Sexual reproduction
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Type of reproduction that has 2 parents and results in genetically unique offspring. Sperm and egg fuse together to form a zyote.
Gametes
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Sex cells formed through process of meiosis. Have 1/2 the number of chromosomes as body cells and are haploid.
Sperm
![card image](../uploads/773/2/_15fed498_1867048583f__8000_00004107.jpg)
Male gamete
Egg
![card image](../uploads/773/2/_15fed498_1867048583f__8000_00004107.jpg)
Female gamete
Fertilization
When sperm and egg fuse together to form a zygote.
Zygote
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Single diploid cell formed after fertilization and develops into embryo.
Meiosis
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Processes that produces gametes for sexual reproduction. A diploid cell undergoes 2 divisions to half the number of chromosomes and forms 4 haploid cells that become sperm or egg.
Diploid
When a cell has 2 sets of chromosomes. In humans = 46 chromosomes
Haploid
When a cell has 1 set of chromosomes. In humans = 23 chromosomes
Interphase
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Stage before cell division where cells grow and DNA replication occurs.
Homologous Chromosomes
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The pair of chromosomes that are the same size and carry the same types of genes - 1 comes from mom and 1 comes from dad.
Crossing Over
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Occurs during Prophase I of meiosis where homologous chromosomes exchange parts to increase genetic variation.
Meiosis I
First division of meiosis that separates the homologous chromosomes resulting in 2 haploid cells. Includes:
- Prophase I - nuclear envelope dissolves, chromosomes condense, homologous chromosomes pair up and crossing over occurs.
- Metaphase I - homologous pairs line up at the middle of the cell.
- Anaphase I - homologous pairs are pulled apart to the opposite ends of the cell.
- Telophase I - nuclear envelope reforms around the 2 sets of chromosomes and chromosomes unwind.
- Cytokinesis I - cytoplasm divides resulting in 2 haploid cells with replicated DNA.
Meiosis II
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Second division of meiosis where the 2 cells at the end of meiosis one separates the sister chromatids resulting in 4 haploid cells. Includes:
- Prophase II: nuclear envelope dissolves, chromosomes condense
- Metaphase II: chromosomes line u p at the middle of the cell
- Anaphase II: sister chromatids pull apart to opposite ends of the cell
- Telophase II: nuclear envelope reforms around the 2 sets of chromosomes and chromosomes unwind.
- Cytokinesis II: cytoplasm divides resulting in 4 haploid cells.
Nondisjunction
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Mutation that can occur during Anaphase I or Anaphase II of meiosis where the chromosomes do not separate properly resulting in cells with either too many chromosomes or not enough chromosomes.