A primer binding site is a

region In geography, regions, otherwise referred to as zones, lands or territories, are areas that are broadly divided by physical characteristics ( physical geography), human impact characteristics ( human geography), and the interaction of humanity an ...

of a

nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecule ...

sequence In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed and order matters. Like a set, it contains members (also called ''elements'', or ''terms''). The number of elements (possibly infinite) is calle ...

where an RNA or DNA single-stranded primer

bind BIND () is a suite of software for interacting with the Domain Name System (DNS). Its most prominent component, named (pronounced ''name-dee'': , short for ''name daemon''), performs both of the main DNS server roles, acting as an authoritative ...

s to start replication. The primer binding site is on one of the two complementary strands of a double-stranded

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

, in the strand which is to be copied, or is within a single-stranded nucleotide polymer sequence.

DNA Replication

Semi conservative replication of DNA (13081032424)

DNA replication In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. DNA replication occurs in all living organisms acting as the most essential part for biological inheritanc ...

is the semi-conservative, biological process of two DNA strands copying themselves, resulting in two identical copies of DNA. This process is considered semi-conservative because, after replication, each copy of DNA contains a strand from the original DNA molecule and a strand from the newly-synthesized DNA molecule. An RNA primer is a short chain of single-stranded RNA, consisting of roughly five to ten

nucleotides Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules with ...

complementary to the DNA template strand.

DNA polymerase A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create ...

will then take each nucleotide and make a new complementary DNA strand to the template strand, but only in the 5' to 3' direction. One of the new strands, the leading strand, moves in the 5' to 3' direction until it reaches the replication fork, allowing DNA polymerase to take the RNA primer and make a new complementary DNA strand to the template strand. The lagging strand moves away from the replication fork in the 3' to 5' direction and consists of small fragments called Okazaki fragments. DNA polymerase makes the lagging strand by using a new RNA primer for each

Okazaki fragment Okazaki fragments are short sequences of DNA nucleotides (approximately 150 to 200 base pairs long in eukaryotes) which are synthesized discontinuously and later linked together by the enzyme DNA ligase to create the lagging strand during DNA ...

it encounters. Overall, the leading strand only uses one RNA primer, while the lagging strand uses a new RNA primer for each Okazaki fragment it comes across.

Polymerase Chain Reaction (PCR)

Polymerase chain reaction (PCR) The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) ...

is a method used in laboratories that significantly increases the production of replicated

DNA sequences A nucleic acid sequence is a succession of bases signified by a series of a set of five different letters that indicate the order of nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. By convention, sequences are us ...

. PCR has revolutionized science by allowing laboratories to replicate up to billions of DNA sequences in only a few hours. This method has been used to diagnose

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

s, sequence and clone genes, detect

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

s, and locate criminals. PCR has even allowed the Human Genome Project to advance immensely. A PCR primer is a short chain of single-stranded DNA, consisting of roughly twenty

complementary to the target sequence of DNA. During PCR, two primers will bind to opposite template strands of DNA. The two primers point towards one another, allowing only a specific region of DNA to be copied. Scientists use PCR primers to analyze a targeted section of DNA. Primer per PCR

References

External links

* Cis-regulatory RNA elements {{molecular-cell-biology-stub