Topic 2.3 Eukaryotic Cells

1. Topic 2.3 Eukaryotic Cells

2. Assessment Statements • 2.3.1: Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell • 2.3.2: Annotate the diagram with the functions of each named structure • 2.3.3: Identify structures from 2.3.1 in electron micrograph of liver cells • 2.3.4: Compare prokaryotic and eukaryotic cells • 2.3.5: State three differences between plant and animal cells • 2.3.6: Outline two roles of extracellular components

3. What is a eukaryotic cell? • Eukaryotic cells range in size: 5 to 100 µm (in diameter) • Most noticeable organelle: nucleus • Others can be noticeable with high enough resolution

4. What is a eukaryotic cell? • Organelles: are non-cellular structures that carry out specific functions • Organelles found in cell vary with the type of cell • Organelles bring out compartmentalization • Allows chemical reactions to be separated (important because some chemical reactions are not compatible with others) • NOT in prokaryotic cells

5. Organelles of Eukaryotic Cells • Common organelles: • Endoplasmic Reticulum (ER) • Ribosomes • Lysosomes (not usually in plants) • Golgi apparatus • Nucleus • Chloroplasts (only in plant and algal cells) • Centrosomes • Centrioles (type of centrosomes—not in plants) • Vacuoles

6. Organelles of Eukaryotic Cells • Cytoplasm-not an organelle but a region • All organelles occur within • The fluid part between the organelles is referred as the cytosol

7. Organelles of Eukaryotic Cells • Endoplasmic Reticulum • Extensive network of tubules or channels that extend almost everywhere in the cell from the nucleus to the plasma membrane • Enables the function of transportation of materials throughout the internal region of the cell • Two general types • Smooth and Rough

8. Organelles of Eukaryotic Cells • Endoplasmic Reticulum (Smooth) • Has no ribosomes attached to it • Has many unique enzymes embedded on its surface • Function: • Production of membrane phospholipids and cellular lipids • Production of sex hormones such as testosterone and estrogen • Detoxification of drugs in the liver • Storage of calcium ions needed for contraction in muscle cells • Transportation of lipid-based compounds • To aid the liver in releasing glucose into the bloodstream when needed

9. Organelles of Eukaryotic Cells • Endoplasmic Reticulum (Rough) • Has ribosomes on the exterior of the channels • Ribosomes involved in protein synthesis • Function: • Protein development and transport • Most cells contain both types of ER with the rough being closer to the nuclear membrane

10. Organelles of Eukaryotic Cells • Ribosome • Not have a exterior membrane • Function: Protein synthesis • Can be found free (in cytoplasm) or attached (ER) • Found in both Eukaryotic and Prokaryotic cells • Ribosomes found in eukaryotic cells are larger and denser then ones in prokaryotic cells • All ribosomes contain 2 subunits • Eukaryotic: 80S • Prokaryotic 70S

11. Organelles of Eukaryotic Cells • Lysosomes • Intracellular digestive centers (come from Golgi ) • No internal structures • They are sacs bounded by a single membrane but contain as many as 40 different hydrolytic enzymes (very acidic) • Function: Fuse the old or damaged organelles from within the cell to break them down so that recycling of the components may occur • Also involved breakdown of materials brought into cell by phagocytosis

12. Organelles of Eukaryotic Cells • Golgi Apparatus • Consists of flattened sacs called cisternae (stacked on top of eachother) • Functions: in collection, packaging, modification, and distribution of materials synthesized in cell • Cisside-near ER, to receive product • Move into the cisternae of the Golgi • Trans side-product is discharged from • small sacs called vesicles are released from this side • These carry modified materials to wherever they are needed inside and outside the cell

13. Organelles of Eukaryotic Cells • Mitochondria • Rod shaped organelle that appear throughout the cytoplasm (same size as a bacterial cell) • Has their own DNA, circular • Double Membrane-Outer (smooth), Inner (Folded into cristae) • Inside the inner membrane is a semi-fluid substance called matrix • Inner membrane spaces-lies between the two membranes

14. Organelles of Eukaryotic Cells • Mitochondria-Function • The cristae provides huge internal surface area for chemical reactions to occur • Most chemical reactions involve the production of usable cellular energy-ATP • Contains its own ribosomes (70S type) • Cells that have high energy requirements, such as muscle cells, have a large numbers of mitochondria

15. Organelles of Eukaryotic Cells • Nucleus-is an isolated region where the DNA resides • Bordered by a double membrane referred to as the nuclear envelope • Allows for separation for the DNA—providing an area where DNA can carry out its functions and not be affected by the other parts of a cell • DNA (genetic material) is usually found in a form of chromosomes • Carry all the information necessary for the cell to exist (allows for survival) • DNA is only found in the form of chromatin during cellular division (formed from histones and DNA (nucleosome) • Nucleosome consists of 8 histones with a DNA wrapped around them

16. Organelles of Eukaryotic Cells • Nucleus • Usually located centrally in the cell • Most cells only contain one! • Cannot reproduce without a nucleus • Only found in very specialized cells (example: blood) • Nucleolus: dark area inside the nucleus • Function of nucleolus: production of ribsomes

17. Organelles of Eukaryotic Cells • Chloroplast • Only occurs in plant and algae cells • Double membrane and is about the size of a bacterial cell • Contains its own DNA (circular) and 70S ribosomes • Also contains granum, thylakoid, and stroma • Granum-is made up of numerous thylakoids stacked in a pile • Thylakoid-are flattened membrane sacs with components necessary for absorption of light • Stroma-similar to cytosol: occurs outside the grana but within the double membrane (contains enzymes and chemicals necessary to complete photosynthesis

18. Organelles of Eukaryotic Cells • Centrosome • Occurs in all eukaryotic cells • Consists of a pair of centrioles at a right angle to one another • Involved in assembling microtubules (important for movement, structure, and cell division) • Plants do not have centrioles but the centrosome is located at one end of the cell close to the nucleus

19. Organelles of Eukaryotic Cells • Vacuoles-are storage organelles that usually form from the Golgi Apparatus • Membrane bound and have many possible functions • Plant cells-occupy VERY large area inside the cell • Allows an uptake of water that provides rigidity • Function: storage of number of different substances including potential food, metabolic wastes and toxins, and water • Enable cells to have higher surface area to volume ratio

20. Comparison of Prokaryotic and Eukaryotic cells (differences)

21. Comparison of Prokaryotic and Eukaryotic cells • Similarities: • Both types of cells have some sort of outside boundary that always involves a plasma membrane • Both types of cell carry out all the functions of life • DNA is present in both cell types

22. Comparison of Plant and Animal cells (differences)

23. Comparison of Plant and Animal cells • The outermost region of various cell types is often unique:

24. Extracellular matrix (ECM): • Extracellular matrix (ECM): composed of collagen fibers plus a combination of sugars and proteins called glycoproteins • Fiber-like structures that anchor the matrix to the plasma membrane—strengthens the plasma membrane and allows attachment between adjacent cells • ECM allows for cell to cell interaction (many researchers believe it is involved in directing stem cells to differentiate)