Week 1 review questions THE CELL Eukaryotic cells contain organelles and histones, they have a well-defined nucleus, and are larger than prokaryotic cells. The histones are binding proteins that cause the supercoiling of DNA into chromosomes and do not affect cellular division, movement, or activities. 3. An organelle that is responsible for the metabolism of cellular energy is referred to as a/an: Mitochondria play a role in cellular metabolism, cellular respiration, and energy production. The Golgi complex is responsible for processing and packaging proteins from the endoplasmic reticulum, where they are synthesized. The nucleolus is a small, dense structure that contains the ribonucleic acid (RNA), DNA, and DNA-binding proteins. 4. Which statement best describes a desmosome? The desmosome is a type of cell junction. The other two types include tight junctions and gap junctions. Desmosomes hold cells together by forming a continuous band of epithelial tissue or belt (or button like) points of contact. They are also a source of structural stability. Tight junctions serve as barriers to diffusion and prevent the movement of substances through transport proteins. Gap junctions are clusters of communicating tunnels. 5. Which statement describes the function of a second messenger? The binding of a ligand to a cell surface receptor triggers the activation of intracellular second messengers. Second messengers activate signal transduction pathways in the cell 2. The function of a histone found in a eukaryote cell focuses on cellular: that can initiate different intracellular events. Cyclic adenosine monophosphate (cAMP) and calcium (Ca++) are the two major second-messenger pathways. First messengers are the extracellular ligands that bind to cell surface receptors. Binding of first messengers can result in the opening or closing of specific cell membrane channels or the activation of second messengers. 6. Which statement is correct regarding cellular energy? Oxidative phosphorylation occurs in the mitochondria. This is the mechanism by which the energy produced from carbohydrates, fats, and proteins is transferred to ATP. Glycolysis is a process that breaks down glucose molecules; it produces a net of two ATP molecules. Oxidation is a process during which a pair of electrons are removed and transferred