Science

Science # 2

2011-07-07T20:45:00.000-07:00

1. Analogous structure: Body parts that once differed in evolutionarily distant lineages but converged in structure and function as responses to similar environmental pressures.

2. Asteroid: Rockymetallic body, a few to 1,000 kilometers across, hurtling through space.

3. Comparative morphology: Scientific study of comparable body parts of adults or embryonic stages of major lineages.

4. Derived trait: A novel feature that evolved but once and is shared only by the descendants of the ancestral species in which it evolved.

5.
Fossil: Recognizable, physical evidence of an organism that lived in the distant past.

6. Fossilization: How fossils form. An organism or evidence of it gets buried in sediments or volcanic ash; water and dissolved inorganic compounds infiltrate it.

7. Geologic time scale: Time scale for the Earth's history with major subdivisions corresponding to mass extinctions. Now radiometrically dated.

8. Gondwana: Paleozoic supercontinent; with other land masses, it formed Pangea.

9. Half-life: The time it takes for half of a given quantity of any radioisotope to decay into a different, and less unstable, daughter isotope.

10. Homologous structure: comparable body parts that show underlying similarity even when they may differ in size, shape, or function; outcome of morphological divergence from a shared ancestor.

11. lineage: Line of descent.

12. Morphological convergence: . In response to similar environmental pressures over time, evolutionarily distant lineages evolve in similar ways and end up being alike in appearance, functions, or both.

13. Morphological divergence: Macro evolutionary pattern; genetically diverging lineages undergo change from body form of a common ancestor.

14. Pangea: Paleozoic supercontinent upon which the first terrestrial plants and animals evolved.

15. Plate tectonics theory: Theory that great slabs (plates) of the Earth's outer layer float on a hot,
plastic mantle.

16. Stratification: Stacked layers of sedimentary rock, built up by gradual deposition of volcanic ash, silt, and other materials over time.

17. Theory of uniformity: Early theory that the earth's surface changes in gradual, uniformly repetitive ways (major floods, earthquakes, and other infrequent catastrophes also occur every year and were not considered unusual).

18. Adaptive radiation: Macroevolutionary pattern; burst of genetic divergences from a lineage that gives rise to many species, each using a novel resource or a new (or newly vacated) habitat.

19. Adaptive zone: Minimum amount of energy required to get a specific reaction going, with or without the help of an enzyme.

Allopathic speciation: Speciation model. A physical barrier arises, separates populations or subpopulations of a species, ends gene flow, and favors divergences that end in speciation.

Anagenesis: Speciation pattern; changes in allele frequencies and morphology accumulate within an unbranched line of descent.

Archipelago: Island chain some distance away from a continent.

Biological species concept: Defines a species as one or more populations of individuals that are interbreeding under natural conditions, producing fertile offspring, and are isolated reproductively from other such populations.

Cladogenesis: Speciation pattern in which a lineage splits and isolated populations undergo genetic divergence.

Dosage compensation: Any mechanism that balances gene expression between the sexes during critical early stages of development.

Evolutionary tree: Treelike diagram; a branch point means divergence from a shared ancestor and branches signify separate lines of descent.

Extinction: Irrevocable loss of a species
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Gene flow: Micro evolutionary process; alleles enter and leave a population as an outcome of immigration and emigration, respectively.

Genetic divergence: Gradual accumulation of differences in gene pools of populations or subpopulations of a species after a geographic barrier arises and separates them; thereafter, microevolution occurs independently in each.

Gradual model of speciation: Idea that species arise by many small morphological changes that accumulate over great spans of time.

Hybrid zone: Where adjoining populations are interbreeding and producing hybrid offspring.

Mass extinction: Catastrophic event or phase in geologic time when entire families or other major groups are irrevocably lost.

Parapatric speciation: Idea that neighboring populations can become distinct species while maintaining contact along a common border.

Punctuation model of speciation: Idea that most morphological changes occur in a brief span when populations start to diverge; speciation is rapid, and the daughter species change little for the next 2-6 million years or so.

Reproductive isolating mechanism: Heritable feature of body form, functioning, or behavior that prevents interbreeding between two or more genetically divergent populations.

Speciation: The formation of a daughter species from a population or subpopulation of a parent species by way of microevolutionary processes.
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Species: One kind of organism. one or more natural populations in which individuals are interbreeding and are reproductively isolated from other such groups.

