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GENETICS

GENETICS. THE SCIENCE OF HEREDITY. HEREDITY AND MENDEL GENETICS. 1. TRAIT:. 2. HEREDITY:. 3 & 4. GENE and LOCUS. homologous. 5. ALLELES:. The different forms of a gene for a particular trait. Example: A , a. 6. DOMINANT ALLELE:.

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GENETICS

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  1. GENETICS THE SCIENCE OF HEREDITY

  2. HEREDITY AND MENDEL GENETICS 1. TRAIT: 2. HEREDITY:

  3. 3 & 4. GENE and LOCUS homologous

  4. 5. ALLELES: The different forms of a gene for a particular trait. Example: A , a

  5. 6. DOMINANT ALLELE: The form of a gene that is expressed and prevents the expression of the other form. They are shown with capital letters like A, B, C etc.

  6. 7.RECESSIVE ALLELE: The form of a gene that is expressed only when paired with a gene coding for the same trait. They are shown with lowercase letters like ,a, b, c etc.

  7. 8.HOMOZYGOUS (PURE BREED): When both alleles are same. Example: BB , bb 9.HETEROZYGOUS (HYBRID): When the alleles are different. Example: Bb

  8. 10. PHENOTYPE: Example: Tall pea plant 11. GENOTYPE: Examples: Heterozygous tall pea plant or Homozygous tall pea plant

  9. 12. PARENTAL GENERATION(P): Example: tall stem X dwarf stem 13. FIRST FILIAL GENERATION (F1): 14. SECOND FILIAL GENERATION (F2): (selfing of the F1 generation)

  10. 15. MONOHYBRID CROSS:

  11. 16. DIHYBRID CROSS: Ex: round, yellow seeded X wrinkled, green seeded

  12. 17.TEST CROSS: Test cross is used to determine if an individual exhibiting a dominant trait is homozygous or heterozygous. Example: Phenotype tall X dwarf Genotype T? tt (TT or Tt) 1. %100tall 2. %50 tall %50 dwarf

  13. 18. PUNNET SQUARE

  14. 19. PEDIGREE CHART: Example: ALBINIZM ı ıı IDENTICALTWINS ııı FRATERNAL TWINS

  15. 19. PROBABILITY: • The Rule of Independent Events: Previous events do not affect the probability of later occurrences of the same event. • Ex. Probability of having a head or tail in a toss is ½

  16. B. The Product Rule: The probability of independent events occurring together is equal to the product of the probabilities of these events occurring separately. Ex. Probability of having one head and one tail is ½ x ½ = ¼

  17. What are the chances that a baby will be born a male or female? Each baby has a 50:50 chance of being either a male or a female. It doesn't matter how many other brothers or sisters are already in the family. Each baby is a separate entity and its sex is not influenced by the sexes of earlier children.

  18. Olasılık ve Genetik • Prensip: Şansa bağlı bir olayın bir defa denemesinden elde edilen sonuçlar, aynı olayın daha sonraki deneme sonuçlarını etkilemez. • 10 defa attığımız paranın 10 defa da tura gelmesi halinde 11. defa tura gelme şansı yine 1/2 dir. • Genotipi Aa olan bir bireyin gametleri 1/2 A ve 1/2 a’dır.

  19. Olasılık ve Genetik • 2. Prensip: İki bağımsız olayın birlikte olma şansı onların ayrı ayrı olma şanslarının çarpımına eşittir. • İki tavla zarını birlikte attığımızda bunlardan birinin 4 gelme şansı 1/6 dır. Diğer zar içinde aynıdır.Aynı anda 4 gelme olasılığı 1/36 dır. • **Bir ailenin doğacak 3 çocuğundan ikisinin erkek birinin kız olma olasılığı (a= kız, b= erkek) • (a+b)3 = a 3 + 3 a2 b+ 3 b2 a + b3 • 3b2 a = 3 (1/2) 2 (1/2) = 3/8

  20. How meiosis produces genetic variation??? 1. Without meiosis, chromosome numbers would continually increase 2. Meiosis ensures daughter cells receive one of each kind of gene; precisely halves the chromosome number 3. Independent assortment provides 2n possible combinations of chromosomes in daughter cells 4. In humans with 23 haploid chromosomes, 2n = 223 = 8,388,608 possible combinations. 5. Variation is added by crossing-over; if only one crossover occurs within each bivalent, 423 or 70,368,744,000,000 combinations are possible 6. Fertilization also contributes to genetic variation; (223)2 = 70,368,744,000,000 possible combinations without crossing-over 7. With fertilization and crossing-over, (423)2 = 4,951,760,200,000,000,000,000,000,000 combinations are possible

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