7.3 Eukaryotic Cell Structures

1. 7.3 Eukaryotic Cell Structures p. 179 - 187

2. The Cell Theory • Cell is the smallest / basic unit of living organisms • Unicellular organisms are made of one cell only • The cells of multicellular organisms are specialized to perform different functions

3. Prokaryotic cell Eukaryotic cell Notice the structures in the eukaryote

4. Two Main Types of Eukaryotic Cells Animal Cell Plant Cell

5. Organelles • Very small size • Can only be observed under a microscope • Have specific functions • Found throughout cytoplasm

6. A Typical Animal Cell lysosome cytoskeleton Golgi apparatus = sorts & transports Plasma membrane = maintains homeostasis centriole Nucleus = control center nucleolus cytoplasm Mitochondrion = transforms energy Free ribosomes Endoplasmic reticulum = responsible for chemical reactions vacuole ribosomes

7. Cell Membrane • Gate keeper or a skinny bouncer • Controls what comes in and out of the cell.

8. Plasma membrane • Boundary between the cell and its external environment • Helps maintain homeostasis • Allows cell to vary shape as needed • Controls movement of materials that enter and exit cell • A continuous double layer of phospholipid molecules

9. Cell membrane Cell Membrane • Lies immediately against the cell wall • Made of protein and phospholipids • Selectively permeable

10. Cell Membrane Cell membrane • Living layer • Controls the movement of materials into and out of the cell

12. Plant Cell ~ Cell Wall Cell wall • The protector • Dead layer • Large empty spaces present between cellulose fibers • Freely permeable

13. Cell wall Plant Cell ~ Cell Wall • Made of cellulose which forms very thin fibers • Strong and rigid • Only found in plant cells

14. Plant Cell ~ Cell Wall Cell wall • Protect and support the enclosed substances (protoplasm) • Resist entry of excess water into the cell • Give shape to the cell

15. Nucleus • Controls the normal activities of the cell • Bounded by a nuclear membrane • Contains chromosomes - blueprints

16. Nucleus Nucleus • Each cell has fixed number of chromosomes that carry genes. • Humans have 23 pairs of chromosomes. • Genes control cell characteristics

17. nucleus • Manages cell functions • Stores hereditary material • Includes chromatin and the nucleolus, which produces ribosomes • Involved in protein synthesis

18. Nucleolus • Cell may have 1 to 3 nucleoli • Inside nucleus • Disappears when cell divides • Makes ribosomes that make proteins

19. Ribosomes • Ribosomes are protein makers

20. Cytoplasm Cytoplasm / cytosol • Jelly-like substance enclosed by cell membrane that contains organelles • Provides a medium for chemical reactions to take place

21. Cytoplasm Cytoplasm • Contains organelles to carry out specific jobs • Examples: chloroplast & mitochondrion

22. Cytosol • The cytosol is the "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs. • Though mostly water, the cytosol is full of proteins that control cell metabolism including signal transduction pathways, glycolysis, intracellular receptors, and transcription factors.

23. Cytoplasm • This is a collective term for the cytosol plus the organelles suspended within the cytosol.

24. Smooth & Rough Endoplasmic Reticulum Smooth ERlacks ribosomes & makes proteins USED In the cell Rough ERhas ribosomes on its surface & makes proteins to EXPORT

25. Endoplasmic reticulum • Provides a large surface area on which chemical reactions can take place • Site for lipid synthesize • Is cell’s delivery system, providing materials for ribosomes as they synthesize proteins • Is connected to the nuclear envelope providing a pipeline between the nucleus and the cytoplasm.

26. Smooth Endoplasmic Reticulum • Smooth tubes • no ribosomes • Makes lipids • Metabolizes carbohydrates & calcium • Works in some poison & drug detoxification • It is important in the creation and storage of steroids.

27. Rough Endoplasmic Reticulum • bumpy tube or channels • has ribosomes on its surface • Attached to the nuclear membrane • Works with the golgi bodies to export protein to outside cell

28. Golgi apparatus / golgi bodies • Like UPS • Packaging and shipping • Wrap & export proteins

29. Golgi apparatus • Receives newly synthesized proteins and lipids from the ER and distributes them to the plasma membrane and other cell organelles • Chemically modifies proteins & lipids (fats), then repackages them for distribution to final destination outside the cell.

30. Golgi Bodies • Stacks of flattened sacs • Have a shipping side & a receiving side • Receive & modify proteins made by ER • Transport vesicles with modified proteins pinch off the ends Transport vesicle

32. Vacuole Vacuole • Huge space • Plants have a large central vacuole • Contains cell sap… sugars, proteins, minerals, wastes, & pigments

33. Vacuole Vacuole • In animal cells, the vacuoles are much smaller if there at all. • There may be more than one in an animal cell. • The vacuoles are also not found in the center but near the edges.

34. Lysosomes • Digests & gets rid of wastes • Garbage disposal • Recycling center • They are bacteria killers

35. Lysosome • Contain digestive enzymes • Break down food and worn out cell parts for cells • Programmed for cell death (lyse & release enzymes to break down & recycle cell parts)

36. Chloroplast Plant Cell ~ Chloroplast • Contain the green pigment chlorophyll • Traps sunlight to make to make sugars (food) • Process called photosynthesis

37. Plastids • Plant organelles that store starches or lipids or that contains pigments • Chloroplasts contain pigment so they are plastids

38. Mitochondria • The “powerhouse” of the cell • Breaks down food molecules to release energy, which is then stored in other molecules that can power cell reactions easily

39. Mitochondrion( mitochondria ) Mitochondria • Power plant • Rod shape • Site of Cellular respiration

40. Mitochondria Mitochondria • Active cells like muscles have more mitochondria • Burn sugars to produce energy ATP

41. Onion Epidermal Cells Guard Cells root hair Root Hair Cell Different kinds of plant cells

42. Animal cell vacuole cytoplasm • No cell wall or chloroplast • Stores glycogen in the cytoplasm for food energy nucleus mitochondrion cell membrane glycogen granule

43. Microtubule organizer Near the nucleus Paired structures Help cell divide Animal Cell ~ Centriole

44. white blood cell Amoeba red blood cell muscle cell sperm cheek cells nerve cell Paramecium Different kinds of animal cells

45. Cytoskeleton • Provides support for organelles • Also helps maintain cell shape • Includes microtubules and microfilaments

46. Microtubules & Intermediate filaments

47. * Centrosomes • The centrosome, or MICROTUBULE ORGANIZING CENTER (MTOC), is an area in the cell where microtubles are produced. • Plant and animal cell centrosomes play similar roles in cell division, and both include collections of microtubules, but the plant cell centrosome is simpler and does not have centrioles.

48. * Peroxisome • Peroxisomes are membrane-bound packets of oxidative enzymes. • In plant cells, peroxisomes play a variety of roles including converting fatty acids to sugar and assisting chloroplasts in photorespiration. • In animal cells, peroxisomes protect the cell from its own production of toxic hydrogen peroxide. • As an example, white blood cells produce hydrogen peroxide to kill bacteria. • The oxidative enzymes in peroxisomes break down the hydrogen peroxide into water and oxygen.

49. * Secretory vesicles • Cell secretions - e.g. hormones, neurotransmitters - are packaged in secretory vesicles at the Golgi apparatus. • The secretory vesicles are then transported to the cell surface for release.

50. Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm Both have a nucleus Both contain mitochondria