Term
| What are the 4 different nitrogenous bases of a DNA molecule? |
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Definition
2 Pyrimidines = T and C (Thymine and Cytosine)
2 Purines = A and G (Adenosine and Guanine) |
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Term
| How do the 4 nitrogenous bases pair up? |
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Definition
T always attaches to A (2 hydrogen bonds)
G always attaches to C (3 hydrogen bonds)
*RNA has no T and uses U (Uracil) instead. So in RNA, U always attaches to A. |
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Term
| What is the structure of a DNA molecule? |
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Definition
| Double helix which gives the molecule the ability to self-replicate (unzips and copies) easily and gives a molecular explanation for genetic inheritance. |
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Term
| What does the DNA molecule consist of? |
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Definition
| DNA (and RNA) are nucleic acids made up of nucleotide monomers (sugar attached to a base). The DNA molecule consists of 2 sugar-phosphate backbones linked together with 4 different nitrogenous bases that form a connecting bridge similar to the rungs on a ladder. |
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Term
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Definition
| DNA = deoxyribonucleic acid |
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Term
| What is meant by "semi-conservative" model? |
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Definition
| Each new DNA molecule "conserves" a single parent strand. Each will have a parental strand and a daughter strand. |
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Term
| What is an Okazaki fragment? |
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Definition
| Okazaki fragments are the lagging strand in DNA replication. They are joined together by an enzyme called DNA Ligase. |
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Term
| What is meant by leading and lagging strands? |
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Definition
| A daughter DNA strand can only grow in the 5' - 3' direction. This means that one strand can be replicated continuously (the leading strand) and the other strand must be formed in fragments called Okazaki fragments (the lagging strand). |
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Term
| Why are there multiple origins of replication called "bubbles?" |
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Definition
| To shortens the overall time needed for replication to occur. |
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Term
| What are replication "bubbles?" |
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Definition
| Replication of a DNA molecule begins at sites called origins of replication. Replication then begins in both directions, creating replication "bubbles." The DNA molecule has multiple sites of replication that can start simultaneously. |
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Term
| DNA is ____________ into RNA. |
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Definition
transcribed
(same language - language of nucleotides) |
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Term
| RNA is ____________ into protein. |
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Definition
translated
(language of nucleotides to language of amino acids) |
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Term
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Definition
| Three nucleotides in mRNA that codes for a single amino acid or a start or stop command in the translation stage of protein synthesis. |
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Term
| Which directly influences the phenotype, DNA, RNA, or protein? |
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Definition
Protein
The presence and action of proteins determine the phenotype of an organism. |
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Term
| How many codons are there? |
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Definition
| 64 codons are possible (61 for amino acids and 3 stop codons). The start codon is always AUG (Methionine). |
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Term
| Does each codon code for a particular amino acid? |
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Definition
| Some amino acids have more than one possible codon (redundancy) but any codon for one amino acid does NOT code for any other amino acid (unambiguous). |
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Term
| Which has a linear sequence of codons rRNA, mRNA, or tRNA? |
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Definition
| mRNA has a linear sequence of codons. |
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Term
| What are sister chromatids? |
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Definition
| Sister chromatids are replicated chromosomes linked together at the centromere and eventually separated during mitosis and meiosis. |
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Term
| What are homologous chromosomes? |
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Definition
| HC are chromosomes that are the same in function and size. Species that are diploid have matching pairs of HCs; one member of each homologous pair is inherited from the male and the second from the female. They are the replicated copies of the same chromosome from different parents that get together and form a tetrad. They contain the same genes in the same locations. |
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Term
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Definition
| A mutation is a change in the nucleotide sequence of DNA. |
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Term
| In what ways can mutations occur? |
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Definition
Base substitutions - replacement of one nucleotide with another. Can be harmless or harmful depending on whether there is an amino acid change that alters the function of the protein.