Sympatric speciation: A speciation event within the home range of an existing species, in the absence of a physical barrier. Such species may form instantaneously, as by polyploidy.

Vocabulary# 3

2011-07-07T20:44:00.001-07:00

angiosperm Flowering plant.

2. archaebacterium Member of the prokaryotic domain Archaebacteria

3.       Archean eon     Eon in which life arose

4.

big bang              Model for origin of universe.

5.

Cenozoic era The present era (65 mya to present).

6. crust, of Earth Outer zone of low-density rocks resting on the Earth's mantle.

7. dinosaur One of a fabulous group of reptiles that originated in the Triassic and became the dominant land vertebrates for 125 million years.

8. Ediacaran One of the species with a highly flattened body that arose in the precambrian.

9. endosymbiosis theory Continuing physical contact between two species, one of which lives and reproduces inside the other's body.

10. eubacterium Prokaryotic cell; has a nucleoid, but no nucleus, cytoplasm, or cell membrane; most have a cell wall, some encapsulated.

11. eukaryotic cell Cell having a nucleus and other membrane-bound organelles.

12. global broiling hypothesis Theory that an asteroid impact caused the K-T mass extinction by creating a colossal fireball.

13. gymnosperm Type of vascular plant in which seeds form on exposed surfaces of reproductive structures (e.g., on cone scales).

14. K-T asteroid impact theory A huge asteroid hit Earth at the K-T boundary; last dinosaurs perished during the mass extinction.

15. mantle Of mollusks, a tissue draped over the visceral mass. Of Earth, a zone of intermediatedensity rocks beneath the crust.

16. Mesozoic era An era (240-65 mya) of spectacular expansion in the range of global diversity.

17. Paleozoic era Era from Cambrian, Ordovician, Silurian, Devonian, Carboniferous, through the Permian (544 to 248 mya).

18. prokaryotic cell Archaebacterium or eubacterium; single-celled organism, most often walled;
.

19. Proterozoic eon Period from 2.5 billion to 570 million years ago; period during which eukaryotic cells arose.

20. protistan Has a nucleus, larger ribosomes, mitochondria, ER, Golgi bodies, chromosomes with numerous proteins, and cytoskeletal microtubules. Range in size from microscopic algae to giant kelps.

21. proto-cell Hypothetic cell-like stage between chemical evolution and the first living cell.
c

22. RNA world One model for prebiotic evolution in which RNA was the template for protein synthesis before the evolution of DNA.

23. stromatolite Fossilized mats of shallow-water microbial communities, mainly cyanobacteria, from Archean to precambrian.

Vocabulary # 4

2011-07-07T20:44:00.000-07:00

1. Adhering junction: Junction where a mass of anchored proteins help adjoining cells adhere.

2. Adipose tissue: A connective tissue having an abundance of fat-storing cells.

3. Blood :Fluid connective tissue of water, solutes, and formed elements (blood cells, platelets).

4. Bone tissue: Of vertebrate skeleton, a tissue of osteoblast secretions hardened with minerals.

5. Cardiac muscle tissue: A contractile tissue that is present only in the heart wall.

6. Cartilage: Connective tissue with solid, pliable intercellular material that resists compression.

7. Dense, irregular connective tissue: Animal tissue with fibroblasts, many asymmetrically positioned fibers in ground substance. In skin and some capsules around organs.

8. Dense, regular connective tissue: Animal tissue with rows of fibroblasts between parallel bundles of fibers. In tendons, elastic ligaments.

9. Ectoderm: The first-formed, outermost primary tissue layer of animal embryos; gives rise to nervous system tissues and integument's outer layer.

10. Endocrine gland: Ductless gland that secretes hormones, which the bloodstream distributes.

11. endoderm: Inner primary tissue layer of animal embryos; source of inner gut lining and derived organs.

12. Epithelium: Animal tissue that covers external surfaces and lines internal cavities and tubes. One surface is free and the other rests on a basement membrane.

13. Exocrine gland: Glandular structure that secretes products, usually through ducts or tubes, to a free epithelial surface.

14. Gap junction Cylindrical arrays of proteins in the plasma membrane that pair up as open channels for signals between adjoining cells.

