DEFINITIONS THAT WILL MAKE YOUR LIFE EASIER

APLOID CELL: A cell which has one copy of each gene, and therefore has only one copy of each chromosome.

GERM CELLS: Cells which create haploid gametes.

GAMETE: A haploid sex cell.

MEIOSIS: Cell division found in eukaryotic organisms. In this process, a haploid cell divides twice in order to produce four haploid cells.

MITOSIS: A type of nuclear division in which somatic cells are produced. Equational division.

MEMBRANE: The "outer covering" of a cell, and it's organelles. All membranes have two layers and are therefore called "bilayers."

CYTOPLASM: The substance contained within the plasma membrane of the cell. The region in which translation takes place.

ORGANELLE: The membrane bound parts of a cell.

RIBOSOME: A cellular component composed of proteins and another class of RNA (rRNA).

ENDOPLASMIC RETICULUM: The area where most proteins and lipids synthesize. A "hallway" between the nucleus and the cytoplasm.

ENZYME: An organic catalyst.

DNA: Deoxyribose nucleic acid. Here's a little something about the structure of DNA and the replication of DNA.

GENE: An inhereted set of instructions for making proteins.

ALLELE: A copy of each gene. There are two alleles for each gene, one maternal copy and one paternal copy.

CODON: A sequence of three nitrogenous bases.

ANTICODON: The sequence of three bases (a codon), found in tRNA, which is complementary to the three bases of mRNA.

mRNA: Messenger RNA. A type of RNA which transports the information about the sequence of the amino acids in the protein to be manufactured, from the nucleus to the ribosomes.

tRNA: Transfer RNA. tRNA binds to a specific amino acid and has an anticodon on one end. The anticodon bears a set of three bases which are complementary to the mRNA codon for that particular amino acid. It carries its amino acid to a ribosome during protein synthesis.

rRNA: Ribisomal RNA. A type of RNA which combines with proteins to form ribisomes. Aids in translation.

DELETION: The processin which nucleotide pairs are removed from a gene.

BENIGN: Cancer which remains confined to its original location.

CANCER: Uncontrolled cell growth.

CARCINOGENS: Causes of cancer.

CARCINOMA: Cancers which arise from the skin. They constitute 90% of all cancers.

CYTOTOXIC T CELLS: "Cancer fighters" produced by the immune system to search for and destroy canceroud cells.

DIPEPTIDE: A chain comprised of two amino acids which are bound by a peptide bond.

EVOLUTION: Inhereted change within a population over time, directed by natural selection acting upon pre-existing variation.

EXPRESSIVITY: The degree to which an individual shows a genetic makeup.

GLYCOLOSIS: A series of enzyme catalyzed reactions that break down a single molecule of glucose into two molecules of pyruvic acid.

INSERTION: New nucleotide pairs are inserted in the middle of a gene.

MALIGNANCY: The process in which a tumor grows into neighboring tissue.

METASTASES: The process in which a piece of tumor is separated from the main tumor mass and goes to other parts of the body to form new cancerous conditions.

MUTATION: A change in the number or structure of chromosomes.

NEUTRAL MUTATION: A mutation which leads to the production of a different amino acid, however the new amino acid

serves the same function as the one which was supposed to be created.

ONCOGENE: A cell which causes cancer by stimulating cell growth and division.

OPERATOR: One of four parts of operons, the packages in which Prokaryotic DNA is organized. An operator directs the RNA polymerase to the promoter.

OPERON: An operon is a package in which prokaryotic DNA is organized. It consists of four different parts: theregulatory gene,

thepromoter, theoperator and the structural gene.

PENETRANCE: The degree to which a gene is manifested by measuring a percentage of the population with the gene.

POINT MUTATION: A mutation which occurs when a nitrogenous base is placed incorrectly.

POLAR: Very soluable in water. The phosphate end in a phospholipid is polar, while the fatty acid end in non-polar.

PROMOTER: One of four parts of operons, the packages in which Prokaryotic DNA is organized. A promoter is the starting

point for transcription in prokaryotes.

REGULATORY GENES: One of four parts of operons, the packages in which Prokaryotic DNA is organized. Regulatory genes control the timing of transcription of other genes.

RNA POLYMERASE: An enzyme, or organic catalyst which increases the rate of reaction, which binds to to the promoter sequence on the DNA, during transcription.

SARCOMA: Cancer of the connective tissue, such as muscle and bone. Sarcomas are very rare in humans.

SPECIES: A group of organisms which has the ability to interbreed and produce fertile offspring, using an isolated pool of genes.

There are an estimated 5-10 million species.

STRUCTURAL GENE: One of four parts of operons, the packages in which Prokaryotic DNA is organized. A structural gene

encodes enzymes and proteins.

TRANSCRIPTION: You get a whole page for this one!

TRANSCRIPTION FACTORS: Proteins which assist in the binding of the RNA polymerase to the promoter sequence.

TRANSLATION: You get a whole page for this one too!

TUMOR SUPRESSOR GENE: A gene which encodes information from proteins to inhibit cancer through regulating the growth

rate. An example is a p53 gene.