Questions and Answers
What happens during Prophase 1 (early)?
DNA condenses, chromosomes become visible.
What occurs in Prophase 1 (late)?
Homologous chromosomes pair up and form tetrads; crossing-over occurs at points called 'chiasmata.'
What occurs during Metaphase 1?
Homologous chromosomes (tetrads) line up along the equator.
Describe the process that happens in Anaphase 1.
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What occurs in Telophase 1?
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What happens during Prophase II?
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What occurs in Metaphase II?
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What happens during Anaphase II?
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What occurs in Telophase II?
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What is the first division of meiosis called?
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What occurs in the second division of meiosis?
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Define mitosis.
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What is Interphase?
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What happens during G1 phase?
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What occurs during S Phase?
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What occurs during the G2 phase?
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What is prophase in mitosis?
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What occurs during metaphase in mitosis?
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What occurs during anaphase in mitosis?
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What is telophase in mitosis?
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Define cytokinesis.
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What is a centrosome?
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What is a spindle?
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Define a chromosome.
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What is a chromatid?
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What is a centromere?
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What are cyclins?
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Define carcinoma.
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What is metastasis?
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What is a mutagen?
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What defines an oncogene?
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What is a kinetochore?
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What is independent assortment?
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Study Notes
Cell Division Overview
- Meiosis consists of two divisions: Meiosis I (reduction division) and Meiosis II.
- Each phase of meiosis prepares chromosomes for the process of separation and ultimately results in four haploid daughter cells.
Meiosis Stages
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Prophase I (Early)
- DNA condenses, and chromosomes become visible.
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Prophase I (Late)
- Homologous chromosomes pair up to form a tetrad.
- Crossing-over occurs at chiasmata, allowing genetic variation.
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Metaphase I
- Tetrads align along the equator of the cell.
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Anaphase I
- Spindle fibers pull homologous chromosomes apart to opposite poles of the cell.
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Telophase I
- Cytoplasm divides, leading to the formation of two smaller daughter cells.
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Prophase II
- Chromosomes condense, becoming visible again. The nuclear membrane dissolves, and spindle fibers reappear.
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Metaphase II
- Chromosomes (each with two chromatids) line up along the equator without homologous pairs.
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Anaphase II
- Sister chromatids are separated and move towards opposite ends of the cell.
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Telophase II
- Nuclear membranes reform, cytoplasm divides, resulting in four haploid daughter cells.
Mitosis Process
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Mitosis is the division of the nucleus, producing two daughter nuclei.
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Prophase (Mitosis)
- Chromosomes condense and become visible as sister chromatids joined at the centromere.
- The nucleolus disintegrates and the nuclear membrane breaks down.
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Metaphase (Mitosis)
- Chromosomes align at the metaphase plate, attaching to microtubules at the kinetochore.
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Anaphase (Mitosis)
- Sister chromatids are pulled apart towards opposite poles; this phase is typically the shortest in mitosis.
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Telophase (Mitosis)
- Chromatids reach poles and are redefined as chromosomes; the nuclear membrane reforms.
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Cytokinesis
- Division of the cell's cytoplasm results in two new cells.
Cell Cycle Phases
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Interphase
- Comprises G1, S, and G2 phases where growth and DNA synthesis occur.
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G1 Phase
- Cell is at its smallest size and grows, followed by a checkpoint for readiness to progress.
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S Phase
- Each of the 46 chromosomes undergoes duplication.
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G2 Phase
- Final growth phase with a checkpoint before mitosis.
Cellular Components
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Centrosome
- Composed of two centrioles, aiding in cell division by organizing spindle fibers.
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Spindle
- A microtubule structure crucial for chromosome separation during division.
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Chromosomes
- Linear DNA molecules wrapped around histones; become visible during prophase.
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Chromatids
- Result from replication of chromosomes, appearing as two strands.
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Centromere
- Region where sister chromatids are joined and where spindle fibers attach.
Cancer and Genetics
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Cyclins
- Proteins that regulate the cell cycle's progression.
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Carcinoma
- A type of cancerous tumor.
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Metastasis
- The process where cancer cells spread beyond their original site.
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Mutagen
- An agent that interacts with DNA, potentially causing mutations.
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Oncogene
- Genes that may cause cancer following mutations.
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Kinetochore
- Structure that links spindle fibers to centromeres during cell division.
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Independent Assortment
- Random assortment of chromosomes during meiosis, contributing to genetic diversity.
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Test your knowledge on the stages of meiosis with these flashcards. Each card contains essential definitions and key processes like prophase, metaphase, and anaphase. Great for students studying cell biology and genetics.