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Understanding Active Transport and Chromosomes

Feb 19, 2025

Active Transport and Chromosomes

Active Transport

  • Definition: Movement of substances against the concentration gradient using energy from ATP.
    • Occurs from an area of low concentration to high concentration.

Types of Bulk Transport

  • Endocytosis: Process where a cell engulfs a substance or another cell by extending its membrane.
  • Exocytosis: Process of releasing contents (e.g., proteins, carbohydrates, waste) from the cell using vesicles.

Chromosomes

  • Structure: Composed of DNA-protein complexes, located in the nucleus of eukaryotic cells.
    • Humans have 46 chromosomes arranged in 23 pairs.
    • Essential for genetic information distribution during cell division (mitosis and meiosis).

Chromosome Components

  • Chromosome: Rod-shaped structure with DNA containing hereditary instructions (genes).
    • Chromatin: Unraveled form of chromosome composed of DNA and proteins.
    • Histones: Specialized proteins around which DNA strands are wrapped.
  • Genes: Sections of DNA storing genetic information.

Chromosomal Regions

  • P-arm and Q-arm: Two main segments extending from the centromere, with the q-arm being longer.
  • Centromere and Kinetochore:
    • Centromere: Central region where sister chromatids attach; crucial for chromatid segregation.
    • Kinetochore: Disc-shaped protein complex where spindle fibers form during cell division.
  • Sister Chromatids: Two identical chromatids connected to each other.
  • Telomeres: Repeated DNA sequences at the chromosome ends, protecting DNA during cell division.

Human Chromosome Classification

  • Genetic Information:
    • Autosomes: Chromosomes carrying genes for traits. Humans have 22 pairs.
    • Allosomes (Sex Chromosomes): Determine sex (X and Y chromosomes).
      • Males: XY, Females: XX.
  • Centromeric Location:
    • Metacentric: Centromere in the center, creating equal arms.
    • Submetacentric: Centromere off-center, creating one longer arm.
    • Acrocentric: Centromere near one end, creating one very long arm.
    • Telocentric: Centromere at one terminal end.

Karyotyping

  • Definition: Laboratory technique to visualize and analyze chromosomes.
    • Involves staining and pairing chromosomes.
    • Used to detect chromosomal abnormalities, represented visually as a karyogram.