Unit 2 PAL Flashcards
Who was Carl Linnaeus?
- Swedish botanist (1707-1778)
- Introduced binomial nomenclature, two part scientific name
- Revolutionized taxonomy
The science of classifying living things
taxonomy
study of the physical form or structure of an organism; anatomy, external structures, skeleton
morphology
the study of the evolutionary relationships among organisms
phylogeny
list 5 sources of information we use in phylogeny
- morphology
- paleontology
- behavior
- development
- molecular data
What can morphology tell us?
-more in common= closer evolutionary relationship
What are some limitations of morphology?
- difficult to compare distantly related species
- some variations are caused by the environment
What can paleontology tell us?
when and where an organism lived
What is a limitation of paleontology?
possible incomplete fossil record; fragmentary fossils
What can behavior tell us?
“active morphology”
-species with similar behavioral patterns may be more closely related
What is a limitation of behavior?
often learned, not genetic
What can developmental patterns tell us?
-some adult species may look totally different, but develop in similar ways (for ex- frog and sea squirt look similar when young)
What can molecular data tell us?
- DNA used to construct phylogenetic tree
- Mutation accumulate over time; fewer differences= closely related
What is a clade?
part of a phylogenetic tree that includes all species linked by descent from a common ancestor
monophyletic
clade
polyphyletic
missing common ancestor
paraphyletic
missing some descendants
What is a taxon?
any species or group of species that we designate or name
What is the biological species concept?
defines a species as a group of individuals/populations that can interbreed with one another and are reproductivly isolated from other such groups
What is reproductive isolation?
groups cannot reproduce with one another (can’t exchange genes)
What is allopatric speciation?
- occurs when populations are separated by a physical barrier
- dominant mode of speciation
- allo= other and patri= land
What is sympatric speciation?
without physical isolation
-sym= same
List 3 prezygotic isolation mechanisms
- mechanical
- behavioral
- temporal
mechanical
difference in size and shape of reproductive organs that makes mating impossible
behavioral
individuals reject or even fail to recognize potential mates
temporal
difference in mating times
What is a post-zygotic isolating mechanism?
- low hybrid fitness
- zygotes or adult offspring have lower fitness, or hybrids infertile
Describe the Dobzhansky Muller Model-
1) an ancestral population is divided
2) 2 groups evolve independently
3) in each group, new alleles become fixed at different loci
4) new alleles at the different loci are incompatible with one another
Chipmunk populations on opposite sides of the Grand Canyon are an example of
allopatric speciation
The biological species concept is not applicable to
asexual organisms
A horse and a donkey mate and produce a mule offspring, which is infertile. This is an example of
a postzygotic isolating mechanism
American toads mate in the early part of the summer, while Fowler’s toads mate later in the season. The two remain separate species as a result of
temporal isolation
Male fireflies flash their lights in specific patterns. Females only respond to signals flashed by their own species. This is an example of
behavioral isolation
How big are bacteria (give an average size or reference)?
1-10 um (about 100 cells stacked up across the width of hair)
List the 3 shapes of bacteria
- bacilli (rods)
- cocci (sphere)
- spirilla (spirals)
diplo
pairs
staphylo
clusters
strepto
chains
List some similarities between Eukaryotes and Prokaryotes
cytoplasm, plasma membrane, need to divide to produce more cells, carry DNA on chromosomes, need to bring a copy of this DNA with then they divide
List some of the differences between Prokaryotes and Eukaryotes (prokaryotes…)
- circular chromosomes
- peptidoglycan cell walls
- smaller ribosomes
- divide by binary fission
- DNA not enclosed in membrane
List some of the differences between Prokaryotes and Eukaryotes (eukaryotes…)
- linear chromosomes
- polysaccharide cell walls
- larger ribosomes
- divide by mitosis
- DNA enclosed in nuclear membrane
What is the function of ribosomes?
protein synthesis
How can we exploit the difference in ribosome size in order to have effective antibiotics?
- prokaryotes have smaller ribosomes
- antibiotics bind to sites on the ribosome and will stop the synthesis of protein, killing cell
How can we exploit differences in the cell wall?
