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Learning objectives

  • Describe the biochemical structure of ribonucleotides
  • Describe the similarities and differences between RNA and DNA
  • Describe the functions of the three main types of RNA used in protein synthesis
  • Explain how RNA can serve as hereditary information

Structurally speaking, ribonucleic acid (RNA) , is quite similar to DNA. However, whereas DNA molecules are typically long and double stranded, RNA molecules are much shorter and are typically single stranded. RNA molecules perform a variety of roles in the cell but are mainly involved in the process of protein synthesis ( translation ) and its regulation.

Rna structure

RNA is typically single stranded and is made of ribonucleotides that are linked by phosphodiester bonds. A ribonucleotide in the RNA chain contains ribose (the pentose sugar), one of the four nitrogenous bases (A, U, G, and C), and a phosphate group. The subtle structural difference between the sugars gives DNA added stability, making DNA more suitable for storage of genetic information, whereas the relative instability of RNA makes it more suitable for its more short-term functions. The RNA-specific pyrimidine uracil forms a complementary base pair with adenine and is used instead of the thymine used in DNA. Even though RNA is single stranded, most types of RNA molecules show extensive intramolecular base pairing between complementary sequences within the RNA strand, creating a predictable three-dimensional structure essential for their function ( [link] and [link] ).

a) diagrams of ribose (in RNA) and deoxyribose (in DNA). Both have a pentagon shape with Oxygen at the top point of the pentagon. Both have an OH at carbon 1 and 3 and a CH2OH at carbon 4 (this last carbon is carbon 5). The difference is that ribose has an OH at carbon 2 and deoxyribose has an H at carbon 2. B) diagrams of thymine (T in DNA) and Uracil (U in RNA). Both have a single hexagon ring containing carbons and nitrogens. Both have a double bound O at the top carbon, and the bottom left carbon. The difference is that the top right carbon has an H in uracil and a CH3 in thymine.
(a) Ribonucleotides contain the pentose sugar ribose instead of the deoxyribose found in deoxyribonucleotides. (b) RNA contains the pyrimidine uracil in place of thymine found in DNA.
a) A diagram of DNA and RNA. DNA has the double helix shape with the helix of sugar-phosphates on the outside and the base pairs on the inside. RNA has a single helix of sugar-phosphates with nitrogenous bases along the length of the helix. B) A diagram showing RNA folding upon itself. The bases attached to the sugar-phosphate backbone can form hydrogen bonds if there are stretches of complimentary bases at some distance from each other on the long strand. Other regions do not have these hydrogen bonds.
(a) DNA is typically double stranded, whereas RNA is typically single stranded. (b) Although it is single stranded, RNA can fold upon itself, with the folds stabilized by short areas of complementary base pairing within the molecule, forming a three-dimensional structure.
  • How does the structure of RNA differ from the structure of DNA?

Functions of rna in protein synthesis

Cells access the information stored in DNA by creating RNA to direct the synthesis of proteins through the process of translation . Proteins within a cell have many functions, including building cellular structures and serving as enzyme catalysts for cellular chemical reactions that give cells their specific characteristics. 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 the existence of an intermediary between DNA and its protein products, which they called messenger RNA. A. Rich. “The Era of RNA Awakening: Structural Biology of RNA in the Early Years.” Quarterly Reviews of Biophysics 42 no. 2 (2009):117–137. Evidence supporting their hypothesis was gathered soon afterwards showing that information from DNA is transmitted to the ribosome for protein synthesis using mRNA. If DNA serves as the complete library of cellular information, mRNA serves as a photocopy of specific information needed at a particular point in time that serves as the instructions to make a protein.

Questions & Answers

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microbial intoxication results when a person ingests a toxin or a poisonous substance that has been produced by a microbe while infectious disease results when a pathogen colonize the body and subsequently cause disease.
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It is mainly used for media preparation and product testing purpose.
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study of living organisms that are too small to be visible with naked eye
microbiology is the study of microscopic organisms, either unicellular(single cell), multicellular( cell colony), or acellular (lacking cell).
is the word Atypical or a typical bacteria. .am confused pliz help
typical bacteria
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atypical means that it has some characters from bacteria not all characters ...but tybical means that it has all the characters that bacteria have
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some examples please
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1) typical bacteria contain a cell wall whereas atypical bacteria usually do not contain a cell . 2) typical bacteria can be either Gram-positive or Gram-negative while atypical bacteria remain colorless with Gram staining. 3) cells of typical bacteria are large ,while cells of the atypical small
Example of atypical : Mycoplasma pneumoniae , chlamydophila pneumoniae , legionella
what is micro biology
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is the study of organisms which can't be viewed by our necked eyes
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Antagonism: the combined action is less than that of the more effective agent when used alone). All these effects may be observed in vitro (particularly in terms of bactericidal rate) and in vivo والله اعلم
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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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