What is a gene?
Identifiable DNA sequence coding for a specific product
Structural genes code for proteins
rRNA, tRNA genes code for ribonucleotide acids
How is a Gene Identified in the Genome?
Always read 5’ → 3’
Introns – intervening sequences
Promoter upstream from exon (includes TATA box and CCAAT box)
What are the Functions of a Gene?
Convert the information encoded by the DNA base sequence into molecules (usually
proteins) that determine cell properties and function
Replicate itself accurately so encoded information can be passed on
Process of converting information in base sequence to gene product
DNA → mRNA → polypeptide → protein
Central dogma of molecular biology
DNA → rRNA or tRNA
“1 gene = 1 protein” no longer valid
Human cell can make 100,000 proteins but only about 22,000 genes in genome
Why do Most Genes Code for Proteins?
Proteins may be:
Enzymes (catalyze metabolic reactions)