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What is the main outcome of meiosis?
What is the main outcome of meiosis?
Mitosis results in cells that are genetically identical to the parent cell.
Mitosis results in cells that are genetically identical to the parent cell.
True
What type of cells does meiosis produce?
What type of cells does meiosis produce?
Gametes
Meiosis occurs in the __________ of an organism to form gametes.
Meiosis occurs in the __________ of an organism to form gametes.
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Match the following phases with their functions in meiosis:
Match the following phases with their functions in meiosis:
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How does meiosis contribute to genetic diversity?
How does meiosis contribute to genetic diversity?
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Compare and contrast the processes of meiosis and mitosis.
Compare and contrast the processes of meiosis and mitosis.
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What role do homologous chromosomes play during meiosis?
What role do homologous chromosomes play during meiosis?
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Why is the reduction of chromosome number important in meiosis?
Why is the reduction of chromosome number important in meiosis?
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What forms the basis of genetic variability in offspring produced by meiosis?
What forms the basis of genetic variability in offspring produced by meiosis?
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Study Notes
Cell Division
- Cell division is the process where a cell divides to form new cells.
- There are three types of cell division or cell reproduction in an organism:
- Prokaryotes (bacteria): Binary fission
- Eukaryotes: Mitosis and Meiosis
Prokaryotic Cell Division (Binary Fission)
- Three major steps:
- DNA Replication: DNA is copied, resulting in two identical chromosomes.
- Chromosome Segregation: Chromosomes separate and move to opposite ends (poles) of the cell.
- Cytokinesis (Separation): The cytoplasm divides, forming two new cells.
- Each new daughter cell is genetically identical to the parent cell.
Eukaryotic Cell Division
- Mitosis: Cell division that results in two daughter cells having the same number and kind of chromosomes as the parent cell.
- Two main steps:
- Mitosis: Four steps [Prophase, Metaphase, Anaphase, Telophase]
- Cytokinesis: Cytoplasm divides, forming two new daughter cells
- Two main steps:
- Meiosis: Cell division that results in four daughter cells, each having half the number of chromosomes as the parent cell.
- Two main steps:
- Mitosis: Four steps [Prophase, Metaphase, Anaphase, Telophase]
- Cytokinesis: Cytoplasm divides, forming two new daughter cells
- Two main steps:
Why Do Cells Divide?
- Growth, development, repair, and reproduction.
- Facilitating the exchange of materials.
- Controlling DNA overloading.
The Cell Cycle (Eukaryotes)
- Sequence of events from when a cell first arises until it divides.
- Two main periods:
- Interphase: Period of growth and DNA replication.
- Three phases:
- G1 Phase: Cell increases in size
- S Phase: DNA replication, two sister strands of DNA called chromatids are produced
- G2 Phase: Organelles double, new cytoplasm forms, all other structures needed for mitosis are formed
- Three phases:
- Mitotic Phase: Cell division.
- Split into two (2) mitotic phases:
- Mitosis: Divided into four stages (Prophase, Metaphase, Anaphase, Telophase)
- Cytokinesis: Cytoplasm divides
- Split into two (2) mitotic phases:
- Interphase: Period of growth and DNA replication.
Mitotic Phase (Mitosis)
- Stage when a cell divides
- Process:
- Division of the nucleus (Mitosis)
- Separation of cytoplasm and the new nuclei into daughter cells (Cytokinesis)
- Four stages of Mitosis:
- Prophase: Chromosomes condense, nuclear membrane fragments, centrioles move to opposite poles, spindle begins to form
- Metaphase: Chromosomes align at the metaphase plate, centrioles project spindle fibers to connect each chromosome
- Anaphase: Paired chromosomes (sister chromatids) separate, move to opposite poles, cytoplasm partially divides
- Telophase: Chromosomes are at the poles, chromosomes uncoil (turn into chromatin), nuclear envelope reforms, spindle fibers disappear
Cytokinesis
- Occurs at the end of mitosis.
- Animal cells: A cleavage furrow separates the daughter cells
- Plant cells: A cell plate separates the daughter cells
- Daughter cells are genetically identical
Meiosis
- Meiosis is sexual reproduction that halves the chromosome number so offspring is normal and shows variation
- Meiosis produces gametes (sex cells)
- Gametes have half the number of chromosomes (Haploid) compared to the original parent cell (Diploid)
Stages of Meiosis I
- Interphase I: Cell buildup energy. DNA replication. No structural changes.
- Prophase I: Longest and most complex phase. Chromosomes condense. Synapsis (homologous chromosomes pairing to form a tetrad) occurs. Crossing over (exchange of genetic material between non-sister chromatids) happens.
- Metaphase I: Homologous pairs align at the cell equator.
- Anaphase I: Homologous chromosomes separate, move to opposite poles
- Telophase I: Spindle fibers disintegrate. Chromosomes partially de-condense. Nuclear membranes may form around genetic material. Cytokinesis occurs.
Stages of Meiosis II
- Prophase II: Nuclear envelopes dissolve, new spindle fibers form.
- Metaphase II: Individual duplicated chromosomes align along the equator.
- Anaphase II: Sister chromatids separate, move to opposite poles.
- Telophase II: Daughter chromosomes reach poles. Two cells invaginate to form four daughter haploid cells (gametes). They uncoil, form chromatin, nuclear envelope and nucleolus for around chromatin. Centrioles for centrosome.
- Result: Four cells with haploid sets of chromosomes.
Errors in Meiosis
- Non-disjunction: Failure of chromosomes to separate as they move to opposite poles during either meiotic division.
- Aneuploid Gametes: Gametes with missing or extra chromosomes.
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Description
Explore the fascinating processes of cell division, including binary fission in prokaryotes and mitosis and meiosis in eukaryotes. This quiz will test your understanding of DNA replication, chromosome segregation, and cytokinesis. Perfect for students studying biology and cell science.
