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Definition
| structures contained within cells, surrounded by a membrane. there are many different types, and each performs specific functions. |
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Definition
| an organelle found in all eukaryotic cells. the nucleus contains chromosomes (nuclear DNA). |
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| structures made up of two or more atoms. molecules can combine with other molecules to form more complex structures. |
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Term
| deoxyribonucleic acid (DNA) |
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Definition
| the double-stranded molecule that contains the genetic code. DNA is a main component of chromosomes. |
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Definition
| a molecule that is similar in structure to DNA. there are several kinds of RNA, and many are single-stranded. three forms of single-stranded RNA are essential to protein synthesis. messenger RNA (mRNA) transfer RNA (tRNA) and ribosomal RNA (rRNA). |
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| the portion of the cell contained within the cell membrane, excluding the nucleus. the cytoplasm consists of a semifluid material and contains numerous structures involved with cell function. |
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| three-dimensional molecules that serve a wide variety of functions through their ability to find to other molecules. |
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| the assembly of chains of amino acids into functional protein molecules. DNA directs the process. |
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| (sing. mitochondrion) structures contained within the cytoplasm of eukaryotic cells that convert energy, derived from nutrients, into a form that is used by the cell. |
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Definition
| structures composed of a form of RNA called ribosomal RNA (rRNA) and protein. ribosomes are found in the cell's cytoplasm and are essential to the manufacture of proteins. |
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| mitochondrial RNA (mtRNA) |
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Definition
| DNA found in the mitochondria. is inherited only from the mother. |
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Definition
| basically, all the cells in the body except those involved with reproduction. |
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Definition
| reproductive cells (eggs and sperm in animals) developed from precursor cells in ovaries and testes. |
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Definition
| a cell formed by the union of an egg and a sperm cell. it contains the full complement of chromosomes (in humans, 46) and has the potential of developing into an entire organism. |
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Definition
| basic units of the DNA molecule, composed of a sugar, a phosphate, and one of four DNA bases. |
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Definition
| the duplicate. the DNA molecule is able to make copies of itself. |
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| specialized proteins that initiate and direct chemical reactions in the body. |
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Term
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Definition
| referring to the fact that DNA bases form base pairs in a precise manner. for example, adenine can bond only to thymine. these two bases are said to be complementary because one requires the other to form a complete DNA base pair. |
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Definition
| a protein molecule that occurs in red blood cells and binds to oxygen molecules. |
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Definition
| substances (usually proteins) that are produced by specialized cells and that travel to other parts of the body, where they influence chemical eactions and regulate various cellular functions. |
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Term
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Definition
| small molecules that are the components of proteins. |
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Definition
| a form of RNA that is assembled on a sequence of DNA bases. it carries the DNA code to the ribosome during protein synthesis. |
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Definition
| triplets of messenger RNA bases that code for specific amino acids during protein synthesis. |
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Definition
| the type of RNA that binds to specific amino acids and transports them to the ribosome during protein synthesis. |
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Term
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Definition
| a change in DNA; can refer to changes in DNA bases (specifically called point mutations) and also to changes in chromosome number or structure. |
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Term
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Definition
| a sequence of DNA baes that specifies the order of amino acids in an entire protein, a portion of a protein, or any functional product. a gene may be made up of hundreds or thousands of DNA bases organized into coding and noncoding segments. (coding sequences produce proteins; noncoding sequences don't.) |
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Definition
| an evolutionary ancient family of regulatory genes that directs the development of the overall body plan and the segmentation of body tissues; also called homeobox or Hex genes. |
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Definition
| discrete structures composed of DNA and protein found only in the nuclei of cells. chromosomes are only visile under magnification during certain phases of cell division. |
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Definition
| the constricted portion of a chromosome. after replication, the two strands of a double-stranded chromosome are joined at the centromere. |
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Term
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Definition
| referring to the members of chromosome pairs. homologous chromosomes carry genes that govern the same traits, and they are alike with regard to size and position of the centromere. during meiosis, homologous chromosomes pair and exchange segments of DNA. |
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Definition
| all chromosomes except the sex chromosomes. |
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Term
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Definition
| in mammals, the X and Y chromosomes. |
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Term
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Definition
| simple cell division; the process by which somatic cells divide to produce two identical daughter cells. |
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Definition
| cell division in specialized cells in ovaries and testes. meiosis involves two divisions and results in four daughter cells, each containing only half the original number of chromosomes. these cells can develop into gametes. |
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Definition
| the exchange of genetic material between homologous chromosomes during meiosis. |
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Definition
| the failure of homologous chromosomes or chromosome strands to separate during cell division. |
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Term
| polymerase chain reaction (PCR) |
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Definition
| a method of producing millions of copies of a DNA segment using the enzyme DNA polymerase. |
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Term
| recombinant DNA technology |
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Definition
| a process in which genes from the cell of one species are transferred to somatic cells or gametes of another species. |
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Definition
| an international effort aimed at sequencing and mapping the entire human genome. |
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Definition
| the entire genetic makeup of an individual or species. in humans, it is estimated that each individual possesses approximately 3 billion DNA nucleotides. |
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