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Cell Division and Growth: A Journey of Life

Explore the impact of cell division on growth and development in organisms. Learn about the stages of life cycles, the process of mitosis, regeneration, and the significance of sexual and asexual reproduction.

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Cell Division and Growth: A Journey of Life

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  1. Chapter 7Growth and InheritanceLesson 1 By: Mr. Vorick

  2. Lesson 1 Essential Question: • How Does Cell Division Affect Growth? • A:

  3. Vocabulary • Life Cycle- The stages that a living thing passes through as it grows and changes • Mitosis- the process by which most cells divide • Chromosome- a threadlike structure in the nucleus, made up of DNA

  4. Cell Reproduction Lab Observation Chart

  5. Cell Reproduction Lab Conclusions • How many new cells does each cell division produce? • What part of a cell changes as the cell divides? What changes take place? • Scientists observe and ask questions based on their observations. What questions do you have about cell division, based on your own observations?

  6. Growth and Development • All organisms start life as a SINGLE cell. • Complete plant and animal cells are made up of trillions of cells!! • Cell division allows your body organs and systems to function properly as you grow.

  7. Baby chick development • Begins life as a single cell • After 7 days the cell divides into many cells • After 14 days, the skeleton and most organs are formed • By day 21, the chick is fully developed, hatched, and lives on its own

  8. Life Cycle • Living things grow and change in stages • These stages make up the organism’s life cycle • Life Cycle begins with a fertilized egg • Some animals develop inside their mother’s body • Other animals develop in a protective egg, then hatch

  9. Life Cycle Cont… • Some organisms are mature as soon as they are formed (bacteria and protists) and can reproduce immediately • Others take months or years to mature before being able to reproduce (mammals)

  10. Metamorphosis • Some animals change types of bodies as they mature • The changes they go through are called Metamorphosis • Ex: Butterflies—egg, caterpillar, pupa, butterfly • Frog—egg, tadpole, frog

  11. Cell Division Mitosis • Most cells divide through Mitosis • Each new cell gets a copy of the parent cell’s chromosomes (passes DNA). The new cells look and function just as the parent cell. • Mitosis is directed by the nucleus. • The nucleus copies its chromosomes • Chromosomes contain DNA that contains the information that directs how a cell functions

  12. Cell Division: Mitosis Cont… • Exact copies of each chromosome are made for the new cell • The new chromosomes separate and the cell membrane pinches in the middle forming two new cells • Each cell is identical to its parent cell • Check out www.hspscience.com for an animation of Mitosis

  13. Cell Division: Regeneration • The process of replacing tissue is called regeneration • Ex: new skin cells replace lost skin cells • Math link—150,000 skin cells in a square centimeter of skin---reproduce twice daily. • Some animals can regenerate entire body parts • Ex: sea stars—loses an arm…regenerates a new arm • Ex: Lizards—loses a tail…regenerates a new tail

  14. Single Celled Reproduction • When single celled organisms divide, the entire organisms reproduces. • Asexual reproduction —when an organism reproduces without joining of cells from different parents • Ex: Yeast

  15. Reproduction • Most multicellular organisms reproduce by the joining of cells from two different individuals— Sexual Reproduction • Cells join forming a Zygote or fertilized egg. • Organisms that reproduce sexually have two types of cells • Body cells • Reproductive cells or gametes • Gametes contain only half the number of chromosomes of body cells. When two gametes meet the zygote then has the same number of chromosomes as the rest of the body cells.

  16. Meiosis • Gametes are formed • The number of chromosomes in a cell is divided in half. 46 to 23 • Meiosis occurs in 2 stages • Stage 1—chromosomes are copied and cell divides • Stage 2—the 2 new cells divide again without copying their chromosomes (now they have 23 instead of 46 chromosomes)

  17. Meiosis Cont.. • Why must gametes contain only half the number of chromosomes??? • A:

  18. Essential Question • How does cell division affect growth? • A: Cell reproduction allows organisms to grow and reproduce.

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