Chromosome

• Chromosome: a thread-like structure of DNA, made up of a string of genes
• Gene: a length of DNA that is the unit of heredity and codes for a specific protein. A gene may be copied and passed on to the next generation
• Allele: any of two or more alternative forms of a gene
• Haploid nucleus: a nucleus containing a single set of unpaired chromosomes (e.g. sperm and egg)
• Diploid nucleus: a nucleus containing two sets of chromosomes (e.g. in body cells)
• Inheritance of gender in humans: woman’s gamete can only carry an “X” chromosome, and a male gamete can carry either an “X” or “Y” chromosome; females are “XX” while males are “XY”. There is always a 50% chance of getting a boy and vice versa.