<span>The gene sequence containing an operator, promoter and repressor is known as an operon. These genes are called as structural genes. the operon is regulated by the presence/absence of the inducer such as glucose/lactose. It may also be a constitutive operon, which works all the time.</span>
Mixtures are combinations of several substances. Each of the substances retains its physical properties. There are no new substances created. This is in contrast to a chemical reaction in which two or more reactants make new products.
There are two types of mixtures. The first kind of mixture is a homogenous mixture. Homogenous mixtures are uniform in the ratio of the combination of substances. throughout. All solutions are homogenous mixtures. Colloids (such as mile) and suspensions are also homogenous mixtures, but their particle sizes are larger than the particles that make up a solution. This larger particle size makes colloids and suspensions appear murky or opaque.
The second kind of mixture is a heterogeneous mixture. Heterogeneous mixtures are not uniform throughout. A classic example of a heterogeneous mixture is a trail mix- every handful you grab will be slightly different. If a suspension is allowed to sit, then its large particles will settle to the bottom of its container. At this point, the suspension would be classified as a heterogenous mixture.
Answer: If a husband and wife who are both carriers of the sickle-cell anemia allele (Ss) but do not have the disease decide to have a child, the offspring can be Normal (SS), carrier (Ss) or sick (ss) with the probability ¼, 2/4 (½) and ¼ respectively.
Explanation: If the mother contributes the dominant allele and the father also contributes the dominant allele, the genotype of the child will be SS. The probability is ¼. This means there is a 25% chance that a randomly selected offspring will be a normal child and will not have sickle-cell anemia.
If the mother contributes the dominant allele and the father contributes the recessive allele, the genotype of the child will be Ss. The probability is 2/4 or ½. This means there is a 50% chance that a randomly selected offspring will be a carrier of sickle cell anemia, but will not have sickle-cell anemia.
If the mother contributes the recessive allele and the father also contributes the recessive allele, the genotype of the child will be ss. The probability is ¼. This means there is a 25% chance that a randomly selected offspring will have sickle cell anemia.
Check attached image for illustrations.
