Chapter 4: “ Cell Structures and Functions ”

1. Chapter 4:“Cell Structures and Functions”

2. 4.1 “The History CellBiology” • Robert Hooke (1665) – Used compound scope to examine thin cork slices. Coined the term “cell” referring to the many little boxes; actually saw dead plant cells • Anton van Leeuwenhoek (1673) with his simple scope, observed first living cells http://www.history-of-the-microscope.org/anton-van-leeuwenhoek-microscope-history.php • Matthias Schleiden (1838) and Theodor Schwann stated that all plants and animals (respectively) are made up of cells • Rudolph Virchow (1855) – cells come only from other cells

3. The Cell Theory • All living things are made up of cells • Cells are the basic unit of structure and function in all living things • Cells come from pre-existing cells

4. 4.2 “Introduction to Cells” 1. Size – Range from 2m (giraffe nerve cell from leg to spine) to .2um (bacteria) Limited by the ratio between outer surface area and their volume. As the surface area to volume ratio decreases, it makes it difficult for information to get around cell and for nutrients to be circulated

6. http://community.nsee.us/concepts_apps/compu_anime/cubebuilding_final.swfhttp://community.nsee.us/concepts_apps/compu_anime/cubebuilding_final.swf

7. Shape –Structure determines function Red Blood Cells are like tubes so they flow easier through blood vessels Nerve cells are like electrical wires Skin cells (Epithelial cells) are flat to act like a shield White Blood cells are amoeboid shaped to move and squeeze into all areas http://www.youtube.com/watch?v=W6rnhiMxtKU

8. 3. Internal Organization – • Organelles – internal structures in a cell. Each has a specific function Most cells contain: a. Plasma (cell) membrane – porous to certain compounds b. Cytoplasm – “cell’s liquid” -http://www.youtube.com/watch?v=W6rnhiMxtKU Organelles are suspended in it c. Nucleus – holds DNA, control center

9. 4. Type a. Prokaryotic cells – cells that lack a nucleus and membrane bound organelles - Bacteria & Archaebacteria - Have a cell wall, cell membrane, cytoplasm, DNA & ribosomes - Pigments and enzymes are suspended in cytoplasm

10. Nucleus • Eukaryotic Cells – contain a membrane bound nucleus and membrane bound organelles - Much more complex cell - All cells other than bacteria. - Protists, Fungus, Animals and Plants

11. Comparing the Two

12. Central Problem #1: A living system MUST be separated from its environment if it is to maintain complex order in a chaotic physical world. 4.3 “Cell Structure and Function” Cell Membrane aka Plasma Membrane – Separates the cell’s internal environment from the external environment - Allows for the passage of some substances based on size and concentration • Selectively Permeable

13. Made up of a bilipid layer (lipid bilayer) – 2 layers of phospholipids with proteins floating through it. • Tails of phospholipids are hydrophobic while the heads are hydrophilic

14. * Peripheral membrane proteins do not penetrate the hydrophobic core of the membrane. They can be easily removed without destroying the membrane structure. • Integral proteins are fully incorporated into the membrane and are in contact with both the inside and the outside of the cell. Some can act as channels for the transport of substances. Others have carbohydrate attached to them – recognition sites. Peripheral protein Integral protein

15. In the "fluid mosaic model" of membrane structure, the membrane is a fluid phospholipid bilayer in which protein molecules are either partially or wholly embedded. These layers easily move around. http://www.youtube.com/watch?v=Qqsf_UJcfBc

16. Cellular Organelles Cytoplasm – not an organelle – “cell’s liquid” Made of gelatinous cytosol where nutrients and minerals carried in solution within it. • Typical Animal Cell • Typical Plant Cell

17. Nucleus • Found ONLY in eukaryotic cells • Stores hereditary information in DNA • Surrounded by a double nuclear envelope. Nuclear pores perforate membrane. • Chromatin - strands of a combination of DNA and protein. These will later become chromosomes. • Nucleolus(one or more) produces ribosomes

18. Mitochondrion (a) - Powerhouse of the cells. - Where cellular respiration occurs and glucose is broken down to release energy (in the form of ATP) to the cell. • Found in greater numbers in cells such as muscle cells and liver cells (2500/cell) • Double membrane with cristae(folds) to increase surface area for reactions to take place • Have their own DNA Cristae Double Membrane

19. Ribosomes • Most numerous organelle. Site of protein synthesis. • Not membrane bound; many found in prokaryotic cells. • Made up of RNA and protein. • May be free floating in cytoplasm or attached to endoplasmic reticulum.

