Lecture Exam #2 Flashcards
two types of cells
1) prokaryote (smaller, unicell)
2) Eukaryote (more complex)
what are prokaryote cells more commonly known as?
bacteria
how big are prokoryote cells?
very small- 10-100 microns
what type of cells are prokoryote cells
single-celled (unicellular) and filamentous (strings of single cells)
prokaryote lifestyle charctericstics (3) (UCF)
1) unicellular: all alone
2) colony- forms a film
3) filamentous- forms a chain of cells
prokaryote nutrition charactertistics (3) (PDD)
1) photosynthetic (energy from sunlight)
2) disease causing (feed on living things)
3) decomposers (feed on dead things- plants or animals )
characteristics of eukaryotes (4) (MHCI)
1) more complicated
2) have organelles
3 )can be multicellular
4) includes animals and plant cells
what type of membranes are organelles?
membrane-bound cell parts
mini “organs” that have unique structures and functions
organelles
where are organelles found?
in cyotplasm
does a plant or animal cells have a rigid cell wall and why?
plant- to prevent bursting
similarities between plant and animals cells (8) (NNREGMC)
Both have:
1) cell membrane
2) nucleus
3) nucleolus
4) ribosomes
5) ER
6) Golgi
7) mitochondria
8) cytoskeleton
differences between animal and plant cells (4) (APPP)
1) animal cells have centrioles and plants do not
2) plant cells have a cell wall and animals do not
3) plant cells have chloroplasts and animals do not
4) plant cells have one big vacuole and animals do not
what does plant cell’s one big vacuole help with?
its shape
what can the whole cell of a eukaryote cell be?
specialized for one job
what can cells work together as in eukaryote cells?
tissues
what can tissues work together as in eukaryote cells?
organs
characteristics of prokaryotes (3) (SFA)
1) simple and easy to grow
2) fast reproduction
3) all the same
characteristics of eukaryotes (3) (CMC)
1) can specialize
2) multicellulality
3) can build large bodies
what did many scientists theorize about how organelles evolved?
that eukaryotes evolved from prokaryote ancestors
what did Lynn Margulis popularize in 1981?
“endosymbioent theory”
in endosymbioyent theory what does a prokaryote eat?
a smaller prokartyote
what does the smaller prokaryote that the prokaryote ate evolve for?
as a way to avoid being digested, and lives inside its new “host” cell like a pet
inside
endo
friend
symbioent
what do the small prokaryote that can do photosynthesis evolve into?
chloroplasts and “pay” their host with glucose
what can the smaller prokaryote that can do aerobic respiration evolve into?
mitochandria
what does the prokaryote that evolves into mitochandria convert the glucose into?
energy the cell can use
who benefits from the endosymbioent relationship?
both the host and the symboient
the origin of new species, is at the focal point of evolutionary theory
speciation
what must an evolutionary theory explain about speciation?
how new species originate and how populations evolve
consists of changes in allele frequency in a population over time (molecular level)
microevolution
refers to broad patterns of evolutionary change above the species level
macroevolution
states that a species is a group of populations who members have the potential to interbreed in nature and produce viable, fertile offspring
biological species concept
what does the biological species concept say that species do NOT have to do?
breed successfully with other populations
in the biological species concept what holds the phenotype of a population together?
gene flow between populations
what is the biological species concept based on?
the potential to interbreed rather than on physical similarity
the existence of biological factors (barriers) that impede two species from producing viable, fertile offspring
reproductive isolation
offspring of crosses between different species
hybrids
what can reproductive isolation be classified by?
whether factors act before or after fertilization
types of prezygotic reproductive barriers (5) (HTBMG)
1) habitat isolation
2) temporal isolation
3) behavioral isolation
4) mechanical isolation
5) Gamatic isolation
types of postzygotic reproductive barriers (3) (RRH)
1) reduced hybrid viability
2) reduced hybrid fertility
3) hybrid breakdown
what does prezygotic barriers block fertilization from?
