Figure 5.1 Despite its seeming hustle and bustle, Grand Central Station functions with a high level of organization: People and objects move from one location to another, they cross or are contained within certain boundaries, and they provide a constant flow as…
Studying Cells A cell is the smallest unit of life. Most cells are so tiny that they cannot be seen with the naked eye. Therefore, scientists use microscopes to study cells. Electron microscopes provide higher magnification, higher resolution, and more…
LEARNING OBJECTIVES In this section, you will explore the following questions: Connection for AP® Courses With the exception of gap junctions between animal cells and plasmodesmata between plant cells that facilitate the exchange of substances, the information presented in Section 4.6|…
LEARNING OBJECTIVES In this section, you will explore the following questions: Connection for AP® Courses All cells, from simple bacteria to complex eukaryotes, possess a cytoskeleton composed of different types of protein elements, including microfilaments, intermediate filaments, and microtubules. The cytoskeleton…
LEARNING OBJECTIVES In this section, you will explore the following questions: Connection for AP® Courses In addition to the presence of nuclei, eukaryotic cells are distinguished by an endomembrane system that includes the plasma membrane, nuclear envelope, lysosomes, vesicles, endoplasmic reticulum,…
LEARNING OBJECTIVES In this section, you will explore the following questions: Connection for AP® Courses Eukaryotic cells possess many features that prokaryotic cells lack, including a nucleus with a double membrane that encloses DNA. In addition, eukaryotic cells tend to be…
LEARNING OBJECTIVES In this section, you will explore the following questions: Connection for AP® Courses According to the cell theory, all living organisms, from bacteria to humans, are composed of cells, the smallest units of living matter. Often too small to…
LEARNING OBJECTIVES In this section, you will explore the following questions: Connection for AP® Courses A cell is the smallest unit of a living thing. A living thing, whether made of one cell (like bacteria) or many cells (like a human),…
Figure 4.1 (a) Nasal sinus cells (viewed with a light microscope), (b) onion cells (viewed with a light microscope), and (c) Vibrio tasmaniensis bacterial cells (seen through a scanning electron microscope) are from very different organisms, yet all share certain characteristics of basic cell…
Synthesis of Biological Macromolecules Proteins, carbohydrates, nucleic acids, and lipids are the four major classes of biological macromolecules—large molecules necessary for life that are built from smaller organic molecules. Macromolecules are made up of single units known as monomers that…