Dna Rna And Protein Synthesis Information To Structure – Structurally, ribonucleic acid (RNA) is similar to DNA. However, while DNA molecules are usually long and double-stranded, RNA molecules are very short and usually single-stranded. RNA molecules perform various roles in the cell, but they are mainly involved in protein synthesis (translation) and its regulatory process.
RNA is generally single-stranded and composed of ribonucleotides linked by phosphodiester bonds. A ribonucleotide in an RNA chain contains a ribose (pentose sugar), one of four nitrogenous bases (A, U, G, and C) and a phosphate group. The subtle structural difference between the sugars gives DNA additional stability, making DNA more suitable for storing genetic information, whereas the relative instability of RNA makes it better suited for its short-lived functions. The RNA-specific pyrimidine uracil forms a complementary base pair with adenine and replaces the thymine used in DNA. Although RNA is unique, most types of RNA molecules exhibit extensive intramolecular base pairing between complementary sequences within the RNA strand, forming a predictable three-dimensional structure essential for their function (Figure 1 and Figure 2).
- 1 Dna Rna And Protein Synthesis Information To Structure
- 2 The Structure, Function And Evolution Of Proteins That Bind Dna And Rna
- 3 The Flow Of Genetic Information
Dna Rna And Protein Synthesis Information To Structure
Picture. (b) RNA has pyrimidine uracil instead of thymine found in DNA.
The Structure, Function And Evolution Of Proteins That Bind Dna And Rna
Figure 2. (a) DNA is usually double-stranded, whereas RNA is usually single-stranded. (b) Although it is single-stranded, RNA folds in on itself, the folds being stabilized by short regions of complementary base pairing within the molecule, forming a three-dimensional structure.
Cells access the information stored in DNA to make RNA, which directs the synthesis of proteins through translation. Proteins within the cell have many functions, including building cellular structures and acting as enzyme catalysts for cellular chemical reactions. The three main types of RNA directly involved in protein synthesis are messenger RNA (mRNA), ribosomal RNA (rRNA) and transfer RNA (tRNA).
In 1961, French scientists François Jacob and Jacques Monod hypothesized that there was an intermediary between DNA and its protein components, which they called messenger RNA. Evidence soon gathered to support their hypothesis, showing that information from DNA was passed to the ribosome for protein synthesis using mRNA. While DNA serves as a complete library of cellular information, mRNA serves as a photocopy of the specific information needed at a particular time, serving as instructions for making a protein.
MRNA carries the message from DNA that controls all cellular functions in the cell. If a specific protein needs to be synthesized for a cell, the gene for this product is turned “on” and mRNA is synthesized through the process of transcription (see RNA transcription). The mRNA then interacts with ribosomes and other cellular machinery (Figure 3) to direct the synthesis of the protein it encodes during translation (see protein synthesis). mRNA is relatively unstable and short-lived in cells, especially in prokaryotic cells, where proteins are made only when needed.
Chapter 4: Dna, Rna, And The Human Genome
RRNA and tRNA are the standard types of RNA. In prokaryotes and eukaryotes, tRNA and rRNA are encoded in DNA, which are then transcribed into long RNA molecules that release smaller fragments containing individual mature RNA species. In eukaryotes, synthesis, splicing, and splicing of rRNA into ribosomes take place in the nucleolus of the nucleus, but these functions occur in the cytoplasm of prokaryotes. Both of these types of RNA lack the instructions to direct polypeptide synthesis, but they play other important roles in protein synthesis.
Ribosomes are composed of rRNA and protein. As its name suggests, rRNA is a major component of ribosomes, making up 60% of the ribosome by mass and providing the mRNA binding site. rRNA ensures proper alignment of mRNA, tRNA and ribosomes; The rRNA of the ribosome has an enzymatic activity (peptidyl transferase) and catalyzes the formation of peptide bonds between two aligned amino acids during protein synthesis. Although rRNA was long thought to play primarily a structural role, its catalytic role within the ribosome was demonstrated in 2000. Scientists in the laboratories of Thomas Steeds (1940–) and Peter Moore (1939–) at Yale University were able to crystallize the ribosome structure.
, a halophilic archaeon isolated from the Dead Sea. Because of the importance of this work, he shared the 2009 Nobel Prize in Chemistry with other scientists who made significant contributions to the understanding of ribosome structure.