20. Endoplasmic Reticulum (ER) – Channels or passageways in the cell. There are two types of ER: 1 – Rough ER with ribosomes attached for the production and distribution of proteins. 2 – Smooth ER for the synthesis of steroids in gland cells, Ca++ regulation in muscle cells and breakdown of toxins in the liver

21. Golgi Apparatus (Bodies) • Stack of smooth flat sacs. • Processing, packaging and secreting organelle of the cell. • Much like a processing and exporting factory. Works in close association with ER.

22. Vesicles • Membrane bound sacs that “bud off” from various components of the cell • Have different roles • “Packages” can remain within the cell, or be exported

23. Lysosomes • Single membrane vesicles- the cell’s garbage disposal system. • They breakdown worn out organelles such as mitochondria and produce enzymes to that degrade DNA, proteins, lipids and carbohydrates (autophagy) • Also responsible for destroying dying or extra cells (autolysis)

24. Vacuoles - Store enzymes, food, water and wastes. - Huge water vacuole in plant cells. - Gives plant cell “turgor” (full of water and fully supported) – 90% of cells may be water. - Some contain metabolic wastes which may be toxic to other organisms (poison ivy).

25. 1  Nucleus    2   Nuclear pore within the nuclear envelope    3  Rough endoplasmic reticulum (RER)    4  Rough endoplasmic reticulum (RER)    5  Ribosome on the rough ER    6 Proteins that are transported    7  Transport vesicle  8 - 11 Golgi apparatus Putting it all together!

26. Cytoskeleton Network of protein strands that provide shape,structureand mobility of organelles in cytoplasm. There are two components of the cytoskeleton: • Microfilaments –involved with cellular movement and muscle contractions • Microtubules – larger structures. Involved with cell division, make up flagella and cilia. Also make up spindle fibers that assist in chromosome migration during cell division.

27. Cilia and Flagella • Extensions from cell membrane. • Assist in movement. • Cilia (um)- short and multiple numbers. • Covering of Paramecium, lining of respiratory tract and nasal passages. • Flagella (um)- long and usually only one to a few. Sperm cells, Euglena. Used for locomotion.

28. Centrioles • Made of two short cylindesr of microtubules, oriented at right angles • Participate in cell division • Absent in plants

29. 4.4 “Features of Plant Cells” • Are eukaryotic and have most of the same organelles as animal cells – in addition: 1. Cell Walls • Made up of cellulose; gives cells rigidity, protection & support. • Also porous.

30. 2.Vacuoles - Store enzymes, food, water and wastes. - Huge water vacuole in plant cells. - Gives plant cell “turgor” (full of water and fully supported) – 90% of cells may be water. - Some contain metabolic wastes which may be toxic to other organisms (poison ivy).

31. Plastids Double membrane, DNA containing to store starch, fats or pigments such as chlorophyll. Chloroplast – where photosynthesis occurs. Made up of membrane stacks called thylakoids. Here is where energy conversion occurs. Leucoplast -store starch

34. Typical Animal Cell 1. _______________ 2. _______________ 3. _______________ (Dots) 4. _______________ 5. _______________ 6. _______________ 7. _______________ 8. _______________ 9. _______________ 10._______________ 11._______________ 12._______________ 13._______________

35. Typical Plant Cell

36. Cheek Cells

37. Cyclosis Elodea

38. Onion Cells

39. Potato Cells