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41 Cards in this Set
- Front
- Back
Aminoacyl-tRNA Synthetase |
Any of a group of enzymes that attach specific amino acids to the correct tRNA during the tRNA-charging reaction. Each of the 20 amino acids has a corresponding enzyme. |
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Amniocentesis |
Indirect examination of a fetus by tests on cultures grown from fetal cells obtained from a sample of the amniotic fluid or tests on the fluid itself. |
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Amnion |
The innermost of the extraembryonic membranes; the amnion forms a fluid-filled sac around the embryo in amniotic eggs. |
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Amniote |
A vertebrate that produces an egg surrounded by four membranes, one of which is the amnion; amniote groups are the reptiles, birds, and mammals. |
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Amniotic egg |
An egg that is isolated and protected from the environment by a more or less impervious shell during the period of its development and that is completely self-sufficient, requiring only oxygen. |
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Ampulla |
In echinoderms, a muscular sac at the base of a tube foot contracts to extend the tube foot. |
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Amyloplast |
A plant organelle called a plastid that specializes in storing starch. |
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Anabolism |
The biosynthetic or constructive part of metabolism; those chemical reactions involved in biosynthesis. |
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Anaerobic |
Any process that can occur without oxygen, such as anaerobic fermentation or H2S photosynthesis. |
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Anaerobic respiration |
The use of electron transport to generate a proton gradient for chemiosmotic synthesis of ATP using a final electron acceptor other than oxygen. |
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Analogous |
Structures that are similar in function but different in evolutionary origin, such as the wing of a bat and the wing of a butterfly. |
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Anaphase |
In mitosis and meiosis 2, the stage initiated by the separation of sister chromatids, during which the daughter chromosomes move to opposite poles of the cell; in meiosis 1, marked by separation of replicated homologous chromosomes. |
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Anaphase-promoting complex (APC) |
A protein complex that triggers anaphase; it initiates a series of reactions that ultimately degrades cohesin, the protein complex that holds the sister chromatids together. The sister chromatids are them released and move toward opposite poles in the cell. |
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Anchoring junction |
A type of cell junction that mechanically attaches the cytoskeleton of a cell to the cytoskeletons of adjacent cells or to the extracellular matrix. |
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Androecium |
The floral whorl that comprises the stamens. |
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Aneuploidy |
The condition in an organism whose cells have lost or gained a chromosome; down syndrome, which results from an extra copy of human chromosome 21, is an example of aneuploidy in humans. |
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Angiosperms |
The flowering plants, one of five phyla of seed plants. In angiosperms, the ovules at the time of pollination are completely enclosed by tissues. |
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Animal pole |
In fish and other aquatic vertebrates with asymmetrical yolk distribution in their eggs, the hemisphere of the blastula comprising cells relatively poor in yolk. |
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Anion |
A negatively charged ion. |
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Annotation |
In genomics, the process of identifying and making note of "landmarks" in a DNA sequence to assist with recognition of coding and transcribed regions. |
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Anonymous markers |
Genetic markers in a genome that do not cause a detectable phenotype, but that can be detected using molecular techniques. |
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Antenna complex |
A complex of hundreds of pigment molecules in a photosystem that collects photons and feeds the light energy to a reaction center. |
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Anther |
In angiosperm flowers, the pollen-bearing portion of a stamen. |
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Antheridium, plural: antheridia |
A sperm producing organ. |
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Anthropoid |
Any member of the mammalian group consisting of monkeys, apes, and humans. |
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Antibody |
A protein called immunoglobulin that is produced by lymphocytes in response to a foreign substance (antigen) and released into the bloodstream. |
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Anticodon |
The three-nucleotide sequence at the end of a transfer RNA molecule that is complimentary to, and base-pairs with, an amino-acid-specifying codon in messenger RNA. |
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Antigen |
A foreign substance, usually a protein or polysaccharide, that stimulates an immune response. |
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Antiporter |
A carrier protein in a cell's membrane that transports two molecules in opposite directions across the membrane. |
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Anus |
The terminal opening of the gut; the solid residues of digestion are eliminated through the anus. |
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Aorta |
The major artery of vertebrate systemic blood circulation; in mammals, Carrie's oxygenated blood away from the heart to all regions of the body except the lungs. |
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Apical meristem |
In vascular plants, the growing point at the tip of the root or stem. |
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Apoplast route |
In plant roots, the pathway for movement of water and minerals that leads through cell walls and between cells. |
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Apoptosis |
A process of programmed cell death, in which dying cells shrivel and shrink; used in all animal cell development to produce planned and orderly elimination of cells not destined to be present in the final tissue. |
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Aposematic coloration |
An ecological strategy of some organisms that "advertise" their poisonous nature by the use of bright colors. |
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Aquaporin |
A membrane channel that allows water to cross the membrane more easily than by diffusion through the membrane. |
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Aquifers |
Permeable, saturated, underground layers of rock; sand, and gravel, which serve as reservoirs for groundwater. |
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Archegonium (plural: archegonia) |
The multicellular egg-producing organ in gametophytes and some vascular plants. |
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Archenteron |
The principal cavity of a vertebrate embryo in the gestural stage; lined with endoderm, it opens up to the outside and represents the future digestive cavity. |
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Arteriole |
A smaller artery, leading from the arteries to the capillaries. |
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Artificial selection |
Change in the genetic structure of populations to the selective breeding by humans. Many domestic animal breeds and crop varieties have been produced through artificial selection. |