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LE BasicGenetics
Question | Answer |
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Genes | segment of DNA on a chromosome that contains the code for a specific trait |
Chromosomes | thick threadlike structure that contains genetic information in form of DNA |
Alleles | any of several forms of a gene |
Dominant | 1 allele masks another in a hybrid mix; expressed allele is dominant |
Recessive | the trait that is hidden or not expressed when in the heterozygous form (Tt) |
Homozygous | having identical pairs of genes for any given pair of hereditary characteristics |
Heterozygous | having dissimilar pairs of genes for any given pair of hereditary characteristics |
Hybrid | having dissimilar pairs of genes for any given pair of hereditary characteristics; heterozygous |
Genotype | genetic make up of the organism |
Phenotype | appearance of the organism |
Segregation | separation of homologous chromosomes in meiosis |
Recombination | restoration of diploid number in fertilization |
Crossing over | the interchange of corresponding chromatid segments of homologous chromosomes with their linked genes |
Synapsis | the pairing of homologous chromosomes, one from each parent, during early meiosis |
Test cross | involves the breeding of an individual with a phenotypically recessive individual, in order to determine genotype of parent |
Intermediate inheritance | the phenotype of the hybrid is different from both parents |
Codominance | the phenotype of both dominant alleles is expressed (AB) |
Independent assortment | traits are inherited independently |
gene linkage | genes on the same chromosome tend to be inherited together |
sex determination | determined by the presence of the y chromosome |
autosomes | non sex chromosomes |
sex chromosomes | x and y chromosomes |
x linkage | trait is located on the x chromosome with no corresponding allele on the y |
hemophilia | inability of blood to clot |
colorblindness | inability to distinguish red/green colors; mostly in males |
mutation | change in genetic material |
nondisjunction | pair of homologous chromosomes fail to separate after synapses gametes with > or < n chromosomes (trisomy 21) |
polyploidy | form of nondisjunction that results in extra set of chromosomes; 3n |
deletion | segment of chromosome is lost |
translocation | segment of chromosome breaks off and reattaches to nonhomologous chromosome |
inversion | segment of chromosome breaks off & reattaches at new point on original chromosome resulting in a change in the order of the genes |
gene mutation | random change in the chemical nature of genetic material (DNA) |
mutagenic agent | substances that cause gene mutations (X rays, UV light, radioactive substances, formaldehyde, asbestos fibers, cigarette smoke) |