Answer:
C. a mutation in the genetic code.
Explanation:
A mutation refers to any change or alteration to the nucleotide sequence of a gene caused by mutagen or mistakes during replication. Depending on the manner of occurrence, mutation can be of different types. In this question, partial DNA sequence for normal hemoglobin is given as: G-G-A-C-T-T-C-T-T while the partial DNA sequence for sickle cell anaemia is given as: G-G-A-C-A-T-C-T-T.
From careful observation of the two two DNA sequences above, it can be realized that a SUBSTITUTION MUTATION from T to A has occurred in the sequence of sickle cell. Note that substitution mutation is the replacement of one base by another in a sequence.
Answer:
1. Anyone can work on selective breeding.
2. It provides improvements to the plants or animals.
1. It may lead to a lack of variety in plant or animal species.
2. Genetic mutations are still going to occur.
The sole reason why red blood cells are unable to replace damaged proteins is that red blood cells lack DNA and cell organelles such as nucleus, ribosomes and mitochondria which are crucial for protein synthesis, assembly and repair. In other words they lack both the information and the machinery for making or repair of proteins.
Due to lack of DNA and cell organelles, red blood cells cannot be able satisfy the central dogma which summarizes synthesis of proteins as DNA → RNA → proteins.
DNA has the genetic information on how proteins should be made, RNA is responsible for transferring the information from DNA in the cell nucleus to the ribosomes in the cytoplasm, then translating or decoding this information, which results in the making of protein.
Answer:
1) Firstly, lets sort out the alleles for the dominant and recessive characteristics. The dominant brown allele will be written as B and the recessive red hair allele will be written as b.
2) Lets sort out the genotype of the parents. The parent having homozygous brown coloured hair will carry the alleles BB. The parent carrying the heterozygous brown coloured hair will carry the alleles Bb.
3) The punnet square from these parents will be drawn as follows:
B b
B BB Bb
B BB Bb
4) Now, lets predict the phenotype of the offsprings. The results from the punnet square show that all of the offsprings will have brown coloured hair.
5) The genotype for the children will have 50% chance to be homozygous brown (BB) and 50% chance to be heterozygous brown (Bb).
