REVIEW FOR CUMULATIVE FINAL Flashcards
Homology
forms related by common ancestry as a result of divergent evolution
Homologous structures
Structures derived by a common ancestor but they may be modified for different function
Convergence
unrelated species have similar adaptations due to being under similar environmental conditions
Allele
one of a number of alternate forms of a DNA sequence at a specific physical location of a gene on a chromosome
Morphological species concept
Organisms that have significant and anatomical differences are different species
Biological species concept
members of the same biological species:
- share the same gene pool
- have gene flow between two populations
- are reproductively isolated from other spp. by biological barriers
Temporal isolation
species have different breeding schedules
Habitat isolation
members of species move or are otherwise seperated (cant mate because they do not meet)
Behavioral isolation
certain actions or behaviors impact reproduction
- gametic isolation where differences in gametic cells prevent fertilization
- mechanical isolation where incompatibility is due to sexual organs
Hybrid in viability
nonviable embryo is produced
Hybrid sterility
produces off spring but they hybrid cannot produce off spring
Hybrid break down
2nd generation of hybrids are feeble or sterile
Genetic variation
new genes and alleles arise by mutation or gene duplication
Microevolution
a change in allele frequencies in population over generations
Relative fitness
reproductive success of individuals and is relative to other individuals in the population.
Directional selection
one extreme phenotype is more fit than the others phenotypes. Shifts variance towards the new and more fit phenotype
Diversifying / Disrupted selection
both extreme phenotypes are more fit than those in the middle. This maintains diversity and increases genetic variance
Stabilizing selection
intermediate phenotype is considered more fit than the extreme ones. This then decreases genetic variance
Mechanisms of microevolution
- natural selection
- genetic drift (founder effect / bottleneck effect)
- Gene flow
Natural selection
- acts non-randomly on phenotypes of individuals
- always leads to adaptation of population
Genetic Drift
- genetic frequency changes due to random events
- often occurs in small populations
- often reduces genetic diversity
- allele may become fixed while others are lost
Gene flow
alleles move in/out of a population
- tends to add genetic diversity to one population
- overall reduces the genetic differences between both populations
Sister taxa
lineage from the same node
Basal Taxon
lineage from the root remains unbranched
Branch point
node where lineage diverges
Clade
group that includes a common ancestor ad ALL the descendants (monophyletic groups)
Cladistic analysis
grouping of organisms in a way that reflects their evolutionary relationship
Paraphyletic clade
consists of ancestral species and some, but not all, descendants
Polyphyletic group
includes distantly related species but does not include their most recent common ancestor
monphyletic clade
consist of all ancestral species and all of its descendants
Endosymbiotic theory
eukaryotic cells are believed to have evolved from early prokaryotes that were engulfed by by phagocytosis. Mitochondria and chloroplast are both organelles suggested to have arisen via endosymbiosis
Lytic cycle
- phage infects cell
- phage DNA circularizes, remaining separate from the host DNA
- phage DNA replicates and creates phage proteins which causes the assembly of new phage particles
- cell lyses, releasing the phages
lysogenic cycle
- the phage infects the cell
- phage DNA becomes incorperated into the host genome
- The cell divides and prophage DNA is passed to daughter cells
- under stressful conditions the phage DNA is excised from the bacterial chromosome and enters the lytic cycle
Oxygenation of the atmosphere
ancestral cyanobacteria oxygenated the atmosphere, increasing O2 concentrations
Gram positive bacteria characteristics
- have a single membrane and thick peptidoglycan layer in their cell wall
- include pathogens such as anthrax and tetanus
- purple
Gram negative bacteria
- have two membranes and between them is a thin layer of peptidoglycan
- outer layer is made out of lipopolysaccharide making them resist drugs and immune system
- pink
Endospores
Dormant and non-reproductive form that bacteria takes when in stressful conditions. They can survive heat and drought for years
Capsule
tightly attached layer on bacterial cells
Slime layer
loosley attached to bacteria and can be washed off
Purpose of capsule and slime layer
- adherence to other cells
- resist attacks from the immune system
- hold in moisture
Stramenopiles
consist of diatoms, brown algae and oomycetes
Diatoms
- unicellular phytoplankton
- key primary producers
- silica walls
- photoautotrophs
Brown Algae
- multicellular
- large thallose form
- cell wall w/ cellulose and algin
- include kelp which is used to make algin
Oomycetes
- superficially resemble fungi
- absorptive heterotrophs
- cell walls have cellulose
- diploid
- spores have flagella
- example includes Phytophthora infestant aka potato blight
Composition of fungal cell wall
Cell walls are made out of chitin
Sexual Fungal reproduction
- mating types (+)and (-)
- homothallic where mycelium has both mating types and is self fertile
- heterothallic where mycelia requires two different but compatible mycelia
Fungal life cycle
- plasmogamy: fusion of + & - hyphae
- heterokaryotic stage: hyphae with unfused haploid nuclei of both types
- karyogamy: fusion of +/- nuclei to form 2n zygote
Characteristics of bryophytes
- haploid gametophyte is dominant form
- makes eggs and flagellated sperm
- most are small, low growing, in moist areas
- diploid sporophyte depends on gametophyte for food and water
- sporohyte grows within the archegonium of gametopyte
- sporangium makes many haploid spores
Seedless Vascular Plants characteristics
- branches sporophytes that are independent of gametophyte
- diploid sporophyte dominates life cycle
- transport in Xylem and phloem
- have true roots and leaves
Plants adaptations to dry land
- seeds which offered embryo protection, nourishment and allows plants to disperse the next generation
- pollen which protect the sperm from desiccation and isn’t dependent on water in order to reach the female organs
Embryonic development
- zygote -> (clevage) -> 2. eight cell stage -> (clevage) -> 3. blastula stage -> (gastrulation) -> 4. grastula stage
Blastula stage
single layer with hollow space called the blastocoel (filled with fluid)
Blastopore
opening of the archenteron
Archeteron
primitive gut
4 distinct periods of animal evolution
- Neoproterozoic
- Paleozoic
- Mesozoic
- Cenozoic
When did dinosaurs become extinct
Cretaceous period
