Investigating Albinism in Barley Plants
Background:
There is a gene controlling pigment production in barley that has the alternate alleles:
A: pigment produced-green (dominant)
a: no pigment-albino (or white) - (recessive)
where pigment production is dominant to albino.
The seeds planted were produced from crossing heterozygous plants for the gene concerned (Aa x Aa).
Procedure:
1. Approximately 35 seeds were germinated by placing them on moistened cotton wool in a small petri dish.
2. The petri dishes were placed in a warm environment of approximately 22-24 C degrees.
3. The cotton wool was kept moist for 6 days and on day 6 the number of seedlings was counted.
4. The seedlings were assessed as either containing chlorophyll or not containing chlorophyll when they had reached a height of 4-5 cm.
Results:
DESCRIPTION|NUMBER OF GREEN PLANTS|NUMBER OF ALBINO PLANTS|INDIVIDUAL GROP RATIO
GREEN : ALBINO|
Our results|7|2|7:2|
Group 2|7|2|7:2|
Group 3|7|3|7:3|
Group 4|7|1|7:1|
Group 5|11|2|11:2|
Group 6|7|2|7:2|
Group 7|5|1|5:1|
Group 8|5|0|5:0|
Group 9|8|2|4:1|
Group 10|11|3|11:3|
Group 11|5|0|5:0|
TOTAL|80|18|40:9 |
Discussion:
The class ratio of green plants to albino plants is 40:9 which can be simplified to approximately 4≈1. This is ratio of 4≈1 is very similar to Mendel's ratio of 3:1.Due to the result the genotypes of the of the parent plants must have been heterozygous x heterozygous (Ff x Ff). This prediction resolves from the fact that some of the plants were also green which means that the genotypes could not have been homozygous recessive as this would have only given rise to albino plants. The genotype of the albino plants must be homozygous recessive (aa) as the albino allele is recessive to the green/chlorophyll allele. The genotype of the green plants could either be heterozygous (Aa) or homozygous dominant (AA) as both of these allele...