Cell-ebrate!Mini-lessons to help students visualize the tiny, but mighty, cell What do people and plants, wombats and weeds, and even dinosaurs from eons ago all have in common? Cells! A cell can be defined as a small organized container that holds chemicals needed for life. Every living thing on earth is made up of cells. Primary Grade Levels MEET THE CELLS Share with your class that the human body is made up of millions of cells and that all of them have some basic things in common. * Let children work in small groups. Give students each a grape and ask them to imagine it is a cell. What do they notice about it as they observe and touch it? For one thing, it has a flexible covering called a cell membrane Cell membrane The membrane that surrounds the cytoplasm of a cell; it is also called the plasma membrane or, in a more general sense, a unit membrane. This is a very thin, semifluid, sheetlike structure made of four continuous monolayers of molecules. . * Now give each group a circular kitchen sponge and suggest that it is a cross-section, or a slice, of the cell. Like the inside of a cell, it has little compartments, or "rooms." * Finally, give each group a round shape, cut from construction paper, on which the word nucleus is written. Have them place it flat in the center of the sponge. Explain that the nucleus is the central "information room" of the cell. Intermediate Grade Levels CELL DIVISION Explain to students that one of the most amazing a·maze v. a·mazed, a·maz·ing, a·maz·es v.tr. 1. To affect with great wonder; astonish. See Synonyms at surprise. 2. Obsolete To bewilder; perplex. v.intr. things about cells is that have the ability to reproduce. They can do this through sexual reproduction sexual reproduction n. Reproduction by the union of male and female gametes to form a zygote. Also called syngenesis. or asexual reproduction asexual reproduction n. Reproduction occurring without the sexual union of male and female gametes. . Let students work with balls of clay in three different colors to visualize the difference. * Asexual reproduction, or mitosis (my-TOE-sis), occurs when a cell splits and creates two new cells, each exactly alike. Give each student a ball of clay to represent one cell. Explain that before a cell divides, it first has to grow. Have students add more clay to the "growing cell a device for preserving alive a minute object in water continually renewed, in a manner to permit its growth to be watched under the microscope. See also: Grow ." Inside the cell, a complex process is taking place. The cell is duplicating material inside its nucleus called DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. (deoxyribonucleic acid), making a complete extra set. DNA, made up of various nucleic acids Nucleic acids The cellular molecules DNA and RNA that act as coded instructions for the production of proteins and are copied for transmission of inherited traits. , determines everything about the cell. * When the duplication is complete, the cell will split in half, each with its own nucleus. To demonstrate this, have students break the ball into two equal pieces. Point out that each piece is an exact copy of its "parent." These two new cells will grow, then also split. * During sexual reproduction, or meiosis (my-OH-sis), a cell produces two haploid cells, each of which contains half of the original cell's material. Haploid cells are also called sex cells - sperm cells in males and egg cells in females. When one haploid haploid /hap·loid/ (hap´loid) 1. having half the number of chromosomes characteristically found in the somatic (diploid) cells of an organism; typical of the gametes of a species whose union restores the diploid number. egg cell fuses with one haploid sperm cell, they create a brand-new cell. Give students two balls of clay in different colors. Tell them to break each ball in two, then to mush (MultiUser Shared Hallucination) See MUD. 1. (games) MUSH - Multi-User Shared Hallucination. 2. (messaging) MUSH - Mail Users' Shell. the two balls together. The size is now the same, yet the resulting new cell is different from the parent cells. All living beings - from the tiniest creature to the tallest tree - are able to exist because they are made up of cells. Cells really do give us reasons to "cell-ebrate"! Lisa Trumbauer is a writer of children's books and educational materials. |
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