A researcher studies two types of fly populations. Population A have stubby bristles which are both shorter and blunter than population B. This is because the flies are homozygous for a certain allele for the stubble gene which affects bristle length. These flies are ebony coloured with black bodies. This is because they are homozygous for a certain allele for the ebony gene that affects body colour. Population B have longer and tapered bristles than population A and are not stubbly in appearance. This is due to them being homozygous for a different allele for the gene that affects bristle length to population A. These flys are not ebony coloured and have brown bodies. This is due to them being homozygous for the gene that affects body colour. The researcher crosses parental flys (P1) from population A with those from population B and counts the number of offspring that have stubble and non-stubble bristles, and the number of offspring that are ebony-coloured and non-ebony-coloured in the F1 generation. The presence of the gene that affects body colour does not affect the inheritance pattern of the gene that affects bristle length, and the presence of the gene that affects bristle length does not affect the inheritance pattern of the gene that affects body colour. A fly can potentially have both stubble bristles and be ebony-coloured. There is a total of 560 flies in the F1 generation. F1 ebony flys - 0 F1 non-ebony flys - 560 F1 stubble flys - 560 F1 non-stubble flies - 0 1. State whether the allele in the populations giving rise to each phenotype (stubble bristle and ebony bodies) is dominant or recessive. 2. Allocate a suitable abbreviation for the following: - Stubbly and Non Stubbly Alleles (2 Alleles) - Ebony and Non Ebony Alleles (2 Allele) 3. Using your abbreviations from step 2, draw two seperate punnett squares to illustrate the P1 cross (one for the stubbly alleles and one for the ebony alleles) showing the individual gametes of each parent, and the combination in the resulting F1 offspring. 4.Taking into account all of the above, explain why there are only stubbly-bristled flies in the F1 generation.
Genetic Variation
Genetic variation refers to the variation in the genome sequences between individual organisms of a species. Individual differences or population differences can both be referred to as genetic variations. It is primarily caused by mutation, but other factors such as genetic drift and sexual reproduction also play a major role.
Quantitative Genetics
Quantitative genetics is the part of genetics that deals with the continuous trait, where the expression of various genes influences the phenotypes. Thus genes are expressed together to produce a trait with continuous variability. This is unlike the classical traits or qualitative traits, where each trait is controlled by the expression of a single or very few genes to produce a discontinuous variation.
A researcher studies two types of fly populations.
Population A have stubby bristles which are both shorter and blunter than population B. This is because the flies are homozygous for a certain allele for the stubble gene which affects bristle length. These flies are ebony coloured with black bodies. This is because they are homozygous for a certain allele for the ebony gene that affects body colour.
Population B have longer and tapered bristles than population A and are not stubbly in appearance. This is due to them being homozygous for a different allele for the gene that affects bristle length to population A. These flys are not ebony coloured and have brown bodies. This is due to them being homozygous for the gene that affects body colour.
The researcher crosses parental flys (P1) from population A with those from population B and counts the number of offspring that have stubble and non-stubble bristles, and the number of offspring that are ebony-coloured and non-ebony-coloured in the F1 generation. The presence of the gene that affects body colour does not affect the inheritance pattern of the gene that affects bristle length, and the presence of the gene that affects bristle length does not affect the inheritance pattern of the gene that affects body colour. A fly can potentially have both stubble bristles and be ebony-coloured. There is a total of 560 flies in the F1 generation.
F1 ebony flys - 0
F1 non-ebony flys - 560
F1 stubble flys - 560
F1 non-stubble flies - 0
1. State whether the allele in the populations giving rise to each
2. Allocate a suitable abbreviation for the following:
- Stubbly and Non Stubbly Alleles (2 Alleles)
- Ebony and Non Ebony Alleles (2 Allele)
3. Using your abbreviations from step 2, draw two seperate punnett squares to illustrate the P1 cross (one for the stubbly alleles and one for the ebony alleles) showing the individual gametes of each parent, and the combination in the resulting F1 offspring.
4.Taking into account all of the above, explain why there are only stubbly-bristled flies in the F1 generation.
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