Welcome to Science

1. Welcome to Science Grade 8s

2. What the curriculum says: “Cells are the smallest unit of life, and each cell is a system nested within a system. In Grade 8, students will continue to develop their knowledge of organisms by focusing on the structure and function of cells in plants and animals. Our knowledge of cells has increased enormously since the middle of the twentieth century, and students will examine the implications of this knowledge for individuals, society, and the environment.” What this means: We will be learning about the structure of cells and how they work in plants and animals Unit 1- Understanding Life Systems: Cells

3. Cells come in many shapes and forms

4. Can anyone guess what type of cells these are?

5. During this unit, we may have the opportunity to do some experiments, build some models, and use some scientific technology. How much hands-on stuff we do depends on how much I can trust you to follow the safety expectations we go over, so, when the time comes, pay attention and be mature Technology in this unit

6. By the end of this unit, you should be familiar with (and using) the following terminology to discuss cells: • organelle, diffusion, osmosis, cell theory, selective permeability, membrane, stage, eyepiece Vocabulary in this unit

7. You need some background knowledge • To start, please flip to page 67 of your student workbooks • Read pages 67-72 and complete the activities on pages 72 to 74 ON LINED PAPER IN YOUR SCIENCE BINDER (do not write in the workbooks) • Right now, we have 34 students in this class. You will be paired up with one person to share a workbook that you will be assigned. • Together you are responsible for keeping your workbook as new as possible Before we can build and explore…..

8. Last class, we looked at the difference between living and non-living things • Living things: • Grow, repair themselves, and reproduce • Need energy • React to changes in their environment • Have a lifespan • Create waste • Are made up of at least one cell From last time….

9. The Cell Theory helps explain the basics of cells and how they work • ***You will be expected to know all 3 parts of the cell theory, so it might be best to write this stuff down • All living things are made up of at least one cell • Cells are the most basic units of life • Every cell comes from cells that already exist The Cell Theory

10. 1. All living things are made up of at least one cell • -some life forms are unicellular (made up of one cell) • -other living things have many, many, many more • Any guesses about how many cells humans have? The Cell Theory

11. 2. Cells are the most basic parts of life • Cells give all living things structure Lesson 2- The Cell Theory

12. 3. Every cell comes from cells that already exist • New cells are “born” through the division of old cells The Cell Theory

13. Please complete worksheet 4.2-1, questions 1-3 • **remember the date and title please • **either write the question down or include part of the question in your response • Example: “The microscope helped scientists form the cell theory by…..” At the bottom of your “Cell Theory” note…

14. As we discussed earlier, we are going to be learning about plant cells and animal cells • The basic structures of each type of cell have some common features and other features that help us separate plant cells and animal cells Lesson 3- Parts of a Cell

15. All cells have small parts/structures that are called organelles • Think of organelles as the organs of the cell • Just like our bodies need our organs to perform specific functions (lungs, heart, liver, etc.), the organelles of cells have very specific jobs to do within the cell -All organelles float around in the cytoplasm (watery fluid) of a cell. Cytoplasm is NOT an organelle **think about cytoplasm is the stuff that holds the parts of the cell in place (like Jell-o in a jellied salad) Common Features

16. 3 organelles exist in both plant and animal cells • cell membrane • Nucleus • vacuoles Common Features

17. The cell membrane is like the jacket, skin, or cover of the cell • It surrounds the cell • Food enters the cell through the cell membrane • Waste exits the cell through the cell membrane Cell Membrane

18. The nucleus is the “control centre” of the cell • Our bodies also have a control centre- what is it? • The nucleus controls most of what happens inside the cell • A nuclear membrane covers the nucleus (like an inner jacket) • The nucleus is where the cell’s chromosomes are • Chromosomes carry information that the cell needs to function • A location on a chromosome with a specific set of information about a living things characteristics (eye colour, hair colour, etc.) is called a gene Nucleus/Nuclei

19. Inside the nucleus

20. Vacuoles are like the gas tanks of cells • They are used to store water, sugar, and other energy sources • Vacuoles also store waste until it can be expelled • *plant cells have much larger vacuoles than animal cells Vacuoles

21. Plant cells have a few extra parts that animal parts do no have • Use the information found on pages 87-88 to complete your chart • At the bottom of your chart, please complete questions 1 and 2 (from page 89) The difference between plant cells and animal cells

22. Last week, your homework was to fill out your cell model organizer to create a proposal for your project. • Please hand it to Mr. T. so he can review it • If you get a thumbs up- you can start building • If you get a thumbs down- you will need to review parts of your proposal before moving forward • If you don’t have it done- I cannot help. Get it handed in ASAP Activity 1- building cell models

23. Next week, you will be given class time to build. So please bring your materials next Wednesday. • If you are building at home, you may treat this period as time to catch up on your other school work or to read. Please come with an alternative activity, or I will find something for you to do. Activity 1- building cell models

24. Last class, we learned that the cell membrane is like the skin or jacket of the cell • This is the outer layer of the cell separates the interior of the cell from its outside environment; it protects the cell • This layer controls what passes into and out of the cell. • The cell membrane is selectively permeable because only certain particles are able to pass through it Lesson 4- Cells in their environment: the cell membrane

25. Things that are permeable let allow other objects to pass through them • Think of a tunnel as permeable • Things that are impermeable do not allow other objects to pass through them • Think of a wall as impermeable • Selectively permeable is in the middle; some things can pass, other things cannot • Think of a strainer or a security guard What the heck does ‘permeable’ mean??

