Broadly speaking, we can say that a cell's gene expression pattern is determined by
information from both inside and outside the cell
. Examples of information from inside the cell: the proteins it inherited from its mother cell, whether its DNA is damaged, and how much ATP it has.
What determines when and where a gene is expressed?
Gene regulation can occur at any point during gene expression, but most commonly occurs at the
level of transcription
(when the information in a gene's DNA is passed to mRNA). Signals from the environment or from other cells activate proteins called transcription factors.
What causes genes to be expressed?
Gene expression is influenced by numerous factors, including molecules within the cell,
mutations causing dominant negative effects and haploinsufficiency
, signaling molecules from surrounding cells and the environment, and epistasis. Various molecules within the cell modulate gene expression.
What is an example of gene expression?
Some simple examples of where gene expression is important are:
Control of insulin expression
so it gives a signal for blood glucose regulation. X chromosome inactivation in female mammals to prevent an “overdose” of the genes it contains. Cyclin expression levels control progression through the eukaryotic cell cycle.
What types of genes are constitutively expressed?
Constitutive genes are those
that are always active
. Genes for ribosomes are an example. They are constantly being transcribed because ribosomes are constantly needed for protein synthesis. Inducible genes are those that have variable activity, depending on the needs of the cell.
What are two different forms of a single gene called?
Different versions of a gene are called
alleles
. Alleles are described as either dominant or recessive depending on their associated traits.
What controls gene expression?
Gene expression is primarily controlled
at the level of transcription
, largely as a result of binding of proteins to specific sites on DNA. … The regulator gene codes for synthesis of a repressor molecule that binds to the operator and blocks RNA polymerase from transcribing the structural genes.
When a gene is expressed what is produced quizlet?
Gene expression occurs when the gene is turned on,
transcription occurs
and the protein is made via translation. -Special proteins called transcription factors bind to the promoter region which helps DNA to bend and initiate transcription.
How do you explain gene expression?
Gene expression is
the process by which the instructions in our DNA are converted into a functional product, such as a protein
. … It acts as both an on/off switch to control when proteins are made and also a volume control that increases or decreases the amount of proteins made.
What are the two stages of gene expression?
It consists of two major steps:
transcription and translation
. Together, transcription and translation are known as gene expression. During the process of transcription, the information stored in a gene's DNA is passed to a similar molecule called RNA (ribonucleic acid) in the cell nucleus.
Are exons genes?
An exon is
the portion of a gene that codes for amino acids
. In the cells of plants and animals, most gene sequences are broken up by one or more DNA sequences called introns.
When a gene is expressed is produced?
Gene expression is the
process the cell uses to produce the molecule it needs by reading the genetic code written in the DNA
. To do this, the cell interprets the genetic code, and for each group of three letters it adds one of the 20 different amino acids that are the basic units needed to build proteins.
What are the stages of gene expression?
- Chromatin structure. Chromatin may be tightly compacted or loose and open.
- Transcription. …
- Processing and export. …
- mRNA stability. …
- Translation. …
- Protein processing.
Are all genes expressed at the same time?
Only a fraction of the genes in a cell are expressed at any one time
. The variety of gene expression profiles characteristic of different cell types arise because these cells have distinct sets of transcription regulators.
What are the different forms of a single gene called?
Two different forms of a single gene are called ‘
alleles
. ‘ The alleles you inherit can be either dominant or recessive.
What are the 3 types of genes?
Type I genes tend to be involved in immune response or sensory receptors while type III genes are involved in cell to cell signalling and type II genes are a complex mix of all three types.
