Two pairs of alleles a pair of opposed control rule trait (gene interaction)
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Gene interaction means between non-allelic affect the same traits through interaction phenomenon. Refers to the interaction between genetic interactions between different non-allelic loci, showed complementary suppressed, the upper and the like.
Various types of gene interaction, the hybrid offspring phenotype and although the proportion of deviation from normal Mendelian inheritance, but gene transfer law still follow the law of free combination.
Gene interaction model and the ratio
| Interaction type | \ (F_2 \) ratio | Testcross ratio |
|---|---|---|
| Recessive epistasis | 9:3:4 | 1:1:2 |
| Dominant epistasis | 12:3:1 | 2:1:1 |
| Jagger action | 9:6:1 | 1:2:1 |
| Cumulative effect | 1:4:6:4:1 | 1:2:1 |
| Overlapping role | 15:1 | 3:1 |
| Dominant complementary | 9:7 | 1:3 |
| Inhibition | 13:3 | 1:3 |
Epistasis
Recessive epistasis
When two pairs of alleles simultaneously control a trait, wherein the pair of recessive gene from another gene
masking effect.
By an explicit significant: explicit and implicit: occulting: faint = 9: 3: 3: 1 projection, if the first host to the recessive allele, then invisible, expressed as a trait with faint, so \ (F_2 \) segregation ratio 9: 3: 4.
example
Genetic maize endosperm protein layer Color: colored (C) / colorless (C); purple (P) / Red (p).
\ [\ Begin {matrix} P & red (CCpp) \ times white (ccPP) \\ & \ downarrow \\ F_1 & Purple (C \ _P \ _) \\ & \ quad \ downarrow \ otimes \\ F_2 & 9 purple (C \ _P \ _): 3 red (C \ _pp): 4 white (3ccP \ _ + 1ccpp) \
end {matrix} \] where cc recessive effect on host P / p.
example
(2010 national college entrance examination new curriculum standards, 32) Fancy some self-pollinated plants are divided into white, red and purple. Homozygous conventional four varieties: I purple (purple), a red (Red), two white (White White A and B). Hybridization experiments to do with these four varieties, were as follows:
Experiment 1: Purple × red, \ (of F_1 \) showed purple, \ (F_2 \) showed 3 Violet: 1 Red;
Experiment 2: Red × White A, \ (of F_1 \) showed purple, \ (F_2 \ ) showed 9 violet: 3 red: 4 white;
experiment 3: white A × white b, \ (of F_1 \) showed a white, \ (F_2 \) showed white;
experiment 4: white b × purple, \ (of F_1 \) showed purple, \ (F_2 \) showed 9 purple: red 3: 4 white.
The above experimental results, answer:
(1) the above-described color laws of inheritance of genetic follow is free combination laws .
(2) Write Experiment 1 (× red purple) genetic scheme (if matched by a pair of alleles, with A, a represents, when two pairs of alleles, with A, a and B, b represents and so on).
Dominant epistasis
Jagger action
Performance when the two genes are dominant a trait that only a pair of genes is another trait a dominant performance, the performance of third recessive traits are both two pairs of genes.
Significantly by an explicit: explicit and implicit: occulting: faint = 9: 3: 3: 1 projection, substantially the same hidden, invisible phenotype, thus \ (F_2 \) Example 9: 6: 1.
example
Southern fruits shaped by A / a, B / b two pairs of alleles joint control.
\ [\ Begin {matrix} P & spherical (AAbb) \ times spherical (aaBB) \\ & \ downarrow \\ F_1 & flat disk-shaped (AaBb) \\ & \ quad \ downarrow \ otimes \\ F_2 & 9 flat disk-shaped (A \ _B \ _): 6 spherical (A \ _bb): 1 oblong (aabb) \ end {matrix} \]
example
Homozygous conventional four varieties of pumpkin, two varieties of fruit showed round shape (a circle A and circle B), expressed as a flat disc shape (flat plate), the performance of an elongated (long). With four varieties made three experimental results are as follows:
Experiment 1: Round A × circle B, \ (of F_1 \) as a flat disk, \ (F_2 \) in the plate: round: length = 9: 6: 1
Experiment 2: flat plate × length, \ (F. \) , For the flat plate, \ (F. \) , the disk: round: length = 9: 6: 1
experiment 3: hybrid combinations of the above two elongated pollen plants are varieties (of F_1 \) \ plants pollinated progeny thereof flat plate: round both equal to
1: 2: 1. The above experimental results, answer:
(2) Ruoguo shape with A, a - represents a pair of alleles, when
controlled by two pairs of alleles with A, a and B, b represents, in such
push , the circular genotype should Aabb, AAbb, aaBB, gaBb
genotype disc should be long _
AABB
,
flat base
genotype should _ AABB AABb AaBB AaBb