1. Chromosomes are threadlike structures in the nucleus of a cell that contain hereditary traits.
2. Genes are segments of DNA on chromosomes that determine specific traits, such as eye color or blood type.
3. Each body cell has 46 chromosomes (23 pairs), while sex cells (sperm and egg) have 23 chromosomes each.
4. During sexual reproduction, a sperm and egg combine to form a zygote with 46 chromosomes (23 from each parent).
5. Chromosomes come in pairs; one chromosome in each pair is inherited from each parent.
6. A gene is a segment of DNA on a chromosome that controls a specific trait.
7. Alleles are different versions of the same gene; for example, brown eyes vs. blue eyes.
8. Homozygous means having two identical alleles for a trait (e.g., BB or bb); heterozygous means having two different alleles (e.g., Bb).
9. Dominant alleles mask recessive alleles; a dominant trait is expressed if at least one dominant allele is present.
10. Recessive traits are only expressed when both alleles are recessive (e.g., bb for blue eyes).
Parent Tip: Review the logic above to help your child master the concept of chromosome worksheet answers.