- bacterial cell walls are made of peptidoglycan
- antibiotics can prevent the formation of functional cell walls
- most effective with gram positive bacteria
How can we exploit differences in chromosomes?
- prokaryotes have circular DNA, not enclosed in a nuclear membrane
- they use DNA gyrase to uncoil the DNA during replication
- antibiotics can be used to target this enzyme, stopping DNA replication and killing cell
What is the difference between gram positive and gram negative bacteria?
gram + = thick peptidoglycan cell wall
gram - = thin peptidoglycan cell wall, has outer membrane
How do we test for whether a bacteria is gram positive or negative?
- gram stain
- stain cells with crystal violet (dye) and if the cells take up this dye, they are gram positive because the thick peptidoglycan wall is holding on to the stain
How do we define a bacterial species?
not very well- there is no currently accepted species concept for bacteria
-current solution: sequence the 16s RNA gene, look for similarities, if they are 95-97% similar they are an “operational taxonomic unit” (OTU)
How do bacteria reproduce?
Binary fission
How do bacteria communicate?
pili
Name 2 mechanisms that bacteria use for protection:
Biofilm and endospores
What is biofilm?
a group of bacteria surrounded by a protective slime making it hard to kill bacteria (ex-plaque on teeth)
Why do endospores form and what is their function?
- produced by bacillus bacteria when cell is starving
- endospores contain a copy of the cell’s DNA
- resistant to heat, drying out, etc
- remain in dormant state until conditions favorable again
What are some ways that bacteria are helpful to us?
- metabolizing medication
- help solve crimes
- help in digestion
- diversity in microbiome keeps potentially harmful bacteria in check
Describe actinobacteria
- high GC (guanine, cytosine) content
- used in development of antibiotics
- found in soil
- ex: streptomyces species
Describe baceriodetes
- gram negative
- rod shaped
- non spore forming
- commonly found in feces
- ex: bacterioides species
Describe proteobacteria
- most abundant, most diverse # of species
- ex: E Coli and Y Pestis
Describe firmicutes
- low GC
- form endospores
- ex: bacillus anthracis
obligate aerobe
cannot survive without O2
obligate anaerobe
will die in the presence of O2
facultative anaerobe
can shift metabolism between anaerobic and aerobic
aerotolerant anaerboe
not damaged by O2, but doesn’t use it
What does it mean if an organism is a chemoautotroph?
gets energy from inorganic compounds and gets carbon from CO2
What does it mean if an organism is a photoheterotroph?
gets energy from sunlight and carbon from organic compounds
a species is defined as
a population of organisms that are able to interbreed
Most frogs do not have lower teeth, but the ancestor of frogs did. One frog genus has regained teeth in the lower frog. This is an example of:
evolutionary reversal
Who developed the two part naming system for classifying organisms?
Carl Linnaeus
There are different species of shrimp present on different sides of the Isthmus of Panama, a tiny strip of land joining North and South America. This is an example of
allopatric speciation
What is the difference between a cladogram and a phylogenetic tree?
In cladograms, the branches are arbitrary. In phylogenetic trees, the branches are proportional to time.
What is an evolutionary reversal?
reverting back to an ancestral trait
Define convergent evolution
- independent evolution of the same trait
- analogous
- homoplasy
- ex: wings, fins and shape of sharks/dolphins
What is the parsimony principle?
tells us to choose the simplest scientific explanation that fits the evidence- in phylogenetic trees, this is the tree with the fewest evolutionary changes
Define monophyletic
clade, common ancestor, and all of its descendants
Define paraphyletic
missing some decendants
Define polyphyletic
missing common ancestor
What is a synapomorphy?
