Life 103 Exam 1 CSU

Science

recognizing patterns in the natural world and understanding the mechanisms that give rise to those patterns

The Diversity of Life

Patterns

How plants and animals work

Mechanisms

Evolution

the change in allele frequencies in a population over time

Four Mechanisms of Evolution

Selection, Genetic Drift, Mutation, and Migration

Selection

changes in allele frequencies due to organisms with advantageous alleles reproducing more successfully than organisms with other alleles

Genetic Drift

random change in allele frequencies in a population

Mutation

the source of all new allelic diversity

Migration

movement of alleles between population

Adaptation

a trait that evolves by selection for a particular function (because it increases fitness) from an ancestor that did not have that trait; these can be morphological, behavioral, or molecular. They solve problems faced by populations and different populations may have different solutions to similar problems

Phylogeny

the evolutionary relationships of a group of organisms (species level and higher)

Phylogenetic Tree

diagram of the ancestral relationships among species; describes patterns, provides information about when certain large events may occur

Taxonomy

the ordered division and naming of organisms

Carl Linnaeus

published a system of taxonomy based on resemblances; two part name for species and hierarchical classification

Binomial

the two part scientific name of a species

Genus

the first part of the name

Specific Epithet

the second part of the name unique for each species within the genus

Taxonomic groups (from broad to narrow)

Domain, kingdom, phylum, class, order, family genus, species

Taxon

a taxonomic unit at any level of hierarchy

Characters

types of data we can use to reconstruct a tree (morphological traits, behavior, chemical composition, chromosome number, DNA)

Character State

Variation among characters

Branch point

represent the divergence of two species

Sister taxa

groups that share an immediate common ancestor

Rooted tree

includes a branch to represent the last common ancestor of all taxa in the tree

Polytomy

a branch from which more than two groups emerge

Ecology

the study of the distribution and interaction of organisms with other organisms and the environment

Population

a group of individuals of the same species living in the same area

Population ecology

focuses on factors affecting how many individuals of a species live in an area (most mathematically based on sub discipline of ecology)

Community Ecology

deals with the whole array of interacting species in a community

Ecosystem Ecology

emphasizes energy flowing chemical cycling among the various biotic and abiotic components (movement of carbon, nitrogen and other chemicals through the ecosystem)

Biotic Factors

organisms interacting with other species (Predator/prey, Herbivore/plant)

Abiotic Factors

Non-living parts of the environment (chemical i.e. pH/salinity)

Dispersal

the movement of individuals; one way trip (migration is a round trip)

Bacterial cells have a variety of shapes, what are the three most common?

spheres (cocci), rods (boccili), and spirals

Peptidoglycan

a network of sugar polymers cross linked by polypeptides

What do most bacterial cell walls contain?

peptidoglycan

What do both eukaryotes and archaea contain?

Polysaccharides and proteins but lack peptidoglycan

Gram Stain

used to make bacteria visible, classifies many bacterial species (gram positive and gram negative)

Gram Negative Bacteria

have less peptidoglycan, have outer membrane that can be toxic, more likely to be antibiotic resistant

Fimbriae

some prokaryotes have fimbriae (aka attachment pili) which allows them to stick to their substrate or other individuals in a colony

How do most motile bacteria propel themselves and how is this different from eukaryotes?

Via flagella. Structurally and functionally different from eukaryotic flagella, allows for taxis.

Taxis

the ability to move in response to stimuli

What do most bacteria and archaea lack?

Complex compartmentalization; no organelles

Bacteria DNA

most of the genome consists of a circular chromosome

Plasmids

smaller rings of DNA; some species of bacteria have plasmids

What is the typical bacterial genome like?

a ring of DNA that is not surrounded by a membrane

What can bacteria form?

Exospores or endospores

Endospores

internal to the bacterium, resistant to UV radiation, desiccation, alcohol, and chemicals; can survive for extended periods of time

Exospores

formed differently, less robust

How do bacteria reproduce?

Quickly by binary fission, and can divide every 1-3 hours

Bacteria and archaea have considerable genetic variation, what are three factors that contribute to this genetic diversity?

