Term
|
Definition
| Alternate forms of a gene at a particular locus |
|
|
Term
|
Definition
| The basic building-block of proteins. Each amino acid consists of an acid (carboxyl) and basic (amino) end. It is the joining between acidic and basic ends of adjacent amino acids (condensation) that forms the protein polymer. |
|
|
Term
|
Definition
| Where there is not a complete set of chromosomes e.g. 2n Ð 1, 2n + 1. |
|
|
Term
|
Definition
| A group of 3 bases on the tRNA. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| A condensed X chromosome in females. (Both males and females only need one active X chromosome.) |
|
|
Term
|
Definition
| The structure formed by the pair of homologous chromosomes during crossing over. Also called a tetrad because it consists of four chromatids. |
|
|
Term
|
Definition
| See Chromosome mutations. |
|
|
Term
|
Definition
| When a person has the gene, but does not show the disease |
|
|
Term
|
Definition
| The attachment point on the chromosome for the spindle fibres. |
|
|
Term
|
Definition
| The visible crossing-over of non-sister chromatids. |
|
|
Term
|
Definition
| A duplicated chromosome joined to its pair. It becomes visible at prophase. When chromatids separate at anaphase they are referred to as chromosomes. |
|
|
Term
|
Definition
| The genetic material during the resting life (interphase) of the cell. Chromosomes are only visible during cell division. |
|
|
Term
|
Definition
| Structure found in the nucleus of eukaryotes and the nuclear region of prokaryotes. It carries the genetic message. |
|
|
Term
|
Definition
| Pieces of chromosomes splitting and moving to give duplication, deletion, inversion and translocation. |
|
|
Term
|
Definition
| A length of DNA that codes for a polypeptide. Used as a more specific term for gene |
|
|
Term
|
Definition
| When both alleles are active, e.g. the A and B blood group alleles |
|
|
Term
|
Definition
| A group of 3 bases on the mRNA that codes for an amino acid or termination signal. |
|
|
Term
|
Definition
| Where both produce a phenotype that could not be produced by each acting independently (9 : 3 : 3 : 1 ratio) |
|
|
Term
|
Definition
| Two bases that pair together. A is complementary to T and C is complementary to G. |
|
|
Term
|
Definition
| Where both genes are needed to produce a phenotype (9 : 7 ratio). (Not specifically in the new prescription) |
|
|
Term
|
Definition
| A cross between 2 genes (4 alleles) |
|
|
Term
|
Definition
| Cells with one 2 sets ( homologous pairs) of chromosomes |
|
|
Term
|
Definition
| Deoxyribonucleic acid The molecule that carries the message within the chromosome. |
|
|
Term
|
Definition
| An allele is dominant if the phenotype is expressed when heterozygous |
|
|
Term
|
Definition
| When either gene by itself produces the same phenotype and only the homozygous recessive is different (15 : 1 ratio). (Not specifically in the new prescription) |
|
|
Term
|
Definition
| A catalyst made of protein. Usually ends in the suffix ÔaseÕ |
|
|
Term
|
Definition
| Where one gene acts on or affects another gene. Note that there is some confusion over this term. Some use it as meaning supplementary genes, as below. Others use it as an umbrella term for any type like collaboration and complementary genes as well as supplementary genes |
|
|
Term
|
Definition
| Type of cell found in Animal, Plant, Fungi and Protist (Protoctist) kingdoms |
|
|
Term
|
Definition
| A region of a gene that is present in mature RNA. |
|
|
Term
|
Definition
| The first generation (children) |
|
|
Term
|
Definition
| The second generation (grandchildren) |
|
|
Term
|
Definition
| A deletion or addition mutation. It results in scrambling of the message. |
|
|
Term
|
Definition
| Sex cells (sperm, pollen, eggs) |
|
|
Term
|
Definition
| A mutation in the sex cells. Can be inherited. |
|
|
Term
|
Definition
