Plant genetics


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Plant genetics

  1. 1. Plant GeneticsPlant Genetics JJA Obico, Department of BiologyJJA Obico, Department of Biology University of the Philippines Manila
  2. 2. Study of heredity and hereditary variationS udy o d y a d d a y a a o Genes - hereditary units - Segments of DNA Chromosomes - DNA + proteins GeneticsGeneticsGeneticsGenetics
  3. 3. A. Interphasep as 1. Gap 1 or G1 phase 2. Synthesis phase or S phase 3. G2 phase B. M-phase (Mitosis or Meiosis) Cell CycleCell CycleCell CycleCell Cycle
  4. 4. 1. G1 h th ll d◦ where the cell spends most of its functional life ◦ Performs metabolic acitivities 2. S-phase ◦ DNA molecules are copied or replicatedcopied or replicated ◦ from single stranded DNA in G1 phase to double stranded DNAstranded DNA 3. G2 ◦ preparing for the actual division events InterphaseInterphase (much protein synthesis- tubulin) InterphaseInterphase
  5. 5. MeiosisMeiosisMeiosisMeiosis
  6. 6. Asexual or Sexual Reproduction?p 1. Crossing over 2. Independent assortment of chromosomes 3. Random fertilization SOURCES OF VARIATIONSOURCES OF VARIATIONSOURCES OF VARIATIONSOURCES OF VARIATION
  7. 7. Crossing overCrossing overCrossing overCrossing over
  8. 8. Independent assortment of chromosomesIndependent assortment of chromosomesIndependent assortment of chromosomesIndependent assortment of chromosomes
  9. 9. 2n 223 The no. of possible combination of maternal and paternal chromosomes in the gametes Random fertilization of an ovumRandom fertilization of an ovum by a spermby a spermby a spermby a sperm
  10. 10. True-breeding plantsu b d g p a s Two varities ◦ Purple flower ◦ White flower Hybridization M h b idMonohybrid cross
  11. 11. Whatever the factor that caused thea a o a aus d purple color was more powerful than the factor for white color Mendel said that the yellow factor "d i t d" th f t"dominated" the green factor.
  12. 12. 1. Alternative version of genes account fora s o o g s a ou o variations in inherited character Mendel’s findingsMendel’s findingsMendel s findingsMendel s findings
  13. 13. 2. For each character, an organism inheritso a a a , a o ga s s 2 alleles: one from each parent Homozygous– identical alleles Heterozygous– different alleles
  14. 14. 3. Dominant allele – fully expressed3 o a a u y p ss d Recessive allele – masked Dominant- uppercase Recessive – lowercase P- purple; p- white
  15. 15. 4. Two alleles for each character segregateo a s o a a a s g ga during gamete production – LAW of SEGREGATION AN ovum or sperm get only ONE of alleles f ll thof all the genes
  16. 16. PUNNETT squareU squa - A tool for predicting the results of a genetic cross P P p Pp Pp p Pp Pp What will be the physicalWhat will be the physical appearance?appearance?appearance?appearance?
  17. 17. Self pollinate Pp individualsS po a p d dua s P p P PP Pp P Pp pp
  18. 18. Pp, PPPp, PP-- same phenotype but different genotypesame phenotype but different genotype
  19. 19. Seed shape and seed colorp Round and wrinkled; yellow and green RRYY x rryy G t RY RY dGametes: RY;RY and ry;ry F1: RrYy self pollinate RrYy x RrYyRrYy x RrYy Gametes (dependent assortment): RY;ry and RY; ryy F2? Are they transmitted as package? Will Y d R d d t t th ? DihybridDihybrid crosscross Will Y and R; and r and y stay together? DihybridDihybrid crosscross
  20. 20. Probabilityobab y The number of ways an event can occur total number of possible outcomesp ranges from 0 to 1 MendelianMendelian inheritance reflectsinheritance reflects rules of probabilityrules of probabilityrules of probabilityrules of probability
  21. 21. Product Ruleodu u ◦ For independent events Sum Rule ◦ Events that can occur in two or more different ways What is the probability of getting a heterozygoteWhat is the probability of getting a heterozygote (Pp) in this cross? A B Pp x Pp 1. P= ½ ; p= ½ ¼ 2 p= ½; P = ½ ¼2. p= ½; P = ½ ¼
  22. 22. 1. Incomplete dominance NonNon mendelianmendelian inheritanceinheritanceNonNon mendelianmendelian inheritanceinheritance
  23. 23. 2. Multiple alleles- more than 2 allelesu p a s o a a s
  24. 24. 3. Polygenic inheritance
  25. 25. 4. pleiotropy- single gene controls morep o opy s g g o o s o than one character eg. one gene affects corolla, anther, calyx, leaf and capsule of tobacco
  26. 26. 5. Linked genes- genes are on the same5 d g s g s a o sa chromosome
  27. 27. 6. Cytoplasmic inheritance6 Cy op as a - Maternal inheritance - Extra nuclear genesg
  28. 28. 7. Epistasis – Cucurbita pepop s as s Cu u b a p po