Genetic Information

1. The RNA intermediate that carries genetic information to cytoplasm is messenger RNA [mRNA]

• 2. mRNA is a complementary copy of 1 of 2 DNA strands in gene (by process called transcription). • Since its sequence is complementary to that of the gene from which it is transcribed, it carries the same information as the gene itself • Allows separation of information storage (in huge, immobile DNA) & information utilization (smaller, more mobile RNA that passes into cytoplasm) • 3. Gene stays safe, while working mRNA copy serves as template to direct incorporation of amino acids into protein (mRNA is relatively unstable; its half-life is short, typically measured in hours). mRNA code read during translation by ribosomes.

1) Selected sites on the DNA are transcribed into premRNAs 2) They are processed into messenger RNAs 3) The messenger RNAs are transported out of the nucleus into the cytoplasm 4) They are translated into polypeptides by ribosomes that move along the mRNA 5) The polypeptide folds to assume its native conformation

• Genes are located on the chromosomes. • Every species has a different number of chromosomes. • There are two types of chromosomes: autosomes and sex chromosomes

• Genes are located on the chromosomes which are found in the nucleus of a cell. • When a cell is undergoing cell reproduction, the chromosomes are visible. Chromosomes appear when the chromatin condenses and become visible. • Most of the time (90%) the genetic material in the form of chromatin. • A genome is the complete genetic information contained in an individual. • (gene + chromosome)

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A long molecule 1 million Daltons Ephemeral Difficult to isolate mRNA provides the plan for the polypeptide chain

• Coiled • Two subunits: a long molecule 1 million Daltons a short molecule 42 000 Daltons • Fairly stable • Found in ribosomes • Made as subunits in the nucleolus • rRNA provides the platform for protein synthesis

• Short molecule...