Deletions or insertions - Alter the reading frame of the mRNA, so that nucleotides are grouped into different codons (everything is now read differently downstream of the mutation and causes a nonfunctional polypeptide to be produced). Can be more harmful. |
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Term
| What is a frame shift mutation? |
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Definition
| A frame shift mutation results when a base gets added or deleted to the mRNA strand. It will change the amino acid sequence from that point on, resulting in a very different and usually non-functioning protein. |
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Term
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Definition
| Gregor Mendel was an Augustinian monk who experimented with the breeding of pea plants. He brought the idea and understanding to evolution and inheritance. He formulated two laws: the law of segregation and the law of independent assortment. |
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Term
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Definition
| Heritable traits that parents pass in discrete units. They retain their integrity from generation to generation. |
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Term
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Definition
| One of the alternate forms of a single gene. Smooth or wrinkled pea pods or brown or blue eyes is an example. |
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Term
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Definition
| A physiological feature, bodily characteristic, or behavoir of an organism. Outward appearance ie short or tall, yellow or red flowers. |
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Term
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Definition
| The genetic makeup of an organism, including all the genes that lie along its chromosomes. AA = homozygous dominant; Aa = heterozygous; aa = homozygous recessive. |
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Term
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Definition
| Having two identical alleles of a gene for a given character (AA). |
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Term
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Definition
| Possessing two different alleles of a gene for a given character (Aa). |
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Term
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Definition
| Term used to designate an allele that is not expressed in the heterozygous condition. Represented by a lower case letter. Traits will be masked in the heterozygous condition and will only show in the phenotype if an individual is homozygous recessive. |
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Term
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Definition
| Term used to designate an allele that is expressed in the heterozygous condition. Represented by an upper case letter. These are traits that WILL BE expressed in the phenotype of a heterozygous individual. |
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Term
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Definition
| Plants that whenever they are self-fertilized the offspring produced have the same phenotype as the parental plant. |
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Term
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Definition
| A condition in which two alleles of a given gene have different phenotypic effects, with both effects manifesting in organisms that are heterozygous for the gene. For example, AB blood type shows codominance. |
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Term
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Definition
| A genetic condition in which the heterozygous phenotype is intermediate between either of the homozygous phenotypes. For example, CC = curly hair; cc = straight hair and Cc = wavy hair. Cc shows incomplete dominance. |
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Term
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Definition
| Sex-linked traits are contained on the sex chromosomes. Since (in humans and most animals) the y chromosome is very small and contains only genes which determine "maleness," nearly all known sex linked traits are carried on the x chromosome which is larger and known to contain genes for a variety of traits. |
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Term
| What is the law of segregation (Mendel's First Law)? |
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Definition
| Differing characters in organisms result from two genetic elements (alleles) that separate in gamete formation, such that each gamete (with equal probability) gets only one of the two alleles. |
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Term
| What is the law of independent assortment (Mendel's Second Law)? |
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Definition
| During gamete formation, unlinked or distantly linked segregating gene pairs assort independently of one another. |
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Term
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Definition
| Anytime you have more than 2 alleles. For example, the presense of three alleles A, B, and O shows multiple alleles in blood type AB. |
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Term
| At what level does evolution occur (individual, populations, or communities)? |
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Definition
Populations.
Individual organisms do not evolve; only populations and species can evolve. |
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Term
| In order for evolution to occur, what three factors must a trait have? |
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Definition
1) The trait must be variable
2) The trait must be heritable
3) There must be a selective advantage of one variation of the trait over another |
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Term
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Definition
A group of actually or potentially interbreeding natural populations that are reproductively isolated from other such populations.
A particular kind of organism. Members are genetically similar, possess similar anatomical characteristics, and can successfully interbreed (ie produce vialbe and fertile young). |
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Term
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Definition
All the members of a species that live in a defined geographic region at a given time.
An interbreeding group of a particular species generally inhabiting a certain geographic region. |
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Term
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Definition
The process through which traits that confer a reproductive advantage to individual organisms grow more common in populations of organisms over successive generations.
Natural selection = the mechanism for evolution. The superior ability of certain genetic variants to pass on their genes to the next generation. Natural selection is not providential (acts only on present circumstances; has no purpose or goals) and it cannot fashion perfect organisms. |
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Term
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Definition
| A modification in the form, physical functioning, or behavior of organisms in a population over generations in response to environmental change. Inherited traits that enhance survival and reproductive success. |
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Term
| What are some categories and examples of adaptation? |
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Definition
Behavioral - Birds migrate during the winter; bears hibernate
Structural - Booby bird has webbed feet to help with swimming
Biochemical - Pesticide resistance in insects |
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Term
| What is a selective agent? |
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Definition
| Any abiotic or biotic factor which can give a competitive edge to a particular genotype, enabling natural selection to occur. |
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Term
| What are some examples of selective agents? |
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Definition
Predation
Competition for food or mates
Disease
Environmental change |
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Term
| Why can inbreeding lead to diseases rarely seen in the general public? |
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Definition
| A rare recessive trait present only as a single allele in the ancestral generation (ie one parent is a carrier, but does not express the trait) can result in expression of the trait in generations subsequent to the consanguineous mating. |
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Term
| Why is predator/prey evolutionary interactions called an "arms race?" |
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Definition
| Predators and prey act on each other as significant agents of natural selection. Over time, predators evolve better weaponry while prey evolve better defenses. |
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Term
| What is sexual selection? |
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Definition
| A form of natural selection that produces differential reproductive success based on differential success in obtaining mating partners. Selection based on variation of secondary sexual traits or characteristics leading to the enhancement of sexual dimorphism. |
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Term
| Who drives sexual selection? |
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Definition
| Sexual selection is usually driven by females upon the males of a species, whereby the males with the biggest antlers or longest, brightest colored tails have a better chance of mating and passing on their genes to the next generation because females will chose to mate with them more frequently. |
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Term
| What is the difference between intrasexual and intersexual selection? Give some examples. |
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Definition
Intrasexual = within the same sex
Example: male antlers for fighting
Intersexual = between the sexes
Example: peacock tails |
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Term
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Definition
The rapid evolution of many species from a single species that has been introduced to a new environment.
