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Biology ICS

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Click on the letter of the topic you are interested in, or use the "find on page option" from your browser to locate specific terms.


A

 

Abiotic: Nonliving

Acetyl CoA: Acetyl coenzyme A; the entry compound for the citric acid cycle in cellular respiration, formed from a fragment of pyruvate attached to a coenzyme.

Acid: A substance that increases the hydrogen ion concentration of a solution

Actin: A globular protein that links into chains, two of which twist helically about each other, forming micro filaments in muscle and other contractile elements in cells.

Active Site: The specific portion of an enzyme that attaches to the substrate by means of weak chemical bonds.

Active Transport: The movement of a substance across a biological membrane against its concentration or electrochemical gradient with the help of energy input and specific transport proteins.

Adaptive Radiation: The emergence of numerous species from a common ancestor introduced into an environment that presents a diversity of new opportunities and problems.

Aerobic: Containing oxygen; referring to an organism, environment, or cellular process that requires oxygen.

Alcohol fermentation: The conversion of pyruvate to carbon dioxide and ethyl alcohol.

Alleles: Alternative versions of an gene that produce distinguishable phenotypic effects.

Allopathic Speciation: A mode of speciation induced when an ancestral population becomes segregated by a geographic barrier or is itself divided into two or more geographically isolated subpopulations.

Amino acid: An organic molecule possessing both carboxyl and amino groups. Amino acids serve as the monomers of proteins.

Anaphase: The fourth stage of mitosis, in which the chromatids of each chromosome have separated and the daughter chromosomes are moving to the poles of the cell.

Adenine - Nucleotide Base


B

 

Bacteria: One of two prokaryotic domains, the other being Archaea

Bacteriophage: A virus that infects bacteria; also called a phage.

Barr body: A dense object lying along the inside of the nuclear envelope in female mammalian cells, representing an inactivated X chromosome.

Base: Substance that reduces the hydrogen ion concentration of a solution.

Biology: The study of life.

Biotechnology: The manipulation of living organisms or their components to produce useful products.

Bottleneck Effect: Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.

 

C

 

Calvin Cycle: The second of two major stages in photosynthesis (following the light reactions), involving atmospheric carbon dioxide fixation and reduction of the fixed carbon into carbohydrate.

Carbohydrate: A sugar (monosaccharide) or one of its dimers (disaccharides) or polymer (polysaccharides).

Carbon Fixation: The incorporation of carbon from carbon dioxide into an organic compound by an autotrophic organism (a plant, another photosynthetic organism, or a chemoautotrophic prokaryote).

Cell: Life's fundamental unit of structure and function

Cell Cycle: An ordered sequence of events in the life of a eukarytoic cell, from its origin in the division of a parent cell until its own division into two.

Cell Division: The reproduction of cells.

Cellular Respiration: The most prevalent and efficient catabolic pathway for the production of ATP, in which oxygen is consumed as a reactant along with the organic fuel.

Cellulose: A structural polysaccharide of cell wall. Ex) Tree bark

Cell Wall: A protective layer external to the plasma membrane in plant cells, prokaryotes, fungi, and some protists. In plant cells, the wall is formed of cellulose fibers embedded in a polysaccharide-protein matrix.

Centriole: A structure in an animal cell composed of cylinders of microtuble triplets arranged in a 9 +0 pattern. An animal cell usually has a pair of centrioles involved in cell division.

Centromere: The centralized region joining two sister chromatids.

Central Dogma: The process from the DNA template to a RNA copy and then then assembled into a protein.

 


D

 

Denaturation: In proteins, a process in which a protein unravels and loses is native conformation thereby becoming biologically inactive. In DNA, the separation of the two strands of the double helix. Denaturation occurs under extreme conditions of pH, salt concentration, and temperature.

Deoxyribonucleic Acid: A double-stranded, helical nucleic acid molecule capable of replicating and determining the inherited structure of a cell's proteins.

Diffusion: The spontaneous tendency of a substance to move down its concentration gradient from a more concentrated to a less concentrated area.

Diploid Cell: A cell containing two sets of chromosomes (2n), one set inherited from each parent.

Directional Selection: Natural Selection that favors individuals at one end of the phenotypic range.

Disruptive Selection: Natural Selection that favors individuals on both extremes of a phenotypic range over intermediate range.

DNA Fingerprint: An individual's unique collection of DNA restriction fragments, detected by electrophoresis and nucleic acid probes.

DNA Polymerase: An enzyme that catalyzes the elongation of new DNA at a replication fork by the addition of nucleotides to the existing chain.

Dominant Allele: An allele that is fully expressed in the phenotype of a heterozygote.

 

 


E

 

Ecology: The study of how organisms interact with their environment.

Electromagnetic Spectrum: The entire spectrum of radiation ranging in wavelength from less than a nanometer to more than a kilometer.

Electron: A subatomic particle with a single negative charge. One or more electrons move around the nucleus of an atom.

Element: Any substance that cannot be broken down to any other substance

Embryo: New developing individual

Emigration: The movement of individuals out of a population

Energy: The capacity to do work (to move matter against an opposing force).

Evolution: All the changes that have transformed life on Earth from its earliest beginnings to the diversity that characterizes it today.

 


F

 

F1 Generation: The first filial, or hybrid offspring in a series of genetic crosses.

F2 Generation: Offspring resulting from interbreeding of the hybrid F1 generation.

Fatty Acid: A long carbon chain carboxylic acid. Fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form fat.

Fermentation: A catabolic processes that makes a limited amount of ATP from glucose without an electron transport chain and that produces a characteristics end product, such as ethyl alcohol or lactic acid.

Fluid Mosaic Model: The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of individual protein molecules drifting laterally in a fluid bilayer of phospholipids.

Founder effect: Genetic drift that occurs when a few individuals become isolated from a larger population, with the result that the new population's gene pool is not reflective of the original population.

Frameshift mutation: A mutation occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper groupings of the following nucleotides into codons.

 


G

 

Gamete: A haploid cell, such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.

Gametogenesis: The process by which gametes are produced in the mammalian body.

Gel electrophoresis: The separation of nucleic acids or proteins, on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel.

Gene: A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses)

Gene Flow: Genetic additions to or subtractions from a population resulting from the movement of fertile individuals or gametes.

Gene Pool: The total aggregate of genes in a population at any one time.

Genetic Drift: Unpredictable fluctuations in allele frequencies from one generation to the next because of a population's finite size.

Genetic Engineering: The direct manipulation of genes for practical purposes.

Genetic Map: An ordered list of genetic loci (genes or other genetic markers) along a chromosome.

Genetics: The scientific study of heredity and hereditary variation.

Genotype: The genetic makeup, or set of alleles, of an organism.

Golgi Apparatus: An organelle in eukaryotic cells consisting of stack so flat membranous sacs that modify store, and route products of the endoplasmic reticulum.

 


H

 

Haploid Cell: A cell containing only one set of chromosomes (n)

Helicase: An enzyme that untwists the double helix of DNA at the replication forks.

Heredity: The transmission of traist from one generation to the next.

Heterozygous: Having two different alleles for a given gene.

Homeostasis: The steady stae physiological condition fo the body.

Homologous Chromosomes: Chromosomes pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One homologous chromsome is inherited from the organisms's father, the other from the mother.

Homozygous: Having two identical alleles for a given gene.

Hybridization: In genetics, the mating, or crossing, of two true-breeding varieties.

Hydrophilic: Having an affinity for water.

Hydorphobic: Having an aversion towater; tending to calesece and from droplets in water.

Hypothesis: A tentative answer to a well-framed question.

 

 

I

Immigration: The influx of new individuals from other areas

Incomplete Dominance: The situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele.

Insulin: A hormone secreted by pancreatic beta cells that lowers blood glucose levels. It promotes the uptake of glucose by most body cells and the synthesis and storage of glycogen in the liver and also stimulates protein and fast synthesis.

Interphase: The period in the cell cycle when the cell is not dividing. During interphase, cellular metabolic activity is high, chromosomes and organelles are duplicated, and cell size may increase. Interpahse accounts for 90% of the cell cycle.

Intron: A noncoding, intervening sequnce within a eukaryotic gene.

Ion: An atom that has gained or lost electrons, thus acquiring a charge.


J

 

Joule: A unit of enegy: 1J: = 0.239 cal' 1 cal = 4.184J.


K

Karyotype: A display of the chromosome pairs of a cell arranged by size and shape.

 


L

 

Law of independent Assortment: Mendel's second law,stating that each pair of alleles segregates independently during gamete formation; applies when genes for two characters are located on different pairs of homologous chromosomes.

Law of Segregation: Mendel's first law,stating that each allele in a pair separates into a different gamete druing gamete formation.

Light Reactions: The steps inphotosynthesis that occur on the thylakoid membranes of the chloroplast and that convert solar energy to chemical energy of ATP and NADPH, evolgin oxygen in the process.

Linkage Map: A genetic map based on the frequencies of recombination between markers during crossing over of homologus chromosomes

Lipid: One of a family of compounds including fats, phospholipds, ans steroids, that are insoludble in water.

Locus: (plural, loci) A specific place along the length of a chromsomes whre a given gene is located.

Longitudinal Waves: The disturbance in longitudinal waves is parallel to the direction of propagation and causes compression and expansion (rarefaction) in the medium carrying the wave. Examples include P-type earthquake waves and sound waves also known as acoustic waves. Animation courtesy of Dr. Dan Russell, Kettering University.

Lysosome: A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of eukaryotic cells.


M

Macromolecules: organic compounds including carbohydrates, proteins, lipids, and nucleic acids.

Mass number: The sum of the number of protons and neurtrons in an atom's nucleus.

Matter: Anything that takes up space and has mass.

Meiosis: A two-stage type of celldivdision in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.

Meiosis I: The first division of a two-stage process of cell division in sexaully reproducing oraganisms that results in cells with half the crhomosome number of the original cell.

Meiosis II: The second division of a two-stage process of cell division in sexaully reproducing oraganisms that results in cells with half the crhomosome number of the original cell.

