Answer:
15. D have specific gened activated
16. G cell division is unregulated
17. D providing information to form proteins
Explanation:
15. When an egg is first fertilised, the cells are very flexible. They are sort of like a "blank slate", and can become any type of cell. From these cells, all the cells in the body are created: brain cells, skin cells, blood cells etc. To become all these different types of cells, they keep dividing, slowly branching off and becoming more specific. This process is called differentiation.
They do this because different patterns and combinations genes are activated that turn them in to these different and specific cell types.
16. One of the hallmarks of a cancer cell is unregulated cell division. Oncogenes start as normal genes (called proto-oncogenes) that function in normal processes, such as the cell cycle, inhibiting apoptosis. However, when they become mutated, they can promote the growth and division of cells and prevent their programmed death. This is because they become more active or present in higher amounts following the mutation. This causes such functions in the cell to become deregulated, leading to uncontrolled cell proliferation and the growth of harmful tumour cells.
17. The central dogma of biology states that DNA --> RNA --> protein. The messenger RNA (mRNA) is transcribed from the DNA. It contains a message that is translated by the protein synthesis machinery to form proteins.
This is how all the proteins in the cell are produced, and the information for how to encode them is entirely dependent upon the sequence of the DNA, which is sent as a coded message in the form of RNA, to the protein synthesis machinery. The protein synthesis machinery makes the proteins according to the DNA sequence (as translated from the mRNA).
