Chapter 1
Which of the following is an informational macromolecule?
ATP DNA polypeptide starch glycogen
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 a basic principle of macromolecular assembly?
A monomer need not be activated before being added to the polymer. Addition of monomers to the polymer involves the addition of water molecules. Monomers activated by ATP are added to only one end of a polymer by condensation. Monomers are added to both ends of a polymer simultaneously.
Which of the following is true of a nanometer?
A nanometer is equivalent to 10 Angstroms (Å).
Which of the following is not attached to the central carbon atom in an amino acid?
An amino functional group A carboxyl functional group A side chain ("R group") An oxygen
The fermentation of sugar to alcohol can take place only if living yeast cells are present.
Louis Pasteur linked the activity of living organisms to specific processes by showing that living cells were needed to carry out the fermentation of sugar into alcohol. In 1897,Eduard and Hans Buchner showed that fermentation could also take place with extract from yeast cells called ferments and intact living cells are not required.
The development of microscopes provided increasingly clear windows to the world of cells. Scientist used microscopes and found cells in every living organism which provided the evidence to a cell theory.
The development of microscopes provided increasingly clear windows to the world of cells. Scientist used microscopes and found cells in every living organism which provided the evidence to a cell theory.
Which of the following functional groups and compounds is polar, contains one or more electronegative atoms in a bond, and can reversibly ionize within the physiological pH range?
amine
hydrophobic interactions
association of non polar groups
Once a scientific theory becomes a law, it
is subject to modification.
covalent bonding
sharing of electrons
Why isn't this insect drowning?
surface tension
Which of the following was not considered part of the "alphabet of biochemistry" by George Wald?
the 20 amino acids seven proteins three lipids the 5 nucleotide bases two sugars
1 mm = ________ nm
1,000,000
Approximately how many bacterial cells would fit in the internal volume of a human liver cell?
2,666 bacterial cells.
Approximately how many liver cells would fit inside a palisade cell?
2.62 liver cells
What are the approximate dimensions of the smallest structure that a contemporary cell biologist should be able to observe with a modern light microscope?
200-350nm
Which of the following is true of an asymmetric carbon atom?
A carbon with hydrogens attached at two locations is usually asymmetric. Methane has an asymmetric carbon. Molecules may have only one asymmetric carbon atom. Only amino acids have asymmetric carbon atoms. Asymmetric carbon atoms create stereoisomers.
The moon lacks life and varies dramatically in temperature. If we could keep a layer of water spread on the surface of the moon, what effect would it have?
Because water has a high heat of vaporization, the temperatures would rise to the upper extremes. Water would absorb and hold heat and moderate the temperature extremes. Physical conditions would remain the same. The temperatures would drop to the lower extremes. Life would be possible, but it would have to withstand these extremes in temperature.
Beadle and Tatum formulate the one gene-one enzyme hypothesis (1940).
Biochemical
Haeckel postulates that the nucleus is responsible for heredity (1868).
Biochemical
Lipmann postulates the central importance of ATP in cellular energy transactions (1940).
Biochemical
Palade, Porter, and Sjøstrand each develop techniques for fixing and sectioning biological tissue for electron microscopy (1952-1953).
Biochemical
In the lab, you choose to design a simple experiment to distinguish between hydrophilic and hydrophobic substances. You start by adding equal amounts of vinegar and oil to a container. After shaking, the vinegar and oil levels separate, based upon polarity and density. To this you add glucose and sodium citrate and shake again. Where do you expect to find the glucose and sodium citrate in greatest quantities?
Both will concentrate in the oil layer. The glucose will concentrate in the vinegar, sodium citrate in the oil. Sodium citrate will concentrate in the vinegar, glucose in the oil. Both will be uniform throughout both layers.Both will concentrate in the vinegar layer.
Which part of an amino acid is always acidic?
Carboxyl functional group
Köllicker describes "sarcosomes" (now called mitochondria) in muscle cells (1857).
Cytological
Davson and Danielli postulate a model for the structure of cell membranes (1935).
Cytology
Lehninger demonstrates that oxidative phosphorylation depends for its immediate energy source on the transport of electrons in the mitochondrion (1957).
Cytology
All cells and many subcellular structures are surrounded by a membrane. Assuming a typical membrane to be about 8 nm wide, how many such membranes would have to be aligned side by side before the structure could be seen with the light microscope? How many with the electron microscope?
Generally by using a light microscope we can observe the objects as small as 0.2micro meters. one micro meter is equal to 1000 nm. so 0.2 micro meters=200nm. Here the membrane is about 8nm wide. The minimun size required to observe the object under light microscope is about 200nm. so total number of membranes each of size 8nm should be required to observe the object under light microscope = 200/8= 25 membranes. so by aligning 25membranes of size 8nm we can observe the object under light microscope.
Claude isolates the first mitochondrial fractions from rat liver (1940).
Genetics
Muller discovers that X-rays induce mutations (1927).
Genetics
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.
Ribosomes are the cell structures in which the process of protein synthesis takes place. A human ribosome is a roughly spherical structure with a diameter of about 30 nm. How many ribosomes would fit in the internal volume of the human liver cell described in Problem 1-2 if the entire volume of the cell were filled with ribosomes?
Number of ribosomes in the cell = volume of Cell / volume of ribosome 1 um = 10-6 m 1 nm = 10-9 m Volume of cell = 4/3 π 20*20*20*10-18 m = 8000 * 10-18 m Volume of ribosome = 4/3 π 30*30*30 * 27000*10-27 m Number of ribosome = 4/3 π 8000 * 10-18 m/ 4/3 π 27000*10-27 m 8000 * 109 / 27000 80000*108 / 27000 = 2.96 * 108 ribosomes.
