Understanding Mitosis and Meiosis: Key Phases and Importance
This resource explores the processes of mitosis and meiosis, highlighting their phases and significance in cellular reproduction. Mitosis involves one division leading to two identical cells for growth and repair, while meiosis entails two divisions producing four genetically diverse gametes (sperm and eggs) essential for sexual reproduction. Key terms such as diploid, haploid, and zygote are explained to aid understanding of the genetic implications of these processes. Helpful links and review materials are provided for deeper learning.
Understanding Mitosis and Meiosis: Key Phases and Importance
E N D
Presentation Transcript
DO NOW! • What does PMAT stand for? • What happens during telophase? • What happens during metaphase?
Agenda • Science fair projects are late. • Parent Letters…I only have about 20 • Many of you did not complete the Protists/Organelles Open Book Test—If you did not, please see me. • Notebook Check tomorrow • Mitosis Review • Meiosis • What is it? • Why do we have it? • Why is it important?
Mitosis Review…for some Candy… • What are the steps of mitosis? • What is the purpose of mitosis? • Is it asexual or sexual? Why?
Vocabulary • Gamete: Sex Cell (sperm or egg) • Diploid: Have pairs of chromosomes • Haploid: Have half the number of chromosomes • Zygote: Combination of Sex Cells after fertilization • Homogolous: Matching pairs
Diploid vs. Haploid http://www.youtube.com/watch?v=MU83VWAvUf4
MEIOSIS is… • Meiosis is a form of cell division that produces SEX CELLS (gametes), such as sperm and egg. • Gametes are haploid; they have only half the number of chromosomes as a normal body cell. • Fertilization restores the chromosomes in body cells to the diploid number.
Purpose of Meiosis • Produce haploid eggs and sperm (23 chromosomes in humans) • Meiosis consists of two cell divisions. • Meiosis I separates pairs of homologous chromosomes (46 chromosomes in each cell) • Meiosis II separates sister chromatids (23 chromosomes in each egg or sperm)
Simplified… • MEIOSIS creates the variety we see among individuals (animals, plants, etc.) because it leads to the mixing of genetic information
Phases of Mitosis • Two phases! • Remember PMAT? • Prophase, Metaphase, Anaphase, Telophase? • In Meiosis there is PMAT TWICE
So is Meiosis Sexual or Asexual? For candy, tell me which one and why….
Some things to look at: • http://www.cellsalive.com/meiosis.htm • http://www.youtube.com/watch?v=D1_-mQS_FZ0 • http://www.youtube.com/watch?v=iCL6d0OwKt8
Mitosis vs. Meiosis • During prophase I: The chromosomes become visible and the centrioles begin forming spindle fibers • At this stage each chromosome is split into two sister chromatids. • The paired chromosomes now have four chromatids (2 sets of 'sisters') pressed together. • Crossing over takes place between two of the non-sister chromatids; the other two remain uncrossed. The crossover results in the exchange chromosomes.
SO TO REMEMBER… • Mitosis— • Growth, Repair, and reproduction of simple cells • One cell to two identical offspring cell • Asexual • PMAT • Meosis— • Reproduction process to create sperm and eggs • One cell to four different offspring cells with half the number of chromosomes • Sexual Reproduction process • PMATPMAT
Exit Ticket Meiosis Mitosis