Rapid reproduction, mutation and genetic recombination

How can bacterial DNA from different individuals be brought together?

Transformation, transduction, and conjugation

Transformation

a bacteria can take up an incorporate foreign DNA from the surrounding environment

What are the bacteria that can transform called?

Competent

Transduction

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

Conjugation

the process where genetic material is transferred between bacterial cells

During conjugation what allows cells to connect and pull together for DNA transfer?

Sex Pili

F Factor

a piece of DNA that is required for the production of sex pili; the F factor can exist as a separate plasmid or as DNA within the bacterial chromosome

R plasmids

carry genes for antibiotic resistance; antibiotics select for genes that are resistant to the antibiotics

Phototrophs

obtain energy from light

Chemotrophs

obtain energy from chemicals; black smoker deep vents, major primary producers

Autotrophs

require CO2 as a carbon source

Heterotrophs

require an organic nutrient to make organic compounds; absorb organic molecules or ingest larger food particles

Bacteria metabolism vary how?

With respect to O2

Obligate aerobes

require CO2 for cellular respiration

Obligate anaerobes

are poisoned by O2 and use fermentation or anaerobic respiration

Facultative anaerobes

can survive with or without O2

What happens in nitrogen fixation?

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

Proteobacteria

these gram negative bacteria include photoautotrophs, chemoautotrophs, and heterotrophs; some are anaerobic others are aerobic

Symbiosis

an ecological relationship in which two species live in a close contact: a larger host and a smaller symbiont (Prokaryotes often form symbiotic relationships with larger organisms)

Extremophiles

archaea that live in extreme environments

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; they are strict anaerobes and are poisoned by O2

Protista

the informal name of the "kingdom" of mostly unicellular eukaryotes; they constitute a large paraphyletic group and now is longer available as a kingdom

What are protists?

Protists are eukaryotes and thus have organelles and are more complex than bacteria or archaea, most are unicellular but there are some colonial and multicellular species.

Protists, which are the most nutritionally diverse of all eukaryotes, include:

Photoautotrophs, Heterotrophs, and Mixotrophs

Photoautotrophs

contain chloroplasts

Mixotrophs

combine photosynthesis and heterotrophic nutrition

How do protists reproduce?

Both sexually and asexually

Excavata

clade that is characterized by its cytoskeleton; some members have a feeding grove

Diplomonads

have modified mitochondria called mitosomes; are often parites

Parabassalids

have reduced mitochondria called hydrogenosomes; include trichomonad vaginalis, the pathogen that causes yeat infections in human females

Euglenozoa

diverse clade that all have spiral or crystalline rod of unknown function inside their flagella

Kinetoplastids

have a single mitochondrion with an organized mass of DNA called a kinetoplast

Euglenids

have one or two flagella that emerge from a pocket at one end of the cell

Chromalveolata

clade is monophyletic and originated by a secondary endosymbiosis event (w/ red alga), thisclade is controversial and includes the alleviates and the stramenopiles

Superphylum Alveolata

protists have membrane bounded sacs (alveoli) just under the plasma membrane

Phylum Dinoflagllates

diverse group of aquatic mixotrophs and heterotrophs; they are abundant components of both marine and freshwater phytoplankton. Each has a characteristic shape that in many species is reinforced by plates of cellulose

Dinoflagellate blooms

the cause of toxic "red tides", not all red tides are red and not all are harmful

Phylum Apicomplexa

parasites of animals and some cause of serious human diseases

Phylum Stramenopila

Heterokonts

Diatoms

unicellular algae with a unique two part, glass like wall of hydrated silica

Golden Algae

unicellular (some colonial) named for their color, which results from their yellow and brown carotenoids

Brown algae

largest and most complex algae; all are multicellular, and most are marine. Include many species commonly called "seaweeds"

The rootlike _____ actors the stemlike _____ which in turn supports the leaflike ______

holdfast; stipe; blades

Alternation of Generations

the most complex life cycles, the alternation of multicellular haploid and diploid forms

heteromorphic

generations are structurally different

Isomorphic

generations look similiar

Rhizaria

DNA evidence supports rhizaria as a monophyletic clade