Transfer RNA is the third major type of RNA and is the smallest, typically only 70–90 nucleotides long. It carries the correct amino acid to the site of protein synthesis in the ribosome. It is the base link between tRNA and mRNA that allows the correct amino acid to be inserted into the polypeptide chain being synthesized (Figure 4). Any mutations in tRNA or rRNA can cause global problems for the cell, as both are essential for proper protein synthesis (Table 1).
Protein Production: A Simple Summary Of Transcription And Translation
Figure 4. The tRNA molecule is a single-stranded molecule that exhibits significant intracellular base pairing, giving it its characteristic three-dimensional shape.
Short (70–90 nucleotides), stable RNA with extensive intramolecular base pairing; There is an amino acid binding site and an mRNA binding site
Ensures proper alignment of mRNA, tRNA, and ribosome during protein synthesis; Promotes the formation of peptide bonds between amino acids
Although RNA does not function as genetic information in most cells, RNA has this function for many non-DNA viruses. Thus, RNA clearly has an additional capacity to act as genetic information. Although RNA is generally isolated within cells, there is significant variation in viruses. Rhinoviruses that cause the common cold; influenza viruses; and Ebola virus are single-stranded RNA viruses. Examples of double-stranded RNA viruses are rotaviruses, which cause severe gastroenteritis in children and other immunocompromised individuals. Since double-stranded RNA is uncommon in eukaryotic cells, its presence serves as an indicator of viral infection. Implications for a virus having an RNA genome instead of a DNA genome are discussed in detail in Viruses.
A Short Explanation Of The Fascinating Process Of Protein Synthesis
A nucleic acid is purified from a compound. The molecules are relatively small, contain uracil, and most are covalently bound to an amino acid. Which of the following is refined? Home Sports & Quiz History & Society Science & Technology Biographies Animals & Nature Geography & Travel Art & Culture Money Videos
The DNA in the cell nucleus contains a genetic code consisting of sequences of adenine (A), thymine (T), guanine (G), and cytosine (C) (Figure 1). RNA that contains uracil (U) instead of thymine carries the code to protein-making sites in the cell. To make RNA, DNA combines its bases with “free” nucleotides (Figure 2). The messenger RNA (mRNA) then travels to ribosomes in the cell cytoplasm, where protein synthesis occurs (Figure 3). Transfer RNA (tRNA) base pairs pair with mRNA and simultaneously place their amino acids into the growing protein chain. Finally, the synthesized protein is released to do its job in the cell or elsewhere in the body.
The specific carrier of genetic information in all living organisms is a nucleic acid called DNA, short for deoxyribonucleic acid. DNA is a double helix, two molecular helices that wrap around each other and connect adjacent bases by chemically linked bonds. Each long ladder-like DNA helix consists of a backbone that consists of an alternating sequence of sugars and phosphates. Attached to each sugar is a “base” consisting of the nitrogen-containing compound adenine, guanine, cytosine, or thymine. Each sugar-phosphate-base “run” is called a nucleotide. A very significant overlap occurs between the bases, ensuring the attachment of adjacent helices. Once the sequence of sites along a helix (half ladder) is specified, the sequence on the other half is also specified. Base pair specificity plays an important role in the replication of a DNA molecule. Each helix forms an identical copy of the other from the molecular building blocks in the cell. These nucleic acid replication events are mediated by enzymes called DNA polymerases. With the help of enzymes, DNA can be prepared in the laboratory.
A cell, whether a bacterium or a nucleus, is the smallest unit of life. Many fundamental properties of cells are a function of their nucleic acids, their proteins, and the interactions between these molecules bound by active membranes. Within the nuclear regions of cells is a complex of twisted and interwoven fine threads called chromosomes. Chromosomes are made up of 50-60 percent protein and 40-50 percent DNA by weight. During cell division, in all cells but bacteria (and some ancestral protists), chromosomes exhibit finely choreographed movement so that each descendant of the original cell receives an equal amount of chromosomal material. This mode of segregation corresponds in all details to the theoretically predicted mode of segregation of genetic material dictated by the basic genetic laws (
The Flow Of Genetic Information
Inheritance). Chromosomal composition of DNA and proteins (histone or protamine)
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