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Genetics

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  • 1. Biological Science By Daisie S. Nubla Assistant professor Ide la salle araneta university
  • 2. Animal and Plant Cell
  • 3. GENETICS
  • 4. GENETICS Ancient Greek γενετικός genetikos means genesis or origin discipline of biology science of genes, heredity and variation in living organisms deals with the molecular structure and function of genes with pattern of inheritance from parent to offspring gene distribution and variation in change in population
  • 5. GENETICS can be applied to the study of any living system from viruses and bacteria through plants (crops) and humans (Medical Genetics) living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding modern science of Genetics, which seeks to understand the process of inheritance only began with the work of Gregor Mendel.
  • 6. GREGOR MENDEL
  • 7. GREGOR JOHANN MENDEL July 22, 1822 – January 6, 1884 Austrian Monk During his child hood, worked as a gardener and studied beekeeping studied at University of Olomouc Upon recommendation of his physics teacher Friedrich Franz he entered the Augustinian Abbey of St. Thomas in Brno in 1843 He took the name Gregor upon entering monastic life
  • 8. GREGOR JOHANN MENDEL He was ordained into priesthood in August 1847 In 1849, he was assigned as a teacher to a secondary school in the city of Znaim He took the licensure exam for teachers but he was failed During middle part of his life, he did groundbreaking into the theory of heredity Using pea pod plants, he studied the seven characteristics of it.
  • 9. GREGOR JOHANN MENDEL By tracing these characteristics, Mendel discovered 3 basic laws which governed the passage of a trait from one member of a species to another member of the same species 1st Law states that the sex cells of a plant may contain two different traits but not both of those traits
  • 10. GREGOR JOHANN MENDEL 2nd Law stated that the characteristics are inherited independently from another (the basis of recessive and dominant gene composition) 3rd Law stated that each inherited characteristic is inherited by two hereditary factors (known more recently as genes. One from each parents, which decides whether a gene is recessive or a dominant.
  • 11. GREGOR JOHANN MENDEL If a seed gene is recessive, it will not show up within a plant, however the dominant trait will. His work later became the basis for the study of modern genetics, and are still recognized and used today‟ His work led to the discovery of particulate inheritance, dominant and recessive traits, genotype and phenotype, concept of heterozygous and homozygous
  • 12. MENDEL‟S EXPERIMENTAL QUANTITATIVE APPROACH Hybridization is matting and crossing of two true-breeding varieties P generation(parental) is the true – breeding parents F1 generation (first filial generation) is a hybrid offspring F2 generation ( second filial genentation) produced if allowing F1 hybrid to self-pollinate
  • 13. LAW OF SEGREGATION allele pairs separate during gamete formation and randomly unite at fertilization. two purpose of this are  developed pure lines  counted the results and kept the statistical notes
  • 14. PURE LINE a population that breeds true for a particular trait [ this was an important innovation because any non-pure (segregating) generation would and did confuse the results of genetic experiments]
  • 15. Results from Mendels Experiments Results from Mendels Experiments F1 Parental Cross F Phenotypic Ratio F2 Ratio Phenotype 2 Round x 5474 Round:1850 Round 2.96:1 Wrinkled Seed Wrinkled Yellow x Green 6022 Yellow:2001 Yellow 3.01:1 Seeds Green Red x White Red 705 Red:224 White 3.15:1 Flowers Tall x Dwarf Tall l787 Tall:227 Dwarf 2.84:1 Plants
  • 16. PHENOTYPE literally means, “the form that it shown” the outward, physical appearance of a particular trait Mendel‟s pea plants exhibited the following phenotypes  round or wrinkled seed  yellow or green seed  red or white flower  tall or dwarf plant
  • 17. PeacolorPeashape
  • 18. DOMINANT The allele that expresses itselfat the expense of an alternateallele, the phenotype that isexpressed in the from the crossof two pure lines
  • 19. RECESSIVEAn allele whose expression issuppressed in the presence of adominant allele, the phenotypethat disappears in the F1generation from the cross of twopure lines and reappears in the F2generation
  • 20. MENDEL‟S CONCLUSION1. The hereditary determinants are of a particulate nature. These determinants are called genes2. Each parent has a gene pair in each cell for each trait studied. The F1 from a cross of two pure lines contains one allele for the dominant phenotype and one from the recessive phenotype. These two allele comprise the gene pair
  • 21. MENDEL‟S CONCLUSION3. One member of the gene pair segregates into a gamete, thus each gamete only carries one member of the gene pair.4. Gametes unite at random and irrespective of the other gene pairs involved.
  • 22. MENDELIAN GENETICS DEFINITIONAllele one alternative form of a given allelic pair, tall and dark are the allele for the height of pea plant; more than two alleles can exist for any specific gene, but only two of them will be found in any individualAllelic pair the combination of two alleles which comprise the gene pair.
  • 23. MENDELIAN GENETICS DEFINITIONHomozygous an individual which contains only one allele at the allelic pair, for example DD is a homozygous dominant; while dd is homozygous recessive, pure lines are homozygous for the gene of interest.
  • 24. MENDELIAN GENETICS DEFINITIONHeterozygous an individual which contains one of each member of the gene pair, example the Dd.Genotype the specific allelic combination for a certain gene or set of genes.
