I. Biology and Society: Antibiotics: Drugs that Target Bacterial Cells

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1 科目 : 生命科學概論教材單元 : A Tour of the Cell 共 8 頁第 1 頁 I. Biology and Society: Antibiotics: Drugs that Target Bacterial Cells 1. A were first isolated from mold in The widespread use of a drastically decreased deaths from bacterial infections 3. Most a kill bacteria while minimally harming the human host by binding to structures found only on bacterial cells 4. Some a bind to the bacterial ribosome, leaving human ribosomes unaffected 5. Other a target enzymes found only in the bacterial cells A. The Microscopic World of Cells 1. Organisms are either a. Single-celled, such as most prokaryotes and p, or b. Multicelled, such as i. p, ii. a, and iii. most f. B. Microscopes as Windows on the World of Cells 1. L microscopes can be used to explore the structures and functions of cells 2. When scientists examine a specimen on a microscope slide, a. light passes through the specimen and b. lenses enlarge, or magnify, the image. 3. M is an increase in the object s image size compared to its actual size 4. R power is the ability of an optical instrument to show two objects as separate 5. Cells were first described in 1665 by Robert H 6. By the mid-1800s, the accumulation of scientific evidence led to the c theory, which states that a. all living things are composed of cells and b. all cells come from other cells. 7. The e microscope (EM) uses a beam of electrons, which results in 100-fold better resolution than light microscope 8. Two kinds of electron microscopes reveal different parts of cells 9. S electron microscopes (SEMs) examine cell surfaces

2 科目 : 生命科學概論教材單元 : A Tour of the Cell 共 8 頁第 2 頁 10. T electron microscopes (TEMs) are useful for studying the internal structure of a cell 11. The most powerful electron microscopes can a. magnify up to 100,000 times and b. distinguish between objects 0.2 nanometers apart. 12. Light microscopes are still very useful for studying living cells C. The Two Major Categories of Cells 1. The countless cells on Earth fall into two basic categories: a. P cells Bacteria and Archaea and b. E cells protists, plants, fungi, and animals. 2. All cells have several basic features a. They are all bounded by a thin plasma m. b. Inside all cells is a thick, jelly-like fluid called the c, in which cellular components are suspended. c. All cells have one or more c carrying genes made of DNA. d. All cells have ribosomes, tiny structures that build proteins according to the instructions from the DNA. 3. Prokaryotic cells are older than eukaryotic cells a. Prokaryotes appeared about 3.5 billion years ago. b. Eukaryotes appeared about 2.1 billion years ago. 4. Prokaryotic cells are a. usually smaller than eukaryotic cells and b. simpler in structure. 5. Eukaryotes a. Only eukaryotic cells have o, membrane-enclosed structures that perform specific functions. b. The most important organelle is the n, which i. houses most of a eukaryotic cell s DNA and ii. is surrounded by a double membrane. 6. A prokaryotic cell lacks a nucleus. Its DNA is coiled into a nucleus-like region called the nucleoid, which is not partitioned from the rest of the cell by membranes D. An Overview of Eukaryotic Cells 1. Eukaryotic cells are fundamentally similar 2. The region between the nucleus and plasma membrane is the c

3 科目 : 生命科學概論教材單元 : A Tour of the Cell 共 8 頁第 3 頁 3. The cytoplasm consists of various organelles suspended in the liquid cytosol 4. Unlike animal cells, plant cells have a. chloroplasts, which convert light energy to the chemical energy of food in the process of photosynthesis, and b. protective cell walls. 5. Only animal cells have lysosomes, bubbles of digestive enzymes surrounded by membranes II. Membrane Structure 1. The plasma membrane separates the living cell from its nonliving surroundings A. The Plasma Membrane: A Fluid M of Lipids and Proteins 1. The remarkably thin membranes of cells are composed mostly of a. lipids and b. proteins. 2. The lipids belong to a special category called p 3. Phospholipids form a two-layered membrane, the phospholipid b 4. Most membranes have specific proteins embedded in the phospholipid bilayer 5. These proteins help regulate traffic across the membrane and perform other functions 6. The plasma membrane is a f mosaic a. Fluid because molecules can move freely past one another. b. A mosaic because of the diversity of proteins in the membrane. B. C. Cell Surfaces 1. Plant cells have rigid cell walls surrounding the membrane 2. Plant cell walls a. are made of c, b. protect the cells, c. maintain cell shape, and d. keep cells from absorbing too much water. 3. Animal cells a. lack cell walls and b. typically have an e matrix, which i. helps hold cells together in tissues and ii. protects and supports them.

4 科目 : 生命科學概論教材單元 : A Tour of the Cell 共 8 頁第 4 頁 4. The surfaces of most animal cells contain cell j, structures that connect cells together into tissues, allowing them to function in a coordinated way III. The Nucleus and Ribosomes: Genetic Control of the Cell 1. The nucleus is the chief executive of the cell a. Genes in the nucleus store information necessary to produce proteins. b. Proteins do most of the work of the cell. A. Structure and Function of the Nucleus 1. The nucleus is separated from the cytoplasm by a double membrane called the nuclear e 2. Pores in the envelope allow materials to move between the nucleus and cytoplasm 3. The nucleus contains a n where ribosomes are made 4. Stored in the nucleus are long DNA molecules and associated proteins that form fibers called c 5. Each long chromatin fiber constitutes one chromosome 6. The number of chromosomes in a cell depends on the species B. Ribosomes 1. R are responsible for protein synthesis 2. Ribosome components are made in the nucleolus but assembled in the cytoplasm 3. Ribosomes may assemble proteins while the ribosomes are a. suspended in the fluid of the cytoplasm or b. attached to the outside of the nucleus or an organelle called the endoplasmic reticulum. C. How DNA Directs Protein Production 1. DNA programs protein production in the cytoplasm by transferring its coded information into m RNA (mrna) 2. Messenger RNA exits the nucleus through pores in the nuclear envelope 3. A ribosome moves along the mrna, translating the genetic message into a protein with a specific amino acid sequence IV. The Endomembrane System: Manufacturing and Distributing Cellular Products 1. Many membranous organelles forming the e system in a cell are interconnected either a. directly by their membranes or