26. Cell membranes are made of a phospholipid bilayer (two layers of fat) • Proteinsare built into these fat layers and serve as channels (doorways) • These proteins open and close to let things pass into and out of the cell (when they are supposed to) • Cells have different sized protein channels so that different sized particles can pass through • Water, oxygen, carbon dioxide particles pass through easily • Larger particles (fats, sugars) do not pass through as easily What are cell membranes made of?

27. Please read the information on page 97, then complete the questions on page 98, the fill-in-the-blank activity on 99 and create your own sketch of the parts of the cell membrane. For your Study Notes

28. Time to stand up!!!! • Everyone to the center of the room as tightly as possible Lesson 5- Cells in their environment- Movement

29. What do you notice?

30. By walking, spread yourselves out as much as possible; use every corner of the classroom Time to separate

31. NOW, what do you notice?

32. What does this have to do with cells?!? Back to your seats please

33. This is how particles move within cells • Particles more from highly concentrated areas (your circle) to less concentrated areas (free space) • Think of a freshly baked apple pie. • Originally you would only smell it if was really close, but as it sits out the smell travels • Same with less desirable smells (those closest will notice it most and strongest) Diffusion

34. When there is unequal concentrations of a particle, it creates a concentration gradient • Diffusion can only happen with a concentration gradient exists • For example, if there is a higher concentration of water particles outside the cell than inside, the cell membrane allows for a transfer of those particles (through the protein channels) into the cell until the concentration is the same inside and out Concentration Gradient

35. Time to get up again!! • We need 5 traffic cops • Everyone else, wait for further instruction Confused?!?

36. Diffusion helps cells “bring in” essential materials and “send out” wastes • Example: blood cells • Blood brings oxygen to your cells for them to be able to function (from highly concentrated areas to areas of lower concentration) • Blood also removes carbon dioxide from your cells (from highly concentrated areas to areas of lower concentration) Why is diffusion important to cells?

37. Please read over pages 100 and 101 • Please complete the questions on pages 102 and 103 For your study notes

38. As I hope you all know, all living things need water to survive • Cells are no different; diffusion provides cells with the water they need to function • Let’s test what you learned from your cell model assignment: what part of the cell allows water to pass into the cell? Lesson 6- An Important type of Diffusion

39. Osmosis is a special type of diffusion. • During osmosis, water travels across the cell membrane from an area of higher water concentration to one of lower concentration • This will only happen when there is a concentration gradient Osmosis

40. Take a look at the picture here. • The diagram on the left represents a situation where we have a higher concentration of sugar inside the cell • Outside the cell the sugar/water solution is diluted Osmosis

41. On the diagram on the right, osmosis is occurring • Water moves through the cell membrane (the line in the middle) from an area of high water concentration to one of low concentration. As a result, there is more water inside the cell. Osmosis

42. Thinking back to Grade 7 Science….. • A solution is made up of two parts: a solute and solvent • The solute is what is dissolved (the sugar) • The solvent is what is doing the dissolving (the water) • The more sugar we have dissolved in the water, the higher the level of concentration. Concentrated- high level of solute Diluted- low levels of solute Water Concentration

43. Sugars, salts, and proteins are common solutes in cells • Water is almost always the solvent in cells • When water moves into or out of the cell through the cell membrane, the concentration of the solution inside the cell changes. Osmosis in Cells

44. There are three pictures above: Each one represents a different state that cells can be in. • Can you guess what the concentration is like in each case? • If so, should water be coming into or out of the cell? Concentration in cells

45. Water moves from where it is more concentrated. • If there is a lower concentration of water inside the cell than outside, water moves into the cell, causing the cell to swell Hypotonic

46. If there is a higher concentration of water inside the cell than outside, water moves out of the cell, causing the cell to shrivel Hypertonic

47. When the concentration of water is the same inside the cell and outside, things are said to be “normal” • Water still moves into and out of the cell but it does so at the same rate Isotonic

49. Especially in plant cells, vacuoles take up most of the space • Vacuoles are storage units, and often store water • When extra water needs to come into the cell, the vacuoles push outward and swells • This is called turgor pressure • When there is not enough water in the cell, the vacuole shrinks and there is less turgor pressure • This causes plants to wilt What causes cells to change shape?

50. Read pages 104-106 from the text book • Questions on pages 107 and 108 For your notes….