The emergence of numerous species from a common ancestor introduced to an environment presenting a diversity of new opportunites and problems (example: Darwin's finches, ciclids in Lake Victoria) |
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Term
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Definition
| A structure that is shared in different organisms owing to inheritance from a common ancestor. They have a common origin and embryonic development. They may have similar or dissimilar functions (example: the forelimb of a dog and the wind of a bird). |
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Term
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Definition
| A structure found in different organisms that is similar in function and appearance but is not the result of shared ancestry. They have a similar function but were developed independently of each other (example: the wing of a bird and the wing of a butterfly). |
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Term
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Definition
| Leads to structures with a common function (analogous) but arose from different ancestry (example: Wings of a butterfly and wings of a bat. Both are used to fly but evolution is not related). |
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Term
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Definition
| Leads to homologous structures in different organisms with a shared ancestry (example: Flipper of a whale and the leg of a dog. Both are mammals with a common ancestor, but have evolved to function differently due to different environments). |
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Term
| What is a bottleneck effect? |
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Definition
| A change in allele frequencies in a population due to chance following a sharp reduction in the population's size. One of the factors that potentiates genetic drift. Sometimes a species may go through a catastrophic reduction in numbers, due to disease, habitat destruction, climate change. May permanently reduce the genetic diversity present within the species. |
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Term
| When was the Permian mass extinction and what % of life died out? |
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Definition
| The Permian extinction was 251 million years ago between the Paleozoic and Mesozoic eras. 96% of shallow water marine species died out and a huge number of terrestrial species also went extinct. |
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Term
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Definition
| Pertaining to nonliving things. |
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Term
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Definition
| Pertaining to living things. |
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Term
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Definition
| The retention of juvenile features in the adult (greek: paedo = child, morphosis = shaping). |
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Term
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Definition
| Master control genes that determine basic features such as where pairs of wings or legs develop on a fruit fly. Turning on or off these genes can sometimes lead to significant differences in development (example: development of terrestrial vertebrates from fishes). |
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Term
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Definition
| In evolution, the type of natural selection in which intermediate forms (phenotypes) of a given character are favored over either extreme (acts against extreme phenotypes). This process tends to maintain average traits for a character. |
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Term
| When is stabilizing selection common? |
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Definition
| Stabilizing selection is very common when environments are stable. |
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Term
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Definition
| In evoltuion, the type of natural selection that moves a character toward one of its extremes. Acts against individuals at one of the phenotypic extremes. |
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Term
| When is directional selection common? |
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Definition
| Directional selection is common during periods of environmental change, or when a population migrates to a new and different habitat. |
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Term
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Definition
| In evolution, the type of natural selection that moves a character toward BOTH of its extremes (favors individuals at both extremes of the phenotypic range), operating against individuals that are average for that character. Less common in nature than stabilizing and directional selection. |
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Term
| Where does disruptive selection occur? |
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Definition
| Disruptive selection may occur in patchy habitats. |
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Term
| What factors can cause evolutionary change in a population? |
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Definition
Mutation - A rare change in the DNA of genes that ultimately creates genetic diversity
Mutagen - A chemical or physical agent that interacts with DNA and causes a mutation
Immigration - The inflow of genes or individuals into a population
Migration - The outflow of individuals and genes from a population |
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Term
| How can new species arise? |
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Definition
Adaptive radiation - The emergence of numerous species from a common ancestor introduced to an environment presenting a diversity of new opportunites or problems
Allopatric speciation - Populations that get separated by a geographic barrier, leading to reproductive isolation
Sympatric speciation - Reproductive isolation can occur without geographic separation (mutation effects - genetic compatibility and behavioral sex selection)
Hybridization - two species which are closely related can sometimes interbreed, resulting in a hybrid (sometimes sterile ie the mule). |
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Term
| What is punctuated equilibrium? |
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Definition
| Punctuated equilibrium is a term coined by paleontologists Stephen Jay Gould and Niles Eldrige that describes how a species may go unchanged for very long periods of time (equilibria) then suddenly evolve rapidly into two or more lineages. |
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Term
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Definition
| Gradualism describes how species change over long periods of time continuously. Change is slow, constant, and consistant. |
