John H. Postlethwait, Janet L. Hopson
Format: PDF / Kindle (mobi) / ePub
An awesome biology textbook.
ionic bond, as shown in Figure 2-4. Thus, the sodium atom undergoes oxidation to form a Naϩ ion. In a reduction reaction, a reactant gains one or more electrons, thus becoming more negative in charge. When a chlorine atom gains an electron to form a ClϪ ion, the atom undergoes reduction. Redox reactions always occur together. An oxidation reaction occurs, and the electron given up by one substance is then accepted by another substance in a reduction reaction. Materials toothpicks, small and
organization. One theme that occurs again and again throughout biology is that form follows function. In other words, a cell’s function influences its physical features. Cell Shape The diversity in cell shapes reflects the different functions of cells. Compare the cell shapes shown in Figure 4 - 4. The long extensions that reach out in various directions from the nerve cell shown in Figure 4 - 4a allow the cell to send and receive nerve impulses. The flat, platelike shape of skin cells in Figure
the bacteria and viruses before they can harm the animal. Word Roots and Origins vesicle from the Latin vesicula, meaning “bladder” or “sac” EXTERNAL ENVIRONMENT Cell membrane Vesicle CYTOSOL FIGURE 5-7 During endocytosis, the cell membrane folds around food or liquid and forms a small pouch. The pouch then pinches off from the cell membrane to become a vesicle. HOMEOSTASIS AND CELL TRANSPORT Copyright © by Holt, Rinehart and Winston. All rights reserved. 105 EXTERNAL ENVIRONMENT
acid into other compounds through additional biochemical pathways that occur in the cytosol. The combination of glycolysis and these additional pathways, which regenerate NADϩ, is known as fermentation. The additional fermentation pathways do not produce ATP. However, if there were not a cellular process that recycled NADϩ from NADH, glycolysis would quickly use up all the NADϩ in the cell. Glycolysis would then stop. ATP production through glycolysis would therefore also stop. The fermentation
. . . 450 CHAPTER 23 Microbiologist . . . . . . . . . . . . . . 464 CHAPTER 27 Ethnobotanist . . . . . . . . . . . . . . 551 CHAPTER 32 Veterinarian . . . . . . . . . . . . . . . 654 CHAPTER 37 Entomologist . . . . . . . . . . . . . . 742 CHAPTER 45 Certified Athletic Trainer . . . . . 918 CHAPTER 11 Milestones in Recent DNA Research . . . . . . . . . . . . . . 227 CHAPTER 17 Milestones in the Classification of Organisms . . . . 340 CHAPTER 22 Milestones in Environmental