Biology Study Guide TopicsEndocrine System | Lymphatic System | Blood | Circulatory System | Skull Bones | Human Skull and Brain | Tissue Types | The Cell | DNA | Anatomy Models | Electron Transport Chain | History of Microbiology | Human Anatomy | Punnett Squares | What is Mitosis | What is Life | Macromolecules | Cellular Respiration | DNA Replication | Enzymes | Pathogenic Bacteria | Natural Selection | Punnett Squares | Transcription and Translation | Exam Notes | Viruses | Osmosis | Protists | Genetic Code | Mendelian Genetics | Meiosis | Sensory Processing | Amino Acids |
Online PresentationsBones of the Human Skull | Tissue Types | Selective and Differential Media
Classroom ActivitiesRecombinant DNA Cut And Tape Classroom Activity
Transcription and Translation
Transcription of RNA from DNA
One of the central concepts of biology is that RNA is transcribed from DNA in a process called transcription. There are several types of RNA that can be transcribed including mRNA, rRNA and tRNA. mRNA (messenger RNA) is the type of RNA which codes for a protein and is ultimatley used to translate protein on the ribosome.
Several post-transcriptional processing steps occur in eukaryotes after the initial transcription of pre-mRNA. The intial pre-mRNA has introns spliced out and exons spliced together. Also, a 5' G-cap is added to the 5' (5 prime) end, and a 3' poly-A tail (many adenines- about 200) are added to the 3' (3 prime) end.
Translation of Protein from RNA
Protein is translated from mRNA on a structure called the ribosome. Ribosomes consist of many subunits of protein and rRNA.
RNA is transcribed from DNA by an enzyme called RNA Polymerase in a process called transcription. Protein is then translated from RNA (mRNA) on the ribosome in a process called translation. Thus, the flow of information in a cell is from DNA to RNA to protein which is referred to as the central dogma of molecular biology.
Three types of RNA are involved in the translation of protein at the ribosome. mRNA (messenger RNA) carries the code for the sequence of amino acids to build, tRNA (transfer RNA) serves as the adaptor which recognizes each codon on the mRNA and carries the corresponding amino acid to the ribosome. rRNA (ribosomal RNA) is a constituent of the ribosome itself and carries out critical enzymatic functions.