THE HISTORY OF CELL BIOLOGY

SECTION 4-1 REVIEW THE HISTORY OF CELL BIOLOGY Define the following terms. 1. cell 2. cell theory Write the correct letter in the blank. 1. One early piece of evidence supporting the cell theory was the observation that a. only plants are composed of cells. c. cells come from other cells. b. only animals are composed of cells. d. animal cells come from plant cells. 2. The scientist who described cells as many little boxes was a. Robert Hooke. c. Theodor Schwann. b. Anton van Leeuwenhoek. d. Rudolf Virchow. 3. Living and nonliving things are different in that only a. nonliving things are made of cells. c. living things are made of cells. b. nonliving things are made of atoms. d. living things are made of atoms. 4. Microscopes were used to study cells beginning in the a. 16th century. c. 18th century. b. 17th century. d. 19th century. 5. The advantage of van Leeuwenhoek s microscopes was that a. they were simple. c. the lenses could be moved. b. they had two lenses. d. the lenses were ground very precisely. 6. Which of the following was a major event in the history of cell biology? a. cloning animals c. discovery of cell parts b. growing bone tissue for transplant d. All of the above 7. A light microscope uses optical lenses to magnify objects by a. bending light rays. c. reflecting beams of light. b. bending electron beams. d. reflecting beams of electrons. Modern Biology Study Guide 19

Answer the questions in the space provided. 1. State the three parts of the cell theory. 2. Why did it take 150 years for the cell theory to be developed after microscopes were invented? 3. Why did Hooke s cork cells appear to be empty? 4. Critical Thinking If you read that a new organism had been discovered, what would you know about the organism without examining it in terms of cells? Use the figure to answer the following questions. Robert Hooke observes cork cells. 1665 1827 Karl Von Baer discovers the mammalian egg. Timeline History of Cell Biology Rudolf Virchow adds to the cell theory. 1855 1. Approximately how many years elapsed between the time cells were discovered and the observation of cell parts in muscle cells? 1857 Kolliker describes mitochondria in muscle. Camillo Golgi discovers the Golgi apparatus in cells. 1996 1897 2004 Researchers in Scotland clone a sheep from an adult sheep cell. Tissue engineering used to grow new skin and bone for transplant. 2. When was the third part of the cell theory added? What was the time interval between this event and the discovery of cells? 20 Section 4-1 Review

SECTION 4-2 REVIEW INTRODUCTION TO CELLS Define the following terms. 1. organelle 2. nucleus 3. eukaryote 4. prokaryote Write the correct letter in the blank. 1. Cells are limited in size by the a. rate at which substances needed by the cell can enter the cell through its surface. b. rate at which the cell can manufacture genetic information. 2. The diameter of most plant and animal cells is about a. 0.1 to 0.2 µm. b. 10 to 50 µm. c. 1 to 2 mm. d. 10 to 50 mm. 3. The characteristic of a nerve cell that relates directly to its function in receiving and transmitting nerve impulses is its a. long extensions. b. flat shape. 4. One difference between eukaryotic and prokaryotic cells is that only a. prokaryotic cells are surrounded by a cell membrane. b. prokaryotic cells have a nucleus. c. amount of material the cell can collect to fill itself. d. amount of cell membrane the cell can produce. c. ability to change shape. d. ability to engulf and destroy bacteria. c. eukaryotic cells have genetic information. d. eukaryotic cells have membrane-bound organelles. Modern Biology Study Guide 21

Answer the questions in the space provided. 1. How is the shape of a skin cell suited to its function? 2. How are the organelles of a single cell like the organs of a multicellular organism? 3. Name two features of eukaryotic cells that prokaryotic cells lack. 4. Critical Thinking When a spherical cell increases in diameter from 2 µm to 20 µm, by what factor does its surface area change? By what factor does its volume change? (The surface area of a sphere 4π radius 2, and the volume of a sphere 4/3π radius 3. Remember that diameter 2 radius.) 1. These figures represent a eukaryotic cell and a prokaryotic cell. In the spaces below the diagrams, indicate which type of cell each diagram represents. X Y a 2. List two features that formed the basis for your identification of these cells. 3. Identify the structures labeled X and Y. SECTION 4-3 REVIEW b 22 Section 4-2 Review

