Cells and Systems

1. Cells and Systems Grade 8 Science

2. Topic 1 – Living Organisms Take a moment to talk to the person next to you about all of the functions an organism needs to do to survive

3. Functions and Structures • All organisms need to perform certain functions to survive and they have certain structures to do it: • Energy: Organisms need to break down food • we use our digestive system to do that physically • at the cellular level, the mitochondria (an organelle) use the energy from sugars for us.

4. Functions and Structures • Environment: Organisms need to be able to adapt to their environment. Our environment is constantly changing, and many of our structures adapt to it. • Growth: We need to grow and develop. We cannot reproduce until adulthood. Even single cells need to grow to a certain point before they can divide.

5. Functions and Structures • Wastes: Structures to get rid of the ‘leftovers’. We have two main systems for that – excretory, and digestive. • Reproduction: Needed to allow the species to continue. If a species were to stop reproducing for one generation, they would go extinct.

6. Define: Organism Cell Life Relate the three to one another in a sentence or two.

7. Levels of Organization

8. Levels of Organization • Starting with the largest level of organization: The organism. • It is the entirety of the a living being. • Each organism has a set of organ systems. • For example the digestive system

9. Levels of Organization • Each organ system is made up of several different organs • The digestive system has the stomach. • Each organ has several different tissues. • The stomach has muscle tissue, mucous layer tissue. • Each tissue type is made up of one type of cell. • Muscle tissue is made up of all muscle cells.

10. Microscopes And Our Discovery of the Cell

11. Your eye • Open your textbook to page 103. • Read the first part ‘A World Too Small to See’ • Observe the 6 different circles. Our eyes can only differentiate between objects that are 0.100mm or bigger.

12. The typical cell is about 10µm, or 0.010mm • Our eyes would have to magnify 10 times more than we see now to see them!

13. A bacteria cell is only about 0.5-2.0µm. Which is 0.0005-0.002mm, far smaller than our eyes could ever see without help. • Enter microscope

14. Microscopes • Anton van Leeuwenhoek (16232-1723) was the first to observe an organism made of only one cell. • He observed blood cells, pond water, and other small accumulations of matter.

15. Cells as a part of a living being • Robert Hooke observed a network of box-like compartments in bark. He called them cellulae, which in Latin means ‘little rooms’. • Our word cell, comes from this

16. The cell theorywas developed, consisting of 2 parts • All living things are composed of one or more cells • Cells are the basic units of structure and function in all organisms • This came from the observation that larger organisms are made of cells at the microscopic level, and that each cell individually performs the 5 functions necessary for life.

17. Parts of a microscope • The microscope is made of several parts that work together to magnify an image.

18. Parts of a Microscope From the top: • Eyepiece – Where you look through • Tube – holds the eyepiece and objective lens a precise distance from one another • (Revolving) Nosepiece – Used to select the objective lens of your choice

19. Parts of a Microscope • Objective Lens – Magnify the object. Usually 4X, 10X, or 40X magnification. Included with the 10X from the eyepiece lens, total magnification is 40X, 100X, or 400X its usual size. • Arm – Connects the base and the tube

20. Parts of a Microscope • Stage – The flat surface with a hole in the center to allow light to pass through and illuminate the specimen. Has clips to hold the specimen in place • Condenser – Directs the light towards the specimen • Diaphragm – Controls the amount of light reaching the specimen

21. Parts of a Microscope • Illuminator – Used to shine light at the specimen, sometimes more light makes picking out finer details easier • Coarse Adjustment Knob – Used to bring the object into focus, used only with a low power lens • Fine Adjustment Knob – Used to bring the object into focus with medium to high power lenses

22. Parts of a Microscope • Base – Structural support

24. The Cell and its Structures Grade 8 Science

25. Cells • According to the cell theory, every organism is made up of cells. • They can either be unicellular (only one cell in an organism) • Example: Bacteria, Amoeba, Algae • They can also be multicellular (more than one cell makes up the organism) • Example: Almost everything living you see! Humans, birds, most plants (except algae)

26. Cells • Every cell is made up of several organelles. • They are analogous (similar) to our organs in our body. • Each organelle performs a certain function. The collective work of all of the cell’s organelles is to perform the 5 functions of life.

27. Animal Cell

28. Plant Cell

29. Organelles • Cell Membrane – Permeable, Semi-Permeable, or Impermeable. Allows nutrients in/out and wastes out as needed.

30. Cytoplasm – Similar to our blood. It moves nutrients around the cell.

31. Organelles • Nucleus – Controls the cell’s activities through DNA, which direct the cell’s growth and reproduction

32. Vacuoles – Large organelles in the cytoplasm which store extra food, wastes, and other substances. Much bigger in in plant cells (provides rigidity).

33. Cell Wall – Only in plant cells. Thicker and rigid to support the plant

34. Chloroplasts – Only in plant cells. Where photosynthesis takes places. Uses sun energy to make carbohydrates (sugars) by using chlorophyll.

35. Amoeba http://www.youtube.com/watch?v=W6rnhiMxtKU

36. Why cells? • Why are larger organisms made up of billions of cells instead of one big cell? • Harder for bigger cells to move nutrients around one another. Think of a human without blood, we would have to absorb everything from our environment! • Many tiny individual cells work as a better transport system.

37. Cell Size • Come in a variety of sizes! • Most cells are approximately 10-50µm. Some are as small as 1-5µm.

38. Topic 4: Fluid Movement in Cells

39. Diffusion Diffusion refers to the process by which molecules intermingle as a result of their kinetic energy of random motion. http://www.youtube.com/watch?v=M30PrtZDB8I&feature=related

40. Consider two separated containers of gas A and B. The molecules of both gases are in constant motion and make numerous collisions with the separation.

41. If the separation is removed, the gases will mix because of the random movement of their molecules. In time, a uniform mixture of A and B molecules will result.

42. The tendency toward diffusion is very strong even at room temperature because of the high molecular velocities associated with particles. • All particles ‘jiggle’.

43. Semi Permeable Membrane A semi-permeable membrane is a membrane which will allow the passage of certain molecules through it (by the process of diffusion), and not other molecules.

44. The rate of passage depends on the pressure, concentration and temperature of the solvent on either side, as well as the permeability (how much it will let through) of the membrane to each type of molecule or solute.

45. Osmosis Osmosis is the diffusion of particles across a semi-permeable membrane

46. The semi-permeable membrane only allows the solvent particles to cross. The solvent particles diffuse until a balance between all the particles is reached.

47. Osmosis is of great importance in biological processes where the solvent is water. The transport of water and other molecules across biological membranes is essential to many processes in living organisms. The energy which drives the process is usually discussed in terms of osmotic pressure.

48. Vascular Tissue Vascular plants contain two main types of conduction tissue, the xylem and phloem. These two tissues extend from the leaves to the roots, and are vital conduits for water and nutrient transport. In a sense, they are to plants what veins and arteries are to animals.

49. Vascular tissue consists of xylem and phloem. These two types of vessels run side-by-side, extending from roots to leaves. They provide channels for the transport of water and nutrients.

50. Xylem Tissue The function of xylem tissue is to: • conduct water and dissolved minerals• Structural support Tracheids Vessel Members