5 科目 : 生命科學概論教材單元 : A Tour of the Cell 共 8 頁第 5 頁 b. by transfer of membrane segments between them. A. The Endoplasmic Reticulum 1. The e r (ER) is one of the main manufacturing facilities in a cell 2. The ER a. produces an enormous variety of molecules, b. is connected to the nuclear envelope, and c. is composed of smooth and rough ER. 3. Rough ER 4. The rough in rough ER refers to ribosomes that stud the outside of this portion of the ER membrane 5. These ribosomes produce membrane proteins and secretory proteins 6. Some products manufactured by rough ER are dispatched to other locations in the cell by transport v, sacs made of membrane that bud off from the rough ER 7. Smooth ER 8. The s ER a. lacks surface ribosomes, b. produces lipids, including steroids, and c. helps liver cells detoxifys circulating drugs. B. The Golgi Apparatus 1. The G apparatus a. works in partnership with the ER and b. receives, refines, stores, and distributes chemical products of the cell. C. Lysosomes 1. A l is a membrane-bound sac of digestive enzymes found in animal cells 2. Lysosomes are absent from most plant cells 3. Enzymes in a lysosome can break down large molecules such as a. proteins, b. p, c. fats, and d. nucleic acids. 4. Lysosomes have several types of digestive functions a. Many cells engulf nutrients in tiny cytoplasmic sacs called food vacuoles.

6 科目 : 生命科學概論教材單元 : A Tour of the Cell 共 8 頁第 6 頁 b. These food vacuoles fuse with lysosomes, exposing food to enzymes to digest the food. c. Small molecules from digestion leave the lysosome and nourish the cell. 5. Lysosomes can also a. destroy harmful b, b. break down damaged o, and c. sculpt tissues during embryonic development, helping to form structures such as fingers. D. Vacuoles 1. V are large sacs of membrane that bud from the a. ER, b. Golgi apparatus, or c. plasma membrane. 2. Contractile vacuoles of protists pump out excess water in the cell 3. C vacuoles of plants a. store organic nutrients, b. absorb water, and c. may contain pigments or poisons. 4. To review, the endomembrane system interconnects the a. nuclear envelope, b. ER, c. Golgi, d. lysosomes, e. vacuoles, and f. plasma membrane. V. Chloroplasts and Mitochondira: Energy Conversion 1. Cells require a continuous energy supply to perform the work of life 2. Two organelles act as cellular power stations: a. c and b. m. A. Chloroplasts 1. Most of the living world runs on the energy provided by p 2. Photosynthesis is the conversion of light energy from the sun to the c energy of sugar and other organic molecules 3. C are

7 科目 : 生命科學概論教材單元 : A Tour of the Cell 共 8 頁第 7 頁 a. unique to the photosynthetic cells of plants and algae and b. the organelles that perform photosynthesis. 4. Chloroplasts are divided into three major compartments by internal membranes: a. the space between the two membranes, b. the s, a thick fluid within the chloroplast, and c. the space within g, membrane-enclosed discs and tubes that trap light energy and convert it to chemical energy. B. Mitochondria 1. M a. are the organelles of cellular respiration, b. are found in almost all eukaryotic cells, and c. produce ATP from the energy of food molecules. 2. An envelope of two membranes encloses the mitochondrion: a. an outer smooth membrane and b. an inner membrane that i. has numerous infoldings called c and ii. encloses a thick fluid called the m. 3. Mitochondria and chloroplasts contain their own DNA, which encodes some of their proteins 4. This DNA is evidence that mitochondria and chloroplasts evolved from freeliving prokaryotes in the distant past VI. The Cytoskeleton: Cell Shape and Movement 1. The c is a network of fibers extending throughout the cytoplasm A. Maintaining Cell S 1. The cytoskeleton a. provides mechanical support to the cell and b. helps a cell maintain its shape. 2. The cytoskeleton contains several types of fibers made from different proteins: a. M are straight and hollow tubes that guide the movement of organelles and chromosomes. b. I filaments and m are thinner and solid. 3. The cytoskeleton provides anchorage and reinforcement for many organelles 4. The cytoskeleton is dynamic

8 科目 : 生命科學概論教材單元 : A Tour of the Cell 共 8 頁第 8 頁 5. Changes in the cytoskeleton contribute to the amoeboid (crawling) movements of a. the protist Amoeba and b. some of our white blood cells. B. Cilia and Flagella 1. Cilia and flagella are motile appendages that aid in movement a. F propel the cell through their undulating, whiplike motion. b. C move in a coordinated back-and-forth motion. c. Cilia and flagella have the same basic architecture, but cilia are generally shorter and more numerous than flagella. 2. Cilia may extend from nonmoving cells 3. On cells lining the human trachea, cilia help sweep mucus with trapped debris out of the lungs