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Meiosis-A prelude to reproduction. I.Terminology A.karyotype –1. human 46 chromosomes –2. homologous pairs –3. diploid condition –4. note various sizes.

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Presentation on theme: "Meiosis-A prelude to reproduction. I.Terminology A.karyotype –1. human 46 chromosomes –2. homologous pairs –3. diploid condition –4. note various sizes."— Presentation transcript:

1 Meiosis-A prelude to reproduction

2 I.Terminology A.karyotype –1. human 46 chromosomes –2. homologous pairs –3. diploid condition –4. note various sizes and shapes

3 B. Chromatin 1. 1.8 meters 2. DNA 3. exists in a non-dividing cell

4 C. Relationship between chromatin and chromosome 1. chromatin 2. chromosomes 3. histone proteins 4. nucleosome 100µm (b)

5 D. Terms of chromosome structure 1. Monad 2. Dyad 3. Centromere 4. Sister chromatids

6 E. Homologous chromosome pairs 1. definition 2.paternal vs. maternal 3.genes vs. alleles 4.synapsis 5.tetrad 6. sister vs. nonsister chromatids

7 How many chromosomes do you see? Enter answer text... 1.4 2.8 3.10 4.No clue

8 II. Review of mitosis A. Prophase B. Metaphase C. Anaphase D. Telophase E. Products

9 III.Meiosis overview A. Importance? B.Two separate divisions –Meiosis I reduction division –Meiosis II “mitotic-like” division C.Where does it occur? D.What does meiosis produce?

10 IV.Meiosis I A.Prophase I B.Metaphase I C.Anaphase I D.Telophase I E.End products

11 V.Meiosis II A.Prophase II B.Metaphase II C.Anaphase II D.Telophase II E.Final products

12 VI.Comparison between mitosis and meiosis EventMitosisMeiosis IMeiosis II Synapsis occurs Sister chromatids separate Homologous chromosomes separate Crossing over occurs Tetrads form Haploid cells form Identical daughter cells form

13 VII. Meiosis and simple inheritance A. Sex determination 1. autosomes 2. sex chromosomes 3. products of meiosis 4. nature of sperm determines sex 5. sex ratios

14 B. Inheritance of somatic traits 1. Theory of particulate inheritance 2. Each body trait is affected by two alleles 3. One inherited from father and other from mother 4. Two factors separate upon gamete formation during meiosis 5. Terms of inheritance a. dominant b. recessive c. genotype d. phenotype

15 6. Inheritance of eye color a. Dominant allele produces pigment (E) b. Recessive allele produces no pigment (e) c. Possible genotypes d. Resulting phenotypes

16 7. Sample problem In humans, freckles are dominant to no freckles. Mary, who has no freckles, is planning on having children with Paul. Paul, who has freckles, was born to a freckless woman. Mary wants to know the probability of her in utero son has of having freckles. How do we start? List the symbols to be used to represent the alleles. What is the mother’s phenotype? Genotype? What is the father’s phenotype? What does his genotype have to be? What alleles are carried in the eggs and sperm of the couple? Create the punnett square. What will be the name of the son which is not born yet?


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