CHAPTER 1 INTRODUCTION TO CELLS 2009 Garland Science Publishing Unity and Diversity of Cells 1 1 Living systems are incredibly diverse in size shape environment and behavior It is estimated that there are between 10 million and 100 million different species Despite this wide variety of organisms it remains difficult to define what it means to say something is alive Which of the following can be described as the smallest living unit a DNA b cell c organelle d protein 1 2 Indicate whether the following statements are true or false If the statement is false explain why it is false A A virus is a living organism B Cells of different types can have different chemical requirements C A human white blood cell is larger than a Paramecium cell 1 3 For each of the following sentences fill in the blanks with the best word or phrase selected from the list below Not all words or phrases will be used each word or phrase should be used only once Cells can be very diverse superficially they come in various sizes ranging from bacterial cells such as Lactobacillus which is a few in length to larger cells such as a frog s egg which has a diameter of about one Despite the diversity cells resemble each other to an astonishing degree in their chemistry For example the same 20 are used to make proteins Similarly the genetic information of all cells is stored in their Although contain the same type of molecules as cells their inability to reproduce themselves by their own efforts means that they are not considered living matter amino acids DNA fatty acids meter micrometer s millimeter s plants plasma membranes viruses yeast 1 4 The flow of genetic information is controlled by a series of biochemical reactions that result in the production of proteins each with its own specific order of amino acids Choose the correct series biochemical reactions from the options presented here a replication transcription translation b replication translation transcription c translation transcription replication d translation replication transcription 1 5 Proteins are important architectural and catalytic components within the cell helping to determine its chemistry its shape and its ability to respond to changes in the environment Remarkably all of the different proteins in a cell are made from the same 20 By linking them in different sequences the cell can make protein molecules with different conformations and surface chemistries and therefore different functions a nucleotides b sugars c amino acids d fatty acids 1 6 Changes in DNA sequence from one generation to the next may result in offspring that are altered in fitness compared with their parents The process of change and selection over the course of many generations is the basis of a mutation b evolution c heredity d reproduction Cells Under the Microscope 1 7 What unit of length would you generally use to measure a typical human cell a centimeters b nanometers c millimeters d micrometers 1 8 Match the type of microscopy on the left with the corresponding description provided below There is one best match for each A confocal B transmission electron C fluorescence D phase contrast E scanning electron F bright field uses a light microscope with an optical component to take advantage of the different refractive indexes of light passing through different regions of the cell employs a light microscope and requires that samples be fixed and stained in order to reveal cellular details requires the use of two sets of filters The first filter narrows the wavelength range that reaches the specimen and the second blocks out all wavelengths that pass back up to the eyepiece except for those emitted by the dye in the sample scans the specimen with a focused laser beam to obtain a series of two dimensional optical sections which can be used to reconstruct an image of the specimen in three dimensions The laser excites a fluorescent dye molecule and the emitted light from each illuminated point is captured through a pinhole and recorded by a detector has the ability to resolve cellular components a small as 2 nm requires coating the sample with a thin layer of a heavy metal to produce threedimensional images of the surface of a sample 1 9 Cell biologists employ targeted fluorescent dyes or modified fluorescent proteins in both standard fluorescence microscopy and confocal microscopy to observe specific details in the cell Even though fluorescence permits better visualization the resolving power is essentially the same as that of a standard light microscope because the resolving power of a microscope is limited by the of light a absorption b intensity c filtering d wavelength The Procaryotic Cell 1 10 By definition procaryotic cells do not possess a a nucleus b replication machinery c ribosomes d membrane bilayers 1 11 Although there are many distinct procaryotic species most have a small range of shapes sizes and growth rates Which of the following characteristics are not observed in procaryotes a a highly structured cytoplasm b endoplasmic reticulum c the ability to divide rapidly d a cell wall 1 12 Indicate whether the following statements are true or false If the statement is false explain why it is false A Oxygen is toxic to certain procaryotic organisms B Mitochondria are thought to have evolved from anaerobic bacteria C Although bacteria use a variety of organic substances as food bacteria are not able live on inorganic substances The Eucaryotic Cell 1 13 Use the list of structures below to label the schematic drawing of an animal cell in Figure Q1 13 A plasma membrane B nuclear envelope C cytosol D Golgi apparatus E endoplasmic reticulum F mitochondrion G transport vesicles Figure Q1 13 1 14 For each of the following sentences fill in the blanks with the best word or phrase selected from the list below Not all words or phrases will be used each word or phrase should be used only once Eucaryotic cells are bigger and more elaborate than procaryotic cells By definition all eucaryotic cells have a usually the most prominent organelle Another organelle found in essentially all eucaryotic cells is the which generates the chemical energy for the cell In contrast the is a type of organelle found only in the cells of plants and algae and performs photosynthesis If we were to strip away the plasma membrane from a eucaryotic cell and remove all of its membrane enclosed organelles we would be left with the which contains many long fine filaments of protein that are responsible for