SECTION 4-3 REVIEW CELL ORGANELLES AND FEATURES Distinguish between the terms in each of the following pairs of terms. 1. nucleoplasm, nuclear envelope 2. cytoskeleton, microtubule 3. cilia, flagella Write the correct letter in the blank. 1. The plasma membrane a. allows all substances to pass into and out of the cell. b. prevents all substances from passing into and out of the cell. 2. Substances produced in a cell and exported outside of the cell would pass through the a. endoplasmic reticulum and Golgi apparatus. b. mitochondria and Golgi apparatus. 3. Cells that have a high energy requirement generally have many a. nuclei. b. flagella. c. mitochondria. d. microfilaments. 4. Viruses, bacteria, and old organelles that a cell ingests are broken down in a. ribosomes. b. lysosomes. c. is composed mainly of a protein bilayer. d. is composed mainly of a lipid bilayer. c. nucleus and lysosomes. d. vacuoles and lysosomes. c. the rough endoplasmic reticulum. d. the smooth endoplasmic reticulum. 5. Organelles that are surrounded by two membranes and contain DNA are the a. nucleus, the endoplasmic reticulum, and lysosomes. b. nucleus, the endoplasmic reticulum, and chloroplasts. c. nucleus and mitochondria. d. endoplasmic reticulum and the Golgi apparatus. Modern Biology Study Guide 23

Answer the questions in the space provided. 1. What roles do membrane proteins play in transporting only certain substances into a cell? 2. What are ribosomes made of? What cellular function are they involved in? 3. What is the cytoskeleton, and what are three of its major components? 4. Describe the structural organization shared by cilia and flagella. 5. Critical Thinking When lipid is added to a solution of a detergent in water, the detergent breaks up large globules of the lipid into much smaller globules. What effect do you think a detergent would have on the integrity of cells? Explain your answer. This diagram represents a typical animal cell. Label each part of the figure in the spaces provided. a. b. c. d. e. f. a b c d e f 24 Section 4-3 Review

SECTION 4-4 REVIEW UNIQUE FEATURES OF PLANT CELLS Define the following terms. 1. cell wall 2. plastid 3. thylakoids 4. chlorophyll 5. central vacuole Write the correct letter in the blank. 1. Which of the following organelles is found in plant cells but not in animal cells? a. nucleus c. mitochondrion b. chloroplast d. Golgi apparatus 2. The end products of photosynthesis include a. carbon dioxide and water. c. carbon dioxide and oxygen. b. sugars. d. oxygen and water. 3. A cell that contains a cell wall, chloroplasts, and a central vacuole is a a. plant cell. b. animal cell. c. prokaryotic cell. d. bacterial cell. 4. A central vacuole forms from a. chloroplasts. c. the fusion of smaller vacuoles. b. fusion of amyloplasts. d. the products of photosynthesis. 5. Thylakoids are located a. between the two membranes of a chloroplast. b. outside the outer membrane of a chloroplast. c. inside the inner membrane of a chloroplast. d. in chromoplasts. Modern Biology Study Guide 25

Answer the questions in the space provided. 1. How are secondary cell walls different from primary cell walls? 2. What are plant cell walls made of? What is the function of cell walls? 3. What is the appearance of a plant cell when water is plentiful? 4. Critical Thinking Bacteria have a region called a nucleoid, in which their genetic material is located. Why, then, are bacteria classified as prokaryotes? Label each part of the figure in the spaces provided. This diagram represents a typical plant cell. a b c d e f g h i 26 Section 4-4 Review

