Explain the difference between replication and protein synthesis (transcription and translation)?

Question

When and why does each process occur?

Answer 1

What do you mean by replication? Is is cell replication, DNA replication...etc?

I will assume DNA replication.

Do not mix up protein synthesis with DNA replication. They are two completely different processes.

Note: I believe DNA replication in the previous answers source is actually making the pre-mRNA transcript. You are not actually making more copies of the DNA.

When:

DNA replication: depends on a number of factors. One during cell replication, during the Interphase, S sub phase.

Or any other time DNA needs to be replicated.

Protein synthesis: Depends on factors. If you need a certain protein, then a signal will be sent out to start transcription.

Why:

DNA replication: in need of DNA or to replace damaged DNA

Protein synthesis: whenever a particular protein is needed. Or for the production of siRNA or any other interfering RNA.

good luck.

Answer 2

DNA replication occurs when the cell is about to divide, during S phase. The amount of DNA in the cell is doubled, although the number of chromosomes remains the same.

The double helix of DNA is unwound by helicase, topoisomerase helps relieve the tension while it's unwinding, and DNA polymerase copies the DNA on the leading strand. However, DNA polymerase can only make DNA 5'->3', since it needs something to latch onto. So, on the lagging strand - where it has to make DNA 3'->5', an enzyme called primase makes a few RNA primers for DNA polymerase to latch onto. Thus, you get a bunch of short DNA fragments called Okazaki fragments. The RNA fragments are removed, and the fragments are joined by DNA ligase.

Thus, all that happens is you get twice as much DNA - each strand of the DNA now has a new complementary strand. DNA replicates, it doesn't change in any way.

Protein synthesis occurs in the two steps - transcription and translation.

Transcription when DNA is *transcribed* to mRNA (messenger RNA) by RNA Polymerase.

It's "transcription" because it's just one type of genetic material to another - the information does not chance significantly. mRNA has U instead of T, and can leave the nucleus.

(the mRNA is then spliced - introns are removed and broken down, and exons are spliced together - but this is post-transcriptional editing)

Translation is done by the ribosome, which reads the nucleotide sequence on the mRNA and *translates* it into an amino acid sequence, which is very different. 3 nucleotides make up an amino acid "code", and the ribosome links the amino acids with a covalent (strongest type) bond.

The linked amino acids become a protein.

Thus, genetic material is *translated* to a functional protein.