15. Gland cell: A cell that secretes products unrelated to their own metabolism for use elsewhere

16. Homeostasis: State in which physical and chemical aspects of internal environment (blood, interstitial fluid) are being maintained within ranges suitable for cell activities.

17. Internal environment: Blood + interstitial fluid.

18. Loose connective tissue: Animal tissue with fibers, fibroblasts loosely arrayed in semifluid ground substance.

19. Mesoderm: Primary tissue layer of all large, complex animals; gives rise to many internal organs and part of the integument.

20. Nervous tissue: Connective tissue composed of neurons and often neuroglia.

21. Neuroglia: Collectively, cells that structurally and metabolically support neurons. They make up about half the volume of nervous tissue in vertebrates.

22. Neuron: Type of nerve cell; basic communication unit in most nervous systems.

23. Organ : Body structure with definite form and function that consists of more than one tissue.

24. Organ system: Organs interacting chemically, physically, or both in a common task.

25. Skeletal muscle tissue: Striated contractile tissue that is the functional partner of bone.

26. Smooth muscle tissue: Nonstriated contractile tissue found in soft internal organs.

27. Tight junction: Cell junction where strands of fibrous proteins oriented in parallel with a tissue's free surface collectively block leaks between the adjoining cells.

28. Tissue : Of multicelled organisms, a group of cells and intercellular substances that function together in one or more specialized tasks.

Vocabulary #1 ¬¬

2011-05-29T11:18:00.000-07:00

Allele :One of two or more molecular forms of a gene that arise by mutation and code for different versions of the same trait.

allele frequency :For a given gene locus, the relative abundances of each kind of allele among all the individuals of a population.

Antibiotic : Metabolic product of soil microbes that kills bacterial competitors for nutrients.

balanced polymorphism :Form of selection in which two or more alleles for a trait are being maintained in a population over time.

Biogeography: Scientific study of the world distribution of species.

Bottleneck :Severe reduction in the size of a population, brought about by intense selection pressure or a natural calamity.

Catastrophism: Idea that abrupt changes in the geologic or fossil record were divinely invoked.

comparative morphology :Scientific study of comparable body parts of adults or embryonic stages of major lineages.

directional selection: Mode of natural selection by which allele frequencies underlying a range of phenotypic variation shift in a consistent direction, in response to directional change or to new conditions in the environment.

disruptive selection Mode of natural selection by which the different forms of a trait at both ends of the range of variation are favored and intermediate forms are selected against.

Evolution: Genetic change in a line of descent. Outcome of microevolutionary events: gene mutation, natural selection, genetic drift, and gene flow.

Fitness :Increase in adaptation to environment, asbrought about by genetic change.

Fixation: Loss of all but one kind of allele at a gene locus for all individuals in a population.

Fossil :Recognizable, physical evidence of an organism that lived in the distant past.

founder effect: A form of bottlenecking. By chance alone, a few individuals that establish a new population have allele frequencies that differ from those of the original population.

gene flow :Microevolutionary process; alleles enter and leave a population as an outcome of immigration and emigration, respectively.

gene pool: All genotypes in a population.

genetic drift :Change in allele frequencies over the generations due to chance alone. Its effect is most pronounced in very small populations.

genetic equilibrium :In theory, a state in which a population is not evolving. Compare Hardy-Weinberg rule.

Hardy-Weinberg rule:Allele frequencies stay the same over the generations when there is no mutation, the population is infinitely large and isolated from other populations of the species, mating is random, and all individuals are reproducing equally and randomly.

Inbreeding :Nonrandom mating among close relatives that share many identical alleles.

lethal mutation :Mutation with drastic effects on phenotype; usually causes death.

Microevolution :Of a population, any change in allele frequencies resulting from mutation, genetic drift, gene flow, natural selection, or some combination of these.

mutation rate: Of a gene locus, the probability that a spontaneous mutation will occur during or between DNA replication cycles.

natural selection: Microevolutionary process; the outcome of differences in survival and reproduction among individuals that differ in details of heritable traits.

neutral mutation: A mutation with little or no effect on phenotype, so natural selection can't change its frequency in a population.

Polymorphism :The persistence of two or more qualitatively different forms of a trait (morphs) in a population.

