1. Sexual Reproduction and Meiosis
Chapter 11-Biology
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2. Adult somatic (body) cells are diploid.
Reduction Division
In sexual reproduction, eggs and sperm (gametes) fuse (fertilization) to produce a zygote.
Gamete formation involves a mechanism (meiosis) that reduces the number of chromosomes to half that found in other body cells.
Adult somatic (body) cells are diploid.
Gamete (reproductive) cells are haploid.
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3. Unique Features of Meiosis (What makes it different from Mitosis)
Synapsis
Homologous pairs of chromosomes pair up on equator
Homologous Recombination
Genetic exchange (crossing over) occurs between homologous chromosomes.
Reduction Division
Chromosomes do not replicate between the two nuclear divisions.
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5. The most important difference between meiosis and mitosis is that meiosis produces _____ cells.
Four diploid
Four haploid
Two haploid
Somatic
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6. Prophase I Chromosomes condense Homologous chromosomes pair up
Crossing over may occur while chromosomes are very close together
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7. Crossing Over-during Prophase I
Chiasmata are X-shaped structures
Presence of chiasmata indicates crossing over has occured
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8. Metaphase I Homologues line up on metaphase plate (equator).
Orientation of each pair is random (mom’s chromosomes vs. dad’s choromosomes may be to the right or to the left)
Tetrads = 1 pair of homologous chromosomes, each with a copied pair of chromatids
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9. Anaphase I Homologues separate
Each pole receives a member of each homologous pair.
Due to random orientation, meiosis results in independent assortment.
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10. Telophase I Chromosomes segregated into two clusters.
Nuclear membrane re-forms around each cluster of chromosomes.
Cells are not identical
Cytokinesis occurs to form 2 haploid cells
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11. No replication of DNA occurs between Meiosis I and Meiosis II
Prophase II - Nuclear envelope breaks down and second meiotic division begins.
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12. Spindle fibers bind to both sides of centromere
Meiosis II
Metaphase II –
Spindle fibers bind to both sides of centromere
Chromosomes line up (single file) along equator
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13. Meiosis II
Anaphase II - Spindle fibers contract and sister chromatids move to opposite poles.
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14. Telophase II - Nuclear envelope re-forms.
Meiosis II
Telophase II - Nuclear envelope re-forms.
Final Result – Cytokinesis makes 4 haploid cells.
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15. Which meiosis phase listed below is the most different from mitosis?
Prophase II
Metaphase I
Telophase II
Cytokinesis
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16. Sexual Reproduction - Produces genetic variability.
Types of Reproduction
Asexual Reproduction - Individual inherits all its chromosomes from a single parent.
Sexual Reproduction - Produces genetic variability.
Segregation of chromosomes tends to disrupt advantageous combinations.
Only some progeny maintain advantages.
Parthenogenesis
Development of adult from unfertilized egg.
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17. Observed plants in the monastery garden
Mendelian Genetics
Gregor Mendel ( )
Austrian monk
Observed plants in the monastery garden
Father of Genetics for determining inheritance patterns in peas
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18. Tool used to predict the next generation of offspring P1 cross
Punnett Squares
Tool used to predict the next generation of offspring
P1 cross
Cross between two parents pure for a trait
Produces F1 generation
F1 cross
Cross between the first generation offspring
Produces F2 generation
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19. What is the genotype that belongs in square 1?TT Tt tt
None of the above 1
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20. Genotype is the letter combination of the alleles GG, Gg, or gg
Punnett Squares
Genotype is the letter combination of the alleles
GG, Gg, or gg
Phenotype is the manifestation (what trait is produced)
Green or yellow
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21. What is the phenotype of the yellow peas?
Green
Yellow GG Gg
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22. What is the genotype of the yellow peas?
Green
Yellow gg Gg
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