1) impeding different species from attempting to mate
2) preventing the succesful completion of mating
3) hindering fertilization if mating is successful
two species encounter each other rarely or not at all, because they occupy different habitats, even though not isolated by physical barriers
habitat isolation
species that breed at different times of the day, different seasons or different years cannot mix their gametes
temporal isolation
courtship rituals and other behaviors uique to a species are effective barriers
behavioral isolation
morphological differences can prevent mating
mechanical isolation
sperm of one species may not be able to fertilize the eggs of another species
gamete isolation
prevents the hybrid zygote from developing into a viable, fertile adult
postzygotic barriers
genes of the different parent species may interact and impair the hybrids development
reduced hybrid viability
even if hybrids are vigorous, they may be sterile
reduced hybrid fertility
some first generation hybrids are fertile, but when they mate with another species or with either parent species, offspring of the next generation are feeble or sterile
hybrid breakdown
what CAN’T the biological species concept be applied to?
fossils or asexual organisms (including prokaryotes)
what does the biological species theory emphasize?
the absence of gene flow
what can gene flow occur between?
distinct species
what is an example of gene flow occurring between distinct species?
grizzly bears and polar bears can mate to produce “grolar bears”
defines a species by structural features
morphological species concept
what does morphilogical species concept apply to and rely on?
it applies to sexual and asexual species but relies on subjective criteria
views a species in terms of its ecological niche
ecological species concept
what does ecological species concept apply to emphasize?
it applies to sexual and asexual species and emphasizes the role of disruptive selection
defines a species as the smallest group of individuals in a phylogenetic tree
phylogenetic species concept
what does phylogenetic species concept apply to and what can it be difficult to determine?
it applies to sexual and asexual species but can be difficult to determine the degree of difference required for separate species
two ways speciation can occur
1) allopatric speciation
2) sympatric speciation
when a population forms a new species while georgraphically isolated from its parent population
allopatric speciation
when a subset of population forms a new species without geographic separation
sympatric speciation
what is interupted or reduced with allopatric speciaton?
gene flow
what is an example of allpatric speciation?
the flightless cormorant of the Galapagos likely originated from a flying species on the mainland
what does the defention of the barrier with allopatric speciation depend on?
the ability of a population to disperse
what is an example of the process of allopatric speciation depending on the ability of a population to disperse?
a canyon may create a barrier for small rodents, but not birds, cayotes or pollen
with allopatric speciation how may separate population evolve?
through mutation, natural selection and genetic drift
what may arise in allopatric speciation as a result of genetic divergence?
reproductive isolation
what is an example of reproductive isolation occuring?
mosquitofish in the Bahamas comprise several isolated populations in different ponds
what type of regions typically have more species?
regions with many geographic barriers
when does reproductive isolation between populations generally increase?
as the distance between them increases between them
what is an example of reproductive isolation increasing as the distance between the population increases?
reproductive isolation increases between dusky salamanders that live further apart
what are barriers to reproduction and what are they not?
intrinsic, separation itself is not a biological barrier
what type of population does sympatric speciation occur?
geographically overlapping populations
the presence of extra sets of chromosomes due to accidents during cell division
polyploidy
what is polyploidy much more common with?
plants rather than animals
an individual with more than 2 chromosome sets, derived from one species
autopolyploid
a species with multiple sets of chromosomes derived from different species
allopolyploid
what is an example of polyploids?
many important crops, (oats, cotton, potatoes, tobacco, wheat)
what can sympatric speciation also result from?
the appearance of new ecological niches
what is an example of sympatric speciation resulting from the appearance of new ecological niches?
the North American maggot fly can live on native hawthorn trees as well as recently introduced apple trees
what can drive sympatric speciation?
sexual selection
what has sexual selection for mates of different colors likely contributed to?
speciation in cichlid fish in Lake Victoria
in sympatric speciation, what isolates a subset of a population without a geographic separation from the parent species?