Messenger RNA (mRNA): A type of RNA, synthesiszed from DNA, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein.

Metaphase: The third stage of mitosis, in which the spindle is complete and the chromosomes, attached to microtubules at their kinetochores, are all aligned at the metaphase plate.

Microevolution: Evolutionary change below the species level; change in the gentic makeup of a population from generation to generation.

Mitochondria: an organelle in eukaryotic cells that serves as teh site of cellular respriation.

Mitosis: A process of nuclear division in eukaryotic cells conventionally divided into four stages: prophase, metaphase, anaphase, and telophase. Mitosis conserves chromsoem number by equally allocating replciated chromosomes to each of the daughter nuclei.

Molecule: Two or more atoms held together by covalent bonds.

Monohybrid: An organism that is heterozygous with respect to asingle gene of interest. All the offspring from a cross between parents homozygous for different alleles are monohybrids. For example, parents of genotypes AA and aa produce a monohybrid of genotype Aa.

Mutation: A change in the DNA of a gene, ultimately crating genetic diversity.


N

 

Natural Selection: Differential success in the reproduction of different phenotypes resluting from the interaction of organisms with their environment. Evolution occurs when natural selction causes changes in relative frequencies of alleles in the gene pool.

Nucleic Acid: A polymer consisting of many nucleotide monomers; serves as a blueprint for proteins and, throguh the actions of proteins, for all cellular activities. Teh two types are DNA and RNA.

Nucleotide: The building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to anitrogenous base and a phosphate group.

Nucleus: The chromosome-containing organelle of a eukaryotic cell.

 

 


O

Oogenesis: The process in the ovary that results in the production of female gametes.

Organelle: One fo several formed bodies with sepcialized functions, suspended in the cytoplasm of eukaryotic cells.

Osmosis: The diffusion of water across a slectively permeable membrane.


P

Passive Transport: The diffusion of a substance across a biological membrane.

Pedigree: A diagram of a family tree showing the occurence of heritable characers in parents and offspring over multiple generations.

Pepsin: An enzyme present in gastric juice that begins the hydrolysis of proteins.

pH: A measure of hygrogen ion concentration equal to -log [H+] and ranging in value from 0 to 14.

Phenotype: The physical and physiological traits fo an oragnism, which are determined by its genetic makeup.

Phylogeny: The evolutionary history of a species or group of related species.

Point mutation: A change in gene at a single nucleotide pair.

Protein: A three-dimensional biological polymer constructed from a set of 20 different monomers called amino acids.

Punnett Square: A diagram used in teh study of inheritance to show the resluts of random fertilization in genetic crosses.

 


Q

 


R

Recessive Allele: An allele whose phenotypic effect is not observed in a hterozygote

Recombinant DNA: A DNA molecule made in vitro with segments from different sources.

Ribosome: A cell organelle constructed in the nucleolus and functioning as the site of protein synthesis in the cytoplas; consists of rRNA and protein moleucles, which make up two subunits.

 


S

 

Sex-Linked Gene: A gene located on a sex chromosome.

Sexual Selection: Natural Selection for mating success.

Sickle Cell disease: A human genetic disease caused by a recessive allele that results in the substitituion of a single amino acid in the hemoglboin protein' characterized by deformed red blood cells that can lead to numerous symptoms.

Smooth ER: That portion of the endoplasmic reticulum that is free of ribosomes

Species: A group whose members possess similar anatomical characteristics and have the ability to interbreed.

Speed of light: The speed at which light travels withing a vaccum. 300,000,000 m/s or 186 miles/sec


T

 

Tay-Sachs disease: A human genetic disease caused by a recessive allele for a dysfunctional enzyme, leading to accumulation of certain lipids in the brain. Seizures blindness, and degeneration of motor and mental performance usually become manifest a few months after birth.

Telophase: The fifth and final stage of mitosis, in which daughter nuclei are forming and cytokinesis has typically begun.

Testcross: Breeding of an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. The ratio of phenotypes in the offspring determines the unknown genotype.

Testis: The male reproductive organ, or gonad, in which sperm and reproductive hormones are produced.

Theory: An explanation that is broad in scope, generates new hypotheses, and is supported by a large body of evidence.

Tissue: An integrated group of cells with a common function, structure, or both.

Trait: Any detectable variation in a genetic character.

Transcription: The synthesis of RNA on a DNA template.

Translation: The synthesis of a polypeptide using the genetic information encoded in an mRNA molecule. There is a change of "language" from nucleotides to amino acids.

 

 

Transverse Wave: The disturbance in transverse waves is perpendicular to the direction of propagation of the wave. Example include S-type earthquake waves and waves from the electromagnetic spectrum. Animation courtesy of Dr. Dan Russell, Kettering University.


U

 


V

 

Valence electron: An electron in the outermost electron shell.

Valence Shell: The outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom.

Vesicle: A sac made of membrane inside of cells


W

 

Wavelength: The distance between crests of waves, such as those of the electromagnetic spectrum.


X

 


Y

 


Z

 

Zygote: The diploid product of the union of haploid gametes in conception; a fertilized egg.