1. Chapter 7 Growth and Inheritance Lesson 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
Animal Cell
Plant Cell

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 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 Meiosis occurs in 2 stages
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.