Cells

1. Cells rahodgdonrhms

2. Prefixes and suffixes to know for this unit: a- means “not.” The word atypical, for example means “not typical.” Bio- means “life” or living. -ology means “the study of,” so biology means “the study of living things.” Uni- means “one.” A unicycle, for example, has only one wheel. “photo-” means light “multi-” means many

3. Introduction: What are cells?

4. What characteristics are found in living things? Grow and develop Get nutrition and pass waste Respond to environment Use ENERGY Reproduce

5. Cells are the smallest unit of life on earth. Most cells cannot be seen without the use of a microscope. Almost all cells live in a liquid environment. In order to survive, cells must carry on the basic functions of life such as obtaining food, responding to their environment, using energy, getting rid of waste, and reproducing.

6. The five basic life functions

7. There is nothing simple about a simple cell.

8. Cells contain a number of different structures. Some of these structures are called organelles. Each structure and organelle has a specific purpose or job.

10. Nucleus- The nucleus controls what the cell does and contains the DNA (genetic information) needed for reproduction. The nucleus is like the control room of the factory; it tells everything else what to do.

11. How do bacteria cells differ from all other types of cells on earth? About half the cells on are planet do not have a nucleus. That’s because bacteria, the most numerous organism on the planet, do not have nuclei. Cells that do not have a nucleus are known as prokaryotic cells. We will discuss them further when we talk about bacteria.

12. Cytoplasm - The cytoplasm is the liquid in the cell that all the other organelles float around in.

13. Mitochondria The mitochondria store energy for the cell to use. They are like the power cells for the factory; they are the powerhouse of the cell. They are like rechargeable batteries, though.

14. Cell membraneThe cell membrane allows certain things to go in and out of the cell. It is like a screen door in a factory; it allows some things to go in and out, but not others.

15. Ribosomes - The ribosomes make andput together the different pieces of proteins that the cell makes. Ribosomes are like the assembly line in the factory; they use certain materials to put together a product. There are hundreds or even thousands in a cell.

16. Some ribosomes are free floating, but most of them are located on an organelle known as the Endoplasmic Reticulum, or ER.

17. The endoplasmic reticulum and the Golgi body are membrane systems within the cell whose jobs include making, transporting, and secreting proteins. Remember, all living things are made out of proteins.Note: in cell diagrams these two structures often look the same. The ER is always near the nucleus and is dotted with ribosomes.

18. Lysosome - The lysosomes secrete powerful enzymes that digest food into food vacuoles in the cell. Once the food has been digested, the lysosomes help the cell get rid of the waste by moving it to the cell membrane where it can be dumped.

19. The smaller organelles and tiny particles inside the cells like proteins don’t just float around in the cytoplasm all willy nilly. Inside each cell is a series of roads and bridges that make up what is called the cytoskeleton. These roads and bridges consist of tiny filaments and tubules.

21. Nucleus: controls all functions of the cell and carries genetic information. Mitochondria- stores energy for cells like little batteries Cell membrane: controls what enters and leaves a cell Cytoplasm: the liquid part of the cell Lysosome: aid in digestion Plant Cell Only F. Chloroplasts-help plant make food G. Central vacuole-store water, support H. Cell wall-Support C B B A D D G A E F H C

22. (C) cell membrane (A) nucleus (B) mitochondria (H) vacuoles (F) ER (F) ribosomes (D) cytoplasm (G) Golgi (E) lysosome

23. Plant cells are similar in most ways to animal cells, however, plants do not have to “eat” in order to grow and reproduce. Plants are able to make their own food by using sunlight to covert carbon dioxide and water into sugars (glucose)which the plant stores and uses for food. This process is known as photosynthesis. The prefix photo- means “light.”

24. What other organelles or structures are found in plants cells that we did not see in animal cells? Central

25. The cell wall is a thick layer of cellulose that surrounds the cell and gives the plant support. The large central vacuole stores water and essential minerals and helps with supportby exerting outward pressure on the cell wall.

26. So, let’s review: plants are able to make their own food through photosynthesis because they contain an amazing substance known as chlorophyll. In plants, chlorophyll is stored in a special organelle known as a chloroplast.

