Cell Size Lab and Cell Theory: Understanding Cell Structure and Function

1. CELLS Chapter 7

2. Cell Size Lab • Cut your agar into three cubes (1x1x1 – 2x2x2 – 3x3x3cm) • Put them in a beaker of vinegar (all at same time). • Leave them in for 8-10 minutes and record the time. • Use a spoon to remove them and blot dry. • Complete the data table (see the board). • Answer the questions: • Did the rate of diffusion change with the cell size? Explain. • How does the surface are to volume ratio change as cells get bigger? • Are larger or smaller cells more efficient at transporting materials in and out of their membrane? Why?

4. Cell Theory • All living things are made of cells • Cells are the basic units of structure and function in living things • New cells are produced from existing cells

5. Microscopes • Compound light microscope – allows light to pass through a specimen and uses two lenses to form an image • Magnifies to 1000x • Stains or dyes are used to show specific features • Fluorescent dies are used to tag molecules produced by cells

6. Microscopes • Electron microscopes – use beams of electrons that are focused by magnetic fields – can be used to see objects one billionth of a meter • Transmission electron microscopes – thin slices , electrons pass through the specimen - 2D image • Scanning electron microscopes – a pencil-like beam is scanned over the surface – makes a 3D image • SEM images

7. Prokaryotes and Eukaryotes • All cells have a cell membrane - a thin flexible barrier surrounding the cell • Not all cells have a nucleus – a large membrane-enclosed structure that contains genetic material in the form of DNA and controls many of the cells activities • Prokaryotes - do not have a nucleus • Typically smaller and more simple • Eukaryotes = have a nucleus • Typically larger and more complex • Can be unicellular or multicellular

8. 7.2 Cell Structure – Eukaryotic Cells • The cytoplasm is the fluid portion of the cell outside the nucleus. • Many cellular structures act as if they are specialized organs. These structures are known as organelles, literally “little organs.”

9. The cell as a factory • The eukaryotic cell is much like a living version of a modern factory. • The specialized machines and assembly lines of the factory can be compared to the different organelles of the cell. • Cells, like factories, follow instructions and produce products.

10. The nucleus • The nucleus = the control center of the cell • It contains most of the cell’s DNA, the instructions for making proteins and other important molecules • Nuclear envelope = surrounds the nucleus • contains pores (holes) that allow material to go in and out of the nucleus • Chromosomes – carry the cell’s genetic information (DNA) • Found in the nucleus • Nucleolus – a small dense region in the nucleus • Ribosomes are assembled here

11. Organelles that store, clean up, and support • Vacuoles –large saclike structures with membranes • Store water, salt, proteins, and carbohydrates • In plants there is often 1 vacuole filled with liquid • Also found in unicellular organisms and animals for storing and moving materials

12. Organelles that store, clean up, and support • Lysosomes – small organelles filled with enzymes • Break down lipids (fats) , carbohydrates, and proteins • Help break down “old” organelles - removes “junk” from the cell • Found in animal cells and some plant cells

13. Organelles that store, clean up, and support • Cytoskeleton – a network of protein filaments that give cells shape and internal organization • Helps maintain cell shape and involved in movement • Microfilaments – form a framework that supports the cell and help them move • Microtubules – hollow structures made of proteins called tubulins and are involved in maintaining cell shape and in cell division • Also form cilia and flagella • Centrioles – located near the nucleus and organize cell division in animals (made of tubulins)

14. Organelles that build protein • Ribosomes – the “protein factory” - where proteins are assembled • small particles of RNA and protein found throughout the cytoplasm in all cells. • produce proteins by following coded instructions that come from DNA. • Each ribosome is like a small machine in a factory, turning out proteins on orders that come from its DNA “boss.”

15. Organelles that build protein • Endoplasmic reticulum (ER) – an internal membrane system where lipids are assembled and proteins and other materials are exported from the cell. • Rough endoplasmic reticulum (rough ER) – the ER where protein synthesis occurs • ribosomes on its surface • Proteins made in the rough ER can be exported out of the cell or transported to other locations in the cell • Smooth endoplasmic reticulum (smooth ER) – the ER where no ribosomes are found • Contains enzymes to do tasks like making membrane lipids or detoxification of drugs

16. Organelles that build protein • Golgi Apparatus - modifies, sorts and packages proteins and other materials from the ER for storage in the cell or transport out of the cell. • Looks like a stack of flattened membranes • “Ships” proteins to their final destination

17. Organelles that capture and release energy • Chloroplasts – capture the energy from sunlight and convert it into food (photosynthesis) • Found in plants and some other organisms • “solar power plants”

18. Organelles that capture and release energy • Mitochondria – “The POWER HOUSE” • convert the chemical energy stored in food into compounds easier for the cell to use • In humans, you inherit most of your mitochondria from your mom • Contain small DNA molecules which suggest they may have been descended from independent microorganisms.