Which monomers make up RNA?
Simple sugars Polymers Nucleotides Amino acids
Which of the following statements about the formation of polypeptides from amino acids is true?
Polypeptides form by condensation or hydrolysis reactions. A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid. A bond can form between any carbon and nitrogen atom in the two amino acids being joined. The reaction occurs through the addition of a water molecule to the amino acids.
Which of the following would NOT be a rational explanation for why the three-dimensional structure of a protein is driven and stabilized largely by noncovalent bonds rather than covalent bonds?
Proteins will need to be unfolded to cross biological membranes, and if their three-dimensional structures were held together by mostly covalent bonding, this might be too difficult to accomplish. Proteins may need to be degraded for energy, and if their three-dimensional structures were held together by mostly covalent bonding, this might be too difficult to accomplish. Protein function (transport, enzyme catalysis, etc.) may require flexibility in the three-dimensional structure to allow for conformational change, and if protein three-dimensional structures were held together by mostly covalent bonding, this might be too difficult to accomplish. All of the other answer choices are rational explanations for why the three-dimensional structure of a protein is driven and stabilized largely by noncovalent bonds rather than mostly covalent bonds.
Each of these statements was once regarded as a biological fact but is now understood to be untrue. In each case, indicate why the statement was once thought to be true and why it is no longer considered a fact. (a) Plant and animal tissues are constructed quite differently because animal tissues do not have conspicuous boundaries that divide them into cells.
The plant and animal cell have constructed quite differently, based on difference in their cell wall construction plants are non-locomotors and animals are locomotors. But the animal cell has clear visible boundaries (the outer plasma membrane is act as distinctive boundary). Thus, the statement becomes false.
Each of these statements was once regarded as a biological fact but is now understood to be untrue. In each case, indicate why the statement was once thought to be true and why it is no longer considered a fact. Genes most likely consist of proteins because the only other likely candidate, DNA, is a relatively uninteresting molecule consisting of only four kinds of monomers (nucleotides) arranged in a relatively repetitive sequence.
Till the middle of twentieth century,it was widely considered that genes most likely consist of proteins because proteins were the only nuclear components that seemed to account for the obvious diversity of the genes. In 1944 ,Avery,MacLeod and McCarty through their landmark experiment clearly showed DNA to be the genetic material and not proteins.Their work mainly focused on the genetic transformation of bacteria and the proved that the factor responsible for the transformation is DNA.
True or false? Enzymes in the digestive tract catalyze hydrolysis reactions.
True
Van der Waals interactions
Weak attractions between molecules or parts of molecules that result from transient local partial charges.
Avery, MacLeod, and McCarty demonstrate that bacterial transformation is attributable to DNA, not protein (1944).
cytological
You have discovered a defective gene that allows cancer cells to use glucose more efficiently and therefore outgrow normal cells to form a tumor. Explain how your discovery likely involves contributions from all three historical strands of cell biology.
cytology = cancer cells differ Biochemistry= identification of the pathways by which cells use glucose for fuel Genetic= DNA is the genetic material and how its defective replication can lead to uncontrolled, cancerous cell division.
Each water molecule is joined to _____ other water molecules by ____ bonds.
four ... hydrogen
Each of these statements was once regarded as a biological fact but is now understood to be untrue. In each case, indicate why the statement was once thought to be true and why it is no longer considered a fact. Each of these statements was once regarded as a biological fact but is now understood to be untrue. In each case, indicate why the statement was once thought to be true and why it is no longer considered a fact.
living organisms are governed by the both laws of chemistry and physics. For example, all animals can applicable for law of gravity. Thus, the given statement is false.
Hydrogen bond
noncovalent attraction between a hydrogen and an electronegative atom
Which of the following sequences correctly lists the hierarchical nature of cellular structures, from smallest to largest?
organic molecules, macromolecules, supramolecular structures, organelles, cells
The unequal sharing of electrons within a water molecule makes the water molecule _____.
polar
In this molecule, what type of bond is found between the oxygen and hydrogens?
polar covalent
Which of the following can only be viewed by electron microscopy?
prokaryotes nuclei mitochondria DNA frog eggs
Which of the following is smallest?
protein
Which polymers are composed of amino acids?
proteins
Which of the following molecules is involved with assisted assembly?
water molecules molecular chaperones helper proteins tobacco mosaic viruses none of the above
What evidence led scientists to develop the basic principles of the cell theory? Note how technology played a role in its development.
The development of microscopes provided increasingly clear windows to the world of cells. Scientist used microscopes and found cells in every living organism which provided the evidence to a cell theory.
The addition of some amphipathic molecules (such as detergents) to water decreases the surface tension of water. Which of the following must be true?
The intermolecular hydrogen bonding of water is being weakened by the detergent.
Which of the following scientists revolutionized biology by demonstrating that living organisms were also governed by the laws of physics and chemistry by synthesizing urea in the laboratory from ammonium cyanate?
Wöhler
Hoppe-Seyler isolates the protein hemoglobin in crystalline form (1864).
biochemical
Ostwald proves that enzymes are catalysts (1893).
biochemical
The tendency of an atom to pull electrons toward itself is referred to as its _____.
electronegativity
ionic bond
the electrostatic attraction that binds oppositely charged ions together