27. Let’s visit Inside a Cell http://learn.genetics.utah.edu/content/begin/cells/insideacell/

28. Cells form tissues. Tissues form organs. Organs form systems. Systems form the organism.

29. Cells form tissues…..

30. Cellular Functions

31. All living things must be able to obtain food and eliminate waste. Cells can obtain food and eliminate waste in two primary ways: Passive Transport and Active Transport

32. Remember… the cell membrane controls what enters and leaves the a cell.

33. PASSIVE TRANSPORT One way the cell does this is through a process known as osmosis. Osmosis is the process where liquids are able to pass through a membrane like a cell membrane. Cell membranes are semi-permeable, meaning they allow only water and certain molecules that are dissolved in the water (solutes) to pass through the cell membrane. Oxygen and carbon dioxide gases both dissolve in water and can move back and forth through the cell membrane with the water. Animal cells need water and oxygen but need to get rid of carbon dioxide. Plant cells need water and carbon dioxide for photosynthesis (and oxygen for cellular respiration. We’ll get to that later), but they also release oxygen as a waste material.

34. Because so much water, oxygen, and carbon dioxide are constantly passing into and out of a cell, it would totally exhaust the cell if the cell had to use its own stored energy (in the mitochondria) for osmosis. Luckily for the cell, osmosisis a typeof passive transport. This means that the cell exerts no energy during osmosis. Remember that most cells live in a liquid environment. There is liquid inside the cell and liquid outside the cell. Since the liquid inside the cell and the liquid outside the cell usually have a bunch of other stuff dissolved in them, we refer to these liquids as solutions. Let’s see how this works.

35. Watch BrainPop: Passive Transport

36. When the concentration of the dissolved particle (indicated by a %) is greater outside the cell than it is inside the cell, it is a hypertonic solution. The prefix hyper means “excessive” or “above normal.” Think (but don’t act) about hyperactivity. When the concentration of the dissolved particle (indicated by a % is greater inside the cell than it is outside the cell, it is ahypotonic solution. The prefix hypo means “under” or “below normal.” Think of (if you dare) a hypodermic needle. Needles go “under” or “below” your skin. Since water will want to move into the cell, think of the needle injecting it in in a hypotonic situation.

37. When the concentration of particles outside the cell is the same as the concentration on the inside, the cell is said to be balanced. Is has reached equilibrium. Cells like to be balanced. When cells are at equilibrium, water flows in and out of the cell at the same rate.

38. So how do particles get balanced in and outside of cells? It’s all about the movement of water. Water will always try to move to the area where the concentration of particles is the greatest. Water is a “party animal.” It wants to go where the crowd is (the crowd meaning the particles.) Salt concentration inside the cell higher . Salt concentration outside the cell higher . water salt

39. When the concentration of salt particles inside and outside of the cell is the same, water moves in AND out of the cell at the same rate.

40. Let’s use salt solutions as an example. Salt is one of those substances that can dissolve in water. Salt, or sodium, is necessary in plants and animals, but too much can cause a lot of problems. Inside of cell. High concentration of water (blue), but low concentration of salt (green) Outside of cell. High concentration of salt (green), but low concentration of water (blue) If water always tries to move to the region where the concentration of solutes is higher, in which direction will the water flow?

41. So, how can this affect a cell then?

42. (Hypertonic) (Hypotonic) Tell the story about the woman and the radio contest.

44. Hypotonic because the solution inside the cell is higher than the solution outside the cell. Hypertonic because the solution outside the cell is higher than the solution inside the cell. Water flows into the plant cell. If too much water flows into the central vacuole, the cell wall can burst. Water flows out of the plant cell. If too much water flows out of the central vacuole, the cell wall starts to buckle and droop..

45. In a hypotonic situation, cells can swell so much with water that they burst. Farmers often fear this will happen after a heavy rain. Fruit crops like tomatoes often burst if they get too much water.

46. Tri-fold Activity

47. Cell Functions Pocket Activity Students will create large “flash cards” illustrating and describing various cell functions such as passive and active transport, cellular respiration, and reproduction. These cards will be stored in a pocket (also made by students) in each students composition folder.

48. So, what’s to keep the dissolved particles from clumping up in one particular area either inside the cell or outside the cell? That’s where something called diffusion comes into play. Water loves a crowd, but particles don’t. When particles are crowded together, they want to spread out.

49. Through diffusion, the particles will continue spreading out until they are distributed uniformly through the solution. Watch BrainPop: Diffusion

50. That’s where the process of diffusion comes in. Diffusion is a process where particles in a crowded area want to move to a less crowded area, spread out. Think about what happens when you make the favorite drink of Southerners: sweet tea. What happens when you first put the tea bag in the hot water? And the sugar? Why do we have to stir the mix once we put the sugar in?