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Questions:

  1. Where are proteins synthesized?
  2. If the sequence of nitrogenous bases in a segment of a strand of DNA is GATACG, what would the sequence of bases in the complementary strand of mRNA be?
  3. Describe in detail the process of transcription and translation.
  4. How does a cell make sure that all the genes in a cell of an organism are the same?
  5. Why are there two different types of synthesis in DNA replication?

Answers:

  1. Proteins are synthesized at the ribosomes.
  2. The sequence would be: CUAUGC.
  3. See answer here
  4. All the genes in a cell of an organism are the same because of DNA replication.  The genes copy themselves exactly, ensuring the same genes in all cells.
  5. DNA is read 3' to 5', but it is built 5' to 3'.  Since there are two strands of DNA, one is 3' to 5' and the other is 5' to 3'.  DNA works only by reading DNA 3' to 5', therefore the two strands are replicated differently.  The 3' to 5' strand undergoes continuous synthesis.  It is the leading strand.  In the 5' to 3' strand, the DNA polymerase can't read in this order, therefore it jumps ahead about 1000-2000 nucleotides and replicates DNA in a direction away from the fork.  This is called discontinuous synthesis and this strand is called the lagging strand.