Mendel’s Genetics

1. Mendel’s Genetics By: Janeth Serratos, William Jo, Shane Berchtold, Simon Kuang

2. Review

3. Meiosis Meiosis is a process of reduction division in which the number of chromosomes per each cell is cut in half.

4. Meiosis

5. Stages of Meiosis • Interphase: • Cells undergo a round of DNA replication, forming duplicate chromosomes. • Prophase 1: • Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. • Metaphase 1: • Spindle fibers attach to the chromosomes. • Anaphase 1: • The fibers pull the homologous chromosomes toward opposite ends of the cell. • Telophase 1 and Cytokinesis: • Nuclear membranes form. The cell separates into two cells.

6. Stages of Meiosis • Prophase 2: • Meiosis 1 results in two haploid (N) daughter cells, each with half the number of chromosomes as the original cell. • Metaphase 2: • The chromosomes line up in a similar way to the metaphase stage of mitosis. • Anaphase 2: • The sister chromatids separate and move toward opposite ends of the cell. • Telophase 2 and Cytokinesis: • Meiosis 2 results in four haploid (N) daughter cells.

7. Gamete Formation • In many female animals, the cell divisions at the end of meiosis 1 and 2 are uneven, so that a single cell, which becomes an egg, receives most of the cytoplasm. The other three cells produced in the female during meiosis are known as polar bodies and usually do not participate in reproduction.

8. Gamete Formation • In male animals, the haploid gametes produced by meiosis are called sperm. In female animals, generally only one of the cells produced by meiosis is involved in reproduction. This female gamete is called an egg in animals and an egg cell in some plants.

9. Gamete Formation

10. Comparing Mitosis and Meiosis • Mitosis results in the production of two genetically identical diploid cells. A diploid cell that divides by mitosis gives rise to two diploid (2N) daughter cells. The daughter cells have sets of chromosomes and alleles that are identical to each other and to the original parent cell.

11. Comparing Mitosis and Meiosis • Meiosis produces four genetically different haploid cells. Begins with a diploid cell but produces four haploid (N) cells. These cells are genetically different from the diploid cell and from one another. Meiosis is how sexually reproductive organisms produce gametes.

12. Vocabulary • Homologous: • Term used to refer to chromosomes that each have a corresponding chromosome from the opposite-sex parent • Diploid • Term used to refer to a cell that contains both sets of homologous chromosomes • Haploid: • Term used to refer to a cell that contains only a single set of chromosome and therefore only a single set of genes.

13. Vocabulary • Meiosis • Process by which the number of chromosomes in cut in half through the separation of homologous chromosomes in a diploid cell • Tetrad • Structure containing 4 chromatids that forms during meiosis • Crossing-over • Process which homologous chromosomes exchange portions of their chromatids during meiosis

14. Quiz

15. Question 1 Different forms of genes are called: Hybrids Dominant Factors Alleles Recessive Factors

16. Answer 1 Different forms of genes are called: Hybrids Dominant Factors Alleles Recessive Factors

17. Question 2 Organisms that have two identical alleles for a particular trait are said to be Hybrid Heterozygous Homozygous Dominant

18. Answer 2 Organisms that have two identical alleles for a particular trait are said to be Hybrid Heterozygous Homozygous Dominant

19. Question 3 The physical characteristics of an organism are its Genetics Hereditary Phenotype Genotype

20. Answer 3 The physical characteristics of an organism are its Genetics Hereditary Phenotype Genotype

21. Question 4 A situation in which a gene has more than two alleles is known as Complete Dominance Co-dominance Polygenic Dominance Multiple Alleles

22. Answer 4 A situation in which a gene has more than two alleles is known as Complete Dominance Co-dominance Polygenic Dominance Multiple Alleles

23. Question 5 Unlike mitosis, meiosis in male mammals results in the formation of One haploid cell Three diploid polar bodies Four diploid gamete cells Four haploid gamete cells

24. Answer 5 Unlike mitosis, meiosis in male mammals results in the formation of One haploid cell Three diploid polar bodies Four diploid gamete cells Four haploid gamete cells

25. Question 6 A gene map shows The number of possible alleles for a gene The relative location of genes on the chromosome Where chromosomes are in the cell How crossing over occurs

26. Answer 6 A gene map shows The number of possible alleles for a gene The relative location of genes on the chromosome Where chromosomes are in the cell How crossing over occurs

27. Question 7 To maintain the chromosome number of an organism, the gametes must Become a diploid Become recessive Be produced by mitosis Be produced by meiosis

28. Answer 7 To maintain the chromosome number of an organism, the gametes must Become a diploid Become recessive Be produced by mitosis Be produced by meiosis

29. Question 8 Which is only correct of a true-breeding plant? If allowed to pollinate itself, it will produce offspring identical to itself. It cannot reproduce if it pollinates itself. It produces a new cell when pollinated. If allowed to pollinate itself, its offspring will not breed with others of a different species.

30. Answer 8 Which is only correct of a true-breeding plant? If allowed to pollinate itself, it will produce offspring identical to itself. It cannot reproduce if it pollinates itself. It produces a new cell when pollinated. If allowed to pollinate itself, its offspring will not breed with others of a different species.

31. Question 9 What happens in crossing over? Exchange of chromosomes in portion I. Formation of six haploid cells in telophase II. Exchange of portions of chromatids in prophase I. Exchange of portions of chromatids in prophase II.

32. Answer 9 What happens in crossing over? Exchange of chromosomes in portion I. Formation of six haploid cells in telophase II. Exchange of portions of chromatids in prophase I. Exchange of portions of chromatids in prophase II.

33. Question 10 What is the result of mitosis? Four genetically different haploid cells. Two genetically identical haploid cells. Four genetically identical diploid cells. Two genetically identical diploid cells.

34. Answer 10 What is the result of mitosis? Four genetically different haploid cells. Two genetically identical haploid cells. Four genetically identical diploid cells. Two genetically identical diploid cells.