a reproductive barrier
what can sympatric speciation result from?
polyploidy, natural selection or sexual selection
a region in which members of a different species mate and produce hybrids
hybrid zone
what are hybrids the result of?
the mating between species with incomplete reproductive barriers
what can a hybrid zone occur in?
a single band where adjacent species meet
what is an example of a hybrid zone occuring in a single band where adjacent species meet?
two species of toad in the genus Bombina interbreed in a long and narrow hybrid zone
what do hybrids often have?
reduced fitness compared with parent species
how can the distribution of hybrid zones be more complex?
if parent species are found in patches within the same region
what are the 3 possible outcomes when closely related species meet in a hybrid zone (RFS)
1) reinforcement
2) fusion
3) stability
barriers occur when hybrids are less fit than parent species
reinforcement
over time what happens to the rate of hybridization?
it decreases
where reinforcement occurs, what should be stronger for sympatric than allpatric species/
reproductive barriers
what is an example of reinforcement occuring and sympatric species are stronger?
in populations, flycatchers, males are more similar in allopatric population than sympatric
with fusion, if hybrids are fit ars parents what can there be between species?
substantial gene flow
with fusion, if gene flow is great enough, what can the parent species fuse into?
a single species
whatis an example of fusion?
researchers think that pollution in Lake Victoria has reduced the ability of female cichlids to distinguish males of different species
with stability, what can extensive gene flow from outside the hybrid zone do?
overwhelm selection for increased reproductive isolation inside the hybrid zone
how can broad patterns of the time course of speciation be studied?
using the fossil record, morphological data or molecular data
examples of what the fossil record includes
1) species that appear suddenly
2) persist essentially unchanged for some time
3) then aparantly dissapear
a term coined by Niles Edlredge and Stephen Jay Gould to describe distinct period of apparant stasis punctuated by sudden change
punctuated equilibria
what does the punctuated equilbrium model contrast with?
a model of gradual of gradual change in a species existence.
two models for the tempo of speciation
1) punctuated pattern
2) gradual pattern
what does the punctuated pattern in the fossil record and evidence from lab studies suggest?
that speciation can be rapid
what is an example of speciation being rapid in the punctuated pattern?
the sunflower Helianthus anomalus originated from the hybridization of two other sunflower species
what can the interval between speciation range from?
4,000 years (some cichlids) to 40 million years (some beetles) with an average of 6.5 million years
the cumulative effect of many speciation and extinction events
macroevolution
what may have produced very simple cells through a sequence of stages?
chemical and physical processes on early Earth
what are the stages that led to the origin of living cells? (4) (AJPO)
1) abiotic synthesis of small organic molecules
2) joining of these small molecules into macromolecules
3) packaging of molecules into protocells
4) origin of self-replicating molecules
despite the four stages that led to living cells was the evidence convincing that early atmosphere was in fact reducing?
no
instead of forming in the atmosphere what may have been synthesized near volcanoes or deep-sea vents
the first organic compounds
what did the Miller-Urey-type experiments demonstrate?
that organic molecules could have formed with various possible atmospheres
were past organisms different from those now alive?
yes, very
what did the fossil record show?
macroevolutionary changes over large time scales
what are example of macroevolutionary changes over large time scales (3) (EIO)
1) the emergence of terrestrial verterbrates
2) the impact of mass extinctions
3) the origin of flight in birds
when did Earth form along with the rest of the solar system?
