ANSWERS
Determine if the following features characterize eukaryotes, prokaryotes, both groups, or neither
group.
1. They use a deoxyribonucleoside triphosphate as their "energy currency".
2. They chiefly use deoxyribonucleic acid molecules to store genetic information.
3. RNA molecules are their main catalysts.
4. Their DNA is typically found within sub-cellular organelles such as mitochondria, chloroplasts but
mainly in the nucleus.
5. Their proteins consist of a common set of 20 different amino acids
6. Most of their genomes comprises protein-coding genes.
7. Their cell membranes chiefly comprise of phospholipid-based bilayer.
1. Neither prokaryotes nor eukaryotes
2. Both prokaryotes and eukaryotes
3. Neither prokaryotes nor eukaryotes
4. eukaryotes
5. Both prokaryotes and eukaryotes
6. prokaryotes
7. Both prokaryotes and eukaryotes
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A. Both EKs and PKs use ATP (or GTP for specialized functions) not dATP or dGTP.
B. All cells use DNA for this purpose.
C. While RNA catalyze some reactions, still most reactions are catalyzed by enzymes which are
proteins..
D. DNA in EKs is found exclusively in the nucleus, in mitochondria and (in plants) plastids. These
organelles are limited by double membranes.
E. All cells do.
F. The PK genome comprises mostly of protein-coding genes. This is in contrast to the EK genome,
only a small portion of which encodes for proteins or functional RNAs. Most of EK DNA has no clear
function and is dubbed (probably incorrectly) as "junk" DNA.
G. All extant cells have bilayer whose main lipid components are phospholipids
Viruses are often not considered " living" because they have the following characteristics
(True/False) :
1) They are acellular.
2) They are not made of organic molecules.
,3) They lack membranes.
4) They lack nuclei.
5) They do not evolve.
6) They don't use DNA as their information storage molecule.
1) True
2) False
3) False
4) False
5) False
6) False
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The only two true statements about viruses relating to them being considered "living" is the fact that
they are acellular and rely on their host cells for providing their basic biological needs (all viruses rely
on host translation for example). Viruses consist of organic molecules, of course. Some viruses are
enveloped by a lipid bilayer (e.g. HIV-1, influenza). Being acellular, viruses obviously lack nuclei but
prokaryotic cells also lack nuclei (and they are certainly "living"). Viruses certainly evolve and many
rely on rather fast evolutionary rates for outsmarting their hosts (e.g. the evolution of drug resistance
among HIV-1 isolates). Some viruses don't use DNA as their information storage molecule, but many
others do
All of the following statements are true EXCEPT _______.
1) Differences in ionic composition may exist between cells in different environments, but the
external and internal ionic compositions of a cell within a certain environment are always identical to
each other.
2) Differences in ionic composition across membranes can be used to drive molecular motor.
3) Differences in ionic composition across membranes can be generated through the action of ATP
driven pumps.
4)Membrane potential associated with differences in ionic composition across membranes can be
quickly and temporarily dissipated by transiently opening ion channels to allow rapid flow of certain
ions according to their concentration gradient.
1) Differences in ionic composition may exist between cells in different environments, but the
external and internal ionic compositions of a cell within a certain environment are always identical to
each other.
The synthesis of the three fundamental polymers of life, DNA, RNA and protein, is template-directed.
This means that _____.
1) the system evolved in direction of more complexity from a 4-letter code of nucleotides to a 20-
letter code of amino acids.
, 2) the monomers are assembled one by one in a sequence prescribed by an existing polymer.
3) all of them utilize a semi-conservative mode of synthesis.
4) DNA is copied from DNA, RNA is copied from RNA and protein is copied from protein.
the monomers are assembled one by one in a sequence prescribed by an existing polymer.
Review Questions 5-9 (DNA % Problems)
HW 1
The diameter of a typical bacteria cell can be all of the following except:
1) between 10-6 m and 2x10-6 m.
2) between 1,000 nM and 2,000 nM.
3) between 104 Å and 2x104 Å.
4) between 0.001 mm and 0.002 mm.
5) between 1.0 µm and 2.0 µm.
between 1,000 nM and 2,000 nM.
Living cells require input of free energy in order to be able to perform all of the following except
_______.
A) Incorrect to accumulate nutrients in the cell.
B) Correct to breakdown macromolecules.
C) to accumulate nutrients in the cell.
D) to synthesize ATP from ADP and inorganic phosphate.
E) transport ions across the membrane against their concentration gradient.
B) Correct to breakdown macromolecules.
The constituents of biological membranes that are most important in facilitation of movement of
hydrophilic compounds across the membrane are ____________.
A) integral membrane proteins.
B) nucleic acids.
C) carbohydrates.
D) phospholipids.
E) peripheral membrane proteins.