| A short region of a chromosome that is responsible for one trait (characteristic). |
|
|
Term
|
Definition
| Addition, deletion, substitution of one or a few bases. |
|
|
Term
|
Definition
| The gene arrangement, e.g. Bb, RrTt |
|
|
Term
|
Definition
| Cells with only a single set of chromosomes eg gametes. |
|
|
Term
|
Definition
| A genotype with different alleles, e.g. Aa |
|
|
Term
|
Definition
| A round protein that DNA coils around during prophase. |
|
|
Term
|
Definition
| A pair of chromosomes with identical loci. One is from the mother and one from the father. |
|
|
Term
|
Definition
| A genotype with the same alleles, e.g. AA or aa |
|
|
Term
|
Definition
| When only one allele is active, eg. the white allele in snapdragon flowers |
|
|
Term
|
Definition
| A molecule that binds to the repressor protein. Transcription occurs because the repressor molecule cannot bind to the operator site and prevent transcription. |
|
|
Term
|
Definition
| Non-coding regions removed from the pre-RNA and so not present in mature RNA. |
|
|
Term
|
Definition
| The chart formed when photographs of chromosomes are laid out in order. Karyotypes are used to identify chromosomal abnormalities. |
|
|
Term
|
Definition
| The strand in replication that is copied 3Õ to 5Õ as Okazaki fragments and then joined up. |
|
|
Term
|
Definition
| The strand in replication that is copied in the 5Õ to 3Õ direction. |
|
|
Term
|
Definition
| A gene that (usually when homozygous) is fatal to the organism, e.g. the roan gene in horses. The offspring is aborted or dies young |
|
|
Term
|
Definition
| Genes on the same chromosome |
|
|
Term
|
Definition
| Where a gene is located on a particular chromosome. |
|
|
Term
|
Definition
| The distance between two linked genes on a chromosome |
|
|
Term
|
Definition
| The chromosome from the mother. |
|
|
Term
|
Definition
| A series of enzyme-controlled reactions that convert compounds from one to another. |
|
|
Term
|
Definition
| When the classical 3 : 1 or 9 : 3 : 3 : 1 ratio is not found, e.g. the 2 : 1 in the roan horse cross (lethal gene) or complementary, collaboration, duplicate and supplementary genes |
|
|
Term
|
Definition
| A cross between one gene pair (2 alleles) |
|
|
Term
|
Definition
| Only one chromosome of that type is present eg males are monosomic for the X chromosome. |
|
|
Term
|
Definition
| Where there are more than two alleles, e.g. there are 3 blood group alleles |
|
|
Term
|
Definition
| Any change in the genetic material. |
|
|
Term
|
Definition
| Chromatids from opposite members of a homologous pair. These cross over at prophase I. |
|
|
Term
|
Definition
| The failure of chromatids to separate during anaphase. This results in aneuploidy. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| The length of DNA complementary to the template strand. It is needed to give shape to the DNA molecule. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| Regions within the nucleus that are rich in RNA. |
|
|
Term
|
Definition
| The basic unit of nuclei acids. Each nucleotide is made up of 1 sugar (ribose or deoxyribose), a phosphate group and 1 of 4 bases. |
|
|
Term
|
Definition
| A small section of DNA. These occur because DNA is replicated in the 5Õ to 3Õ direction and on the other strand must be made up in short sections (the Okazaki fragments). |
|
|
Term
|
Definition
| The site that a repressor protein can bind to to prevent transcription |
|
|
Term
|
Definition
| One or more structural genes plus the associated regulators (including operator site, promotor site and regulator gene). |
|
|
Term
|
Definition
|
|
Term
|
Definition
| The chromosome from the father. |
|
|
Term
|
Definition
| When a gene is expressed regardless of the environment |
|
|
Term
|
Definition
| A polymer of 2Ð10 amino acids. |
|
|
Term
|
Definition
| The physical expression of the genotype |
|
|
Term
|
Definition
