Biology Chapter 8 Flashcards

Cell Division and Reproduction

• Cell Division: Fundamental process by which a cell reproduces, involving genome duplication and cytoplasmic division.
• Asexual Reproduction: Offspring produced from a single parent with identical genetic material, thereby eliminating the need for gametes.
• Sexual Reproduction: Involves fusion of two haploid gametes, resulting in genetically unique diploid offspring.

Chromosomal Structure and Dynamics

• Chromosomes: Threadlike structures in the eukaryotic cell nucleus, most evident during cellular division.
• Chromatin: DNA-protein complex forming chromosomes, critical for processes like mitosis.
• Sister Chromatids: Identical strands of duplicated chromosomes, linked at the centromere until division.

Cell Cycle and Stages of Mitosis

• Cell Cycle: Series of phases from cell formation to division, consisting primarily of interphase and the mitotic phase.
• Interphase: Majority duration of the cell cycle focused on growth and replication.
• Mitotic Phase: Cell division phase including mitosis and cytokinesis, essential for producing daughter cells.

Stages of Mitosis

• Prophase: Initial phase where chromatin condenses into visible chromosomes; mitotic spindle begins to form.
• Prometaphase: Nuclear envelope dismantles; spindle fibers attach to kinetochores of chromosomes.
• Metaphase: Chromosomes aligned at the cell's equatorial plane, ensuring proper distribution during division.
• Anaphase: Separation of sister chromatids, moving towards opposite poles, ensures equal genetic material distribution.
• Telophase: Formation of daughter nuclei at each pole, concluding mitotic division alongside cytokinesis.

Cytokinesis

• Cytokinesis: Divides cytoplasm to form two daughter cells; in animals, it forms a cleavage furrow, while in plants, a cell plate emerges.

Cancer and Cell Regulation

• Tumor: Uncontrolled mass of cells, with benign staying localized and malignant capable of metastasis.
• Growth Factors: Proteins that promote cell division and growth.
• Cell Cycle Control: Proteins ensuring orderly progression through the cell cycle, critical for normal function and prevention of cancer.

Genetic Material and Chromosome Types

• Homologous Chromosomes: Paired chromosomes equivalent in size and gene position but may carry different alleles.
• Sex Chromosomes: X or Y chromosomes that determine an individual's sex.
• Autosomes: Non-sex chromosomes present in pairs, contributing to the organism’s genetic traits.

Meiosis and Genetic Diversity

• Meiosis: Specialized cell division reducing chromosome number by half, resulting in four haploid gametes from one diploid cell.
• Tetrads: Formed during prophase I; pairs of homologous chromosomes allow genetic recombination via crossing over.
• Crossing Over: Exchange of chromatid segments between homologous chromosomes that increases genetic diversity in gametes.

Chromosomal Abnormalities

• Nondisjunction: Failed separation of chromosomes or chromatids, potentially leading to genetic disorders.
• Trisomy 21/Down Syndrome: Genetic disorder caused by an extra copy of chromosome 21, resulting in distinct physical and cognitive traits.
• Karyotypes: Ordered display of chromosomes used for identifying structural anomalies or genetic disorders.

Mutations and Genetic Variation

• Deletions: Loss of nucleotides or chromosomal segments, which may alter gene function.
• Duplications: Repeated sections of chromosomes that can lead to genetic imbalance.
• Translocations: Attaching a chromosomal fragment to a nonhomologous chromosome, potentially leading to cancer or genetic disorders.