Chapter 1: Preview of Cell Biology

My colleague and I worked with bacterial viruses. We were able to demonstrate that DNA-not protein-was the genetic material of the cell.

Alfred Hershey and Martha Chase

The Latin phrase omis cellula e cellula refers to a cellular principle. Which of the following statements is the best interpretation of this phrase?

All cells arise only from preexisting cells.

I am a seventeenth-century shopkeeper from Holland. My hobby involves hand-polishing glass to make lenses, some of which can magnify almost 300-fold. I was the first to observe living cells and am known as the "Father of Microbiology."

Antonie van Leeuwenhoek

________ improved the original light microscope in the late 1600s, allowing the visualization of __________.

Antonie van Leeuwenhoek; sperm cells bacteria, algae, and other protists.

Match each scientist or group of scientists on the left with the appropriate phrase to the right. Walter Sutton

chromosome theory of heredity

Which of the following types of light microscopy improves the resolution of thick specimens by illuminating one plane of the specimen at a time?

confocal microscopy

Which of the following is true of nanometer? - A nanometer is about the size of a common bacterial cell. - A nanometer is one millionth of a meter. - A nanometer is equivalent to 10 Angstroms. - The nanometer is the most common measurement used in measuring whole cells. - None of the above

A nanometer is equivalent to 10 Angstroms

Which of the following statements is false? - All organisms consist of one or more cells. - All cells arise from preexisting cells. - The cells is the basic unit of structure for all organisms. - All cells have a membrane-bound nucleus. - Cells come in a wide variety of sizes and shapes.

All cells have a membrane-bound nucleus.

You have identified a new molecule associated with the immune system that drastically reduces cell division by tumor cells in vivo. Develop a hypothesis and design an experiment to test your hypothesis using a model organism. Include an explanation as to why it is the best model for your experiment.

Answers will vary; however, the hypothesis would indicate the utility of the cytokine for lymphoma treatment. The obvious model organism would be the mouse model. It shares a great many similarities to humans at the cellular, anatomical, and physiological levels. It is well characterized, and the genome has been sequenced. Further, there is a mouse model of lymphoma currently available. Mice are easy to care for and require a relatively small amount of space to maintain.

Glycolysis is also called the ________ pathway after the scientists who did most of the work to define it.

Embden-Meyerhof

We worked out the double helix model of DNA structure in 1953. We later received the Nobel Prize for this work.

James Watson and Francis Crick

At the University of California, Berkeley, I worked with radioisotopes. In the late 1940s and early 1950s, I used 14C to identify the most common pathway for photosynthetic carbon metabolism.

Melvin Calvin

How does bright field microscopy allow images to be visualized?

Specimens are illuminated with white light

Match the type of microscopy with the appropriate characteristic. phase-contrast

amplifies variation in density

In 1880, Walther Flemming identified ________, threadlike bodies seen in dividing cells.

chromosomes

Match the type of microscopy with the appropriate characteristic. scanning electron microscopy

detects electrons deflected from the surface of the specimen

Once a scientific theory becomes a law, it

is subject to modification

Match the type of microscopy with the appropriate characteristic. fluorescence

shows specific molecules

A microtome is used to?

slice thin sections of specimens

Wohler revolutionized biology through his demo that biological molecules are governed by the ordinary laws of physics and chemistry. He demonstrated this principle by

synthesizing urea in the laboratory from ammonium cyanate

To be useful to scientists, a hypothesis must be ________; in other words, the hypothesis must be able to be confirmed or discredited.

testable

Match each scientist or group of scientists on the left with the appropriate phrase to the right. Louis Pasteur

"ferments" of yeast

Match each scientist or group of scientists on the left with the appropriate phrase to the right. George Beadle and Edward Tatum

"one gene-one enzyme" DNA

1 mm= ______ nm

1,000,000

Melvin Calvin used ________, a specific ________, to deduce the Calvin cycle of photosynthesis.

C; radioisotope

Which of the following is mismatched?

Caenorhabditis elegans - photosynthesis

________ is a biochemical technique that allows one to separate biological molecules based on size, shape, and/or affinity for specific molecules or functional groups.

Chromatography

Which of the following can only be viewed by the electron microscopy? - frog eggs - DNA - nuclei - mitochondria - prokaryotes

DNA

Match each scientist or group of scientists on the left with the appropriate phrase to the right. James Watson and Francis Crick

DNA double helix

I am a nineteenth-century German chemist. By synthesizing an organic molecule from inorganic components, I dispelled the idea that biological processes were exempt from the laws of chemistry.

