Overview
This lecture explains the concepts of haploid and diploid cells, focusing on chromosome sets in humans and their biological significance.
Chromosome Sets and Ploidy
- Haploid cells contain one set of chromosomes, represented as N.
- Diploid cells have two sets of chromosomes, represented as 2N.
- In humans, diploid cells contain 46 chromosomes (23 pairs).
- Each chromosome pair consists of one chromosome from the mother and one from the father.
- Homologous chromosomes in each pair are genetically different but code for the same characteristic (e.g., eye color).
- Having pairs means humans have 23 types of chromosomes, each in duplicate.
Chromosomes in Human Cells
- All human organs and tissues are made of diploid cells.
- Each diploid cell has two of each chromosome type (e.g., two type 1, two type 2, etc.).
- Sperm and egg cells are haploid, each with 23 unpaired chromosomes.
- Upon fertilization, haploid sperm and egg combine to make a diploid cell.
Biological Significance
- One set of chromosomes is inherited from each parent, leading to genetic variation.
- The distinction between haploid and diploid is important in understanding reproduction and genetics.
Key Terms & Definitions
- Haploid (N) — a cell with one set of chromosomes.
- Diploid (2N) — a cell with two sets (pairs) of chromosomes.
- Homologous Chromosomes — chromosome pairs, one from each parent, coding for the same traits with variant alleles.
Action Items / Next Steps
- Review the definitions of haploid and diploid.
- Memorize that humans have 23 chromosome pairs (46 chromosomes) in diploid cells.
- Understand which human cells are haploid and which are diploid.