Heredity - Genes, Chromosomes, Solving a Punnett Square and Non-Mendelian Inheritance
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The document discusses the structure and function of chromosomes, detailing their role in heredity and the genetic characteristics of various organisms. It explains the difference between autosomes and sex chromosomes, the concept of genes, alleles, and linked genes, as well as the expression of traits through dominance and multiple alleles. Additionally, it addresses sex-linked traits and includes examples of genetic disorders like hemophilia and the inheritance patterns of traits among genders.
Heredity - Genes, Chromosomes, Solving a Punnett Square and Non-Mendelian Inheritance
- 3. • They are the carriers of genes, the unit determiners of hereditary characteristics. • They are located in the nucleus of the each body cells.
- 4. Species Number of Chromosomes Species Number of Chromosomes Human 46 Earthworm 36 Gorilla 48 Puffer Fish 42 Donkey 62 Dog 78 Cat 38 Fruit Fly 4 Cow 60 Mosquito 6 Goldfish 94 Pea plant 14 Horse 64 Sunflower 34
- 5. • Each chromosomes is made up of two long DNA molecule called the blueprint of life or the genetic plan of the organism. The entire DNA in the body cells is called genome.
- 6. • From among the 46 chromosomes of humans, 22 pairs have almost the same size and shape and have the same genes on them and they are called homologous chromosomes.
- 7. • 1. Centromere – divides the chromosomes into two arms. • 2. q arm – the long arm region. • 3. p arm – the short arm region. • 4. Kinetochore – attaches to the spindle fiber during cell division.
- 9. • Autosomes – aka body chromosomes, are the first 22 pairs of chromosomes which are the same in both female and males.
- 10. • Sex Chromosomes – determine the sex of the organism. The Y- chromosome trigger the development of specific male characteristics.
- 11. • Females have XX chromosomes (homogametic) • Males have XY chromosomes (heterogametic) • They are not homologous because X is bigger than Y chromosome.
- 12. • Genes are the determiners of hereditary characteristics. • They are the portions of DNA molecule, the fundamental unit of heredity.
- 13. • Through the Human Genome Project, biologists found out that humans have about 30,000 genes. • Locus – the specific location of the genes along the entire length of the chromosomes.
- 14. • A member of homologous chromosomes has the same pair of genes. The member of each pair of genes is called the allele.
- 15. • Linked Genes – genes that are located on the same chromosomes and are tend to be inherited together at the same time.
- 17. • One allele is not completely dominant over the other resulting in the blending of characteristics. • Common in Hibiscus and Mirabilis jalapa.
- 18. P1 Red Flowers White Flowers RR x WW Formation of Gametes (P2) x F1 Ratio Genotypic Ratio = 4:0 or 100% RW Phenotypic Ratio = 4:0 or 100% Pink Flowers R R RW RW RW RW R R W W
- 19. P1 White Fur Black Fur WW x BB Formation of Gametes (P2) x F1 Ratio Genotypic Ratio = Phenotypic Ratio = W W B B
- 20. P1 White Fur Black Fur WW x BB Formation of Gametes (P2) x F1 Ratio Genotypic Ratio = 4:0 or 100% B Phenotypic Ratio = 4:0 or 100% B B B B B B W W B B
- 21. • In some cases, the heterozygous characteristics are fully expressed in the F offspring resulting to both traits to be expressed in the organism.
- 22. P1 Red Flowers White Flowers Rr x Ww Formation of Gametes (P2) x F1 Ratio Genotypic Ratio = 2:2 or 50% RW and 50% Wr Phenotypic Ratio = 2:2 or 50% Pink and 50% R r RW Wr RW Wr R r W W
- 23. P1 Orange Fur(Incomp.Dominant) Black Fur x BB Formation of Gametes (P2) x F1 Ratio Genotypic Ratio = Phenotypic Ratio = R B B
- 24. P1 Orange Fur Black Fur RY x BB Formation of Gametes (P2) x F1 Ratio Genotypic Ratio = 2:2 or 50% BR and 50% B Phenotypic Ratio = 2:2 or 50% Dark Red and 50% R BR BR R Y B B
- 25. • There are some traits that are not controlled by two alleles but by multiple alleles. • Common example is human blood groups – A, B, AB and O.
- 26. Blood Groups (Genotypes) Phenotypes Antigen (Type of Protein) Antibodies (Plasma of the Blood) lAlA or lAi Type A Antigen A Anti – b lBlB or lBi Type B Antigen B Anti – a lAlB Type AB Antigen A and B None ii Type O None Anti a and b
- 27. G1 Blood Type A- Blood Type B- lAi x lBi Female Male Formation of Gametes (P1) x G2 Ratio Genotypic Ratio Phenotypic Ratio lAlB Blood Type AB lBi Blood type B- lAi Blood type A- ii Blood type O lA i lB lAlB (Type AB) lBi (Type B-) i lAi (Type A-) ii (Type O) lA i lB i
- 29. • Traits that are controlled by the genes found in the sex chromosomes. Sex-linked traits are mostly recessive and can be inherited from one or both parents.
- 30. • Males are common to these traits because they carry only one X- chromosome inherited from their mother. If that X-chromosome carries a genetic disorder, it will be expressed.
- 31. • In contrast, the two X- chromosomes of the female offspring should both carry the disorder before it will be expressed. • Ex:Hemophilia and Color blindness
- 32. • Hemophilia – a recessive genetic disorder wherein the blood does not clot. Also known as bleeder’s disease. This is because of lack of genes that synthesizes protein for blood clotting.
- 33. P1 ♀ Hemophilia Carrier ♂ Normal XX x XY F1 Ratio Genotypic Ratio = 1:1:1:1 Phenotypic Ratio = 2:1:1 only one X is affected
- 34. • Is carried by the autosomes not the sex chromosomes. So, this trait is not limited to male humans alone. They are mostly recessive but because of sex hormones it acts like a dominant allele.
- 35. • For example if a male has an allele for baldness, which is recessive, but since he has testosterone, it will act as dominant allele. • If a female inherits an allele for baldness it will remain recessive but can still be passed on.
- 36. Male Phenotypes Genotypes Bald XBYb Bald XbYb Not Bald XBYB Female Phenotypes Genotypes Bald XbXb Not Bald XBXb Not Bald XBXB
- 37. P1 ♀ Not Bald ♂ Bald XBXb x XbYb F1 Ratio Genotypic Ratio ♀ = 1:1 XBXb XbXb ♂ = 1:1 XBYb XbYb Phenotypic Ratio ♀ = 1:1 Bald Not Bald ♂ = 2:0 Bald Xb Yb XB XBXb XBYb Xb XbXb XbYb
- 38. • The trait is only expressed only in one gender and does not appear in the other. One typical example is production of milk in lactating mothers. It is only observable in females since they exhibit the normal condition(well developed breasts) for such effect to happen.
- 39. G1 Blood Type A Blood Type B- lA lA x lBi Female Male Formation of Gametes (P1) x G2 Ratio Genotypic Ratio Phenotypic Ratio lAlB Blood Type AB lAi Blood type A- lA lA lB lAlB (Type AB) lAlB (Type AB) i lAi (Type A-) lAi (Type A-) lA lA lB i
- 40. P1 ♀ Not Bald ♂Hetero Bald XBXB x XBYb F1 Ratio Genotypic Ratio ♀ = 2:0 XBXB ♂ = 2:0 XBYb Phenotypic Ratio ♀ = 2:0 Not Bald ♂ = 2:0 Bald XB Yb XB XBXB XBYb XB XBXB XBYb