Structure of m RNA

-

 

Structure of mRNA (Messenger RNA)

mRNA is a single-stranded RNA molecule that carries genetic information from DNA to ribosomes for protein synthesis.

1. General Features

  • Composed of ribonucleotides (A, U, G, C)

  • Single-stranded and linear

  • Has 5′ → 3′ polarity

  • Sequence is complementary to the DNA template strand

2. Structural Components of Eukaryotic mRNA

1. 5′ Cap

  • Modified 7-methyl guanosine (m⁷G) added to the 5′ end

  • Functions:

    • Protects mRNA from degradation

    • Helps ribosome binding

    • Required for nuclear export

2. 5′ Untranslated Region (5′ UTR)

  • Lies between the 5′ cap and start codon

  • Regulates translation initiation

3. Coding Region

  • Begins with start codon (AUG)

  • Ends with a stop codon (UAA, UAG, or UGA)

  • Contains codons that specify amino acids

4. 3′ Untranslated Region (3′ UTR)

  • Located after the stop codon

  • Involved in:

    • mRNA stability

    • Regulation of translation

5. Poly-A Tail

  • A stretch of adenine nucleotides (≈50–250 A’s) at the 3′ end

  • Functions:

    • Prevents degradation

    • Enhances translation

    • Aids nuclear export

3. Structure of Prokaryotic mRNA (Brief)

  • No 5′ cap

  • No poly-A tail (or very short)

  • Often polycistronic (codes for multiple proteins)

  • Contains Shine–Dalgarno sequence for ribosome binding

Diagram (Text Representation)

5′ Cap — 5′ UTR — AUG — Coding Region — Stop Codon — 3′ UTR — Poly-A Tail

If you want, I can also give a short exam answer, labeled diagram, or difference between prokaryotic and eukaryotic mRNA.

Popular posts from this blog

transport of metabolites from source to sink

-
  The transport of metabolites from a source to a sink location, primarily in plants, is a crucial process for nutrient distribution and growth. This process is mainly carried out by the   phloem , a vascular tissue. Here's a breakdown of the process: 1. Defining Source and Sink Source:  Any part of the plant that produces or releases metabolites in excess of its own needs, typically through photosynthesis or storage breakdown. Primary sources include mature leaves (producing sugars) and storage organs during mobilization (e.g., tubers converting starch to sugar). Sink:  Any part of the plant that consumes or stores metabolites. Sinks include growing regions (e.g., roots, young leaves, developing fruits, flowers, shoot tips), and storage organs during accumulation (e.g., tubers, fruits). 2. The Phloem Transport System The phloem consists mainly of: Sieve tube elements:  Living cells that form the transport pathway, specialized for bulk flow by lacking a nucleus ...
Read more

Chelating agents

-
  Chelating agents in plants play a crucial role in nutrient dynamics and heavy metal detoxification. They are organic molecules that can bind to metal ions, forming a stable, water-soluble complex called a chelate. This process significantly influences the availability and movement of essential micronutrients and toxic heavy metals within the plant and its environment. Here are the key functions of chelating agents in plants: Enhancing Micronutrient Availability and Uptake: Solubilization:  Many essential metal micronutrients (e.g., iron (Fe), zinc (Zn), manganese (Mn), copper (Cu)) exist in the soil in forms that are insoluble or poorly available for plant uptake, especially in alkaline soils. Chelating agents bind to these metal ions, converting them into soluble complexes that plants can more easily absorb through their roots. Transport:  Once absorbed, chelating agents can facilitate the transport of these metals from the roots to other parts of the plant (stems, lea...
Read more

Temperature stress

-
  Temperature stress in plants refers to the adverse effects on plant growth, development, and productivity caused by temperatures that deviate significantly from the optimal range for a specific plant species. These stresses can be categorized into heat stress (temperatures above optimal) and cold stress (temperatures below optimal). I. Heat Stress Heat stress occurs when temperatures rise to levels that inhibit physiological functions and can cause irreversible damage or even death. Prolonged exposure to temperatures just a few degrees above optimal can lead to stress. Physiological Effects: Membrane Damage:  High temperatures increase the fluidity of cell membranes, leading to leakage of ions and metabolites, disrupting membrane integrity and function. Protein Denaturation and Aggregation:  Enzymes and structural proteins lose their three-dimensional structure, leading to loss of function. This particularly affects critical metabolic enzymes. Photosynthesis Inhibition:...
Read more