among observed inheritance patterns caused by several types of genetic traits (dominant, recessive, codominant, sex-linked, polygenic, incomplete dominance, multiple alleles). 3.5 Describe how Mendel s laws of segregation and independent assortment can be observed through patterns of inheritance (e.g., dihybrid crosses). 3.6 Use a Punnett Square to determine the probabilities for genotype and phenotype combinations in monohybrid crosses.

2 Genetics- the scientific study of heredity. Heredity- passing of genetic traits from parent to offspring. Trait- any characteristic that can be passed from parent to offspring. The varied patterns of stripes on Zebras are due to differences in their genetic codes. What are some of your traits?

3 Humans have controlled traits for years. ex. Indians with corn, breeding of dairy cows. Aristotle- pangenes in blood. Bloodlines and Blood Relative. Gregor Mendel *Became a priest and studied math and science at the University of Vienna. *Spent 14 years working in a monastery and teaching at the high school. *Was in charge of the monastery garden and carried out his work on garden pea plants.

4 Plant Reproduction A flower is the reproductive structure of a plant. It contains the male and female sex organs which produce pollen and eggs by meiosis. Fertilization results in a zygote which is contained in a seed.

5 Mendel's Experiments *Pea plants are easy to grow so he could study many generations. *Self Pollenating *Show several traits in contrasting forms. No blending inheritance. What he did:

6 Mendel s Experiments Dominant Trait Recessive Trait F1 Generation F2 Generation Ratio Red Flowers White Flowers All Red 705 Red/224 White 3.15 : 1 Smooth Seeds Wrinkled Seeds All Smooth 5474 Smooth/1850 Wrinkled 2.96 : 1 Yellow Seeds Green Seeds All Yellow 6022 Yellow/2001 Green 3.01 : 1 Inflated Pods Constricted Pods All Inflated 882 Inflated/299 Constricted 2.95 : 1 Green Pods Yellow Pods All Green 428 Green/152 Yellow 2.82 : 1 Axial Flowers Terminal Flowers All Axial 651 Axial/207 Terminal 3.14 : 1 Tall Stems Short Stems All Tall 787 Tall/277 Short 2.84 : 1

7 Mendel's Conclusions: Vocab: alleles are different forms of a gene. i.e. red flower allele and white flower allele *Parent plants contain two alleles (genes) for each trait. *Parent plants pass only one allele (gene) to their offspring. Therefore, gametes contain only one gene for each trait. Mendel's 3 Principles: The Principle of Dominance: some alleles are dominant and others are recessive. The Principle of Segregation: alleles for each trait segregate independently into gametes. Dominant alleles get passed equally to recessive alleles. The Principle of Independent Assortment: alleles for one trait are sorted independently of the alleles for other traits during gamete formation.

8 Probability Expected vs. Observed

9 Mendel's Experiments: Monohybrid Crosses

10 Test Cross- Allows you to determine the Trait: Rabbit Fur Color genotype of an unknown phenotype. B=brown fur allele b= white fur allele If you have a brown furred rabbit, do you know its genotype for sure?

11 Incomplete Dominance (Blending Inheritance) when a heterozygous genotype results in an intermediate phenotype. There are no dominant nor recessive alleles. Ex. Trait: Snap Dragon Flower Color ALLELES GENOTYPES PHENOTYPES R= red flower allele RR Red flowered plants W= white flower allele WW White flowered plants RW (incomplete dominance) Pink flowered plants

12 Cross a red flowered snap dragon with a white flowered snap dragon. What are the genotypic and phenotypic ratios in the F1 generation?

13 Multiple Alleles and Co-dominance Ex. Trait: Human Blood Types ALLELES GENOTYPES PHENOTYPES I A = Type A allele I A I A and I A i Type A Blood I B = Type B allele I B I B and I B i Type B Blood i = Type O allele i i Type O Blood *multiple alleles (3) in I A I B (co-dominance) Type AB Blood the population

14 Sex-linked or X-linked traits- genes that appear The color vision gene is located on the X chromosome. on the X chromosome. B = Normal color vision allele GENOTYPES PHENOTYPES b = Color Blind allele X B B X Normal Color Vision Female X B X b X b X b Normal Color Vision Female (carrier) Color Blind Female X B Y X b Y Normal Color Vision Male Color Blind Male

15 Sex-linked or X-linked traits- genes that appear The color vision gene is located on the X chromosome. on the X chromosome. B = Normal color vision allele GENOTYPES PHENOTYPES b = Color Blind allele X B B X Normal Color Vision Female X B X b X b X b Normal Color Vision Female (carrier) Color Blind Female X B Y X b Y Normal Color Vision Male Color Blind Male

16 Cross a normal color vision man with a normal color vision woman, whose father was colorblind. What are the male and female genotypic and phenotypic ratios of their children?

17 Dihybrid Crosses- crosses that involve two traits. Traits: Mendel's Pea Plant Height and Flower Color. T = Tall Plant Allele t = Short Plant Allele R = Red Flower Allele r = White Flower Allele Cross a pure bred tall, purebred red flowered plant with a short plant with white flowers.

18 F.O.I.L.-USED TO FIND ALL THE POSSIBLE COMBINATIONS OF ALLELES FOR TWO TRAITS.