SNC 2D1

1. SNC 2D1 The Cell Theory & Structure & Function of the Cell

2. Cellular Organization • Cell • Tissue – group of cells functioning together. • Organ – group of tissues functioning together. • Organ System – group of organs functioning together. • Organism – group of organ systems functioning together.

3. The History of the Cell • The Cell • The basic unit of an organism • Discovery made possible by the invention of the microscope

4. Microscopes and Cells • 1600’s. • Anton van Leeuwenhoek first described living cells as seen through a simple microscope.

5. Microscopes and Cells • Robert Hooke used the first compound microscope to view thinly sliced cork cells. • Hooke was the first to use the term “cell”. • Compound scopes use a series of lenses to magnify in steps.

6. Microscopes and Cells • 1830’s • Mathias Schleiden identified the first plant cells and concluded that all plants are made up of cells. • Thomas Schwann made the same conclusion about animal cells.

7. The Cell Theory • All living things are composed of one or more cells. • The cell is the smallest entity that retains the property of life. • New cells arise only from pre-existing cells. • The life properties of an organism depend on the life properties of its individual cells.

8. Two Basic Cell Types • Prokaryote • Lacks internal compartments. • No membrane bound organelles. • No true nucleus. • Most are single-celled (unicellular) organisms. • Single circular loop of DNA • Ribosomes • Examples: bacteria

9. nucleoid (DNA) ribosomes food granule prokaryotic flagellum plasma membrane cell wall cytoplasm

10. Two Basic Cell Types • Eukaryote • Has several internal structures (organelles). Most organelles are enclosed by a membrane • True nucleus. Larger nucleus. • DNA is organized into linear chromosomes • Can be either unicellular or multicellular. • Unicellular example: yeast • Multicellular examples: plants, animals and fungi

11. chromatin (DNA) nucleus nucleolus nuclear envelope flagellum intermediate filaments cytoplasm plasma membrane rough endoplasmic reticulum ribosome lysosome microtubules smooth endoplasmic reticulum Golgi complex free ribosome vesicle mitochondrion vesicle

12. microtubules (part of cytoskeleton) mitochondrion chloroplast Golgi complex central vacuole smooth endoplasmic reticulum vesicle cell wall rough endoplasmic reticulum plasma membrane nucleolus nuclear pore nucleus chromatin nuclear envelope intermediate filaments free ribosome ribosomes

13. Similarities of Plants and Animal Cells • Both constructed from eukaryotic cells • Both contain similar organelles • Both surrounded by cell membrane

14. Differences of Plants and Animal Cells • Plants have • Cell wall made of cellulose provides strength & rigidity • Have chloroplasts, so are photosynthetic • Animals have • Other organelle not found in plants (lysosomes formed from Golgi Bodies) • Centrioles, important in cell division • Fungi have • Cell wall made of chitin

15. The Parts of The Eukaryotic Cell • Plasma Membrane (Cell Membrane) • Serves as a boundary between the cell and its external environment. • Allows materials to pass in and out of the cell.

16. Cell Wall • Surrounds the plasma membrane of the cells of plants, bacteria, and fungi. • Plant cell walls contain cellulose while fungi cell walls contain chitin.

17. Nucleus • Regulates cell function, is the control centre of the cell. • Surrounded by a double-layered membrane (nuclear enveloped) with large pores that allow materials to pass in and out of the nucleus. • Contain nucleoli: synthesizes ribosomal RNA • Contains chromatin – long tangles of DNA.

18. Nucleolus • Darker structure inside the nucleus. • Responsible for ribosome production. • Ribosomes are the sites of protein production.

19. nuclear envelope nucleolus nuclear pores chromatin

20. nucleus nuclear pores

22. Cytoplasm • The jelly-like polysaccharide (sugar) material that surrounds the organelles. • Mostly made of water.

23. Endoplasmic reticulum • Folded membrane that acts as the cell’s delivery system. Attached to nucleus. • Smooth E.R. contains enzymes for lipid synthesis. • Rough E.R. is studded with ribosomes for protein synthesis and secretion.

24. rough endoplasmic reticulum ribosomes 0.5 micrometers smooth endoplasmic reticulum 0.5 micrometers vesicles

25. Ribosomes Assemble amino acids into polypeptide chains Associated with the E.R. Composed of nucleic acids (DNA-like material)

26. Ribosomes (small dots) rough endoplasmic reticulum (tubes) 0.5 micrometers

27. vesicles smooth endoplasmic reticulum 0.5 micrometers

28. Golgi apparatus (or Golgi body) • A series of flattened sacs where newly made fats and proteins from the E.R. are repackaged and shipped to the plasma membrane. • (Lysosomes are Golgi-derived vesicles, containing digestive enzymes.)

29. vesicles from ER Golgi complex

30. Vacuoles • A sac of fluid surrounded by a membrane used to store food, fluid, or waste products. • In plants, a large water vacuole takes up much of the space inside the cell • These water vacuoles provide water pressure (Turgor pressure) that helps keep the cells rigid – without it, plants would wilt.

31. Lysosomes • Contain a digestive enzyme. • Can fuse with vacuoles to digest food, or can digest worn cell parts. • Also known as “suicide sacs” because they can also destroy the whole cell.

32. Mitochondria • Produce the energy for the cell. • Also known as the “powerhouse of the cell”. • Has a highly folded inner membrane (cristae). • Have their own DNA and ribosomes; self replicate • Found in cells of all eukaryotes (plants, animals and fungi)

34. Chloroplasts • Found in plant cells and some protists. • Transforms light energy into chemical energy which is stored in food molecules. • Contain chlorophyll – a green pigment that traps light energy and gives plants their green color. • stroma/grana (thylakoid stacks) • Have their own DNA and ribosomes; self – replicate

37. Cilia • Short, numerous, hair-like projections from the plasma membrane. • Move with a coordinated beating action.

38. Flagella • Longer, less numerous projections from the plasma membrane. • Move with a whiplike action.

39. Centrioles • made of protein. • play a role in the splitting of the cell into two cells. • found in animal and fungi cells.

41. Cell Size • Range from 1–100µm • Why is there a limit to cell size? • Surface area-to-volume ratio gets too small – a point will be reached where there is not enough surface are to service all of the cytoplasm • Materials cannot diffuse into center of cell such as oxygen, and food (glucose) and wastes cannot get out

43. Cells must divide • For reproduction • Asexual reproduction • Sexual reproduction • For growth • For repair