6. By neutralizing small amounts of acid or base that may be added to a solution, buffers keep ph values at normal and safe levels. The control of ph is essential for the function of enzymes. 7. Since a tenfold increase in H 3 O ion concentration reflects a decrease of one ph unit, a 100-fold increase in concentration reflects a decrease of two ph units. Therefore, the new ph would be 5.5. Drawings should show two water molecules below and one above the central water molecule. The molecules below should have their H atoms facing away from the central molecule, and the molecule above should have one of its H atoms pointing toward the central molecule. Dashed lines should be drawn between each H atom in the central molecule and the O atom in each of the lower water molecules, and between the O atom in the central molecule and the nearer H atom in the upper water molecule. Section 3-1 1. An organic compound is a compound containing carbon atoms covalently bonded to other carbon atoms and to other elements. Examples: any carbon-containing compound, such as benzene, ethanol, glycerol, glucose, fructose, sucrose, ATP, and ADP. 2. A functional group is a cluster of atoms in a compound that influences the properties of that compound. Examples: hydroxyl group, phosphate group. 3. An alcohol is an organic compound with a hydroxyl group attached to one of its carbon atoms. Examples: ethanol, methanol, glycerol. 4. A monomer is a simple molecule that can bond to others of its kind to form more complex molecules. Examples: glucose, fructose. 5. A polymer is a complex molecule that consists of repeated, linked units. Example: DNA, proteins. 1. a 2. c 3. b 4. a 5. d 1. The hydroxyl group on alcohols is polar, and this makes alcohols polar compounds. Alcohols can therefore form hydrogen bonds. 2. carbon atom, monomer, polymer, macromolecule 3. The glucose molecule releases a hydroxide ion, OH, and the fructose molecule releases a hydrogen ion, H. These two ions combine to produce water, H 2 O. 4. The hydrolysis products are ADP and inorganic phosphate. Energy is released. 5. With seven electrons in its outermost energy level, carbon could not form double or triple bonds with other atoms, so far fewer organic compounds could be formed. 1. Forward reaction: reactants, glucose and fructose; products, sucrose and H 2 O. 2. condensation reaction 3. Reverse reaction: reactants, sucrose and H 2 O; products, glucose and fructose. 4. hydrolysis Section 3-2 1. A monosaccharide is a simple sugar containing carbon, hydrogen, and oxygen in a ratio of 1:2:1; a polysaccharide is a complex molecule composed of three or more monosaccharides. 2. An amino acid is a compound containing carbon, hydrogen, oxygen, and nitrogen. A protein is a large polymer of amino acids. 3. A nucleotide is a compound containing a phosphate group, a five-carbon sugar, and a ringshaped nitrogen base; a nucleic acid is a very large polymer of nucleotides. 1. c 2. a 3. d 4. b 5. d 1. The storage form is glycogen, and the quick-energy form is glucose. Glycogen consists of hundreds of glucose molecules linked in a highly branched chain. 2. Starch, 1; proteins, 20. 3. Phospholipid composes most of the cell membrane. The hydrophobic tails of the phospholipids provide a barrier between the inside and outside of the cell. 4. Steroids are lipids made of four fused carbon rings. Examples: testosterone and cholesterol. 5. Wax serves as a waterproof layer, limiting water loss and preventing insects from drying out. a, substrate; b, enzyme; c, products Section 4-1 1. A cell is the smallest unit that can carry on all of the processes of life. 2. The cell theory states that all living organisms are made of one or more cells, that cells are the basic units of structure and function, and that cells come only from the reproduction of existing cells. 1. c 5. d 2. a 6. d 3. c 7. a 4. b 1. (1) All living things are composed of one or more cells. (2) Cells are the basic units of structure and function in an organism. (3) Cells come only from the reproduction of existing cells. 2. Information about cells could not be understood and organized into a central theory until microscope technology had improved and accurate observations were made. 3. The cork cells that Hooke observed were the remains of dead plant cells. The material from the inside of the cells had been lost or destroyed. 4. You would know that it was made of cells and the cells reproduce to make more cells. Modern Biology Study Guide Answer Key 3

