Sexual Reproduction Genetic materials from two different cells combine Produces offspring Egg- forms in overy Sperm- forms in testis
Fertilization Egg and sperm join to form a new cell Zygote- new cells formed by fertilization Zygote goes through mitosis and cell division
Types of Cells 2 types of cells → sex cells and body cells Similar characteristics occur in pairs Diploid cells are cells that have pairs of chromosomes
Homologous Chromosomes Homologous chromosomes- pairs of chromosomes that have genes for the same traits arranged in order. Chromosomes from each parent is different EX. (dad- blue eyes/ mom- brown eyes)
Number of chromosomes Different organisms have different numbers of chromosomes. EX. Cat- 38, human- 46, dog- 78, fly- 8 Too many or not enough chromosomes will develop problems. (down syndrome)
Haploid cells Cells that only have 1 chromosome from each pair Sexual reproduction forms sperm and eggs (sex cells) Occurs because of meiosis → 1 diploid cell divides and makes 4 haploid sex cells Meiosis only occurs during the formation of sex cells
Phases of Meiosis Interphase- copy made Meiosis 1 1) -Prophase membrane breaks apart -Chromosomes condense and form homologous pairs -Nucleus disappears
Phases of Meiosis 2) metaphase 1 (middle) -chromosomes line up along center of cell - spindle fibers attach to each chromosome 3) anaphase (away) -chromosomes separate and are pulled to opposite ends - sister chromatids stay together 4) Telophase 1 - nuclear membrane forms around each set of chromosomes -cytoplasm divides- forms 2 daughter cells - sister chromatids stay together