3.1 - Biological Information Flow Flashcards
What is the role of RNA molecules as a link between genes and proteins?
The process from gene to protein consists of two main steps - transcription and translation.
There are three main types of RNA: mRNA, rRNA, and tRNA.
mRNA is made from genes through transcription, carrying complementary genetic code copied in the form of triplets of nucleotides called codons.
rRNA binds to proteins and enzymes in the cytoplasm to form ribosomes that serve as sites for protein synthesis. These complex structures travel along mRNA molecules during translation, facilitating the assembly of amino acids to form polypeptide chains.
tRNAs are an essential component of translation, where their main function is the transfer of amino acids during protein synthesis.
Source: Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology. 4th edition.
Other types of RNA (Further Reading):
In addition to the major role of RNA in protein synthesis, several species of RNA are involved in post-transcriptional modifications, DNA replication and gene regulation.
Small nuclear RNA: snRNA is involved in the processing of pre-messenger RNA (pre-mRNA) into mature mRNA.
Regulatory RNAs: A number of types of RNA are involved in regulation of gene expression, including micro RNA (miRNA), small interfering RNA (siRNA) and antisense RNA (aRNA).
Transfer-messenger RNA (tmRNA) tag the proteins encoded by mRNAs that lack stop codons for degradation, and prevents the ribosome from stalling due to the missing stop codon.
Double-stranded RNA (dsRNA): a type of RNA has two strands bound together, as with double-stranded DNA. dsRNA forms the genetic material of some viruses.
Source: Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology. 4th edition.
What is the biological information flow from DNA to proteins in cells?
The central dogma of molecular biology describes the flow of genetic information in cells from DNA to messenger RNA (mRNA) to protein. It states that genes specify the sequence of mRNA molecules, which in turn specify the sequence of proteins.
What are the 3 steps that are common to transcription?
initiation, elongation, and termination.
