1. MEIOSIS SOURCE BIOLOGY: CONCEPTS AND CONNECTIONS BY CAMPBELL, REECE, MITCHELL, TAYLOR

2. 4.1 Chromosomes, genes, alleles and mutation Define: A. Chromosome: is made of long thread of DNA packaged with proteins. It is replicated before division and visible in a stained cell. B. Chromatin: eukaryotic genetic material made of DNA and protein. C. Chromatid: one of the two copies of chromosome after it has replicated. D. Gene: a heritable character that controls a specific character.

3. More definitions E. Genome: the genetic complement of an organism. F. Mutation: change in the nucleotide sequence of a DNA of a chromosome H: Homologous chromosome: chromosomes in the diploid cell which contains the same sequence of genes from different parents.. Distinguish eukaryotic DNA and prokaryotic DNA

4. Gene mutation Gene mutation: mutation happens on only one gene. Chromosomal mutation: mutation affects more than one genes.

5. Figure 10.16A Normal hemoglobin DNAMutant hemoglobin DNA mRNA Sickle-cell hemoglobin Normal hemoglobin Glu Val C T T G A A CT GA A U

6. Figure 10.16B Normal gene Nucleotide substitution Nucleotide deletion Nucleotide insertion Inserted Deleted mRNA Protein Met Lys Phe Lys Phe Ala Gly Ser AUGAAGUUU GGC G CA GC G CA A G UUU AUGAA Met Lys Ala His Leu GUU AUGAA GGC G CA U U Met Lys Ala His Leu GUU AUGAA G G C UG G C

7. MEIOSIS OVERVIEW * Diploid cell produces 4 haploid daughter cells * Daughter cells are NOT genetically identical to the parent or to each other (there is genetic variation) * Sex cells (gametes: egg and sperm) are produced by meiosis * Meiosis is the basis of sexual reproduction (two parents produce sex cells that fertilize to form the zygote)

8. PREPARED BY CANAN ÇERMEN SOURCE: BIOLOGY: CONCEPTS AND CONNECTIONS BY CAMPBELL, REECE, MITCHELL, TAYLOR

10. MEIOSIS consists of 2 consecutive cell divisions: Meiosis I and Meiosis II

11. INTERPHASE These events are same as mitosis: * DNA and centriole replication * Protein synthesis increases * ATP synthesis increases

12. PROPHASE I These events are same as mitosis: * Chromatin condenses into visible chromosomes * Nucleolus disappears * Nuclear membrane disappears * Duplicated centrioles start moving to opposite poles * Spindle fibers begin to form

13. PROPHASE I continued These events are different than mitosis: * Homologous chromosomes pair up forming tetrads * Crossing-over occurs between non-sister chromatids of homologous chromosomes (Crossing-over: exchange of genetic material) PREPARED BY CANAN ÇERMEN SOURCE: BIOLOGY: CONCEPTS AND CONNECTIONS BY CAMPBELL, REECE, MITCHELL, TAYLOR

14. HOMOLOGOUS CHROMOSOMES * carry same genes for the same characteristics * they are of same length, same shape * one is inherited from the organism’s father, the other from the mother

17. METAPHASE I These events are different than mitosis: * Tetrads line up at the equator of the cell These events are same as mitosis: * Spindle fibers are attached to the chromosomes at the centromeres

18. ANAPHASE I These events are different than mitosis: * Homologous chromosomes are pulled to opposite poles by the spindle fibers

20. TELOPHASE I These events are same as mitosis: * Chromosomes decondense into chromatin * Nucleolus reforms * Nuclear membrane reforms * Spindle fibers disappear * Cytokinesis starts

21. MEIOSIS I is a reduction division. * The chromosome number is halved: 2 haploid cells are produced. * These haploid cells are different than normal haploid cells: their chromosomes have 2 sister chromatids.

22. MEIOSIS II is the same as mitosis. The difference is that it starts with haploid cells. The aim of meiosis II is to create real haploid cells where chromosomes have only single chromatids.

23. PREPARED BY CANAN ÇERMEN SOURCE: BIOLOGY: CONCEPTS AND CONNECTIONS BY CAMPBELL, REECE, MITCHELL, TAYLOR

24. PROPHASE II METAPHASE II ANAPHASE II TELOPHASE II CYTOKINESIS These events are same as mitosis.

27. FACTORS LEADING TO GENETIC VARIATION IN SEXUAL REPRODUCTION * Crossing-over * Random orientation of chromosomes * Separation of homologous chromosomes * Fertilization

31. Karyotype of human female

32. PREPARED BY CANAN ÇERMEN SOURCE: BIOLOGY: CONCEPTS AND CONNECTIONS BY CAMPBELL, REECE, MITCHELL, TAYLOR

33. Karyotype of human male

34. NONDISJUNCTION * An error in meiosis, in which either homologous chromosomes or sister chromatids do not separate. * It can happen with autosomal chromosomes or gonosomal chromosomes.

38. PREPARED BY CANAN ÇERMEN SOURCE: BIOLOGY: CONCEPTS AND CONNECTIONS BY CAMPBELL, REECE, MITCHELL, TAYLOR

39. Trisomy Down syndrome

41. If a normal gamete fertilizes a gamete with nondisjunction, the fertilized egg will have either one more or one less copy of an autosomal or gonosomal chromosome.

45. HL 10.1 Outline the formation of chiasmata in the process of crossing over. - Two homologous chromosomes come together by synapsis. - Two homologous chromosomes overlap each other (attach each other at different points). - The connection parts are called chiasmata. - They exchange genetic materials. - They separate from each other.

47. 10.1.3. Explain genetic variation Depending on how homologous pairs line up during metaphase 1, the genetic combination of daughter cells will change.

49. Tetrad (pair of homologous chromosomes in synapsis) Breakage of homologous chromatids Joining of homologous chromatids Chiasma Separation of homologous chromosomes at anaphase I Separation of chromatids at anaphase II and completion of meiosis Parental type of chromosome Recombinant chromosome Parental type of chromosome Gametes of four genetic types 1 2 3 4 C ce E C ce E ce C E Ce e C E c cE C E C e c E e c Crossing over