a unifying trait of a clade
Define competition
both are harmed
Define predation
one harmed, one benefits
Define mutualism
both benefit
List three types of viruses
- Single stranded RNA viruses (negative sense, positive sense, retrovirus)
- Double stranded RNA viruses
- Double stranded DNA viruses (bacteriophages)
Describe single stranded RNA viruses
- injects RNA into host cell
- replication occurs in cytoplam of host cell
Describe negative sense
complementary RNA to mRNA so it needs to first be transcribed into mRNA before it can be translated into protein (rabies)
Describe positive sense
like mRNA, already set for translation (polio)
Describe retrovirus
undergoes reverse transcriptase to form DNA (HIV)
Describe double-stranded RNA viruses
- replication occurs in cytoplasm of host cell
- ex: bluetongue virus in ruminants
Describe double stranded DNA viruses
- replication occurs in nucleus of host cell
- ex: smallpox
List the similarities of life in all domains
- have plasma membranes
- have ribosomes
- use DNA in central dogmai
What was the significance of the development of the cytoskeleton?
- provides support for the cell
- moves materials throughout the cell
- helps with distribution of chromosomes in mitosis
What is phagocytosis and why is it important in the evolution of eukaryotes?
ability to engulf other organisms
engulfed bacteria evolved into organelles
mitochondria and chloroplasts
What are the main differences between Archaea and other domains?
- over half of their genes are unique
- lipids in cell membrane are branched
- ether linkages
Describe the events in the origin of eukaryotic cells:
- loss of cell wall (flexible cell surface)
- cytoskeleton developed
- phagocytosis (ability to engulf other organisms)
- mitochondria and chloroplasts
What was the significance of the loss of the cell wall?
ratio of surface area to volume decreased
infolding of membrane increased surface area
What is endosymbionic theory?
engulfed bacteria became organelles (photosynthetic bacteria= chloroplasts, aerobic bacteria= mitochondria)
What evidence do we have to support endosymbionic theory?
size and shape
circular DNA in organelles
size of ribosomes
Dinoflagellates
- most photosynthesize
- have flagella
- symbiotic relationship with coral
Apicomplexans
- parasites
- ex) plasmodium (malaria), toxoplasma (toxoplasmids-litter box)
Ciliates
-heterotrophic
-cilia for locomotion
-vacuoles (digestive- food, contractile- expel water)
PARAMECIUM
Diatoms
- unicellular or form colonies in the shape of filaments
- photosynthetic (20% of world’s carbon supply)
- bilaterally or radially symmetric
Radiolarians
- radial symmetry
- thin/stiff psuedopods
- elaborate skeletons
Foraminiferans
-shells made of calcium carbonate (accumulate to form limestone)
Heterolobosean
- Naegleria folwer (“brain eating” amoeba)
- amoeboid body form, not actually amoeba
Euglenids
have one flagella, some photosynthetic
Kinetoplastids
parasites,
Ex- trypanosoma (chagas, sleeping sickness)
-undulating membrane (looks like ribbon)
Loboseans
- phagocytosis
- very large
- have pseudopods
- don’t have flagella or cilia
Plasmodial slime mold
- mass of cytoplasm and nuclei
- no plasma membrane
- “streams over substrate”- eating
- transforms into fruiting structures
- sporangia holds haploid spores
Cellular slime molds
-retain plasma membrane, individual cells, haploid
As adaptations for flight, the wings of bats and the wings of birds are an example of
convergent evolution
shared traits derived from a common ancestor are also known as
synapomorphies
in the study of evolution scientists often look at homologous features in species. What cannot be used as a homologous feature?
evolutionary reversal
the common ancestor of all the species displayed in a phylogenetic tree lies at the (blank) of the tree
root
what is formed when two branches diverge from each other in a phylogenetic tree?
node
the evolutionary relationship among organisms is known as
phylogeny
the classification of organisms based on appearance alone is known as the (blank) species concept
morphological
the (blank) species concept holds that species are groups of actually or potentially interbreeding natural populations that are reproductively isolated from each other
biological
what is not a characteristic of prokaryotic cells?
membrane enclosed nucleus
what is found in both eukaryotes and prokaryotes?
a system for generating ATP
Endospores
- survive harsh environmental conditions
- contain some cytoplasm and replicated nucleic acid
- enclosed within a tough cell wall
- resting structure (not reproductive)
- parent cells only produce one
