Probability,
a fundamental concept in genetics, represents the likelihood of an event
occurring. For instance, when a coin is tossed, the chances of obtaining either
heads or tails are equal, resulting in a 50:50 probability, expressed as 1/2
for each outcome. This equilibrium is reflected in ratios like 1/2 head : 1/2
tail or simply 1:1. To calculate the probability of two consecutive heads, one
multiplies 1/2 by 1/2, yielding an answer of 1/4. It's essential to note that
the outcome of one event doesn't influence subsequent occurrences of the same
event.
Example
Scenarios
Cross: AA x Aa
Possible
Offspring: AA, AA, Aa, Aa
Phenotype: All dominant
Genotype
Ratio: 2:2
Cross: Aa x Aa
Possible
Offspring: AA, Aa, Aa, aa
Phenotype
Ratio: 3:1
Genotype
Ratio: 1:2:1
Problem Scenario:
Albinism Trait
Considering
that albinism is a recessive trait in humans, when two normal parents have an
albino child, the next child's probability of being normal or albino can be
assessed.
Answer
of the above problem
The
probability that their next child will be normal is 2/3 (or approximately
66.67%), while the probability of the child being albino is 1/3 (or
approximately 33.33%). This prediction is based on the fact that both parents
carry a recessive allele for albinism (Aa) while having a normal phenotype.
When they reproduce, there's a 25% chance of having an AA child (normal), a 50%
chance of having an Aa child (normal carrier), and a 25% chance of having an aa
child (albino). Therefore, the overall probabilities for the next child being
normal or albino are 2/3 and 1/3, respectively.
