bio exam 3 / final

a very small infectious particle consisting of only nucleic acids enclosed in a protein coat (sometimes a membranous envelope)

double or single stranded rna / dna

the protein shell that encloses the genome (nucleic acids) of the virus.

capsomeres

a limited number of host cells that each virus can infect

the cell begins to manufacture viral proteins

a virus that infects a bacterium by infecting it then reproducing in it

a phage replicative cycle that ends in the death of the host cell

a bacterial defense against phages, they recognize and cut up certain phage DNA

a phage that reproduces only by the lytic cycle

this cycle replicates the phage genome without destroying the host. the viral DNA is known as prophage

1 - recognize foreign (viral) dna

2 - files copies of it

3 - cuts it when it appears in the cell

they use the enzyme reverse transcriptase to copy their RNA genome into dna

(HIV is the retrovirus that causes AIDS)

harmless derivatives of pathogenic microbes that stimulate the immune system to mount defenses against the harmful pathogen

the transfer of a virus to another plant is known as horizontal transmission. the inheritance of a virus from a parent plant is called vertical transmission

a slow- acting, virtually indestructible infectious proteins that cause brain diseases in mammals

the direct manipulation of genes for practical purposes

uses living bacteria to do the work of producing many copies of the gene we want

dna molecules formed by combining dna segments from two different sources (ie, two different species)

small circles of dna that carry extra genes not found in the bacterial chromosome

they only ever cut where a specific code of dna is present, they are very specific. the area where these codes are present is called a restriction site

the fragments that result from the cutting of the restriction enzyme

produces many copies of a specific segment of dna without the use of live cells, just some enzymes of cells. it works in a three-step cycle - heating, cooling, and replication

gene cloning uses living cells, pcr does not. pcr uses the same enzymes and processes as gene cloning, it just happens outside of the cell

uses gel as a molecular sieve to spread out dna restriction fragments by their size through an electric current

dna fragments produced by restriction enzyme digestion of a dna molecule are sorted by gel electrophoresis

metagenomics is the sequencing of dna from a whole group of species collected from a single environmental sample. it eliminates the need to culture species separately in the lab

a stem cell is a relatively unspecialized cell that can reproduce itself indefinitely and differentiate into specialized cells

the systematic study of all proteins encoded by a genome and how they are regulated and interact in living organisms

generally, prokaryotic genomes are much smaller than eukaryotic species

a sequence that moves from one site to another in the genome. they are present in both eukaryotes and prokaryotes

transposons: move by means of a dna intermediate. they “cut and paste”

retrotransposons: move by means of an rna intermediate. they always move by “copy and paste”, and always result in an increased number of transposable elements in the genome

block

an enzyme that helps protect animals against bacterial infection

humans didn’t evolve from chimps, and neither did they evolve from us! we both evolved from a common ancestor

1. individuals in a population vary greatly in their traits (dog breeds / colors)

2. traits are inherited from parent to offspring

3. all species are capable of producing a great abundance of offspring

4. owing to a lack of food or other resources, many of these offspring don’t survive to reproduce

1. it is due to differences in their inherited traits that some individuals will survive longer and produce more offspring than others.

2. this unequal ability of individuals to survive and reproduce (fitness) will lead to the accumulation of favorable traits in the population over generations (natural selection for those traits)

random changes to the genetic code due to damage to the dna or errors in copying the dna

natural selection can only increase or decrease the prevalence of heritable traits in a population. it doesn’t create new alleles, it simply sorts the ones already present in the population.

the evolution of superficially similar (analogous) features in distantly related species. this convergence is evidence of adaptation to similar environmental conditions

• allopatric speciation is when a population forms a new species while geographically isolated from its parent population. mating is interrupted or reduced when a population is divided into geographically isolated subpopulations. (no contact = no mating)

• sympatric speciation is when a subset of a population forms a new species without geographic separation. the speciation takes place in geographically overlapping populations

essentially, it’s natural selection on features directly related to mating. (think the bigger the peacocks feathers are, the more attractive they are for the females, which means those genes are eventually going to be more prevalent)

natural selection acts on individuals, but only the population as a whole evolves.

microevolution: a change in allele frequencies in a population over generations

a graded change in a trait along a geographic axis

1- no mutations are occurring within the population

2- truly random mating is occurring

3- no natural selection

4- there is a very large population (large gene pool)

5- no gene flow (movement of alleles between populations)

1- genetic drift

2- gene flow

3- natural selection

describes how allele frequencies fluctuate unpredictably from one generation to the next

a sudden reduction in population size due to a change in the environment

1. genetic drigt is significant in small populations

2. genetic drift causes allele frequencies to change randomly

3. genetic drift can lead to a loss of genetic variation within populations

4. genetic drift can cause harmful alleles to become fixed

gene flow consists of the movement of alleles among populations. it tends to reduce variation among populations, as well as it can increase / decrease the fitness of a population.

essentially, makes the 2 populations more similar to each other. can be caused by mating with another population or the influx of a different gene pool

the contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals.

1. directional selection favors individuals at one end of the phenotypic range

2. disruptive selection favors individuals at both extremes of the phenotypic range

3. stabilizing selection favors intermediate variants and acts against extreme phenotypes

• intrasexual is the competition among individuals of one sec (usually males) for mates of the opposite sex

• intersexual selection occurs when individuals of one sex (usually females) are choosy in selecting their mates

  • male “showiness” due to mate choice can increase a male’s chances of attracting a female, while decreasing his chances of survival

occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population.

includes heterozygote advantage and frequency-dependent selection.

a trait that doesnt have to do with any reproductive organs, but still affects reproduction (a peacock’s tail feathers)

eons are broader, when you zoom into an eon, there are multiple eras

since rust only forms when there is O2 in the air, we found rust in the crust of the earth which indicated that oxygen had become part of the atmosphere

it’s important to note that oxygen is actually really bad for life, when it entered the atmosphere, it destroyed most of the live organisms at the time.

photosynthesis

refers to the sudden appearance of fossils resembling modern animal phyla in the cambrian period

the evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities

4.6 billion years old

prokaryotes, atmospheric oxygen, single-celled eukaryotes, multicellular eukaryotes, animals

the active science of describing biodiversity, includes the naming and ordered division into groups of organisms

a taxon is any group used in this classifying

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

in descending order ^

• homology is a similar trait due to a shared ancestry

• analogy is a superficial or misleading similarity

  • mimicry is an example of analogy

morphological homology refers to a structure found in two (or more) different species, but derived from a common ancestral structure

developmental homology compares their embryonic development.

contain species / lineages which are more closely related to each other than to any outside of the group. they share a most recent common anscestor

occurs when similar environmental pressures and natural selection produce similar (analogous) adaptations in organisms from different evolutionary lineages.

a species or a group of species that is closely related to the in-group, the various species being studied.

how far back in time you have to go for their common ancestor, not their horizontal proximity

gram-positive bacteria have simpler walls with a large amount of peptidoglycan

gram-negative bacteria have less peptidoglycan and an outer membrane that can be toxic

taxis

by means of flagella

movement of genes that occur between different species.

transformation: a prokaryotic cell can take up and incorporate foreign dna from the surrounding environment

transduction: the movement of genes between bacteria by bacteriophages

conjugation: genes are transferred from one prokaryotic cell to another. a donor cell attaches to a recipient by a plius, pulls it closer, and transfers dna

a piece of DNA that is required for the production of pili

cells containing the plasmid function as DNA donors during conjugation. the f factor is transferable during conjugation.