Sunken Lesson Animal Growth and Heredity

1. Sunken Lesson Animal Growth and Heredity Grade 5

2. How Organisms Grow • Nearly all body cells produce exact copies of themselves. • Producing identical cells allows organisms to function properly and grow.

3. Cell Division • The nucleus controls everything a cell does and tells it when to divide. • Cell division is called mitosis. • During mitosis a cell makes exact copies of itself.

4. Mitosis • To prepare itself for mitosis, a cell makes an exact copy of its chromosomes • During mitosis, the chromosomes pull apart, and the cell membrane pinches in at the middle • Two new cells are formed that are identical to the parent cell

5. Regeneration • Regeneration is a kind of healing, or tissue replacement • When our skin is damaged, we heal through regeneration of new skin cells • Some plants and animals can regenerate major body parts – lizards can grow new tails and starfish can grow new arms

6. Asexual Reproduction • Many primitive organisms such as one celled bacteria reproduce by simple cell division • Only one parent is required for asexual reproduction • Yeast reproduce by budding – a new bud forms on the parent cell, grows, and then separates to form a new cell

7. Sexual Reproduction • Most organisms require two parents to reproduce • Parent cells go through meiosis to copy its chromosomes and divide • Then they go through a second stage of division where they split their chromosomes in half. • Gametes are formed with half the chromosomes of the parent cells • Two gametes join to form a one new cell

8. Life Cycles • Most organisms grow and mature through several distinct stages of life • These stages of life are called life cycles • All life cycles start with a young organism

9. Direct Development • In direct development, the young organisms are identical to the adult organism except for size • The young grow larger, but keep the same body features, such as shape, all their lives

10. Metamorphosis • Some organisms change greatly from the time that they are young to the time that they are adults. • The changes in the shape or characteristics of an organisms body as it grows and matures are called metamorphosis

11. Complete metamorphosis • Complete metamorphosis has four stages: egg, larva, pupa, adult

12. Incomplete metamorphosis • Incomplete metamorphosis has three stages: egg, nymph, adult

13. Inherited Traits • Many characteristics of an organism are passed from parent to offspring • Hair or fur color, eye color, attached or free earlobes, short or long eyelashes, tongue rolling, and dominant thumbs are examples of traits that are inherited • Traits can be dominant, or strong and seen, while others are recessive, or weak and hidden

14. Genes • Genes are structures on chromosomes that are found in a cell’s nucleus • Genes contain the code for the traits that an organism gets from its parents

15. Recessive Traits • If a recessive trait (such as light brown fur in a rabbit or blue eyes in a human) is seen, then the organism MUST have TWO genes for that trait. • That means that they received the recessive gene from both parents

16. Dominant Traits • If a dominant trait (such as dark fur or brown eyes) is seen, then the organism only needs one gene for that trait. • That means they only had to receive the dominant gene from one parent