Population : All individuals of the same species that are occupying a specified area.

sampling error: Use of a sample or subset of a population, an event, or some other aspect of nature for an experimental group that is not large enough to be representative of the whole.

sexual selection: A microevolutionary process; a type of selection that favors a trait giving an individual a competitive edge in attracting or keeping a mate (favors reproductive success).

stabilizing selection: Mode of natural selection by which intermediate phenotypes in the range of variation are favored and extremes at both ends are eliminated.

theory of uniformity: Early theory that the earth's surface changes in gradual, uniformly repetitive ways Has since been replaced by plate tectonics theory.

Vocabulary #3 ¬¬

2011-04-09T18:54:00.000-07:00

1.adenine:A purine; a nitrogen-containing base in certain nucleotides.

2. bacteriophage:Category of viruses that infect bacterial cells.

3. cloning: Making a genetically identical copy of DNA or of an organism.

4. cytosine:Pyrimidine; one of the nitrogen-containing bases in nucleotides.

5. deoxyribonucleic acid (DNA):Of cells and many viruses, the molecule of inheritance. H bonds join its two helically twisted nucleotide strands, one for synthesizing all of the enzymes and other proteins required to build and maintain cells

6. DNA ligase:Enzyme that seals new base-pairings during DNA replication.

7. DNA polymerase:Enzyme of replication and repair that assembles a new strand of DNA on a parent DNA template.

8. DNA repair:Enzyme-mediated process that fixes small-scale alterations in a DNA strand by restoring the original base sequence.

9.DNA replication :Any process by which a cell duplicates its DNA molecules before dividing.

10. guanine:Nitrogen-containing base in one of four nucleotide monomers of DNA or RNA.

11. nucleotide:Small organic compound with deoxyribose and aMonomer for adenosine phosphates, nucleotide coenzymes, and nucleic acids.

12. thymine:A nitrogen-containing base; one of the nucleotides in DNA .

13. x-ray diffraction image:Pattern that forms on film exposed to x-rays that have been directed at a molecule; reveals positions of atoms, not the molecular structure.

14. anticodon :Series of three nucleotide bases in tRNA; can base-pair with an mRNA codon.

15. base sequence:Sequential order of bases in a DNA or RNA strand.

16. base-pair substitution:One amino acid has replaced another during protein synthesis.

17. carcinogen :Any substance or agent that can trigger cancer.

18. codon: A code word for an amino acid in a polypeptide chain; a few codons also act as START or STOP signals for translation.

19. deletion:At cytological level, loss of a segment from a chromosome. At molecular level, loss of one to a few base pairs from a DNA molecule.

20. exon :One of the base sequences of an mRNA transcript that will become translated.

21. gene mutation: A small-scale change in the nucleotide sequence of a DNA molecule.

22. genetic code :The correspondence between nucleotide triplets in DNA and specific sequences of amino acids in a polypeptide chain; the basic language of protein synthesis in cells.

23. insertion :Insertion of one to a few bases into a DNA strand., a movable attachment of muscle to bone.

24. intron :A noncoding portion of a pre-mRNA transcript; excised before translation.

25. ionizing radiation :High-energy wavelengths.

26. mRNA (messenger RNA): A single strand of ribonucleotides transcribed from DNA, then translated into a polypeptide chain.

27. mutation rate:Of a gene locus, the probability that a spontaneous mutation will occur during or between DNA replication cycles.

Vocabulary #2 ¬¬

2011-03-26T12:47:00.001-07:00

abortion	spontaneous or induced expulsion of the embryo or fetus from uterus.

