Human+Bio+HW3+MC

CHAPTER 3 CELL STRUCTURE:

1.	What does the cell theory state? The cell theory states that a cell is a basic unit of life. Nothing smaller than a cell is alive. All living things are made up of cells and new cells arise only from preexisting cells. 2.	 Why are cells so tiny? It’s explained by considering the surface area-to-volume ratio of cells. Nutrients enter the cell, but the wastes leave the cell at its surface. So the greater the amount of surface, the greater the ability to get material in and out of the cells. 3.	What are the three main parts of a eukaryotic cell? The three main parts are the nucleus, a plasma membrane, and the cytoplasm. 4.	Explain how the eukaryotic cell gained mitochondria and chloroplasts. As some of the organelles in eukaryotic cells are raised by engulfing prokaryotic cells, it gives the eukaryotic cell a mitochondrion and chloroplast. 5.	What are glycoprotein’s, and what functions do proteins, including glycoprotein’s, have in the plasma membrane? Glycoprotein’s are short chains of sugars attached to the outer surface of some protein and lipid molecules. Glycoprotein’s help mark it as belonging to a particular individual and account for why people have blood types. They act as a receptor for a chemical messenger, such as a hormone. Proteins form channels in which certain substances can enter cells. Others are enzymes that catalyze reactions. 6.	What is endocytosis and exocytosis, and how do they occur? They are both processes that occur in the plasma membrane. During endocytosis, a portion of the plasma membrane invaginates, or forms, a pouch to envelope a substance and fluid. During exocytosis, a vesicle fuses with the plasma membrane as secretion occurs. 7.	The nucleus, ribosomes, and rough endoplasmic reticulum make what contribution to protein synthesis? They all help determine a cell’s specificity. 8.	The endoplasmic reticulum and the Golgi apparatus make what contribution to the processing of proteins? The Golgi apparatus modifies the proteins and lipids received and it helps detoxify drugs. Attached ribosome’s may be secreted from the cell of become part of the plasma membrane. It produces testosterone. It also forms transport vesicles in which large molecules are transported to other parts of the cell. 9.	What is the function of smooth endoplasmic reticulum and lysosomes? Smooth endoplasmic reticulum synthesizes the phospholipids that occur in membranes and has various other functions depending on the particular cell. Lysosomes help digest things into simpler subunits that then enter the cytoplasm. 10.	 What is the function of the mitochondria? Mitochondria use up oxygen and give off carbon dioxide. It converts the chemical energy of glucose products into the chemical energy of ATP molecules.