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Term
| How old are the oldest fossils of life on earth? |
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Definition
| The earliest evidence of life are stromatalites (photosynthetic prokaryotes) and dates to 3.5 billion years ago. |
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Term
| When did the colonization of land occur? |
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Definition
| Fossil evidence of photosynthetic prokaryotes lived in damp terrestrial environments about 1 billion years ago but multicellular fungi, plants, and animals colonized about 500 million years ago. |
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Term
| Carbon 14 can be used to date fossils up to what age? |
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Definition
| 75,000 years old (young fossils) |
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Term
| Potassium 40 can be used to date fossils up to what age? |
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Definition
| Can date rocks 100s of millions of years old. |
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Term
| When was the Cretaceous extinction? |
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Definition
| The Cretaceous extinction occured 65 million years ago. |
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Term
| What were the possible causes of the Permian extinction? |
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Definition
| Extreme vulcanism in Siberia released CO2, warmed global climate, slowed mixing of ocean water, and reduced O2 availablity in the ocean. Also, the oceans may have become more acidic from dissolved CO2, causing shells to dissolve and not be able to form. |
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Term
| What were the possible causes of the Cretaceous extinction? |
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Definition
| Likely caused by a large asteroid that struck the Earth, blocking light and disrupting the global climate. |
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Term
| What are the possible causes of extinctions in general? |
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Definition
| Extinctions are probably due to several factors including climate change, continental drift, changes in food supply, disease, and more recently, human impacts. |
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Term
| Are most mutations beneficial? |
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Definition
| Most mutations are either neutral or harmful, but some can be beneficial. |
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Term
| Is the evolution of new species goal directed? |
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Definition
| No, those with novel features that enhance survival and reporduction are the ones that leave the most offspring, so adaptive traits survive, nonadaptive ones go extinct. |
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Term
| What is the hierarchal order of taxonomy? |
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Definition
Kingdom
Phylum (Division for plants)
Class
Order
Family
Genus
Species
Think: "King Phillip Cried "'Oh For Goodness Sake'" |
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Term
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Definition
| Polymerase Chain Reaction - A technique for generating many copies of a DNA sequence from a small starting sample. It amplifies a specific segment of a DNA molecule. |
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Term
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Definition
| Restriction Fragment Length Polymorphism is a variation in the size of DNA fragments due to a SNP (Single Nucleotide Polymorphism) that alters a restriction site. RFLP analysis involves comparison of sizes of restriction fragments by gel electrophoresis. |
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Term
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Definition
| Single Nucleotide Polymorphism is a variation at one base pair within a coding or noncoding sequence (example: AATCGCGGAC vs AATCTCGGAC). |
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Term
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Definition
| Gel electrophoresis separates DNA molecules based on size. Shorter DNA fragments move through the gel pores more quickly and travel farther through the gel than larger fragments. |
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Term
| How is DNA sorted by gel electrophoresis? |
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Definition
-DNA sample is placed at one end of a porous gel
-Current is applied and DNA molecules move from the negative electrode toward the positive electrode
-Shorter DNA fragments move through the gel pores more quickly and travel farther through the gel
-DNA fragments appear as bands, visualized through staining or detecting radioactivity or fluorescence
-Each band is a collection of DNA molecules of the same length |
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Term
| What percentage of human DNA is noncoding for proteins? |
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Definition
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Term
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Definition
| Vaccines are a harmless version of proteins from the surface of an infectious agent which stimulate an immune response by injection. |
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Term
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Definition
| Two or more segments of DNA that have been combined by humans into a sequence that does not exist in nature. |
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Term
| What are the benefits and possible problems assoiciated with genetically engineered organisms? |
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Definition
Benefits - Pest resistance, herbicide resistance (Monsanto & round-up), increased yeild, increased nutritional value, increased hardiness (drought, flood, etc).
Concerns - Can introduce allergens into the food supply, may spread genes to closely related organisms creating hybrids. |
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Term
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Definition
| DNA from different sources are combined into one organism, not into one molecule. |
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Term
| How can genomic sequencing aid in medicine and evolutionary studies? |
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Definition
| In medicine it has created therapeutic hormones (insulin, HGH, etc), vaccines, and helps with diagnosis and treatment of disease (testing for inherited diseases, detects infections agents such as HIV). |
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Term
| Approximately what percentage of the human genome is identical to that of chimpanzees? |
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Definition
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