Answer:
Carbon can form four covalent bonds
Explanation:
The mutation resulting in sickle cell disease changes one base pair of DNA so that a codon now codes for a different amino acid, making it an example of a missense mutation. Missense mutation is the mutation characterized with <span>changes in one base pair so that the whole amino acid is changed.</span>
Identifying the genetic sex of a child is based on finding intracellular Barr bodies that consist of inactive chromatin material.
Inactive chromatin material is the one where no transcription takes place. It is also known by the name heterochromatin. It appears as a dark condensed form in the chromatin.
Barr bodies are the inactive X chromosomes. These are mad inactive by a process termed as lyonization. It is essential to make the chromosome inactive in organisms with XY type of sex determination. They are present at the periphery of the nucleus. Inactivation of X chromosome makes the amount of X chromosomes equal in both, males and females.
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Answer:
4. B cells become activated by interacting with helper T cells.
1. B cells display antigens in MHC class II receptors on the cell surface.
2. Antibodies released by plasma cells bind to the antigen so they will be destroyed by other cells of the immune system.
3.B cells rearrange their DNA to create a unique B-cell receptor.
5. B cells undergo clonal expansion.
6. B cells digest antigens that bind to the antibodies on their surface.
Explanation:
B-cells get activated by interacting with helper T cells when they bind to the antigen to receptors i.e (MHC class II receptors on the cell surface) on the surface of the cell. Series of activities such as release by plasma cells which cause rearrangement of B cells causes the cell to divide and proliferate. The process through which daughter cells arise from a parent cell called clonal expansion.
