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genetics exam 4
| Question | Answer |
|---|---|
| Genes that are on the same chromosome | syntenic genes |
| The physical linkage of genes on the same chromosomes | synteny |
| The term means that two or more genes do not assort independently and are transmitted together. Which means a chromosome is referred to as | linkage group |
| Human linkage groups | 22 autosomal linkage groups, one X chromosome linkage group, one Y chromosome linkage group |
| What is the process of homologous chromosomes exchanging pieces with each other during which process of prophase in meiosis I | genetic recombination during crossing over |
| Crossing over produces | recombinant phenotypes |
| Cells without crossing over | nonrecombinant cells |
| Cells with crossing over | recombinant cells |
| The likelihood of crossing over depends on what between two genes | the distance between two genes |
| Morgan realized that linkage of autosomal genes in Drosophila could be interpreted using | a two-point test-cross analysis |
| The purpose of genetic mapping is to determine what of genes along the same chromosome | the linear order and distance |
| Genetic maps can be made by | recombination analysis |
| Genetic maps are based on the number of times that a crossover event occurs between genes and creates | a linkage map |
| Genetic mapping is usually done by doing | testcrosses between a heterozygote and homo recessive |
| recombination frequency = | map units |
| Geneticists can efficiently map three linked genes simultaneously by performing | a three-point test-cross analysis |
| Separates the gene in the middle from the other two genes at either end | a double crossover |
| What does it mean when we say genes are syntenic | they are located on the same chromosome |
| Which of the following statements is true A. Genes that are closer together are less likely to experience crossing over B. Genes that are further apart are less likely to experience crossing over C. Recombination frequency overestimates the distance | A. Genes that are closer together are less likely to experience crossing over |
| You set up the following two-point test cross: purple flowers, long pollen x red flowers, round pollen. If flower color, and pollen shape are on the same chromosome then what would you expect to see in the F2 offspring | a high number of purple/long and red/round then purple/round and red/long |
| What is the basis behind the production of recombinant cells | the crossing over of homologous chromosomes during meiosis I |
| How many linkage groups are present in humans | 24 |
| What is the purpose of doing genetic mapping | to determine the linear order and distance of genes |
| Why is the maximum recombination frequency 50% | 50% recombination is what occurs when genes are on different chromosomes |
| Why do recombination frequencies tend to underestimate true physical distance | due to multiple crossovers between a gene pair |
| How do you set up a testcross | cross a heterozygote to a homozygous recessive |
| The order of three genes one a chromosome is A-B-C. Genes A and B are 10 cM apart and genes B and C are 20 cM apart. From a ABC/abc individual, what is the likelihood of getting a Abc gamete | 4% |
| Differences in alleles and chromosomes, either among members of the same species or among different species | genetic variation |
| variations in specific genes, can also occur in chromosome structure and number | allelic variations |
| Scientists who studies chromosomes under a microscope | cytogeneticists |
| Centromere near the middle | metacentric |
| Centromere slightly off center | submetacentric |
| Centromere more off center | acrocentric |
| Centromere at the end | Telocentric |
| Micrograph of metaphase chromosomes from a cell arranged in a standard fashion | karyotype |
| Giemsa staining stains regions of high A-T bonding to produce | G bands |
| Portion of chromosome missing | deletion |
| Portion of chromosome repeated | duplication |
| Change in direction of part of chromosome | inversion |
| Two non-homologous chromosomes swap segments | translocation |
| Crossover at misaligned sites on homologs | nonallelic homologous recombination |
| Type of structural variation in which a DNA segment 1000 bp or larger has copy number differences in members of the same species | copy number variation |
| A gene normally found in two copies in a diploid cell may be found in three or more copies | segmental duplication |
| Duplications can provide additional genes leading to | gene families |
| Two or more genes derived from a common ancestral gene are | homologous |
| Homologous genes within a single species are called | paralogs |
| Segment of chromosome that has been flipped to the opposite orientation | chromosomal inversion |
| The centromere is within inverted region | pericentric inversion |
| The centromere is outside the inverted region | paracentric inversion |
| The breaks leading to the inversion occurs in a vital gene | breakpoints |
| Gene is repositioned in a way that alters expression | position effect |
| For the normal and inversion chromosome to synapse, they must form | an inversion loop |
| Crossover within inversion loop can lead to | dicentric chromosomes |
| 2 centromeres connected by dicentric bridge | dicentric chromosomes |
| Chromosome with no centromere | acentric fragments |
| Single piece of chromosome is attached to another chromosome | simple translocation |
| Two nonhomologous chromosomes exchange pieces | reciprocal translocation |
| Ends of eukaryotic chromosomes that prevent translocations from occuring | telomeres |
| Lead to rearrangement of the genetic material, not a change in the amount | balanced translocations |
| Carriers of a balanced translocations are at risk of having offspring with significant portion of genetic material duplicated or missing | unbalanced translocation |
| Alternate segregation | balanced |
| Adjacent-1 segregation | unbalanced |
| Adjacent-2 segregation | unbalanced |
| What causes the most effects on phenotypes | unbalanced translocation |
| Variation in the number of particular chromosomes (trisomy 2n+1, monosomy 2n-1) | Aneuploidy |
| Variation in the number of complete sets of chromosomes (triploidy 3n, tetraploidy 4n) | Euploidy |
| Organisms with 3 more sets are also called | polyploid |
| Diploid animals that produce polyploid tissues | Endopolyploidy |
| Polyploids with an odd number of chromosome sets are usually | sterile |
| Failure of chromosomes to segregate properly during anaphase | nondisjunction |
| Nondisjunction in meiosis I | two n+1, two n-1 |
| Nondisjunction in meiosis II | n+1, n-1, two normal |
| All the chromosomes can undergo nondisjunction and migrate to one daughter cell | complete disjunction |
| The diploid cell can participate in fertilization with a normal gamete, yielding a triploid individual | autopolyploidy |
| Mitotic nondisjunction occurs after fertilization and can lead to one of the chromatids not migrating to a pole and is degraded. leads to normal and monosomic daughter | chromosome loss |
| Results from interspecies crosses usually by two closely related species | allopolyploidy |
| Occurs when a person has two or more genetically different sets of cells in their body | mosaicism |
| Down syndrome (extra chromosome 21) is an example | trisomy |
Created by:
Timmay1520
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