Current estimates suggest that the human genome is comprised of < 20,000 genes (roughly 1.5% of the total sequence)
The vast majority of the genome consists of non-coding DNA sequences, much of which is repetitive
These highly repetitive DNA sequences differ from unique, single copy gene sequences in a number of key respects:
- Proportion: Highly repetitive DNA makes up a much greater proportion of the genome than gene sequences
- Rate of mutation: Gene sequences have a lower mutation rate (as any errors may affect protein synthesis)
- Occurrence: Gene sequences are typically unique and occur once in the genome, whereas repetitive DNA is recurring
- Function: Gene sequences are translated and code for proteins, highly repetitive DNA sequences are typically non-coding
- Identification: Repetitive DNA sequences are commonly used for DNA profiling, gene sequences are not (too similar)
- Length: A gene is made of a long unique sequence, while repetitive DNA sequences are typically composed of short repeats
- Example: An example of a gene sequence is an exon, while an intron may be an example of non-coding, repetitive DNA
Mnemonic: PROFILE
Genes versus Repetitive DNA