aneuploidy	Having one extra or one less chromosome to the parental number.
autosome	Any chromosome that is the same in males and females of the species.
crossing over	an interaction in which non-sister chromatids of a pair of homologous chromosomes break at corresponding sites and exchange segments.
deletion	At cytological level, loss of a segment from a chromosome.
disease	Outcome of infection mobilized fast enough and a pathogen's activities interfere with normal body functions.
double-blind study	investigators independently collect, then compare data.
duplication	Gene sequence repeated several to many hundreds or thousands of times. Even normal chromosomes have such sequences.
genetic abnormality	A rare or less common version of a heritable trait.
genetic disorder	Any inherited condition that causes mild to severe medical problems.
genetic recombination	any process that puts new genetic information into a DNA molecule.
homologous chromosome	Of cells with a diploid chromosome number, one of a pair of chromosomes identical in size, shape, and gene sequence. Nonidentical sex chromosomes (e.g., X and Y) also interact as homologues during meiosis.
in-vitro fertilization	Conception outside the body (''in glass'' petri dishes or test tubes).
independent assortment	each pair of homologous chromosomes are sorted before shipment to gametes independently of how the other pairs were sorted. Later modified to account for the disruptive effect of crossing over on linkages.
inversion	Part of a chromosome that became oriented in reverse, with no molecular loss.
karyotype	Preparation of metaphase chromosomes sorted by length, centromere location, other defining features.
linkage group	All genes on a chromosome.
mosaicism	Cells of same type express genes differently, so phenotypic differences emerge in same type of tissue. E.g., occurs by X chromosome inactivation in female mammals.
Non-disjunction	Failure of sister chromatids or a pair of homologous chromosomes to separate during meiosis or mitosis.
polyploidy	Having three or more of each type of chromosome in the nucleus of a eukaryotic cell at interphase.
reciprocal cross	A paired cross. In the first cross, one parent displays the trait of interest , the other parent displays it.
sex chromosome	A chromosome with genes that affect sexual traits. Depending on the species, somatic cells have one or two sex chromosomes of the same or different type (e.g., in mammals, XX females, XY males).
syndrome	A set of symptoms that may not individually be a telling clue but collectively , a genetic disorder or disease.
translocation	movement of a stretch of DNA to a new chromosomal location with no molecular loss. Of vascular plants, distribution of organic compounds by way of phloem.
X chromosome	A type of sex chromosome. An XX mammalian embryo becomes female; an XY pairing causes it to develop into a male.
Y chromosome	A type of sex chromosome. An XX mammalian embryo becomes female; an XY pairing causes it to develop into a male.

Vocabulary #1 ¬¬

2011-03-07T08:48:00.000-08:00

allele	two or more molecular that arise by mutation and code for different versions of the same trait.
codominance	In heterozygotes, simultaneous expression of a pair of nonidentical alleles that specify different phenotypes.
continuous variation	Of a population, a more or less continuous range of small differences in a given trait among its individuals.
dihybrid cross	An intercross between two F1 heterozygotes that are identical for two gene loci; the dihybrids are offspring of parents that bred true for different versions of two traits.
epistasis	Interaction among the products of two or more gene pairs.
F₁	The offspring of an initial genetic cross.
F₂	The offspring of parents who are the first filial generation from a genetic cross.
gene	Unit of information for a heritable trait, passed from parents to offspring.
genotype	Genetic constitution of an individual; a single gene pair or the sum total of an individual's genes.
heterozygous	Having a pair of nonidentical alleles at a gene locus (that is, on a pair of homologous.
homozygous dominant	Having a pair of dominant alleles at a gene locus.
homozygous recessive	Having a pair of recessive alleles at a gene locus .
hybrid offspring	Of a genetic cross, offspring having a pair of nonidentical alleles for a trait.
incomplete dominance	Condition in which one allele of a pair is not fully dominant; a heterozygous phenotype somewhere between both homozygous phenotypes emerges.
independent assortment	Mendelian theory that by the end of meiosis, each pair of homologous chromosomes are sorted before shipment to gametes independently of how the other pairs were sorted. Later modified to account for the disruptive effect of crossing over on linkages.
monohybrid cross	Intercross between two F₁ heterozygotes that are identical for one gene locus; offspring of two parents that breed true for different forms of a trait.
multiple allele system	Three or more slightly different molecular forms of a gene that occur among individuals of a population.
phenotype	Observable trait or an individual that arise from gene interactions and gene-environment interactions.
pleiotropy	Positive or negative effects on two or more traits of alleles at a single gene locus. Effects may or may not emerge
probability	The chance that each outcome of a given event will occur is proportional to the number of ways the outcome can be reached.
Punnett-square method	Construction of a simple diagram ,to predict probable outcomes of a genetic cross.
segregation	Sexually reproducing organisms inherit pairs of genes each pair are separated from each other at meiosis, and they end up in separate gametes.
testcross	Experimental cross to determine an individual of unknown genotype that shows dominance for homozygous dominant or heterozygous.
true-breeding lineage	Of sexually reproducing species, a lineage in which only one version of a trait appears over the generations in all parents and their offspring