Lesson Overview. Homeostasis and Cells. Lesson Overview. 7.4 Homeostasis and Cells

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Leonard Hutchinson
6 years ago
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1 Lesson Overview 7.4

2 THINK ABOUT IT What s the smallest part of any living thing that still counts as being alive? Can we just keep dividing living things into smaller and smaller parts, or is there a point at which what s left is no longer alive? As you will see, there is such a limit. The smallest living unit of any organism is the cell.

3 The Cell Theory Soon after the invention of the microscopek, observations were made by scientists that made it clear that cells were the basic units of life. In 1838, German botanist Matthias Schleiden concluded that all plants are made of cells. The next year, German biologist Theodor Schwann stated that all animals were made of cells. In 1855, German physician Rudolf Virchow concluded that new cells could be produced only from the division of existing cells, confirming a suggestion made by German Lorenz Oken 50 years earlier.

4 The Cell Theory These discoveries are summarized in the cell theory, a fundamental concept of biology. The cell theory states: -All living things are made up of cells. -Cells are the basic units of structure and function in living things. -New cells are produced from existing cells.

THINK ABOUT IT The diversity of life is so great that you might have

the same basic chemistry, and even contain the same kinds of

Differences arise from the ways in which cells are specialized and

5 THINK ABOUT IT The diversity of life is so great that you might have to remind yourself that all living things are composed of cells, use the same basic chemistry, and even contain the same kinds of organelles. This does not mean that all living things are the same. Differences arise from the ways in which cells are specialized and the ways in which cells associate with one another to form multicellular organisms.

6 Multicellular Life The cells of multicellular organisms are interdependent, and like the members of a successful baseball team, they work together. In baseball, players take on a particular role, such as pitcher, catcher, infielder, or outfielder. Messages and signals are sent and understood by teammates and coaches to play the game effectively. Cells in a multicellular organism work the same way. The cells of multicellular organisms become specialized for particular tasks and communicate with one another in order to maintain homeostasis. This is referred to as Division of Labor.

7 Cell Specialization The cells of multicellular organisms are specialized, with different cell types playing different roles. Some cells are specialized to move, others to react to the environment, and still others to produce substances that the organism needs. No matter what the role, each specialized cell contributes to the overall homeostasis of the organism.

8 Specialized Animal Cells Particles of dust, smoke, and bacteria are part of even the cleanest air. Specialized animal cells act like street sweepers to keep the particles out of the lungs. These cells are full of mitochondria, which provide a steady supply of the ATP that powers the cilia on their upper surfaces.

9 Levels of Organization 1.Cell

10 Levels of Organization The specialized cells of multicellular organisms are organized into tissues, then into organs, and finally into organ systems. Cell: The smallest living unit of any organism

11 2. Tissue

12 Levels of Organization Tissue: a group of similar cells that performs a particular function.

13 3. Organ

14 Levels of Organization Organ: many groups of tissues work together to perform complicated tasks. Each type of tissue performs an essential task to help the organ function. In most cases, an organ completes a series of specialized tasks.

15 4. Organ System

16 Levels of Organization Organ system: a group of organs that work together to perform a specific function For example, the stomach, pancreas, and intestines work together as the digestive system.

17 5.Organism

18 Levels of Organization The organization of the body s cells into tissues, organs, and organ systems creates a division of labor among those cells that allows the organism to maintain homeostasis.

Lesson Overview. Homeostasis and Cells. Lesson Overview. 7.4 Homeostasis and Cells

Lesson Overview. Homeostasis and Cells. Lesson Overview. 7.4 Homeostasis and Cells Lesson Overview 7.4 THINK ABOUT IT The diversity of life is so great that you might have to remind yourself that all living things Are composed of cells Use same basic chemistry Contain same kinds of organelles.