Friedrich Wohler

________ synthesized urea in the laboratory from inorganic starting materials. Much of what is now called ________ dates from this discovery.

Friedrich Wohler; biochemistry

Match each scientist or group of scientists on the left with the appropriate phrase to the right. Gregor Mendel

Hereditary factors

All the following are model organisms, except

Homo sapiens

Which of the following is an application of immunofluorescence microscopy? - Visualization of the natural fluorescence of a specimen under UV light. - Identification of specific components of the immune system. - Identifying which organelle or cellular compartment contains a particular protein. - Visualization of the surface structures of a specimen. - Construction of three-dimensional images of structures smaller than 10 nm.

Identifying which organelle of cellular compartment contains a particular protein

In studying osteoporosis in humans, you wish to test a newly designed treatment for efficacy. Your best choice for a model organism would be

Mus musculus

After reading this paragraph, list the steps of the scientific method, and list the activities that correspond to the steps of the scientific method. A rancher noticed that several grazing animals had become sick after grazing in a new area. The rancher asked a team of scientists to analyze this problem. They visited the area and found that the food available to the animals was similar to the food they had been eating. The water supply in the area was adequate but limited to a single spring. Some of the scientists felt that the water might be contaminated with a pathogen. Therefore, they collected water samples from the spring in the new area and compared them with water samples taken from previous grazing sites. The scientists noticed that water from the new area was cloudier than water obtained from other areas. Culturing this water revealed that a pathogenic strain of bacteria was present. This bacterial strain was found to be identical to a strain obtained from sick animals. This strain was not present in healthy animals. They concluded that a contaminated water supply in the new area was responsible for the problem and instructed the rancher to avoid the water supply. The disease was not found in the rancher's livestock again.

Observation. The rancher and the scientists made initial observations regarding the food and water that the livestock consumed. Hypothesis. The water supply was contaminated with a pathogen. Experimentation. Water was collected, examined, and cultured. Collect data. The turbidity of the water was examined. The cultures were positive for a pathogenic strain of bacterium. Interpret results. The data was compared to other water samples. The cultures were compared to those obtained from livestock. Draw conclusion. The water was contaminated and responsible for the outbreak

________ is the ability to distinguish two objects that are close together as separate. In any microscope, this ability is determined by ________.

Resolution; wavelength

Around 1914, ________ determined that DNA was an important component in ________ by using a staining technique that is still in use today.

Robert Feulgen; chromosomes

I was the Curator of Instruments for the Royal Society of London in 1665. I developed a microscope that could magnify around 30-fold. I examined plant material and observed many small chambers that I called cells.

Robert Hooke

I am a Swedish scientist. I developed the ultracentrifuge to determine sedimentation rates of proteins. The ultracentrifuge was later used to isolate subcellular fractions.

Theodor Svedburg

Which of the following is closest to a micrometer in size? - the width of a strand of DNA - the length of a plant cell - the length of a chicken egg - a typical prokaryotic cell - the size of a ribosome

a typical prokaryotic cell

A number of different types of microscopy exist. Each type of microscopy has advantages and disadvantages. Can you identify the microscope that would be most advantageous for the situations below? a. A cell biologist wishes to visualize the ribosomes of a cell. b. A microbiologist wishes to examine the motility of a bacterium. c. An immunologist wishes to determine if a lymphocyte possesses a certain surface protein. d. A virologist is trying to determine the three-dimensional shape of a virus. e. A pathologist is trying to examine the cytoplasm of a cell for changes that result from viral infection.

a. Electron microscopy, preferably transmission electron microscopy, should be used. b. Phase contrast or differential-interference-contrast would be most helpful. c. Fluorescence microscopy is often used. d. Scanning electron microscopy should be used. e. Transmission electron microscopy will enable the pathologist to visualize the interior.

Scanning electron microscopy (SEM) is especially suited to

creating a sense of depth

Match each scientist or group of scientists on the left with the appropriate phrase to the right. Thomas Hunt Morgan

fruit fly

Gregor Mendel was most influential in which field of biology?

genetics

To which of the following do Mendel's observations relate?

heredity

Scientists use various terms to describe conclusions reached through the scientific method. Which of the following terms conveys the least degree of certainty?

hypothesis

The outcome of the joining go cytology and biochemistry yielded a better understanding of the cell by

identification of cellular structures and biochemical pathways

A scientific ________ must be so thoroughly confirmed that virtually no doubt remains about its accuracy.

law

Match the type of microscopy with the appropriate characteristic. brightfield

light passes directly through specimen

The steps of the scientific method, in the correct order, are

make observations, formulate the hypothesis, design experiments, collect, data, interpret results, and draw conclusions.

