Genetics guides
Guides on DNA, genes, chromosomes, genome sequencing, and sequence file formats.
Genetics ·
How to use Clustal Omega online
Learn how to align protein, DNA or RNA sequences with Clustal Omega online. Choose the sequence type and output format, read the conservation symbols and check whether the alignment is trustworthy.
Genetics ·
Introns vs exons: what is the difference?
Exons are the parts of a gene kept in mature RNA, while introns are removed by splicing. Learn how much of a human gene is intron, why exons are not the same as coding DNA, and what happens when splicing fails.
Genetics ·
How much DNA do humans share with other animals?
Humans and chimpanzees are 98.8% identical across aligned DNA. ProteinIQ's Ensembl analysis of 21 species shows how genome alignment, shared genes, and protein identity diverge with distance.
Genetics ·
How much DNA do humans share with bananas?
ProteinIQ found banana counterparts for 18% of human protein-coding genes, with proteins about 40% identical. Matching coding DNA spans about 0.08% of the human genome.
Genetics ·
How much does it cost to sequence a genome?
A human genome costs about $220 to $450 at university sequencing labs and $399 to $595 as a consumer test. ProteinIQ's survey of US core facilities puts the median lab price at $419 before analysis.
Genetics ·
How to make a FASTA file
Create a FASTA file in Notepad or TextEdit, convert text, Word, or Excel data to FASTA, download FASTA from NCBI or UniProt, and avoid the mistakes that make tools reject the file.
Genetics ·
How long is DNA?
Human DNA is about 2 meters long per cell and 2 nanometers wide. See the calculations, chromosome lengths, and why whole-body estimates differ.
Genetics ·
How many chromosomes do different species have?
Compare chromosome counts across species, explore our analysis of 465 mammals, and check the evidence behind chromosome-number records and life-cycle exceptions.
Genetics ·
How many genes do humans have?
Humans have 19,442 protein-coding genes in GENCODE Release 50. Counting non-coding genes, pseudogenes and other categories, the reference annotation lists 78,733 gene entries.
Genetics ·
How many genes are in mitochondrial DNA?
Human mitochondrial DNA has 37 canonical genes. Compare the standard count with evidence for additional small proteins and mtDNA copy numbers across tissues.
Genetics ·
How big is the human genome?
Compare human genome size in base pairs, nucleotides, picograms, and gigabytes, with reference assembly totals and verified download sizes.
Genetics ·
How to use Primer3 online
Learn how to use Primer3 online to design PCR primers, set target regions and product sizes, tune Tm and GC limits, inspect secondary-structure controls, and validate specificity before ordering.
Genetics ·
How accurate is DNA sequencing?
DNA sequencing accuracy ranges from about 99% per raw base to above 99.9% for high-quality or consensus reads. The exact figure depends on the platform, chemistry, software, sample, and metric.
Genetics ·
How many genomes have been sequenced?
NCBI indexes 3.67 million current public genome assemblies. See bacterial, plant, human, species, and GenBank sequence counts for 2026.
Genetics ·
How many types of RNA are there?
There are three major RNA types: mRNA, rRNA, and tRNA. rRNA is the most abundant by mass, tRNA is the smallest of the three, and mRNA can be the longest.
Genetics ·
How many transcripts are in the human transcriptome?
The current human reference annotation contains 644,292 transcript models, 278,455 of them protein-coding. Database records, expressed isoforms and RNA molecules are different counts.
Genetics ·
Which organisms have the largest and smallest genomes?
Compare 27 genome size records across animals, plants, fungi, protists, and bacteria, from a 160.45-billion-base-pair fern genome to a 50,141-base-pair bacterial symbiont genome.
Genetics ·
What are the largest and smallest human genes?
RBFOX1 is the largest human protein-coding gene by GENCODE v50 genomic span. MLDHR is the shortest under an HGNC-approved protein-coding filter, at 96 base pairs.
Drugs ·
How many druggable genes are there?
About 4,500 human genes are considered part of the druggable genome. A major analysis counted 4,479 drugged or druggable genes, equal to 22% of protein-coding genes.
Genetics ·
How long does PCR take?
Most PCR runs take about 45 minutes to 2 hours in a thermocycler. Compare conventional PCR, qPCR, and RT-qPCR times and see how cycle count and target length affect the run.
Genetics ·
How long does whole-genome sequencing take?
Human whole-genome sequencing can generate genome data in hours to about a day. Sample preparation, analysis, interpretation, and reporting can extend the full turnaround to weeks.
Genetics ·
How long does mRNA last in a cell?
Cellular mRNA has a half-life of a few minutes in bacteria, about 18 minutes in budding yeast, and several hours in cultured human cells.
Genetics ·
How many nucleosomes are in a human cell?
A typical diploid human cell contains about 30 million nucleosomes. See how that estimate is calculated and why a nucleosome can be described as containing 146, 166, or about 200 base pairs.
Genetics ·
How many RNA polymerases do eukaryotes have?
Eukaryotes have three canonical nuclear RNA polymerases, while land plants have five. DNA polymerase counts vary by species, from five in E. coli to 16 in humans.