BIOL 1510 Midterm Exam

Macroevolution

Macroevolution

the broad pattern of evolution above the species level

Protocell

an abiotic precursor of a living. ell that had a membrane-like structure and that maintained an internal chemistry different from that of its surroundings

Hydrothermal Vents

an area on the deep sea floor where heated water and minerals from Earth’s interior gush into the seawater

Alkaline Vents

a deep sea hydrothermal vent that releases water that is warm rather than hot and that has a high pH

Ribozymes

an RNA molecule that functions as an enzyme, such as an intron that catalyzes its own removal during RNA splicing

Radiometric Dating

a method for determining the absolute age of rocks and fossils, based on the half-life of radioactive isotopes

Half-Life

amount of time it takes for half of a sample of a radioactive isotope to decay

Geologic Record

a standard time scale dividing Earth’s history into time periods, grouped into four eons - Hadean, Archaean, Proterozoic, and Phanerozoicand further subdivided into eras, periods, and epochs

Stromatolites

layered rock that results from the activities of prokaryotes that bind thin films of sediment together

Endosymbiont Theory

the theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by a host cell. the engulfed cell and its host cell evolved into a single organism

Serial Endosymbiosis

a hypothesis for the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts, and perhaps other cellular structures were derived from a small prokaryotes that had been engulfed by larger cells

Cambrian Explosion

a relatively brief time in geologic history when many present-day phyla of animals first appeared in the fossil record. 535-525 million years ago, the emergence of the first large, hard-bodied animals

Plate Tectonics

the theory that the continents are part of great plates of earth’s crust that float on the hot, underlying portion of the mantle. movements in the mantle cause the continents to move slowly over time

Pangaea

the supercontinent that formed near the end of the Paleozoic era, when plate movements brought all the landmasses of Earth together

Mass Extinction

the elimination of a large number of species throughout Earth, the result of global environment changes

Adaptive Radiations

period of evolutionary change in which groups of organisms form many new species whose adaptions allow them to fill different ecological roles in their communities

Heterochrony

evolutionary change in the time or rate of an organism’s development

Paedomorphosis

the retention in an adult organism of the juvenile features of its evolutionary ancestors

Homeotic Genes

any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the development fate of groups of cells

Phylogeny

the evolution of history of a species or group of related species

Systematics

a scientific discipline focused on classifying organisms and determining their evolutionary relationships

Taxonomy

a scientific discipline concerned with naming and classifying the diverse forms of life

Binomial

the two-part latinized format for naming a species, consisting of the genus and specific epithet

Linean Classification

Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species

Taxon

a named taxonomic unit at any given level of classification

Phylogenetic tree

a branching diagram that represents a hypothesis about the evolutionary history of a group of organisms

Phylocode

proposed system of classification of organisms based on evolutionary relationships: only groups that include a common ancestor and all of its descendants are named

Branch Points

the representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor

Rooted

describing a phylogenetic tree that contains a branch point representing the most recent common ancestor of all taxa in the tree

Basal taxon

in a specified group of organisms, a taxon whose evolutionary lineage diverged early in the history of the group

Polytomy

in a phylogenetic tree, a branch point from which more than two descendant taxa emerge. a polytomy indicates that the evolutionary relationships between the descendant taxa are not yet clear

Analogy

similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait

Homoplasies

a similar structure or molecular sequence that has evolved independently in two species

Molecular Systematics

a scientific discipline that uses nucleic acids or other molecules to infer evolutionary relationships between different species

Cladistics

an approach to systematics in which organisms are placed into groups called clades based primarily on common descent

Clades

a group of species that includes an ancestral species and all of its descendants

Monophyletic

pertaining to a group of taxa that consists of a common ancestor and all of its descendants. a monophyletic taxon is equivalent to a clade

Paraphyletic

pertaining to a group of taza that consists of a common ancestor and some, but not all, of its descendants

Polyphyletic

pertaining to a group of taxa derived from two or more different ancestors

Shared Ancestral Character

a character, shared by members of a particular clade, that originated in an ancestor that is not a member of taht clade

Shared Derived Character

an evolutionary novelty that is unique to a particular clade

Outgroup

a species or group of species from an evolutionary lineage that is know to have diverged before the lineage that contains the group of species being studied. an outgroup is selected so that its members are closely to the group of species being studied, but not as closely related as any study-group members are to each other

