1. Chapter 7.4
Homeostasis and Cells

2. Daily Objectives
Compare and contrast how unicellular and multicellular organisms maintain homeostasis.
Explain why cell specialization is important for multicellular organisms.

3. Homeostasis
Homeostasis is relatively constant internal physical and chemical conditions.
Both unicellular and multicellular organisms must maintain homeostasis.
In the box on your notes draw a diagram that will help you remember homeostasis.

4. Homeostasis
Homeostasis is relatively constant internal physical and chemical conditions.
Both unicellular and multicellular organisms must maintain homeostasis.
In the box on your notes draw a diagram that will help you remember homeostasis.

5. Homeostasis

6. Unicellular Organisms
Cells are the basic living units of all organisms, but sometimes one cell is the entire organism
In order to maintain homeostasis unicellular organisms must:
Grow
Respond to the environment
Transform energy
Reproduce

7. Unicellular Organisms include:
Prokaryotes (Bacteria)
Remarkably adaptable
Live almost everywhere (including inside of us)
Eukaryotes (Protists , algae, and yeast)
Have a nucleus
Contain membrane bound organelles
Live in a variety of places
Able to do everything necessary to live independently

8. Examples of Unicellular Organisms

9. Multicellular Organisms
Always Eukaryotes
Like unicellular organisms, multicellular organisms show all the characteristics of life
However, multicellular organisms depend on communication and cooperation among specialized cells
Cell specialization - Cells throughout an organism develop in different ways to perform different tasks

10. Analogy for Cell Specialization
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11. Examples of Specialized Animal Cells
Red Blood Cells – Specialized to transport oxygen
Contain a protein (hemoglobin) that binds to oxygen
Pancreatic Cells – Specialized to produce enzymes (proteins) that make it possible to digest food
What organelles would pancreatic cells have a lot of?
Skeletal Muscle Cells – Specialized to produce a force using a dramatically overdeveloped cytoskeleton → so organisms can move

12. Examples of Specialized Animal Cells

13. Levels of Organization
Used to make it easier to describe multicellular organisms
Cells → Tissues → Organs → Organ Systems → Organism

14. Tissues A group of similar cells that perform a particular function
Example: skin tissue, muscle tissue, or nerve tissue

15. Organs
Many tasks within the body are too complicated to be carried out by just one type of tissue
Many groups of tissues work together as an organ → each tissue performs an essential task to help the organ function
In most cases, organs complete a series of specialized tasks
Example: lung, heart, and brain

16. Organ Systems
A group of organs that work together to perform a specific function is called an organ system
Example:
Cardiovascular System
Respiratory System
Digestive System

17. Importance of Cell Specialization
Organization of the body’s cells into tissues, organs, and organ systems creates a division of labor among those cells that makes multicellular life possible

18. Cellular Communication
Cells in a large organism communicate by chemical signals that are passed from one cell to another
These signals can speed up or slow down activities in the cell, or completely change what the cell is doing
Ex. Hormones in the body

19. Review of Daily Objectives
Compare and contrast how unicellular and multicellular organisms maintain homeostasis.
Explain why cell specialization is important for multicellular organisms.