Jacques Monod and Francois Jacob deduced the mechanism responsible for the regulation of prokaryotic gene expression. They are, therefore, responsible for launching the era of

molecular genetics

Which organelle stores most of the DNA in plant and animals cells?

nucleus

The classic work of Friedrich Wohler (1828) that united the fields of biology and chemistry was based on the

production of urea in the lab

Which of the following is the smallest? - ribosome - virus - protein - mitochondrion - prokaryote

protein

The total protein content of the cell is called the ________.

proteome

Melvin Clavin and his colleagues used which of the following to deduce the steps in the Calvin cycle?

radioisotopes

You are studying the response of macrophages infected with the intracellular bacterium Brucella, specifically by examining which gene products are being expressed. You would be studying the macrophage ________ to obtain this information.

transciptome

Match each scientist or group of scientists on the left with the appropriate phrase to the right. Oswald Avery, Colin MacLeod, and Maclyn McCarty

transformation

You are working on a project that involves the direct observation of DNA molecules. The microscope that would give you the best information at this time would be the?

transmission electron microscope

The ________ was developed in the late 1920s by Theodore Svedberg. He originally used it to determine the sedimentation rate of proteins.

ultracentrifuge

A(n) ________ is an instrument used to separate sub cellular structures and macromolecules on the basis of size, shape, and density. ________ developed this instrument in Sweden during the period 1925-1930.

ultracentrifuge; Theodor Svedberg

Because of the low penetration power of electrons, samples for transmission electron microscopy must be extremely thin. A(n) ________ is able to cut sections as thin as 20 nm.

ultramicrotome

Match each scientist or group of scientists on the left with the appropriate phrase to the right. Friedrich Wohler

urea

Match the type of microscopy with the appropriate characteristic. confocal

uses a laser to view a single plane of a specimen

Which of the following is an important characteristic for the model organism?

widely studied

You have been given a sample of Mimivirus, which has the largest capsid diameter of all currently known viruses (600 nm) and has the form of a 20-sided polyhedron (an icosahedron). Based on your knowledge of microscopes, what would you be able to see/determine about mimiviral structure using each of the following microscopes? a. simple compound (light) microscope b. fluorescent microscope using fluorescently labeled antibodies to a novel capsid protein c. scanning electron microscope

a. Light microscope: will be able to see basic viral shape, especially if particles are stained b. Fluorescent microscope: should illuminate the outside of the viral particles c. Scanning electron microscope: would allow imaging of the surface structure of the virus

Cell biology emerged from which of the fields of biology?

biochemistry, genetics, and cytology

Which type of microscopy enhances and amplifies slight changes in the phase of transmitted light?

both differential interference contrast microscopy and phase-contrast microscopy

Early microscopes did not allow clear visualization of cells because they were limited by?

both magnification and resolution

Match each scientist or group of scientists on the left with the appropriate phrase to the right. Matthias Schleiden

cell theory

You wish to obtain a purified sample of mitochondria from lysed cells. The best way to obtain this sample would be

centrifugation

Robert Hooke coined the term cell when studying thin slices of cork. These _____________ were the first cells observed because _____________.

dead plant cells; the thick cells walls did not require high resolution or magnification to view

Match the type of microscopy with the appropriate characteristic. transmission electron microscopy

detects electrons passing through a specimen

A scientist is examining motile protist. He wishes to determine their direction of movement. Which of the following microscopic techniques is least likely to be used to view these cells? - light microscopy - electron microscopy - differential interference contrast microscopy - fluorescence microscopy - phase-contrast microscopy

electron microscopy

Which type of microscopy has the greatest resolving power?

electron microscopy

Which of the following biochemical techniques uses an electrical field to separate macromolecules based on their mobility through a semisolid gel?

electrophoresis

The limit of resolution can best be defined as

the distance that two objects must be apart to be distinguished as separate objects.

The scientific work that established DNA, rather protein, as the molecule of heredity was performed prior to

the elucidation of the double helix structure of DNA