Meiosis Worksheet #1

How Many Chromosomes in Every Cell?How Are They Arranged? In mitosis, a cell makes an exact copy of itself by copying all 46 of its chromosomes.This is a picture of the 46 chromosomes that are found in one cell. It is called a KARYOTYPE.Notice that although there are 46 chromosomes total in each cell, they are paired up with like chromosomes (HomologousChromosomes). This gives every cell 23 pairs.This pairing becomes very important as we start to talk about meiosis, the production of sperm and egg. Meiosis Why are all people different from one another?We all have different DNA.We get 50% of our DNA from our mom → found in the female gamete (the egg).We get 50% of our DNA from our dad → found in the male gamete (the sperm).These sex cells (sperm and egg) only have 1 the number of chromosomes in them. (23 chromosomes in each) so they are called haploid cells (n).How are these gametes (sex cells) made with only 1 the chromosomes and made differently each time?The answer is a process called meiosis.In meiosis, the chromosomes, make copies of themselves, but they line up in tetrads.A tetrad means 4 chromosomes across. Each chromosome lines up with its homologous pair.A HOMOLOGOUS PAIR is → A pair of chromosomes with the same length, shape, and function. They possess the same genes.After the homologous pairs divide from each other twice, and meiosis is complete, sex cells are made.These Haploid cells (23 Chromosomes) join together in a process known as fertilization to create a diploidcell with 46 chromosomes.This single diploid cell is known as a ZYGOTE. Meiosis Video Watch the video on Meiosis and notice the different things happening to the DNA. Meiosis Review Match the term with the correct definition. Female gamete egg Male gamete sperm Haploid 1 the number of chromosomes Diploid Full number of chromosomes Homologous Pair pair of chromosomes with same length, shape and function Meiosis Process that forms sex cells Zygote Cell formed after fertilization, now diploid Fertilization joining together of haploid cells into a diploid cell