Tetrad analysis is also a valuable tool in determining the genotypes of certain phenotypes, as well as linkage between two genes. If linkage is occurring between genes then the NPD is very rare to see compared to the PD and TT. If linkage is not occurring then the ratios of PD:NPD:TT are roughly 1:1:4. Once linkage has been determined and the ratios have been confirmed, it is easy to determine which phenotype is PD, NPD, or TT and simply match it to the correct genotype.
Mutations can be located at several different locations on a gene. Despite being able to be located at several different points on a gene, different mutations can lead to the same phenotype. Sometimes mutations occur at the same location of a gene, so when two organisms with the same mutation mate the mutation persists to the next generation. Sometimes two organisms will display the same mutated phenotype but will have mutations at different locations from one another. When mated together, the offspring of these two organisms will no longer display the mutated phenotype, resulting in a process called complementation.
Mutations can occur at several locations on a gene yet result in the same phenotype. Yeast are a good organism to study the heritability of mutations because of their small size, easy and quick growth, and easily definable phenotypes. These factors also make yeast good for using tetrad analysis to determine genotypes. To study this, several crosses were carried out on adenine deficient agar plates to see what haploid gametes and what diploid cells could survive without adenine present. It was found that HA0 is the only haploid yeast cell that can grow without adenine, while HA1, HA2, and HB1 cannot grow without adenine. HB1xHA0 and HB1xHA2 were able to grow without adenine present, while HB1xHA1 and HA1xHA2 were unable to grow without adenine present. These results occurred because of the locations of the mutations on the gene, resulting in dominant alleles, mutation matches, complementation, and non-mating. A tetrad analysis was then taken of HB1xHA2. The results of the analysis show that there is a roughly 1PD:4TT, with three unknown tetrads due to culture deaths. While the analysis showed the correct ratio of PD:TT, it cannot be confirmed if the genes are linked or not due to the undefined tetrads.
Mutations can occur at several locations on a gene yet result in the same phenotype. Yeast are a good organism to study the heritability of mutations because of their small size, easy and quick growth, and easily definable phenotypes. These factors also make yeast good for using tetrad analysis to determine genotypes. To study this, several crosses were carried out on adenine deficient agar plates to see what haploid gametes and what diploid cells could survive without adenine present. It was found that HA0 is the only haploid yeast cell that can grow without adenine, while HA1, HA2, and HB1 cannot grow without adenine. HB1xHA0 and HB1xHA2 were able to grow without adenine present, while HB1xHA1 and HA1xHA2 were unable to grow without adenine present. These results occurred because of the locations of the mutations on the gene, resulting in dominant alleles, mutation matches, complementation, and non-mating. A tetrad analysis was then taken of HB1xHA2. The results of the analysis show that there is a roughly 1PD:4TT, with three unknown tetrads due to culture deaths. While the analysis showed the correct ratio of PD:TT, it cannot be confirmed if the genes are linked or not due to the undefined tetrads.
Plants have several different types of circadian rhythm. The first is that plants orient themselves towards the sun during the day to maximize photosynthesis. Plants also undergo another circadian rhythmic nastic movement called nyctinasty. Nyctinasty is a response in higher plants to the onset of darkness. An example of nyctinasty in plants is when the leaves and petals of plants close at night. The action is brought about by darkness and is an evolutionary reaction that preserves water and sugar levels in the plant when conditions are not optimal for photosynthesis.
Circadian rhythm is a biological process that displays a pattern of biological actions over the course of roughly 24 hours. All types of organisms display a circadian rhythm, including plants and animals. In animals, circadian rhythm is the animals sleep schedule. When it gets dark out the animal will get sleepy, and when the sun comes up the animal will feel energized. In plants, circadian rhythm is the plant’s orientation. Plants will reposition themselves at different times of the day in order to maximize photosynthetic output.
A LOV domain stands for a light-oxygen-voltage-sensing domain. This LOV domain is a protein sensor used by a large variety of higher plants to control phototropism, chloroplast relocation, and stomatal opening. The LOV domain has been found to do this by controlling gene expression through DNA binding. The LOV domain is also involved in redox-dependent regulations.
Plants are photosynthetic and require light to survive. When plants are left in the shade they don’t die immediately though. When left in the shade, plants become etiolated. Etiolation results in stem elongation, paleness, and a lack of photosynthetic maturation. Etiolation occurs usually in plants below a canopy. Far red light is what triggers etiolation, which penetrates through the shade of the canopy. In order to reverse etiolation, all that would be necessary would be for the plant to be exposed to red light again, because red light is what activates de-etiolation.
Plants are photosynthetic and require light to survive. When plants are left in the shade they don’t die immediately though. When left in the shade, plants become etiolated. Etiolation results in stem elongation, paleness, and a lack of photosynthetic maturation. Etiolation occurs usually in plants below a canopy. Far red light is what triggers etiolation, which penetrates through the shade of the canopy. In order to reverse etiolation, all that would be necessary would be for the plant to be exposed to red light again, because red light is what activates de-etiolation.
Plants use a technique called photomorphogenesis. Photomorphogenesis is the development of form and structure in a plant that is affected by light. This is a response to light that is independent of other light-based responses in the plant, such as photosynthesis. Some examples of photomorphogenesis in plants are their day/night cycles or hourly orientation towards the sun. Changing the day length will change how the flower or leaf orients itself at certain times in the day.
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