Overview
This lecture covers the structure and types of human chromosomes, their arrangement in males and females, and how they determine the sex of offspring.
Structure of Human Chromosomes
- The human body is made up of cells, each containing a nucleus with chromosomes.
- Humans have 46 chromosomes, organized into 23 pairs.
Types of Chromosomes
- Chromosomes are divided into autosomes (body chromosomes) and gonosomes (sex chromosomes).
- Autosomes: 44 chromosomes in both males and females.
- Gonosomes: Different in males (XY) and females (XX).
Chromosomes in Males and Females
- Male chromosomes: 44 autosomes + XY (can also be written as 22 pairs AA + XY = 23 pairs).
- Female chromosomes: 44 autosomes + XX (or 22 pairs AA + XX = 23 pairs).
Sex Cell Chromosomes (Gonosomes)
- Male sex cells (sperm) have two types: 22 autosomes + X or 22 autosomes + Y.
- Female sex cells (ovum) only have one type: 22 autosomes + X.
Determination of Offspring Sex
- If an X-type sperm fertilizes the ovum (X), the result is 44 autosomes + XX (female offspring).
- If a Y-type sperm fertilizes the ovum (X), the result is 44 autosomes + XY (male offspring).
Key Terms & Definitions
- Chromosome — a structure in cell nuclei carrying genetic information.
- Autosome — a non-sex chromosome (body chromosome); 22 pairs in humans.
- Gonosomes — sex chromosomes (X and Y); different combinations determine biological sex.
- Sperm — male sex cell, carrying either X or Y chromosome.
- Ovum — female sex cell, always carrying an X chromosome.
Action Items / Next Steps
- Complete the assigned task on human chromosomes for Samisanov 11 training.