In
biochemistryBiochemistry is the study of the chemical processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules....
,
heat shock is the effect of subjecting a cell to a higher temperature than that of the ideal
body temperatureThermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different...
of the organism from which the
cell lineCell culture is the process by which cells are grown under controlled conditions. In practice the term "cell culture" has come to refer to the culturing of cells derived from multicellular eukaryotes, especially animal cells...
was derived.
Heat shock proteinHeat shock proteins are a class of functionally related proteins whose expression is increased when cells are exposed to elevated temperatures or other stress. This increase in expression is transcriptionally regulated. The dramatic upregulation of the heat shock proteins is a key part of the...
s (HSPs) are a part of the
cellThe cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos...
's internal repair mechanism. They are also called stress-proteins. They respond to heat, cold and
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
deprivation by activating several cascade pathways. Heat shock proteins are also present in cells under perfectly normal conditions.
In
biochemistryBiochemistry is the study of the chemical processes in living organisms. It deals with the structure and function of cellular components such as proteins, carbohydrates, lipids, nucleic acids and other biomolecules....
,
heat shock is the effect of subjecting a cell to a higher temperature than that of the ideal
body temperatureThermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different...
of the organism from which the
cell lineCell culture is the process by which cells are grown under controlled conditions. In practice the term "cell culture" has come to refer to the culturing of cells derived from multicellular eukaryotes, especially animal cells...
was derived.
Heat shock proteinHeat shock proteins are a class of functionally related proteins whose expression is increased when cells are exposed to elevated temperatures or other stress. This increase in expression is transcriptionally regulated. The dramatic upregulation of the heat shock proteins is a key part of the...
s (HSPs) are a part of the
cellThe cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos...
's internal repair mechanism. They are also called stress-proteins. They respond to heat, cold and
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
deprivation by activating several cascade pathways. Heat shock proteins are also present in cells under perfectly normal conditions. They act like ‘chaperones,’ making sure that the cell’s proteins are in the right shape and in the right place at the right time. For example, HSPs help new or distorted proteins fold into shape, which is essential for their function. They also shuttle proteins from one compartment to another inside the cell, and transport old proteins to ‘garbage disposals’ inside the cell. Heat shock proteins are also believed to play a role in the presentation of pieces of proteins (or
peptidePeptides are short polymers formed from the linking, in a defined order, of α-amino acids. The link between one amino acid residue and the next is called an amide bond or a peptide bond....
s) on the cell surface to help the
immune systemAn immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumour cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own...
recognize diseased cells.
In fish that survive at 0°C, heat shock can be induced with temperatures as low as 5°C, whereas
thermophilic bacteriaA thermophile is an organism — a type of extremophile — that thrives at relatively high temperatures, between 45 and 80 °C...
that proliferate at 50°C will not express heat shock proteins until temperatures reach approximately 60°C
http://arjournals.annualreviews.org/doi/pdf/10.1146/annurev.ge.22..?cookieSet=1. The process of heat shocking can be done in a CO
2 incubator, O
2 incubator, or a hot water bath.
Induction of heat shock is a method by which
geneA gene is the basic unit of heredity in a living organism. All living things depend on genes. Genes hold the information to build and maintain their cells and pass genetic traits to offspring...
s can be introduced into cells via a vector. This is done by mixing the vector with competent bacteria in a
microcentrifuge tubeA laboratory centrifuge is a piece of laboratory equipment, driven by a motor, which spins liquid samples at high speed. There are two main sizes for laboratory centrifuges. The larger ones are known simply as centrifuges; samples are contained in centrifuge tubes or centrifuge tips...
. First, the tube is cooled to a low temperature for several minutes, usually with an ice bath. The tube is then quickly moved into warm water, preferably around 42°C. This sudden change in temperature causes the pores to open up to larger sizes, allowing
DNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
molecules to enter. After a brief interval, the tube is quickly cooled to a low temperature again. This closes up the pores, and traps the DNA inside. With this, the cells would have been transformed. However, as with almost all transformation techniques, this method is far from 100% efficient.