Chapter+3+Hw+DW

DeMarcus Waggoner August 19, 2008 Human Bio

Chapter 3. Cell Structure

1. What does the cell theory state? The cell theory is that the cell is the basic unit of life. 2. Why are cells so tiny? “The Small size if cells is explained by considering the surface area-to-volume ratio of cells. Nutrients enter a cell and wastes exit a cell at its surface; therefore the greater the amount of surface area the reater the ability to get material in and out of the cell.” 3. What are the three main parts of a eukaryotic cell? The three main parts of the eukaryotic cell are the plasma, cytoplasm, and the organelles. 4. Explain how the eukaryotic cell gained mitochondria and chloroplasts. The “organelles in the eukaryotic cells may have arisen by engulfing prokaryotic cells.” 5. What are glycoproteins, and what functions do proteins, including glycoproteins, have in the plasma membrane? Glycoproteins are “short chains od sugar that are attached to the outer surface of some protein and lipid molecules.” They specify what blood[type we are and they also can “act as a receptor for a chemical messenger, such as a hormone. 6. What is endocytosis and exocytosis, and how do they occur? Endocytosis is when the substance is takin inot the cell and excytosis is when the substance is being released from the cell. 7. The nucleus, ribosomes, and rough endoplasmic reticulum make what contribution to protein synthesis? “The nucleus contains chromatin. Chromatin has a special region called the nucleolus, which is where rRNA is produced and ribosome’s subunits are assembeles. The nuclearenvelope contains pores that alow substances o enter and exit the nucleus to and from the cytoplasm. The nuclear envelope is attatched to the endoplasmic reticulum, which often has attached ribosome’s, where protein synthesis occurs.” 8. The endoplasmic reticulum and the Golgi apparatus make what contribution to the processing of proteins? They modify “lipids and proteins from their ER; sorts and packages them in vesicles. 9. What is the function of smooth endoplasmic reticulum and lysosomes? Smooth ER “synthesis lipids and has various other functions”, and lysosomes “contain digestive enzymes that break down cell parts or substances entering by vesicles.” 10. What is the function of the mitochondria? The mitochondria is the “powerhouse of the cell” it converts “the chemical energy of ATP molecules.” “The mitochondria use up oxygen and molecules.”