Biology 2 - OSU - Unit 3

Inbreeding

a form of non-random mating

Self-fertilization (selfing)

most extreme form of inbreeding, contain both male and female organs, homozygous parents produce only homozygous offspring, heterozygous parents produce offspring in a 1:2:1 ratio

Inbreeding increase ______________ and decreases ______________

homozygosity; heterozygosity

Inbreeding does not cause __________

evolution, because it doesn’t change allele frequencies as a whole

Nonrandom mating is not an ______________ ____________

evolutionary process, because it only changes genotype frequencies and not allele frequencies

Inbreeding’s influence on evolution

can speed the rate of evolutionary change by increasing the rate at which natural selection eliminates recessive deleterious alleles from a population

Inbreeding causes a decline in average _________

fitness

Macroevolution

changes in allele frequency in a population lead to a new species

Speciation

splitting event that creates two or more distinct species from an ancestral species, rapid or gradual, starts with genetic isolation then genetic divergence

Biological species concept

reproductive isolation between populations, don’t produce viable fertile offspring

Morphospecies concept

isolation by different characteristics, differ in size shape or other morphological feature, cannot identify cryptic species, very subjective

Phylogenetic species concept

the smallest monophyletic group on a phylogenetic tree is a species, can be applied to any type of population

Monophyletic group (clade or lineage)

on a phylogenetic tree, consists of an ancestral population and all of its descendants

Synapomorphies

homologous traits found in common ancestors and descendants but missing in more distant ancestors, what identifies monophyletic groups

Nodes

represent speciation events in a phylogenetic tree

Outgroup

a taxon that diverged before the taxa that are the focus of the study of the tree, helps form the root of the tree

Mechanisms of reproductive isolation

breed at different times, breed in different habitats, different courtship displays, incompatible reproductive structures, egg and sperm are incompatible, off spring do not develop normally and die early, off spring are sterile

Cryptic species

species that differ in non-morphological traits

Systematics

a discipline of biology that characterizes and classifies relationships among organisms

Taxonomy

the practice of describing, naming, and classifying individual species

Intact fossil

a fossil that forms when decomposition does not occur and the organic remains are preserved intact

Compression fossil

fossil that forms when sediment accumulates on top of the organism and becomes cemented into rocks

Cast fossil

fossil that forms when a buried organism decomposes leaving an empty cavity in sediment that then fills with dissolved minerals and hardens

Permineralized fossil

a fossil that forms when organisms decompose extremely slowly, dissolved minerals gradually infiltrate the interior of cells and harden into stone

Trace fossils

fossils that form when sedimentation and mineralization preserve indirect evidence of an organism in the environment, like foot prints

Biogeography

the study of the distribution of species across the planet

Homologous structures

similar body parts that reflect shared ancestry

Convergent evolution

similar characteristics due to similar environmental conditions, are not closely related, analogous traits

Analogous structures

did not evolve in a shared ancestor, like wings in insects, bats, and birds - their common ancestor did not have wings

Vestigial traits

traits that are no longer useful but do not cause any harm so they stay

Virus

an obligate intracellular parasite, uses a host cell’s biosynthetic machinery to replicate, not technically alive because they need a host cell to replicate

Virus categories

some have a capsid or protein shell that contains the virus and some have a capsid and also one or more membranous envelopes

Capsid

a protein shell, protects the genome while outside the host, releases the genome when infecting a new cell

Viruses cannot carry out ____________ or _____________ independently

transcription; translation

Lateral gene transfer

done by viruses, introduce foreign genes into cellular genomes, shuttle genes from one organism to another

__ to __% of the human genome consists of remnants of viral genomes from past infections

5; 8

Microbiome

bacteria and archaea, prokaryotic and unicellular

Differences between bacteria and archaea

bacteria have a peptidoglycan cell wall, archaea have unique phospholipids in the call membrane, have different ribosome and RNA polymerase structures

Extremophiles

bacteria that live in unusual environments, can help us understand the origin of life,

DNA cloning

a human gene that produces an important protein is isolated, this protein is inserted into a bacterial plasmid, bacteria multiply and so does the protein

Pathogenic bacteria

bacteria that come from several different lineages in the domain of bacteria, tend to affect tissues at entry points into the body

Infectious diseases are caused by _________

Koch’s postulate, microbes

Infectious diseases are spread……

Koch’s postulate, from person to person, from bites of insects or animals, from ingesting contaminated food or water

Transformation

when bacteria or viruses naturally take up DNA from the environment, caused diversification between bacteria and Archaean’s

Transduction

when viruses pick up DNA from one prokaryotic cell and transfer to another cell, caused diversification between bacteria and archaean’s

Conjugation

when genetic information is transferred by direct cell-to-cell contact, caused diversification between bacteria and archaean’s

Gram-positive bacteria

have a cell wall with abundant peptidoglycan, stains dark purple when exposed to a Gram stain

Gram-negative bacteria

have a cell wall with a thin layer of peptidoglycan surrounded by a phospholipid bilayer, stain light pink when exposed to a Gram stain

Phototrophs

use light energy to energize electrons, producing ATP by photophosphorylation

Chemoorganotrophs

oxidize organic molecules with high potential energy such as sugars

Chemolithotrophs

oxidize inorganic molecules with high potential energy, such as ammonia or methane

Autotrophs

use carbon dioxide or methane to build their own carbon-containing compounds

Heterotrophs

acquire carbon-containing compounds from other organisms

Bacteria and archaea enzymes

extremely sophisticated, allows them to live in extreme environments and use toxic compounds as food

Cyanobacteria

lineage of photosynthetic bacteria, first to perform oxygenic photosynthesis, responsible for changing earths atmosphere to one with a high concentration of oxygen

Molecular nitrogen (N2)

very abundant in the atmosphere, cannot be used by plants directly, need ammonia or nitrate

Nitrogen fixation

certain bacteria and archaea are the only organisms capable of converting N2 to NH3, live in close association with plants

NH3 fertilizers

bacteria use much of it as food which causes pollution, waste products can cause decrease in oxygen content causing anaerobic or oxygen dead zones

Fungi

release nutrients from dead plants and animals into the soil or obtain nutrients and then transfer them directly to living plants and animals, recycle many key elements like carbon, nitrogen, and phosphorus and therefore profoundly influence ecosystem productivity

Fungi positive impacts

source of many antibiotics, food, yeast for food and drinks, fungal enzymes that can improve taste in some foods

Mycorrhizal fungi

live in close association with plant roots, increases plant growth

Saprophytic fungi

fungi that digest dead plant material, helps cycle carbon though terrestrial systems (carbon cycles)

Yeasts

single celled forms of fungi

Mycelia

multicellular filamentous forms of fungi, constantly grow in the direction of food sources and die back in areas where food is running out

Hyphae

the long narrow filaments of mycelium, causes a very high surface area- to - volume ratio, extremely efficient nutrient absorption, absorb the nutrients from extracellular digestion

Lignin and cellulose

in the cell walls of plants, two most abundant organic molecules on earth, digested by fungi

Fungi are more closely related to _______ than to land plants

animals

Fungal infections are more difficult to treat than bacterial infections because…

have recent shared ancestry and therefore have similar cellular and molecular structures