Search results
Results from the WOW.Com Content Network
At the top level are all alpha proteins (domains consisting of alpha helices), all beta proteins (domains consisting of beta sheets), and mixed alpha helix/beta sheet proteins. While most proteins adopt a single stable fold, a few proteins can rapidly interconvert between one or more folds. These are referred to as metamorphic proteins. [5]
The RNA world hypothesis describes an early Earth with self-replicating and catalytic RNA but no DNA or proteins. [178] Many researchers concur that an RNA world must have preceded the DNA-based life that now dominates. [179] However, RNA-based life may not have been the first to exist.
In contrast, other proteins have evolved to bind to particular DNA sequences. The most intensively studied of these are the various transcription factors, which are proteins that regulate transcription. Each transcription factor binds to one particular set of DNA sequences and activates or inhibits the transcription of genes that have these ...
The DNA segments that carry this genetic information are called genes. Other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information. Along with RNA and proteins, DNA is one of the three major macromolecules that are essential for all known forms of life.
The DNA of a prokaryotic cell consists of a single circular chromosome that is in direct contact with the cytoplasm. The nuclear region in the cytoplasm is called the nucleoid. Most prokaryotes are the smallest of all organisms, ranging from 0.5 to 2.0 μm in diameter. [1] [page needed] A prokaryotic cell has three regions:
This protein was the first to have its structure solved by X-ray crystallography. Toward the right-center among the coils, a prosthetic group called a heme group (shown in gray) with a bound oxygen molecule (red). Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues.
The non-histone proteins, are a large group of heterogeneous proteins that play a role in organization and compaction of the chromosome into higher order structures. They play vital roles in regulating processes like nucleosome remodeling, DNA replication, RNA synthesis and processing, nuclear transport, steroid hormone action and interphase ...
The human cyclophilin family, as represented by the structures of the isomerase domains of some of its members. A protein family is a group of evolutionarily related proteins.In many cases, a protein family has a corresponding gene family, in which each gene encodes a corresponding protein with a 1:1 relationship.