3. Inheritance The transfer or transmission of some features from one generation to the next is called inheritance. The characteristics are controlled by genes which are like coded instruction. Genes from one generation are transmitted to the next in the gametes.

4. Inheritance At fertilization, the gametes fuse to form a zygote which contains the genetic information from both parents. A new individual grows from the zygote – half of its genetic information comes from its male parent and half from its female parent

5. What are chromosomes? Genetic materials found inside the nucleus of a cell Made up of DNA & protein Appear as very thin & thread-like structures called Chromatins Each cell in each type of organism has a definite number of chromosomes ( human has 46 chromosomes in their nucleus)

6. chromosome gene controlling skin colour gene controlling tongue rolling gene controlling eye colour gene controlling blood group A gene is a short length of DNA on a chromosome which is a unit determining an inherited character It consists of a chemical substance called deoxyribonucleic acid (DNA)

7. chromosome gene controlling skin colour gene controlling tongue rolling gene controlling eye colour gene controlling blood group DNA is responsible for telling the cell to make the right type of protein & control the metabolic activities of the cells

8. Chromosomes always exist in pairs in the body (somatic) cells Each human somatic cell has 46 chromosomes (diploid number) –23 pairs of homologous chromosomes

9. Alternative forms of genes on the same position of the homologous chromosomes which control the same character but have different expressions

10. Members of homologous chromosomes carry the same genes (controlling the same character) in same loci But the genes on the members of homologous chromosomes may be of different forms (effects)  Alleles allele for white skin colour allele for dark skin colour

11. The first scientist develop a method for predicting the outcome of inheritance patterns. Performed his work with pea plants, studying seven traits: plant height, pod shape, pod color, seed shape, seed color, flower color, and flower location. Pea plants develop individuals that are homozygous for particular characteristics. These populations are known as pure lines. Gregor Mendel: Father of Modern Genetics

12. ILLUSTRATION

13. Creating sentences DNA – nucleus Inheritance – traits Chromosome – chromatin Haploid – gamete Zygote – diploid chromosome Diploid number– human cell Gene – DNA Genetic – inherited Mendel - genetics

14. Mendelian crosses In his work, Mendel took pure-line pea plants and cross-pollinated them with other pure-line pea plants. He called these plants the parent generation. When Mendel crossed pure-line tall plants with pure-line short plants, he discovered that all the plants resulting from this cross were tall. He called this generation the F1 generation (first filial generation). Next, Mendel crossed the offspring of the F1 generation tall plants among themselves to produce a new generation called the F2 generation (second filial generation).

15. Two Innovations of Mendel 1.Developed pure lines 2.Counted his results and kept statistical notes Pure Line (galur murni) - a population that breeds true for a particular trait

16. Mendelian crosses To predict the possibility of an individual trait, several steps are followed: 1.The dominant allele is represented by a capital letter while the recessive allele by the corresponding lowercase letter. Homozygous dominant individual (the genotype is EE); heterozygous individual (the genotype is Ee); and for a homozygous recessive person (the genotype is ee). 2.Performing a genetic cross is determining the genotypes of the parents and the genotype of the gametes. A heterozygous male and a heterozygous female to be crossed have the genotypes of Ee and Ee. During meiosis, the allele pairs separate. A sperm cell contains either an E or an e, while the egg cell also contains either an E or an e.

17. Mendelian crosses 3. To continue the genetics problem, a Punnett square is used. A Punnett square is a boxed figure used to determine the probability of genotypes and phenotypes in the offspring of a genetic cross. 4.This is done by filling in each square with the alleles above it and at its left. 5.Therefore, the ratio of phenotypes is 3 with curly hair to 1 with straight hair (3:1). The ratio of genotypes is 1:2:1 (1 EE : 2 Ee : 1 ee).

18. Monohybrid cross Involves a study of inheritance patterns for organisms differing in one traits. Using symbols we can predict the cross of tall (DD) and short (dd) pea plants in the following manner:

19. Dihybrid Cross Problem Set A dihybrid cross involves a study of inheritance patterns for organisms differing in two traits. Mendel invented the dihybrid cross to determine if different traits of pea plants, such as flower color and seed shape, were inherited independently.

