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