Transcript RNA
RNA Higher Human Biology • Genotype = genetic constitution • Phenotype = physical and chemical state • The phenotype is determined by the proteins synthesised when the genes are expressed Structure of RNA • Ribose Sugar, base, phosphate • Uracil is the complementary base partner of Thymine • One strand Types of RNA • Messenger RNA (mRNA) – formed during transcription of DNA in the nucleus and is the template for protein synthesis at the ribosomes • Transfer RNA (tRNA) – carries specific amino acids to the ribosomes for translation of the genetic code • Ribosomal RNA (rRNA) – binds to proteins to form ribosomes Proteins • Polypeptide chains • Subunits called amino acids • Structure and function of protein depend on sequence of amino acids • This is controlled by the sequence of bases on the DNA Genetic Code • The sequence of bases along a DNA strand are grouped into triplets • Each amino acid in a protein is coded for by one or more of these triplets. Gene Expression • Genetic code is carried on DNA in the nucleus of the cell • Assembly of amino acids into polypeptides happens in the cytoplasm • Ribosomes Protein synthesis • A molecule of mRNA (messenger RNA) is transcribed in the nucleus • It leaves the nucleus via a pore in the nuclear membrane • Carries the information to ribosomes • The mRNA meets tRNA (transfer RNA) and the information is translated into a protein. By the end of the lesson • Draw a labeled diagram of a strand of RNA in your jotters • Cope the diagram at the foot of page 34 • Make a note of the 3 differences between RNA and DNA • Complete glossaries up until mRNA