20. Terms to know in Mendelian Genetics 1. Alleles: The different forms of a gene. Y and y are different alleles of the gene that determines seed color. Alleles occupy the same locus, or position, on chromosomes. 2.F1 generation Offspring of a cross between true breeding plants, homozygous for the trait of interest 3.F2 generation Offspring of a cross involving the F1 generation. 4.Homozygote - an individual which contains only one allele at the allelic pair; for example DD is homozygous dominant and dd is homozygous recessive; pure lines are homozygous for the gene of interest

21. 5. Heterozygote - an individual which contains one of each member of the gene pair; for example the Dd heterozygote 6. Incomplete dominance The flowers of the snapdragon plant can be red, pink, or white. The genotype RR results in red flowers and rr results in white flowers. The heterozygote genotype of Rr results in pink flowers. 7. Genotype - the specific allelic combination for a certain gene or set of genes based on trait. 8. Monohybrid cross. Cross involving parents differing in only one trait. Terms to know in Mendelian Genetics

22. 9. Phenotype The physical appearance of an organism with respect to a trait, i.e. yellow (Y) or green (y) seeds in garden peas. The dominant trait is normally represented with a capital letter, and the recessive trait with the same lower case letter. 10. Recessive trait. The opposite of dominant. A trait that is preferentially masked. 11. Dominance - the ability of one allele to express its phenotype (trait)

23. Terms to know in Mendelian Genetics 12. Backcross - 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 fully recessive parent 13. Testcross - the cross of any individual to a homozygous recessive parent; used to determine if the individual is homozygous dominant or heterozygous 14. Monohybrid cross - a cross between parents that differ at a single gene pair (usually AA x aa) 15. Monohybrid - the offspring of two parents that are homozygous for alternate alleles of a gene pair

24. EXERCISES-1 1.Human blood type is determined by codominant alleles. There are three different alleles, known as IA, IB, and i. The IA and IB alleles are co-dominant, and the i allele is recessive. The possible human phenotypes for blood group are type A, type B, type AB, and type O. Type A and B individuals can be either homozygous (IAIA or IBIB, respectively), or heterozygous (IAi or IBi, respectively). A woman with type A blood and a man with type B blood could potentially have offspring with which of the following blood types? A. type Atype A B. type Btype B C. type ABtype AB D. type Otype O E. all of the aboveall of the above

25. What are the possible blood types of the offspring of a cross between individuals that are type AB and type O? (Hint: blood type O is recessive) A. AB or OAB or O B. A, B, or OA, B, or O C. A or BA or B D. A, B, AB, or OA, B, AB, or O E. A, B, or ABA, B, or AB EXERCISES-2

26. Meiosis  Producing cells with chromosome number half of the parent cell  Two nuclear divisions – Meiosis I and meiosis II  Four haploid cells are produced

27. First Meiotic Division Chromosomes become visible Nuclear membrane disappears

28. Homologous chromosomes pair up (not in mitosis) Crossing-over (not in mitosis) may occur between homologous chromosomes genetic materials exchanged

29.  Homologous chromosomes line up in the middle of cell randomly

30.  The 2 members of each homologous chromosome separate from each other and move towards the opposite poles of the cell

31.  Nuclear membrane reforms  Followed by cytoplasmic cleavage

32. Second Meiotic Division  Separation of chromatids of each chromosome  4 daughter cells with half of the chromosome number of the parent cell are formed

33. Occurrence of meiosis  Plants: anthers and ovules  Mammals: testes and ovaries

34. Comparison between Mitosis & Meiosis MitosisMeiosis Number of division 12 No. of daughter cells produced Type of cells produced Chromosome number of daughter cells 2 Somatic (body) cells Same as parent cell (diploid) 4 Gametes (sex cells) Half of parent cell (haploid)

35. MitosisMeiosis Pairing of homologous chromosomes NoYes Occurrence Role Growing tissues For Growth & Replacement Reproductive tissues (gonads) For Gamete Formation Comparison between mitosis & meiosis

36. Significance of meiosis  Produce haploid gametes which, after fertilization, can restore normal diploid conditions  Produce genetic variations

37. Sources of genetic variation Different combination of the genes of each gamete Random fusion of gametes during fertilization

38. ~ END ~