4.6 billion years ago
what likely vaporized water and prevented seas from forming before about 4 billion years ago?
bombardment of earth by rocks and ice
what did earth’s early atmosphere likely contain?
water vapor and chemicals released by volcanic eruptions (nitrogen, nitrogen oxides, carbon dioxide, methane, ammonia, hydrogen)
in the 1920’s what did A.I Oparin and J.B.S. Haldane hypothesize?
that the early atmosphere was a reducing environment
in 1953, what did Stanley Miller and Harold Urey conduct?
lab experiments that showed that the abiotic synthesis of organic molecules in a reducing atmosphere is possible
refers to the sudden appearance of fossils ressembling modern animal phyla in the Cambrian period (535 to 525 million years ago)
the Cambrian explosion
what animal phyla appeared even earlier than the cambrian explosion? (3) (SCM)
1) sponges
2) cnidarians
3) molluscs
what did the cambrian explosion provide?
the first evidence of predator-prey interactions
what does the fossil record show about most species that have ever lived?
that they are now extinct
what can extinctions be caused by?
changes to a specie’s environment
what can cause a mass extinction?
at times, the rate of extinction increased dramatically
what is mass extinction the result of?
disruptive global environmental changes
what has many effects on living organisms?
continental drift
examples of continental drift
1) a continent’s climate can change as it moves north or south
2) separation of land masses can lead to allopatric speciation
2 examples of mass extinctions
1) the cretaceous mass extinction
2) the permian extinction
what can mass extinction alter?
ecological communities and the niches available to organisms
what can take from 5-10 million years as a consequence of mass extinction?
the diversity to recover following a mass extinction
what can mass extinctions change?
the types of organisms found in ecological communities
what is an example of mass extinctions changing the types of organisms found in ecological communities?
the percentage of marine organisms that were predators increased after the Permian and Cretaceous mass extinctions
a mass extinction that occured 65.5 million years ago where organisms that went extinct include about half of all marine species and many terrestrial plants and animals, including dinosaurs
the creataceous mass extinction
a mass extinction that defines the boundary between the Paleozoic and Mesozoic era 251 million years ago. occured in less than 500,000 years and ccaused the extinction of about 96 % of marine animal species
the permian extinction
factors that may have contributeed to these mass extinctions (3) (IGA)
1) intense volcanoism in what is now Serbia
2) global warming and ocean acidification resulting from the emission of large amoutns of CO2 from volcanoes
3) anoxic conditions resulting from nutrient enrichment of ecosystems
what did mammals undergo after the extinction of terrestrial dinosaurs
adaptive radiation
what allowed for the expansion of mammals in diversity and size?
the dissapearance of dinosaurs (except birds)
other notable radiations (5) (PLLIT)
1) photosynthetic prokaryotes
2) large predators in the Cambrian
3) land plants
4) insects
5) tetrapods
what type of lineages can be lost during mass extinctions?
ones with novel and advantagous features
by eliminating so many species, what did mass extinction pave the way for?
adaptive radiations
the rapid evolution of diversly adapted species from a common ancestor
adaptive radiation
what may adaptive radiations follow?
1) mass extinctions
2) the evolution of novel characteristics
3 )the colinization of new regions
what can occur when organisms colonize new environments with little competition?
adaptive radiations
what is one of the world’s great showcases of adaptive radiation?
Hawaii islands
what is most atmospheric oxygen?
of biological origin
how did O2 produced by oxygenic photosynthesis react?
with disolved iron and precipated out to form banded iron formations
what did the prokaryotic ancestors of mitochondria and plastids probably gain entry to?
the host cells as undigested prey or internal parasites
what would have the host and endosymboients become in the process of becoming more independent?
a single organism
supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events
serial endosymbiosis
characteristics of what eukaryotic cells have (4) (NMEC)
1) nuclear envelope
2) mitochondria
3) endoplasmic reticulum
4) cytoskeleton
proposes that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells
endosymbioent theory
where does an endosymboient cell live within?
a host cell
key evidence supporting an endosymbiotic origin of mitochdonria and plastids (4) (IDTT)
1) inner membranes are similar to plasma membranes of prokaryotes
2) division and DNA structure is similar in these organelles and some prokaryotes
3) the orgnaelles transcribe and translate their own DNA
4) their ribosomes are more similar to prokaryotic than eukaryotic ribosomes
