RNA
Cards (12)
- created by a chain of nucleotides
- sugar molecule (ribose)
- phosphate group
- nitrogenous base
- cytosine, guanine, adenine, uracil
- messenger RNA takes genetic code into cytoplasm from nucleus. it allows genetic code to be ‘read’ by ribosome. it is made in the nucleus
- ribosomal RNA ensures the correct alignment of mRNA, tRNA and ribosomeand an enzymic role in formation of peptide bonds between amino acids. makes up around 60% of the mass of a ribosome
- transfer RNA is able to carry a specific amino acid. it is a small molecule containing only 70-90 nucleotides
- transcription is the process by which genetic instructions are copied from DNA to mRNA molecule
- transcription is triggered by chemical messengers from cytosol that bind to DNA at relevant gene causing RNA polymerase to begin the process of making mRNA
- transcription process :
- Helicase enzyme makes DNA come apart. Usually separating 17 pairs at a time
- RNA polymerase joins nucleotides with complementary bases to template strand
- Sequence of bases tells RNA polymerase to stop copying
- mRNA is formed with bases same as the coding strand
- mRNA leaves nucleus into cytoplasm through nuclear pores
- often multiple other RNA polymerases will follow the first to make multiple copies of mRNA
- translation is the production of protein using information that is coded in the mRNA molecule
- translation process :
- Ribosomes attaches to one end of mRNA molecule at particular sequence of bases (start codon), this ensures ribosome attaches to correct end of mRNA
- Ribosome moves along mRNA three bases at a time. Each 3 bases is a codon and corresponds to a specific amino acid
- As ribosome reads codons, tRNA with complementary anticodon joins to mRNA
- Once amino acid is delivered, tRNA detaches from ribosome and can pick up another amino acid from cytosol
- For each bond formed between amino acids, energy form one ATP molecule is required
- folds in on itself forming hydrogen bonds between complimentary bases