DNA Replication and Gene Expression

Sections of DNA code for different genes. DNA is an ideal molecule to carry this inherited information, because it can be replicated.

We need to know what the base sequence of a new strand of DNA, if we know the base sequence of the original strand of DNA.

We also need to understand that this is where a lot of mistakes can happen. Just like copying a computer file, errors can occur when DNA is replicated. A change to the base sequence is called a mutation.

Some mutations are benign. This means there is no effect on the gene. The same amino acids are made, even with the error in the base sequence. This is like making a minor spelling mistake in a sentence.

Other mutations cause changes to the base sequence. These mutations can result in new alleles for the gene. They can also lead to complications such as cancer, where the change causes the cell to grow and reproduce uncontrollably.

To understand the effect of mutations, it is useful to know about how the DNA is "read" by the cell. This is called gene expression and results in protein synthesis.

For a complete overview of DNA structure and replication, check out this video:

And this one gives a complete overview of gene expression: