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Presentation on theme: "Heredity (B) -2013 Heredity (B) -2013 KAREN LANCOUR HEREDITY NATIONAL SUPERVISOR NATIONAL SUPERVISOR"— Presentation transcript:


2 Event Rules – 2013 DISCLAIMER This presentation was prepared using draft rules. There may be some changes in the final copy of the rules. The rules which will be in your Coaches Manual and Student Manuals will be the official rules.


4 TRAINING MATERIALS Training Power Point – content overview Training Handout - content information Sample Tournament – sample problems with key Event Supervisor Guide – prep tips, event needs, and scoring tips Internet Resource & Training CDs – on the Science Olympiad website at under Event Genetics CD (new) Biology-Earth Science CD, Genetics CD (new) for Heredity and Designer Genes as well as the Division B and Division C Test Packets are available from SO store at

5 Heredity (B) Content Content Basic principles of genetics Some possible areas – dominant, recessive, incomplete dominance, co-dominance, monohybrid & dihybrid crosses, test cross, multiple alleles, sex-linkage, genotype, phenotype, epistasis, mutations, multifactorial traits, pedigrees, karyotypes, mitosis, meiosis, nondisjunction, genetic disorders, DNA structure and replication, transcription, translation, common genetic disorders Process Skills Process Skills – data analysis, predictions, calculations, inferences, observations

6 Possible Topics for Various Levels Regional & State National (all topics) Monohybrid crossDihybrid crossPedigree construction and analysis Dominant and recessive allelesSex-linked traitsProduction of gametes with Abnormal #s of chromosomes Genotype vs. phenotypePedigree analysisTrihybrid cross (probability analysis) Human sex determinationMultiple allelesAnalysis of karyotypes for deletion, addition, translocation Gene: protein relationshipDNA structure & replication Transcription and translation MitosisMeiosis and gamete formation Multifactorial traits Human karyotypes analysis for nondisjunction disorders Co-dominance & Incomplete Dominance Epistasis

7 PRINCIPLES OF GENETICS GENES GENES – come in pairs Section of DNA – codes protein or part of protein One from each parent ALLELE ALLELE – different forms of a gene MULTIPLE ALLELES MULTIPLE ALLELES – more than 2 forms of a gene HOMOZYGOUS HOMOZYGOUS – same alleles HETEROZYGOUS HETEROZYGOUS – different alleles

8 Dominant vs. Recessive Dominant Dominant – always expressed Capital letters – N Homozygous - NN Heterozygous - Nn Recessive Recessive – prevented by dominant Lower case letters – n Homozygous – nn Punnett Square – Box showing allele combinations

9 Dominant and Recessive Autosomal Dominant Autosomal Dominant Dominant gene on an autosome Autosomal Recessive Autosomal Recessive Recessive gene on an autosome Sex-linked Dominant Sex-linked Dominant Dominant gene on a sex chromosome Sex-linked Recessive Sex-linked Recessive Recessive gene on a sex chromosome

10 Monohybrid Cross Hybrid Hybrid – Ss X Ss One Trait One Trait – Smooth vs wrinkled Two gametes per parent S and s Punnett Square Punnett Square with 4 boxes – 4 offspring

11 Genotype & Phenotype GenotypePhenotype Genotype Phenotype SS or Ss Round ss Wrinkled Genotype frequency 1:2:1 Phenotype frequency 3:1

12 Dihybrid Cross Dihybrid Dihybrid – 2 traits Gametes per parent Gametes per parent = 4 Punnett Square Punnett Square – 16 boxes Genotype ratio 1:2:1:2:4:2:1:2:1 Phenotype ratio 9:3:3:1

13 Incomplete Dominance Hybrid Hybrid is a blend of two traits Genotype frequency Genotype frequency 1:2:1 Phenotype frequency Phenotype frequency 1:2:1 Examples Examples: Flowers, Animal fur

14 Co-dominance More than one dominant allele More than one dominant allele Blood types – A,B,O alleles Blood types – A,B,O alleles Phenotypes Genotypes Phenotypes Genotypes A I A I A or I A i B I B I B or I B i AB I A I B O ii

