81 Chromsomes

1
8-1 Chromsomes
2
Structure

• Rod-shaped
• Made of DNA and proteins (histones)
• Two identical halves (chromatids)
• Joined by a centromere

3
Chromosome Number

• Each species has a characteristic number
• Humans have 46 (diploid number/2n) in all cells
  except sex cells
• Humans have 23 (haploid/n) in sex cells
  (gametes/eggs and sperm)
• Chromosomes occur in homologous pairs
• One of each pair is from the mother and one from
  the father

4
Chromosome Categories

• Sex Chromosomes determine sex
• Human Male XY, Female XX
• Autosomes all other chromosomes

5
Karyotype photomicrograph of chromosomes