Ingroup

a species or group of species whose evolutionary relationships we seek to determine

Maximum Parsimony

a principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts

Maximum Likelihood

as applied to molecular systematics, a principle that states that when considering multiple phylogenetic hypotheses, one should take into account the hypothesis that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes ove time

Orthologous Genes

homologous genes that are found in different species because of speciation

Paralogous Genes

homologous genes that are found in the same genome as a result of gene duplication

Molecular Clock

a method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes evolve at a constant rate

Neutral Theory

the hypothesis that much evolutionary change in genes and proteins has no effect on fitness and therefore is not influenced by natural selection

Horizontal Gene Transfer

the transfer of genes from one genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity, and perhaps fusion of different organisms

Peptidoglycan

a network of sugar polymers cross-linked by polypeptides

Gram Stain

used to classify bacteria by cell wall composition

Gram-Positive Bacteria

simpler walls with a large amount of peptidoglycan (stains purple)

Gram-Negative Bacteria

have less peptidoglycan and an outer membrane that can be toxic (stains red)

Capsule

the cell wall of many prokaryotes is surrounded by a sticky layer of polysaccharide or proteins

Endospores

a way of withstanding harsh conditions, certain bacteria develop resistant cell called this

Fimbriae

hairlike appendages that stick to substrates

Pili (sex-pili)

appendages that pull two cells together prior to DNA transfer from one cell to another

Taxis

the ability to move toward or away from a stimulus

Nucleoid Region

chromosome is located here

Plasmids

some species of bacteria also have smaller rings of independently replicating DNA called this

Three factors that contribute to genetic diversity

Rapid Reproduction, Mutation, Genetic Recombination

Genetic Recombination

the combining of DNA from two sources, contributes to diversity

Transformation

a prokaryotic cell can take up and incorporate foreign DNA from the surrounding environment

Transduction

the movement of genes between bacteria by bacteriophages (viruses that infect bacteria)

Conjugation

the process where genetic material is transferred between prokaryotic cells

F Factor

piece of DNA that is required for the production of pili

F Plasmid

cells containing this functions as DNA donors during conjugation

R Plasmid

carry genes for antibiotic resistance

Phototrophs

obtain energy from light

Chemotrophs

obtain energy from chemicals

Autotrophs

require CO2 as a carbon source

Heterotrophs

require an organic nutrient to make organic compounds

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

Nitrogen Fixation

some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3)

Heterocysts

nitrogen-fixing cells

Extreme halophiles

live in highly saline environments

Extreme Thermophiles

thrive in very hot environments

methanogens

live in swamps and marshes and produce methane as a waste product

Decomposers

breaking down dead organisms and waste products

Symbiosis

an ecological relationship in which two species live in close contact. a large host and a smaller symbiont

Mutualism

both symbiotic organisms benefit

Commensalism

one organism benefits while neither harming nor helping the other in any significant way

Parasitism

an organism called a parasite harms but does not kill its host

Pathogens

parasites that cause disease

Exotozins

secreted and cause disease even if the prokaryotes that produce them are not present

Endotoxins

released only when bacteria die and their cell walls break down

Algae (alga)

a photosynthetic, plantlike protist

Alternation of Generations

a life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants

Alveolata

a protistan clade that includes dinoflagellates, apicomplexans, and the ciliates. have small membrane-bounded cavities called alveoli under their cell surfaces. function is unknown

Amoeba

a type of protist characterized by great flexibility and the presence of pseudopodia

Apicomplexan

one of a group of parasitic protozoans, some of which cause human diseases

Blades

a leaflike structure of a seaweed that provides most of the surface area for photosynthesis

Brown Algea

one of a group of marine, multicellular, autotrophic protists, the most common type of seaweed. include the kelps

Cellular Slime Mold

a type of protist that has unicellular amoeboid cells and multicellular reproductive bodies in its life cycle

Ciliate

a type of protozoan that moves by means of cilia

Conjugation in bacteria

the direct transfer of DNA between two cells that are temporarily joined

Diatom

a unicellular photosynthetic alga with a unique, glassy cell wall containing silica