| When a gene has more than one function, e.g. the roan gene in horses |
|
|
Term
|
Definition
| The addition, deletion or substitution of a single base. Often used interchangeably with gene mutation. |
|
|
Term
|
Definition
| Where one trait is controlled by more than one gene, e.g. human height and skin colour |
|
|
Term
|
Definition
| A polymer of 11Ð100 amino acids. |
|
|
Term
|
Definition
| Cells with three or more sets of chromosomes. |
|
|
Term
|
Definition
| Type of cell found in bacteria and blue-green algae. They lack mitochondria, chloroplasts, a true nucleus and have a single loop of DNA without protein. |
|
|
Term
|
Definition
| A region necessary for the initiation of transcription. Transcription occurs when the RNA polymerase binds to the promotor. |
|
|
Term
|
Definition
| A polymer of more than 100 amino acids. The primary structure is the order or sequence of amino acids, the secondary structure is the coiling and the tertiary structure is the folding of the protein. Where two or more proteins interact eg in the haemoglobin molecule there is a fourth level (quartenary) structure. |
|
|
Term
|
Definition
| The recessive allele is only expressed when homozygous |
|
|
Term
|
Definition
| Exchange of genetic material from maternal and paternal chromosomes during crossing-over. |
|
|
Term
|
Definition
| A gene that regulates the action of other genes. |
|
|
Term
|
Definition
| Copying of the DNA strands. In semi-conservative replication each new DNA molecule is made of one old and one new strand. |
|
|
Term
|
Definition
| A molecule that can bind to the operator site, preventing transcription. |
|
|
Term
|
Definition
| A molecule made from RNA and protein that makes the rough ER ÔroughÕ. It attaches to the mRNA during translation. Ribosomes both on the RER and in the cytoplasm translate the mRNA. |
|
|
Term
|
Definition
| Ribonucleic acid. A single-stranded molecule. Unlike DNA it uses the sugar ribose instead of deoxyribose and uses the base uracil (U) rather than thymine (T). The 3 types of RNA are mRNA (messenger), tRNA (transfer) and rRNA (ribosomal). |
|
|
Term
|
Definition
| Rough Endoplasmic Reticulum A series of tubes and sacs in the cytoplasm, where some protein synthesis is carried out. |
|
|
Term
|
Definition
| In humans, the X and Y chromosomes |
|
|
Term
|
Definition
| A gene found on one of the sex chromosomes |
|
|
Term
|
Definition
| A mutation that occurs in the body cells. Cannot be inherited. |
|
|
Term
|
Definition
| The codon that initiates the protein: AUG. |
|
|
Term
|
Definition
| The codon that ends the protein: UAA, UAG, UGA . |
|
|
Term
|
Definition
| A gene that is transcribed. |
|
|
Term
|
Definition
| The substance that an enzyme acts on. |
|
|
Term
|
Definition
| Where one gene controls the expression of another (9 : 4 : 3) |
|
|
Term
|
Definition
| The act of forming a bivalent. |
|
|
Term
|
Definition
| The DNA strand that carries the genetic message. Sometimes it is called the ÔcodingÕ, ÔreadÕ or ÔsenseÕ strand. |
|
|
Term
|
Definition
| A cross with the homozygous recessive. It is used to determine the phenotype of the organism crossed |
|
|
Term
|
Definition
|
|
Term
|
Definition
| The copying of a DNA message onto mRNA. This occurs in the nucleus. |
|
|
Term
|
Definition
| Any protein or enzyme, other than RNA polymerase that is required for transcription. |
|
|
Term
|
Definition
|
|
Term
|
Definition
| A group of 3 bases on the sense strand of the DNA. |
|
|
Term
|
Definition
| Where there are three chromosomes of that type, eg Down syndrome is trisomy 21. |
|
|
Term
|
Definition
| Alternate forms of a gene at a particular locus |
|
|
Term
|
Definition
| The basic building-block of proteins. Each amino acid consists of an acid (carboxyl) and basic (amino) end. It is the joining between acidic and basic ends of adjacent amino acids (condensation) that forms the protein polymer. |
|
|
