A gene product is the biochemical material, either
RNA
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydra ...
or
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
, resulting from
expression
Expression may refer to:
Linguistics
* Expression (linguistics), a word, phrase, or sentence
* Fixed expression, a form of words with a specific meaning
* Idiom, a type of fixed expression
* Metaphorical expression, a particular word, phrase, o ...
of a
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
. A measurement of the amount of gene product is sometimes used to infer how active a gene is. Abnormal amounts of gene product can be correlated with
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 ...
-causing
allele
An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution.
::"The chro ...
s, such as the overactivity of
oncogene
An oncogene is a gene that has the potential to cause cancer. In tumor cells, these genes are often mutated, or expressed at high levels. s which can
cause cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...
.
A
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
is defined as "a hereditary unit of DNA that is required to produce a functional product".
Regulatory elements
A regulatory sequence is a segment of a nucleic acid molecule which is capable of increasing or decreasing the expression of specific genes within an organism. Regulation of gene expression is an essential feature of all living organisms and vi ...
include:
*
Promoter region
In genetics, a promoter is a sequence of DNA to which proteins bind to initiate transcription of a single RNA transcript from the DNA downstream of the promoter. The RNA transcript may encode a protein (mRNA), or can have a function in and of ...
*
TATA box
In molecular biology, the TATA box (also called the Goldberg–Hogness box) is a sequence of DNA found in the core promoter region of genes in archaea and eukaryotes. The bacterial homolog of the TATA box is called the Pribnow box which has ...
*
Polyadenylation sequences
*
Enhancers
In genetics, an enhancer is a short (50–1500 bp) region of DNA that can be bound by proteins ( activators) to increase the likelihood that transcription of a particular gene will occur. These proteins are usually referred to as transcriptio ...
These elements work in combination with the open reading frame to create a functional product. This product may be transcribed and be functional as RNA or is translated from
mRNA
In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein.
mRNA is ...
to a protein to be functional in the cell.
RNA products
![Label RNA pol II](https://upload.wikimedia.org/wikipedia/commons/f/fc/Label_RNA_pol_II.png)
RNA molecules that do not code for any proteins still maintain a function in the cell. The function of the RNA depends on its classification. These roles include:
* aiding protein synthesis
* catalyzing reactions
* regulating various processes.
Protein synthesis is aided by functional RNA molecules such as tRNA, which helps add the correct amino acid to a polypeptide chain during
translation
Translation is the communication of the Meaning (linguistic), meaning of a #Source and target languages, source-language text by means of an Dynamic and formal equivalence, equivalent #Source and target languages, target-language text. The ...
, rRNA, a major component of
ribosome
Ribosomes ( ) are macromolecular machines, found within all cells, that perform biological protein synthesis (mRNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA (mRNA) molecules to ...
s (which guide protein synthesis), as well as mRNA which carry the instructions for creating the protein product.
One type of functional RNA involved in regulation are
microRNA
MicroRNA (miRNA) are small, single-stranded, non-coding RNA molecules containing 21 to 23 nucleotides. Found in plants, animals and some viruses, miRNAs are involved in RNA silencing and post-transcriptional regulation of gene expression. miRN ...
(miRNA), which works by repressing translation. These miRNAs work by binding to a complementary target mRNA sequence to prevent translation from occurring.
Short-interfering RNA (siRNA) also work by negative regulation of transcription. These siRNA molecules work in RNA-induced silencing complex (
RISC) during
RNA interference
RNA interference (RNAi) is a biological process in which RNA molecules are involved in sequence-specific suppression of gene expression by double-stranded RNA, through translational or transcriptional repression. Historically, RNAi was known by ...
by binding to a target DNA sequence to prevent transcription of a specific mRNA.
Protein products
Proteins are the product of a gene that are formed from translation of a mature mRNA molecule. Proteins contain 4 elements in regards to their structure: primary, secondary, tertiary and quaternary. The linear amino acid sequence is also known as the primary structure. Hydrogen bonding between the amino acids of the primary structure results in the formation of
alpha helices
The alpha helix (α-helix) is a common motif in the secondary structure of proteins and is a right hand-helix conformation in which every backbone N−H group hydrogen bonds to the backbone C=O group of the amino acid located four residues ear ...
or
beta sheet
The beta sheet, (β-sheet) (also β-pleated sheet) is a common motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone hydrogen bonds, forming a g ...
s.
These stable foldings are the secondary structure. The particular combination of the primary and secondary structures form the tertiary structure of a polypeptide.
The quaternary structure refers to the way multiple chains of
polypeptides
Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.
A p ...
fold together.
Protein functions
Proteins have many different functions in a cell and the function may vary based on the polypeptides they interact with and their cellular environment.
Chaperone proteins work to stabilize newly synthesized proteins. They ensure the new protein folds into its correct functional conformation in addition to making sure products do not aggregate in areas where they should not. Proteins can also function as
enzyme
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. A ...
s, increasing the rate of various biochemical reactions and turning substrates into products.
Products can be modified by attaching groups such as phosphate via an enzyme to specific amino acids in the primary sequence.
Proteins can also be used to move molecules in the cell to where they are needed, these are called
motor proteins.
The shape of the cell is supported by proteins. Proteins such as
actin
Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over ...
,
microtubules
Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 an ...
and
intermediate filaments provide structure to the cell.
Another class of proteins are found in plasma membranes.
Membrane protein
Membrane proteins are common proteins that are part of, or interact with, biological membranes. Membrane proteins fall into several broad categories depending on their location. Integral membrane proteins are a permanent part of a cell membrane ...
s can be associated with the plasma membrane in different ways, depending on their structure.
These proteins allow the cell to import or export cell products, nutrients or signals to and from the extracellular space.
Other proteins help the cell to perform regulatory functions. For example,
transcription factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The fu ...
s bind to DNA to help transcription of RNA.
References
{{DEFAULTSORT:Gene Product
Gene expression