utosomes 22 pairs Control most body traits Example: eye color, height, hair type 2. Sex chromosomes 1 pair Determine biological sex Usually: XX = female XY = male What do chromosomes do? Chromosomes contain genes that tell the body: how to grow how cells work how proteins are made inherited traits For example: hair color blood type some diseases Why are chromosomes important? When cells divide, chromosomes copy and pass information to new cells. If chromosome number changes, it can cause genetic conditions. Example: People with Down syndrome usually have 47 chromosomes instead of 46 because there is an extra chromosome 21. 的热门建议 |