DNA-RNA: Structure, Function, and Replication Process
Classified in Biology
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DNA-RNA: Chemical Composition
Formed by deoxyribonucleotides made up of phosphate, deoxyribose, and nitrogenous bases (adenine, guanine, cytosine, thymine), and by ribonucleotides made up of phosphate, ribose, and uracil.
Molecular Structure
Double-stranded structure and single.
Types
- Nuclear DNA found in chromatin, mitochondrial DNA in mitochondria, plastid DNA in chloroplasts.
- Messenger (mRNA), transfer, ribosomal.
Cell Location
- Chloroplast, mitochondria, nucleus.
- Cytoplasm, free or associated with ribosomes.
Function
- Contains the organism's genetic info.
- Synthesizes proteins according to genetic info in DNA.
Replication
Molecule of DNA replicates in the nucleus.
- The double helix of DNA opens and the strands separate.
- Free nucleotides attach to the separated DNA strands.
- Attached nucleotides join together.
- Two identical molecules of DNA are obtained.
Transcription
Molecule of mRNA is synthesized using a fragment of DNA as a template in the cytoplasm.
- Double helix of DNA opens.
- Complementary nucleotides are placed in front of the strands.
- Only one DNA strand is copied.
- An mRNA strand complementary to the DNA is created.
- The mRNA molecule exits the cell nucleus.
Translation
Protein is synthesized using info in mRNA in ribosomes.
- An mRNA molecule is created from the transcription of a DNA fragment.
- Ribosomes can be free in the cytoplasm or joined to the endoplasmic reticulum.
- tRNA carries amino acids to the ribosomes.
- Free amino acids in the cytoplasm.
Process:
- mRNA exits the nucleus with the copied DNA info.
- mRNA places itself on top of the ribosomes.
- tRNA carries amino acids to the ribosomes according to the genetic message in mRNA.
- Ribosomes translate mRNA into a protein.
- The finished protein separates from the ribosome.
Central Dogma of Molecular Biology
Modified due to the belief that cannot be questioned, discovery of certain viruses, prions, and ribozymes.