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science: Genetics
Names and deifintions of words
| Question | Answer |
|---|---|
| Gene | A section of a chromosome (0r D.N.A ) which codes for a protein. |
| Chromosome | A collection of genes. Chromosomes are found in the nucleus of a cell. |
| D.N.A | (Deoxyribonucleic acid). This molecule is what chromosomes are made of. It can replicate (make copies of itself). |
| Alleles | Alternative forms of a gene. There are often dominant and recessive alleles for the same gene. |
| Heterozygous | A pair of alleles where there is a dominant and a recessive allele. |
| Homozygous | A pair of alleles where either both genes are recessive or both genes are dominant. |
| Dominant | A gene whose characteristic always appears even if only one copy is inherited. |
| Recessive | A gene whose characteristic only appears if copies are inherited from both parents. |
| Mutation | A ‘mistake’ in a gene or chromosome which usually occurs when it replicates. |
| Gamete | These are reproductive cells. They contain half the number of chromosomes of a body cell. Animal gametes are egg and sperm, plant gametes are pollen and ovule. |
| Mitosis | This type of cell division occurs in body cells. The chromosomes replicate so that the two new cells both have the same genetic composition as the original cell. |
| Meiosis | This type of cell division produces gametes. The chromosomes divide so that each new cell has half the number of the original cell. |
| Genotype | . The genes that an individual has |
| Phenotype | The characteristics that an individual has as a result of their genes. |
| Asexual reproduction | This is reproduction with only one parent. The offspring are clones of their parent. |
| Sexual reproduction | Reproduction where there are two parents and there is genetic recombination. |
| Clone | Clones are individuals with the same genetic make up. Identical twins are clones |
| Continuous variation | A characteristic which shows a continuous range in a population e.g height |
| Discontinuous variation | A characteristic which shows distinct groups in a population e.g blood groups. |