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Biology 26, 27,
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Bartending
12th Grade
01/31/2013

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Term
Descriptives of protists:
Definition
small, but there are many
thrive almost everywhere
They have an astonishing genetic diversity
Prokaryotes are divided into two domains: bacteria and archaea
Term
capsule
Definition
a gel like substance coating a prokaryote that keeps it from drying out
Term
sex pili
Definition
allow prokaryotes to exchange DNA
Term
fimbriae
Definition
allow them to stick to their substrate or other individuals in a colony
Term
Most motile bacteria propel themselves by flagella that are structurally and functionally different from eukaryotic flagella
Definition
In a heterogeneous environment, many bacteria exhibit taxis, the ability to move toward or away from certain stimuli
Term
Prokaryotic cells usually lack complex compartmentalization
Definition
Some prokaryotes do have specialized membranes that perform metabolic functions
Term
The prokaryotic genome has less DNA than the eukaryotic genome
Most of the genome consists of a circular chromosome
Definition
Some species of bacteria also have smaller rings of DNA called plasmids
Term
Prokaryotes reproduce quickly by binary fission and can divide every 1–3 hours
Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries
Definition
Prokaryotes reproduce by binary fission, and offspring cells are generally identical
Mutation rates during binary fission are low, but because of rapid reproduction, mutations can accumulate rapidly in a population
High diversity from mutations allows for rapid evolution
Term
Three factors contribute to this genetic diversity of prokaryotes
Definition
Rapid reproduction
Mutation
Genetic recombination
Term
Additional diversity arises from genetic recombination
Definition
Prokaryotic DNA from different individuals can be brought together by transformation, transduction, and conjugation
Term
transformation
Definition
A prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment
Term
transduction
Definition
is the movement of genes between bacteria by bacteriophages
Term
Conjugation is the process where genetic material is transferred between bacterial cells
Sex pili allow cells to connect and pull together for DNA transfer
A piece of DNA called the F factor is required for the production of sex pili
The F factor can exist as a separate plasmid or as DNA within the bacterial chromosome
Definition
Cells containing the F plasmid function as DNA donors during conjugation
Cells without the F factor function as DNA recipients during conjugation

The F factor is transferable during conjugation
Term
R plasmids carry genes for antibiotic resistance
Antibiotics select for bacteria with genes that are resistant to the antibiotics
Definition
Term
Prokaryotic metabolism varies with respect to O2:
Definition
Obligate aerobes require O2 for cellular respiration
Obligate anaerobes are poisoned by O2 and use fermentation or anaerobic respiration
Facultative anaerobes can survive with or without O2
Term
In nitrogen fixation, some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3)
Definition
Term
In some prokaryotic species, metabolic cooperation occurs in surface-coating colonies called
Definition
biofilms
Term
table 27.2
Definition
eukarya, prokatyote, and archae characterisitics
Term
Some archaea live in extreme environments and are called extremophiles
Definition
Extreme halophiles live in highly saline environments
Extreme thermophiles thrive in very hot environments
Term
Methanogens live in swamps and marshes and produce methane as a waste product
Methanogens are strict anaerobes and are poisoned by O2
Definition
Term
cyanobacteria
Definition
photoautotrophs that generate O2
Plant chloroplasts likely evolved from cyanobacteria by the process of endosymbiosis
Term
Gram-positive bacteria include
Actinomycetes, which decompose soil
Bacillus anthracis, the cause of anthrax
Clostridium botulinum, the cause of botulism
Some Staphylococcus and Streptococcus, which can be pathogenic
Mycoplasms, the smallest known cells
Definition
Prokaryotes play a major role in the recycling of chemical elements between the living and nonliving components of ecosystems
Chemoheterotrophic prokaryotes function as decomposers, breaking down corpses, dead vegetation, and waste products
Nitrogen-fixing prokaryotes add usable nitrogen to the environment
Term
Symbiosis is an ecological relationship in which two species live in close contact: a larger host and smaller symbiont
Definition
Prokaryotes often form symbiotic relationships with larger organisms
Term
mutualism
Definition
, both symbiotic organisms benefit
Term
commensalism
Definition
one organism benefits while neither harming nor helping the other in any significant way
Term
parasitism
Definition
an organism called a parasite harms but does not kill its host
Term
pathenogens
Definition
parasites that cause diesease
Term
Phylogeny
Definition
the evolutionary history of a species or group of related species
Term
The two-part scientific name of a species
Definition
binomial
Term
A taxonomic unit at any level of hierarchy is called
Definition
a taxon
Term
polytomy
Definition
a branch from which more than two groups emerge
Term
Homology is similarity due to shared ancestry
Definition
Analogy is similarity due to convergent evolution
Term
A valid clade is monophyletic
Definition
signifying that it consists of the ancestor species and all its descendants
Term
A paraphyletic grouping consists of
Definition
an ancestral species and some, but not all, of the descendants
Term
A polyphyletic grouping consists of
Definition
various species that lack a common ancestor
Term
A shared ancestral character is a character that
Definition
originated in an ancestor of the taxon
Term
A shared derived character is
Definition
an evolutionary novelty unique to a particular clade
Term
In some trees, the length of a branch can reflect the number of genetic changes that have taken place in a particular DNA sequence in that lineage
Definition
In other trees, branch length can represent chronological time, and branching points can be determined from the fossil record
Term
Maximum parsimony assumes that
Definition
the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely

The principle of maximum likelihood states that, given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events
Term
Phylogenetic bracketing allows us
Definition
to predict features of an ancestor from features of its descendents
Term
Orthologous genes
Definition
are found in a single copy in the genome and are homologous between species
Term
Paralogous genes
Definition
result from gene duplication, so are found in more than one copy in the genome
Term
molecular clock
Definition
uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change
In orthologous genes, nucleotide substitutions are proportional to the time since they last shared a common ancestor
In paralogous genes, nucleotide substitutions are proportional to the time since the genes became duplicated
Term
Difficulties with Molecular Clocks
Definition
The molecular clock does not run as smoothly as neutral theory predicts
Irregularities result from natural selection in which some DNA changes are favored over others
Estimates of evolutionary divergences older than the fossil record have a high degree of uncertainty
The use of multiple genes may improve estimates
Term
Horizontal gene transfer
Definition
is the movement of genes from one genome to another
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