Meiosis vs Mitosis

Cells divide and reproduce in two ways: mitosis and meiosis. Mitosis is a process of cell division that results in two genetically identical daughter cells developing from a single parent cell. Meiosis, on the other hand, is the division of a germ cell involving two fissions of the nucleus and giving rise to four gametes, or sex cells, each possessing half the number of chromosomes of the original cell. Mitosis is used by single-celled organisms to reproduce; it is also used for the organic growth of tissues, fibers, and membranes. Differences in Purpose Though both types of cell division are found in many animals, plants, and fungi, mitosis is more common than meiosis and has a wider variety of functions. Meiosis is a more specific type of cell division (of germ cells, in particular) that results in gametes, either eggs or sperm, that contain half of the chromosomes found in a parent cell. A diagram showing the differences between meiosis and mitosis. Meiosis and Genetic Diversity

NOVA Cells Divide: Mitosis vs. Meiosis by Rick Groleau As viewed from a human perspective, nature has done some ingenious engineering to overcome some of the obstacles it has faced. Take the evolution of sex, for instance. Mitosis describes the process by which the nucleus of a cell divides to create two new nuclei, each containing an identical copy of DNA. How exactly does meiosis mix and halve chromosomes? Flash is a plug-in that allows for increased interactivity. Rick Groleau is managing editor of NOVA Online. This feature originally appeared on NOVA's "18 Ways to Make a Baby" Web site, www.pbs.org/nova/baby/. Watch the Program | The Stem-Cell Debate | Windows on the Womb Great Expectations | How Cells Divide | How is Sex Determined? Search | Site Map | Previously Featured | Schedule | Feedback | Teachers | Shop Join Us/E-Mail | About NOVA | Editor's Picks | Watch NOVAs online | To print PBS Online | NOVA Online | WGBH

Cell Structure & Function Cell Structure and Function Organelles and Their Functions In this lab you will look at the eukaryotic cells of plants and animals. Think of the cell as a microscopic city. The NUCLEUS (“mayor of city hall”) The nucleus houses the majority of genetic material of a cell. A nucleus with the DNA coiled into chromatin. RIBOSOMES (“lumber or brick yard”) The ribosomes carry out manual labor in the form of protein synthesis for the nucleus. The large and small subunits of ribosomal RNA translating an mRNA strand into a polypeptide chain. The ENDOPLASMIC RETICULUM (“highways and road systems”) There are two types of endoplasmic reticulum (ER) – Smooth ER and Rough ER. Can you tell the difference between the smooth and rough ER? CELL MEMBRANE (“City Border”) and CELL WALL (“City Wall”) Cell membranes are found in animal cells whereas cell walls are found in plant cells. Artist rendition of an animal cell membrane. CYTOSKELETON (“steel girders”) CYTOPLASM (“lawns and parks”) Plant versus Animal Cells

Cell City Teacher Page Teacher Page: This project can be done as a two day, or on-going project. The Team Page and the Activity Page can be done separately if time is limited. This project could be done anytime during your study of the cell. Below are some suggested analogies for city structures. It would be wise to discuss the definition of an analogy with the class. Enrichment activity: Have the students design a giant cell mural on your wall or white/ black board using their organelle/city drawings. Standards connection: The following California Science Content Standards are related to this lesson: Grade 7, Life Science 1. a. cells function similarly in all living organisms. b. the characteristics that distinguish plant cells from animal cells, including chloroplasts and cell walls. c. the nucleus is the repository for genetic information in plant and animal cells. d. mitochondria liberate energy for the work that cells do, and chloroplasts capture sunlight energy for photosynthesis.

Traveling Nitrogen Classroom Activity The illustration above shows how nitrogen travels through the living and non-living parts of the Earth system. Click on image for full size NCAR Welcome to the resource page for the Traveling Nitrogen Classroom Activity! In this classroom activity, students play the role of nitrogen atoms traveling through the nitrogen cycle to gain understanding of the varied pathways through the cycle and the relevance of nitrogen to living things. The latest version of this activity is linked below with the other associated files that you will need to play the game in your classroom. Links to related articles on Windows to the Universe provide background information and learning extensions for students. The Traveling Nitrogen Activity: Related Articles on Windows to the Universe An older version of the game which utilized rubber stamps instead of stickers is also available. Shop Windows to the Universe Science Store! Our online store includes fun classroom activities for you and your students. Nitrogen