Basic Cell Structure

1. Basic Cell Structure Modified by Georgia Agricultural Education Curriculum Office June, 2002

2. Cells • Basic building blocks of life • Understanding of cell morphology is critical to the study of biotechnology

3. Cell • Smallest living unit of an organism • Grow, reproduce, use energy, adapt, respond to their environment

4. Cell • Many cannot be seen with the naked eye • A cell may be an entire organism or it may be one of billions of cells that make up the organism

5. Cells • Divided and classified in many ways • One common classification method is the presence or absence of a cell nucleus

6. Nucleus • Relatively large structure within a cell • Directs cell activities • Some simple single-celled organisms lack a nucleus

7. Nucleus • Prokaryotes – have no nucleus • Eukaryotes – have a nucleus

8. Prokaryotes • Single celled organism • Kingdom Monera • Lacks a cell nucleus • Internal structure is less organized than other cells

9. Prokaryotes • Genetic info needed is within the cell • Two most common – blue green bacteria and true bacteria

10. Blue green bacteria • Have ability to produce their own food like plants • Most bacteria get their food from other sources

11. Prokaryotes • Less complex than eukaryotes • Still have many of the basic internal characteristics

12. Common prokaryote structures • Cytoplasm • Chromosomal material • Cell membrane and wall • Ribosomes • Some have flagellum for mobility

13. Eukaryotes • Organism made up of cells that have a nucleus • May be single celled – Kingdom Protista • May have billions of cells like plant and animal kingdoms

14. Eukaryotes • Single celled eukaryotes include paramecia, euglena, and diatoms

15. Eukaryotes • Typically are highly organized • Infinite number of shapes and purposes

16. Eukaryotes • Human body has at least 85 different cell types • All eukaryotes have a number of structures in common

17. Common structures • Organelles – smaller parts of the cell with specific functions • Cell membrane – acts as a gatekeeper

18. Cell membrane • Controls what enters and leaves the cell • Plants, algae, and bacteria typically have a tough outer structure known as a cell wall

19. Cell wall • Provides additional structure and protects the cell from pressure caused by movement of water • Animal cells do not have walls

20. Cytoplasm • Organelles are surrounded by a jelly-like substance • Primary component is water

21. Nucleus • Largest and most identifiable part of the cell

22. Other organelles • Ribosomes • Mitochondria • Golgi bodies (apparatus) • Endoplasmic reticulum

23. Other organelles • Lysosomes • Vacuoles • Chloroplasts in plants

24. Nucleus • Brain of the cell • Site of much of the manipulation done in biotechnology

25. Nucleus • Controls activity of the cell • Round or oval structure • Typically found in the middle of the cell • Appears darker than surrounding material

26. Nucleus • Surrounded by a membrane that controls passage of materials in and out of the area

27. Nucleus • Contains DNA • DNA is located on chromosomes • Most organisms are diploid – have tow chromosomes for each trait

28. Diploid • Humans – 23 pair • Goldfish – 90 chromosomes, 45 pair

29. Cytoplasmic Organelles • Organelles are required for proper cell function • Ribosome – make proteins for cellular use and communication • May be attached to endoplasmic reticulum

30. Endoplasmic reticulum • Layered membraneous • Make and transport proteins

31. Vacuole • Large organelle, without specific shape • Store waste or raw materials used in synthesis of proteins

32. Golgi Bodies • Golgi apparatus • Similar to endo. Ret. • Look like a thick elastic band that has been folded several times

33. Golgi Bodies • Adds modifications to unfinished proteins • Makes lysosomes

34. Lysosome • Small and round • Store enzymes that break down food into chemical compounds • Destroy cell organelles and the cell itself

35. Mitochondria • Energy factories • Rod-shaped • Change food into molecules that can be used for energy

36. Mitochondria • Contain DNA • Can replicate themselves

37. Chloroplast • Found in plants and some other organisms • Contain chlorophyll

38. Cellular processes • Respiration • Osmosis • Diffusion • Photosynthesis

39. Respiration • Cells break down carbohydrates and other molecules to produce energy • Oxidation of glucose is one of most common forms

40. Respiration • Breaking down of sugar into water, carbon dioxide, and energy • Energy is used to do the work of the cell

41. Osmosis & Diffusion • Transportation of raw materials, wastes, and synthesized materials out of the cell

42. Diffusion • Movement of molecules; especially gases and liquids from areas of high concentration to areas of low concentration

43. Osmosis • Specific type of diffusion • Movement of water through a membrane from areas of high concentration to areas of low concentration

44. Equilibrium • Diffusion and osmosis happen to enable a cell to reach equilibrium

45. Cellular reproduction • Three ways: • Fission • Mitosis • Meiosis

46. Fission • Prokaryotes • Cell grows larger and makes a second copy of its DNA • At some point the cell membrane divides the cell by the growth of a transverse septum

47. Fission • Two new cells are formed as the division grows inward from either side of the cell • Two cells now called “daughter cells” • Sometimes known as “binary fission”

48. Mitosis • Eukaryotes • Requires 6 stages • Interphase, prophase, metaphase, anaphase, telophase, cytokinesis

49. Mitosis • Creates cells that are identical to the original cell. • Have the entire compliment of chromosomes existing in pairs - diploid

50. Meiosis • Division of sex cells • Stages of Meiosis I: Interphase I, prophase I, metaphase I, anaphase I, telophase I, cytokinesis I