15 Co-dominance co-dominance co-dominance – both dominant alleles (genes) in an individual are expressed as blood types A and B genes are co-dominant and both dominant over the O gene which is recessive

16 ABO Blood System

17 Independent Assortment vs. Linkage Independent Assortment Independent Assortment – genes on different chromosomes separate independently during meiosis Linkage Linkage – genes on the same chromosome are inherited as a group Autosomal linkage– on autosomes Autosomal linkage – on autosomes Sex-linked– on sex chromosomes Sex-linked – on sex chromosomes

18 Linkage – Sex Linkage Linkage Linkage – genes on the same chromosome inherited as a group Sex-linkage Sex-linkage – genes on sex chromosomes (esp. X) Y-chromosome shorter Y-chromosome shorter – some genes from X missing X-linked traits X-linked traits more common in men Men get X-chromosome from mom Red-green colorblindness, hemophilia

19 Environmental influence on genes expression Gene function is influenced by environment as with identical twins Genes have blueprint for proteins or parts of proteins Proteins can be structural proteins (parts of body) or functional proteins (hormones/enzymes)

20 Epistasis and Multifactorial Inheritance Epistasis - the interaction between two or more genes to control a single phenotype Multifactorial inheritance - many factors (multifactorial) both genetic and environmental are involved in producing the trait or condition. Examples: height, weight, cleft palate, spina bifida

21 Pedigree Symbols Generations Generations = I – Original Parents, II- F1 (children), III – F2 (grandchildren)

22 Pedigree – Curly vs Straight Hair Types of Analysis Relationships Relationships Dominant Gene – H Dominant Gene – HCurly Recessive Gene – h Recessive Gene – hStraight Genotypes Genotypes Phenotypes Phenotypes

23 Karyotypes Pairs 1-22 Pairs 1-22 =Autosomes XY XY = Sex chromosomes Male Male = X & Y Female Female = only X Nondisjunction Nondisjunction Extra chromosomes Extra chromosomes(Trisomy) Missing chromosomes Missing chromosomes(Monosomy)

24 Cell Cycle Interphase Interphase G1 G1 S – DNA replicates S – DNA replicates G2 G2 Mitosis Mitosis Prophase Prophase Metaphase Metaphase Anaphase Anaphase Telophase Telophase

25 Mitosis vs Meiosis Mitosis Mitosis Growth and Asexual Reproduction One division – 2 diploid cells Genetically same as original Meiosis Meiosis Gametes for Sexual Reproduction 2 divisions – 4 haploid cells


27 DNA Structure Double helix Double helix Antiparallel Antiparallel – 3 to 5 Nucleotide Nucleotide Deoxyribose sugar Phosphate Nitrogen bases Adenine Thymine Guanine Cytosine

28 DNA Replication Replication Replication (in nucleus) DNA DNA uncoils & splits Reads Reads 3 to 5 Assembles Assembles 5 to 3 4 types 4 types of nucleotides Okazaki Okazaki fragments

29 Types of RNA Differences between DNA & RNA Differences between DNA & RNA Single strand Ribose instead of Deoxyribose Uracil instead of Thymine Messenger RNA Messenger RNA – carries blueprint Transfer RNA Transfer RNA – brings amino acids Ribosomal RNA Ribosomal RNA – reads code

30 Transcription & Translation Transcription Transcription – makes RNA (in nucleus) Translation (protein synthesis) Translation (protein synthesis) -Reads blueprint and makes protein or part of protein (in cytoplasm at the ribosome)

31 Transcription of RNA from DNA Transcription: Synthesis of RNA from a DNA Template. Requires DNA-dependent RNA polymerase plus the four nucleotides (ATP, GTP. CTP and UTP). Synthesis begins at a the initiation site on DNA The template strand is read 3' to 5' and the mRNA is synthesized 5' to 3'

32 Translation – Protein Synthesis

33 Mutations Mutation Mutation – any change in the DNA Gene mutation Gene mutation Chromosomal mutation Chromosomal mutation Agents causing mutations Agents causing mutations – radiation, chemicals, excess heat


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