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during dna replication, several natural proofreading mechanisms are in place to prevent an error from occurring. however, errors can occur occasionally. if the error is not fixed, it becomes a genetic mutation.
how can a mutation affect protein synthesis by a cell? do you think there are different consequences if it happens in a gamete cell (sperm or egg) versus a non-gamete cell?

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

the real answer is b. scintillation counter

the unequal cytoplasmic division that  results  in  one egg  and three polar bodies ensures that a fertilized  egg has  ample nutrients  forits journey  to  the uterus.