  • 25. DIFFERENT TYPE OF CROSS IN GENETICSBackcross the cross of an F1 hybrid to one of the homozygous parents; for pea plant height the cross would be Dd x DD or Dd x dd; most often though a backcross is a cross to a full recessive parent.
  • 26. DIFFERENT TYPE OF CROSS IN GENETICSTestcross the cross of any individual to a homozygous recessive parent, used to determine if individual is homozygous dominant or heterozygous.Monohybrid cross a cross between parents that differ at a single gene pair (usually AA x Aa)
  • 27. DIFFERENT TYPE OF CROSS IN GENETICSMonohybrid the offspring of two parents that are homozygous for alternate alleles of a gene pair.  is good for describing the relationship between alleles.  when an allele is homozygous it will show its phenotype  it is the phenotype of the heterozygous which permit us to determine the relationship of the allele
  • 28. DIFFERENT TYPE OF CROSS IN GENETICSDominance the ability of one allele toexpress its phenotype at the expense of analternate allele.  the major form of interaction between alleles  generally the dominant allele will make a gene product that the recessive can not.  therefore the dominant allele express itself whenever it is present
  • 29. PUNNETT SQUAREA handy diagrammatic device forpredicting the allele composition ofoffspring from a cross betweenindividuals of known genetic make up
  • 30. LAW OF INDEPENDENT ASSORTMENTMendel derived this law by performingbreeding experiments in which hefollowed only a single character.  He identified this law by following two characteristics at the same time.  example 2 of the 7 characters Mendel‟s studied is were seed color and seed shape Each pair of alleles segregates independently of other pairs of alleles during gamete formation
  • 31. LAW OF INDEPENDENT ASSORTMENT seed color may be yellow (Y) or green(y) seed shape round (R) or wrinkled (r) example YYRR will have a parentalcross with yyrr  F1 plants will be dihybrids heterozygous YyRr  phenotypic categories with a ratio of 9:3:3:1  9 yellow-round to 3 green-round to 3 yellow-wrinkled to one- green wrinkled
  • 32. COMPLETE DOMINANCEOccurs when the phenotype o theheterozygote is completelyindistinguishable from that of thedominant homozygote
  • 33. INCOMPLETE DOMINANCEOccurs when phenotype of theheterozygous genotype is anintermediate of the phenotypes of thehomozygous genotypes.  example the snap dragon flower color is either homozygous for red or white  when the red homozygous flower is paired with the white one, the result is pink  pink now is being called as this
  • 34. CO - DOMINANCEOccurs when the contributions of bothalleles are visible in the phenotype  example is A and B alleles are codominant in producing AB blood group phenotype  in which A- and B- type antigens are being made
  • 35. TAY SACHS DISEASE fatal, recessive genetic disorder in children that causes progressive destruction of the Central Nervous System Infants having this kind of disease are normal for the first few months relentless deterioration of mental and physical abilities becomes blind, deaf and unable to swallow
  • 36. EPISTASIS Greek word that means „stopping‟ A gene at one locus alters the phenotypic expression of a gene at a second locus
  • 37. PLEIOTROPY from a Greek word pleion have multiple phenotypic effects responsible for the multiple symptoms associated with certain hereditary diseases  cystic fibrosis  sickle cell disease
  • 38. Many HumanTraits Follow Mendelian Patterns of Inheritance
  • 39. PEDIGREE ANALYSIS To analyze the results of matting that have already occurred collection of information about a family‟s history for a particular trait and assembling this information into a family tree describing the interrelationship of parents and children across the generation
  • 40. PEDIGREE ANALYSIS one importance of this is to help us predict the future a serious matter when the alles in question cause disabling or deadly hereditary diseases instead of innocuous human variation such as hairline or earlobe configuration
  • 41. RecessivelyInherited Disorder
  • 42. CYSTIC FIBROSIS Most common lethal genetic disease in U.S. chloride transport of channels are defective or absent in the plasma membrane of a children result is abnormally high concentration of extracellular chloride which causes mucus that coats certain cells to become thicker and stickier Most children die before their 5th birthday
  • 43. SICKLE CELL DISEASE most common inherited disorder caused by substitution of single amino acid by the hemoglobin protein of red blood cells. multiple effect of a double dose of this is an example of pleiotropy no cure
  • 44. MATING OF CLOSE RELATIVES forbidden loveconsanguineous a disease causingrecessive allele more likely produce offspringhomozygous for recessive traits
  • 45. DOMINANTLY INHERITED DISORDERS Achondroplasia a form of dwarfism heterozygous individuals have the dwarf phenotype therefore all people who are not achondroplastic dwarf are homozygous for recessive allele
  • 46. NEW BORN SCREENING some genetic disorders can be detected at birth one common screening program is Phenylketonuria (PKU) phenylalanine and its by-product phenylpyruvate can accumulate to toxic levels in the blood causing mental retardation.
  • 47. NEW BORN SCREENING some genetic disorders can be detected at birth one common screening program is Phenylketonuria (PKU) phenylalanine and its by-product phenylpyruvate can accumulate to toxic levels in the blood causing mental retardation.