cell cycle

Chapter 10: Sexual Reproduction and Genetics CHROMOSOMES AND CHROMOSOME NUMBER -Human body cells have 46 chromosomes -Each parent contributes 23 chromosomes -Homologous chromosomes- one of two paired chromosomes, one from each parent -Same length -Same centromere position -Carry genes that control the same inherited traits HAPLOID AND DIPLOID CELLS -An organism produces gametes to maintain the same number of chromosomes from generation to generation -Human gametes contain 23 chromosomes -A cell with n chromosomes is a haploid cell -A cell with 2n chromosomes is a diploid cell - MEIOSIS I -The sexual life cycle in animals ivolves meiosis -Meiosis produces gametes -When gametes combine in fertilization, the number of chromosomes is restored MEIOSIS

Chapter 9: Cellular Reproduction CELLULAR GROWTH -As the cell grows, its volume increases much more rapidly than the surface area. -The cell might have difficulty supplying nutrients and expelling enough waste products. TRANSPORT OF SUBSTANCES -Substances move by diffusion or by motor proteins. -Diffusion over large distances is slow and inefficient. -Small cells maintain more efficient transport systems. CELLULAR COMMUNICATIONS -The need for signling proteins to move throughout the cell also limits cell size. -Cell size affects the ability of the cell to communicate instructions for cellular functions. THE CELL CYCLE -Cell division prevents the cell from becoming too large -It also is the way the cell reproduces so that you grow and heal certain injuries