19. Cellular Boundaries • Cell Wall – supports, shapes, and protects the cell • Allow water, oxygen, carbon dioxide to pass through • Found in prokaryotes and eukaryotes (NOT ANIMALS) • Provides strength in plants (wood is made of mostly cell walls) • Cell Membrane – controls what enters and leaves the cell and supports • Made of a lipid bilayer (see the next slide)

20. PLANT VS ANIMAL CELLS pg 206

21. Cell Videos Intro to the Cell Review Organelles Review

22. Cell Analogy • Use the organelles on your spreadsheet to create wanted posters for organelle characters that you have transformed into wanted fugitives or superheroes.

23. Organelle Quiz • Tell the basic function of the following organelles: • Nucleus • Mitochondria • Chloroplast • Ribosome • Nucleolus • Rough ER • Golgi Apparatus/Body • Lysosome • Vacuole • Cell Wall • What is the difference between prokaryotes and eukaryotes.

24. Cellular Boundaries • The cell membrane is made of a double layered sheet with lipids and proteins • The cell membrane is selectively permeable – some substances are allowed to pass and some are not.

25. 7.3 Cell Transport • Passive Transport = The movement of materials across the cell membrane without using cellular energy is called passive transport. • Diffusion - The process by which particles move from an area of high concentration to an area of lower concentration

26. Passive Transport Cont. • Facilitated Diffusion – the process where molecules that cannot directly diffuse across the membrane pass through special protein channels • Osmosis –the diffusion of water through a selectively permeable membrane • Water moves across a membrane until equilibrium is reached

27. Osmosis Types of Solutions • Isotonic = When the concentration is the same on both sides of the membrane • Hypertonic = The more concentrated solution • Hypotonic = The dilute solution • Osmotic pressure = the net movement of water out of or into a cell exerts a force

30. Active Transport • Active transport = the movement of materials against a concentration difference (requires energy

31. Movement of large molecules

32. Cell Videos Cell Membrane Cellular Transport

33. Chapter 9 – Energy and Exercise (pg 265) Your body uses energy in the form of ATP • Quick energy • First few seconds (50 m of a race) – use ATP stored in cells • Up to 90 seconds (200-300 m) – lactic acid fermentation (make lactic acid – to get rid of it, you need oxygen = breathing hard) • Long-term energy • Over 90 seconds – cellular respiration • glycogen (carbohydrate stores) are used up in 15-20 minutes followed by other molecules including fats.

34. Choose the correct Organelle 1. • Nucleus • Nuclear Membrane • Nucleolus • Golgi • Smooth ER • Rough ER 2. 3. 4.

35. Choose the correct letter 5. 6. • Vacuole • Chloroplast • Cytoplasm • Cell Wall • Cell Membrane • Mitochondria 7. 8. 9. 10.

36. Match the structure and function • Nucleus • Nuclear Membrane • Nucleolus • Cytoplasm • Cell Wall • Cell Membrane 11. Controls what enters and leaves the cell 12. Gives support to cells, found in plants 13. Contains genetic material in the form of DNA and controls many of the cells activities 14. Makes ribosomes 15. fluid portion of the cell outside the nucleus. 16. Controls what goes in and out of the nucleus

37. Match the Structure and Function • Ribosomes • Smooth ER • Rough ER • Golgi Bodies • Vacuole • Lysosome 17. Storage 18. Breaks down “old junk” 19. “Protein factory” 20. Membrane that has ribosomes on it – makes proteins 21. Membrane that does not have ribosomes – makes lipids 22. modifies, sorts and packages proteins and other materials

38. Match the structure to the function • Mitochondrion • Chloroplast • Chromosomes • Prokaryote • Eukaryote 23. A cell with a nucleus 24. A cell without a nucleus 25. The “power house” 26. Structures in the nucleus made of DNA 27. Convert energy in sunlight to food

41. Stem Cells What are they? Cells that can develop into different types of cells in the body. They also act as a repair system in the body because of their ability to divide so quickly. Why are they medically important? They can be engineered to become any type of tissue which means that they could be used to treat a multitude of diseases and regenerate damaged tissues within te body Types of stem cells: Embryonic Somatic Induced Pluripotent (iPSC’s)

42. 2012 Nobel Peace Prize Last year Gurdon, 79, of Dippenhall, England, and Yamanaka, 50, of Osaka, Japan earned a nobel peace prize for the following discovery: "mature, specialised cells can be reprogrammed to become immature cells capable of developing into all tissues of the body,"

43. Ethical Issues Embryonic Stem Cells vs Medical Uses Is this still an issue with new IPSC’s?