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.