Exam 3 Flashcards
Bacteria and Archaea play a central role in the global carbon cycle because
a) some species of bacteria can fix carbon dioxide through photosynthesis
b) because some species of Archaea can produce methane
c) they have important roles in the metabolism of organic maPer in terrestrial and aqua/c
environments
d) statements (b) and (c) are correct
e) statements (a), (b) and (c) are correct
a) some species of bacteria can fix carbon dioxide through photosynthesis
b) because some species of Archaea can produce methane
What characteristics make a gene a good candidate for determining the evolutionary relationships
between organisms?
IT has both highly conserved and variable regions and it is universally distributed
Linking an ORF (open reading frame) with a specific protein is an example of gene
annotation
Gene islands in the chromosome typically contain clusters of genes that encode for
virulence, biodegradation of pollutants, or symbiotic relationships
Orthologs are
genes in different species that evolved from a common ancestor while retaining the same function
Genomes of species in both bacteria and archaea show a strong correlation between genome size and ___
number of ORFs
AT rich DNA will melt at
a lower temperature than GC rich DNA
Horizontal gene transfer has been convincingly demonstrated for genes involved in
antibiotic resistance genes and virulence and degradation functions
Which of the following places the steps of PCR in the correct order?
(1) Incubate at 94°C to denature DNA strands;
(2) Incubate at 72°C for DNA synthesis;
(3) Incubate at 60°C for primer hybridization
1, 3, 2
Consider the following. The necessary ingredients for DNA synthesis are mixed together in a test
tube. Aferwards the DNA polymerase from Thermus aqua+cus and human DNA are added. The DNA
synthesized would be most similar to
Human DNA
Reverse transcriptase is a(n)
RNA-dependent DNA polymerase
Which of the following statements about the phenetic species concept is not true?
a) It provides a hierarchical classification.
b) Organisms are assigned to categories based on phenotypic characteristics.
c) it relies entirely on the analysis of DNA sequences.
d) Organisms are given binomial names.
e) All of the above.
it relies entirely on the analysis of DNA sequences.
Professor Carl Woese proposed the three-domain system based on differences in the ____________
of organisms.
rRNA sequences
Whether an organism is classified as a photoheterotroph or a photoautotroph depends on the
kinds of carbon sources used
The calvin cycle
uses CO2, NAD(P)H, and ATP to make anabolic precursors with ribulose bisphosphate
carboxylase (RubisCO) and phosphoribulokinase.
Genome assembly relies on
aligning large numbers of short sequences that overlap with one another.
Evolution is driven by
selection pressure applied to random mutations.
Which of the following is an assumption used in phylogenetic analysis?
a) Nucleotide changes are generally not transferred to progeny.
b) Nucleotide changes are not random.
c) Nucleotide changes accumulate in a sequence in proportion to time.
d) Nucleotide changes are subject to intense selective pressure.
e) Nucleotide changes occur rapidly in short periods of time.
Nucleotide changes accumulate in a sequence in proportion to time
The phenomenon whereby H2 consumption by one organism positively affects the energetics of the
reaction of the H2 producer (making it an exothermic reaction) is called
syntrophy
Correct order for genetic cloning
Isolate genomic DNA; cut genomic DNA with a restriction enzyme; insert genomic DNA
fragments into a plasmid vector; transform recombinant plasmid into host; host replication of
recombinant vector.
In agarose electrophoresis a DNA fragment of 2,000 bp will end up ______________ in the agarose
gel than a 20,000-bp fragment, because it migrates ______________ through the agarose than the
larger fragment.
further away from the negative electrode / more rapidly
Methanogens
produce methane as a part of their energy metabolism
Species of Rhizobium
fix atmospheric nitrogen symbiotically with legumes (a plant)
The evolutionary history of a group of organisms is called its ________ and it is inferred from
________.
phylogeny / nucleotide sequence data
the most widely used molecules in sequence-based evolutionary analyses are ____
16S and 18S rRNA genes
Two eukaryotic organelles that are hypothesized to be the result of endosymbiosis are the
________ and the ________.
mitochondrion / chloroplast
Three domains of life
Archaea, eukarya, and bacteria
You are studying 12 new isolates from the human skin. The average nucleotide identity for their 16S
rRNA gene sequences is >97%. These isolates would be considered
individual strains of the same species
Microbial species have a core genome and a pan genome. What is the difference between the two?
The core genome is a set of genes shared by all members of a species, while the pan genome
includes the core genes as well as genes that are not shared by all members.
The pan genome of a microbial species is constantly changing because of
horizontal gene transfer
an open reading frame (ORF) encodes for
a polypeptide
Transcriptome analysis is useful in relation to genome analysis because
it analyzes mRNA, thus it reveals which genes are expressed under different conditions.
A metagenome
consists of all the genome sequences present in a microbial community
Chemoorganotrophs
are organisms that oxidize the chemical bonds in organic compounds as their energy source
and obtain carbon that they need for cellular biosynthesis from organic compounds.
“cultivation-independent” methods
are commonly used to determine microbial community composition, structure and function.
A key concept in evolution is that all mutations are
random
Many phenotypic traits are found in multiple phyla. What accounts for this
1) convergent evolution
2) gene loss
3) horizontal gene transfer
The reverse citric acid cycle is used by some autotrophs to
make anabolic intermediates
Ammonification — the metabolism of nitrogen containing carbon compounds — can only be done by
Archaea.
False
Organisms grown with CO2 as a sole carbon source require energy in the form of ATP as well as
reducing power.
True
Despite rapid advances in technology, it is not possible to create a synthetic bacterial genome.
False
Anoxygenic photosynthesis does not involve a membrane associated electron transport chain.
False
Organisms that can grow using carbon compounds lacking C-C bonds are called methylotrophs
True
In the process of cloning a chromosomal gene into a plasmid, the chromosomal and plasmid DNA
should be cut with different restriction enzymes.
False
When a bacterial cell has sufficient arginine, the biosynthesis of arginine is halted because the corepressor
(arginine) binds to the repressor and this complex binds to the operator preven/ng
transcription of the operon.
True
The maltose operon is under positive control and gene expression only occurs when maltose binds to
the maltose activator protein and this complex binds to the operator preventing transcription of the
operon.
False
Eukaryotes originated after the rise in atmospheric oxygen.
True