1. Approximately 200 years elapsed between the discovery of cells in 1665 and the observation of mitochondria in muscle cells in 1857. 2. The third part of the cell theory was added in 1855. This was 190 years after cells were discovered. Section 4-2 1. An organelle is a cell component that performs specific functions for the cell. 2. The nucleus is an organelle that contains coded information in the form of DNA for regulating functions and reproduction and directs most of the activities of the cell. 3. A eukaryote is an organism whose cells contain a membrane-bound nucleus and other organelles. 4. A prokaryote is an organism that lacks a nucleus and membrane-bound organelles. 1. a 2. b 3. a 4. d 1. Its flat platelike shape covers and protects the body s surface. 2. Just as organs carry out the organism s life functions, organelles maintain the life of the cell. 3. Eukaryotic cells have a membrane-bound nucleus and membrane-bound organelles. 4. The surface area increases by a factor of 100. The volume increases by a factor of 1,000. 1. a, prokaryotic cell; b, eukaryotic cell. 2. Features: eukaryotic cell has a nucleus and other membrane-bound organelles, but the prokaryotic cell does not; prokaryotic cell is smaller. 3. X, nucleus; Y, cell membrane Section 4-3 1. The nucleoplasm is the jellylike liquid that fills the nucleus. The nuclear envelope is a double membrane that surrounds the nucleus. 2. The cytoskeleton is the network of tubes and filaments that give a cell its shape and serves as tracks for the movement of organelles in the cell. Microtubules are one of three structural elements that make up the cytoskeleton. 3. Both are hairlike organelles that extend from the surface of a eukaryotic cell, but cilia are shorter and are present in larger numbers on a cell. 1. d 2. a 3. c 4. b 5. c 1. Some proteins form channels or pores through which certain substances can pass. Other proteins bind to a substance on one side of the membrane and carry it to the other side. 2. Ribosomes are made of proteins and RNA. They are involved in protein synthesis. 3. The cytoskeleton is a network of long protein strands located in the cytosol. Three major components are microfilaments, microtubules, and intermediate filaments. 4. Cilia and flagella are composed of nine pairs of microtubules arranged around a central pair. 5. The detergent would cause the cells to disintegrate because it would break up the plasma membrane as well as organelle membranes, all of which are largely composed of lipid. a. mitochondrion; b. nucleus; c. nucleolus; d. Golgi apparatus; e. rough endoplasmic reticulum; f. ribosome Section 4-4 1. A cell wall is a rigid layer that lies outside the plasma membrane of a plant cell. 2. A plastid is an organelle that is surrounded by a double membrane and contains DNA. 3. Thylakoids are flattened membranous sacs that contain chlorophyll. 4. Chlorophyll is a green pigment that absorbs light and captures energy for a plant cell. 5. A central vacuole is a large, fluid-filled organelle that stores water, enzymes, and wastes in plant cells. 1. b 2. b 3. a 4. c 5. c 1. Primary cell walls are assembled on the surface of the plasma membrane while the cell is growing. They can grow as the cell grows. Secondary cell walls are produced after the cell has stopped growing. Secondary cell walls cannot expand. 2. Plant cell walls are made of cellulose embedded in proteins and carbohydrates. Cell walls help support and protect the plant. 3. When water is plentiful, the central vacuole expands. The other organelles are pushed against the plasma membrane in a thin layer. 4. The nucleoid is not surrounded by a membrane and is therefore not a nucleus. Bacteria do not have an internal membrane system or membranebound organelles. a, Golgi apparatus; b, cell wall; c, vacuole; d, nucleus; e, nucleolus; f, mitochondrion; g, ribosome; h, chloroplat; i, endoplasmic reticulum Section 5-1 1. A difference in the concentration of molecules in two areas, called a concentration gradient, can result in diffusion, the movement of molecules from the area of higher concentration to the area of lower concentration. 2. Osmosis is the diffusion of water molecules across a cell membrane. When osmosis results in water molecules entering a plant cell, the molecules exert a pressure against the cell wall, called turgor pressure. 3. A hypertonic solution has a higher solute concentration than the cytosol of a cell. In a hypertonic solution a plant cell will lose water and shrink away from the cell wall, a process called plasmolysis. 1. d 2. b 3. a 4. c 5. b 4 Modern Biology Study Guide Answer Key