1. Chapter 2 Sec. 3-4
The Cell in Action

2. Section 3:Objectives Explain the process of diffusion
Describe how osmosis occurs
Compare passive and active transport
Explain how large particles get into and out of cells.

3. Exchange with the Environment
An organism is sort of like a factory.
It must be able to do 2 things:
Obtain energy and raw materials
Get rid of waste
These things help keep cells healthy so that they can divide.
The exchange of materials between a cell and its environment takes place at the cell membrane.

4. Exchange with the Environment
Diffusion: the movement of particles from regions of higher density to regions of lower density
Diffusion occurs within and between living cells.
Cells do not use energy for diffusion.

5. Exchange with the Environment

6. Exchange with the Environment
Example:
When someone makes coffee, diffusion is occurring.
The coffee pot represents the inside of the cell and the coffee filter represents the cell membrane.
Semi-permeable: only certain substances can pass through

7. Exchange with the Environment
Osmosis: the diffusion of water through a semipermeable membrane
Osmosis is important to cellular functions.
Osmosis occurs in plant cells:
When a wilted plant is watered, it enters the cell membrane and supplies the plant with water. The plant then looks healthy.

8. Exchange with the Environment
Small particles, such as water and sugar, cross the cell membrane through channels
Active transport: movement of particles across cell membrane with energy
High to low concentration
Passive transport: movement of particles across cell membrane without energy
Diffusion and osmosis are examples

9. Exchange with the Environment

10. Exchange with the Environment
Larger particles enter/exit the cell by one of the following 2 processes:
Endocytosis: process by which a cell membrane surrounds a particle without the use of energy
Exocytosis: process by which a cell releases a particle by enclosing the particle in a vesicle that then moves to the cell’s surface and fuses with the cell membrane

11. Exchange with the Enviroment

12. Exchange with the Environment
EXOCYTOSIS
“Exo”= Exit
“Osis”= Process
Large particles are packaged in vesicles  vesicle travels to cell membrane  cell releases particle
ENDOCYTOSIS
“Endo” = To enter
“Osis” = Process
Cell comes into contact with particle  cell membrane wraps around particle  particle enters cell

13. Cell Membrane

14. Phospholipids

15. Diffusion Examples

16. Osmosis Example

17. Section 3: Review Questions
1) What is the difference between active and passive transport?
2) What takes place at the cell membrane?
3) Is energy required for diffusion?
4) List 1 example of diffusion.
5) When is osmosis important?
6) How do small particles cross the cell membrane?

18. Section 4: Objectives
Describe photosynthesis and cellular respiration.
Compare cellular respiration with fermentation.

19. From Sun to Cell Nearly all energy that fuels life comes from the sun.
Plants capture energy from the sun and change it into food through a process called photosynthesis.
What happens to the food plants make?

20. From Sun to Cell
Plant cells contain chlorophyll, a green pigment that absorbs light energy.
This gives plants their green color.
Where is the chlorophyll located in plant cells?

21. From Sun to Cell
Plants use the energy captured by chlorophyll to change carbon dioxide and water into food.
Glucose is the food that plants make.
Glucose is a simple sugar. (carbohydrate)

22. From Sun to Cell
Animal cells have different ways of getting energy from food:
Cellular respiration: uses oxygen to break down food
Fermentation: breakdown of food without the use of oxygen

23. From Sun to Cell Respiration = “breathing”
Food is broken down into CO2 and H2O.
Most of the energy released maintains body temperature.
Some of the energy is used to form ATP.
Most of cellular respiration takes place in the cell membrane.

24. From Sun to Cell Fermentation example:
One example of fermentation is when your muscles and tissues produce lactic acid.
The buildup of lactic acid contributes to muscle fatigue and causes a burning sensation.

25. Chapter 2 Sec. 4 Recap
1) T/F Nearly all energy that fuels life comes from the sun.
2) What is chlorophyll?
3) What type of substance is glucose?
4) List 2 ways animal cells get energy from food.
5) In plant cells, list 2 things that food is broken down into.
6) List one example of fermentation.

26. Section 3: Objectives Explain how cells produce more cells.
Describe the process of mitosis.
Explain how cell division differs in plant and animal cells.

27. The Cell Cycle As you grow, you pass through different stages.
Cells also pass through different stages (cell cycle: life cycle of a cell)
Growth begins when the cell if formed and ends when the cell divides.

28. The Cell Cycle Before a cell divides, it copies its DNA.
DNA is the hereditary material that controls cell division.
The DNA of a cell is organized in structures called chromosomes.
Why is copying DNA important in cell division?

29. The Cell Cycle
Prokaryotic cells are less complex than eukaryotic cells.
Cell division in bacteria is called binary fission.
It results in 2 cells, each with one copy of the DNA.

30. The Cell Cycle Eukaryotes are more complex than prokaryotic cells.
Eukaryotes contain more DNA than prokaryotic cells.
Different eukaryotes have different numbers of chromosomes.
What is the total # of chromosomes in humans?
How many pairs of chromosomes is that?

31. The Cell Cycle The eukaryotic cell cycle has 3 major stages:
1st phase: cell copies organelles and chromosomes
Once chromosomes are copied they are called chromatids
2nd phase: chromatids separate (enters mitosis)
3rd phase: cell splits into 2 cells

32. The Cell Cycle Cell division begins at the cell membrane.
The division of cytoplasm is called cytokinesis.
Eukaryotic cells that have a cell wall form a cell plate which divides the cell in half.

33. The Cell Cycle There are 6 steps to mitosis: Interphase Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

34. Diffusion/Osmosis Critical Thinking Exercise
Cell A contains 70% water and is normal. Cell B contains 85% water and is abnormal. Cell B continually takes in water and cannot release any. From what we have learned about diffusion, answer the following questions:
What part of the cell is not working properly?
If this continues what will happen to the cell?
Why is this not a characteristic of diffusion working properly?

35. Cell Cycle: Review Questions
The cell cycle begins when the cell is _______ and ends when the cell ______.
Before a cell divides, it copies its _____.
Cell division in bacteria is called ______.
Different eukaryotes have different numbers of ________.
List the 6 steps of mitosis.
___________ cells are less complex than eukaryotic cells.

36. Chapter 2 Sec. 3-4 Vocabulary Review
1) _____: a series of chemical reactions that convert the energy in food molecules into a useable form of energy called ATP
2) _____: the movement of substances across the cell membrane without using the cell’s energy
3) _____: the diffusion of water molecules only through a membrane
4) _____: a process by which glucose is broken down into smaller molecules

37. Chapter 2 Sec. 3-4 Vocabulary Review
5) ____: a series of chemical reactions that convert light energy, water, and carbon dioxide into glucose and give off oxygen
6) ____: a reaction that eukaryotic and prokaryotic cells can use to obtain energy from food when oxygen levels are low
7) ____: the movement of substances through the cell membrane only by using the cell’s energy

38. Chapter 2 Sec. 3-4 Vocabulary Review
8) _____: when molecules pass through a cell membrane using special proteins called transport proteins
9) _____: the movement of substances from an area of higher concentration to an area of lower concentration
10) ____: the process in which the cell takes in a substance by surrounding it with the cell membrane
11) ____: the process by which a cell’s vesicles release their contents outside the cell