Ch. 14 Gene to Protein Date: 12/12/2018 AP BIO What you need to know: (WORK ON WORKSHEET) (THE GENETIC CODE SLIDE) ● The key terms: gene expression, transcription, and translation. ● The major events of transcription. ● How eukaryotic cells modify RNA after transcription. ● The steps to translation. ● How point mutations can change the amino acid sequence of a protein.
Concept 14.1: Genes specify proteins via transcription and translation Gene Expression: process by which DNA directs the synthesis of proteins (or RNAs) ● Old idea: one gene-one enzyme hypothesis (Function of a gene = dictate production of specific enzyme) Proposed by Beadle & Tatum – mutant mold experiments ● Newer idea: one gene-one polypeptide hypothesis ● Most accurate: one gene-one RNA molecule (which can be translated into a polypeptide) Flow of genetic information ➔ Central Dogma: DNA → RNA → protein ➔ Transcription: DNA → RNA ➔ Translation: RNA → protein ➔ Ribosome: site of translation
Flow of Genetic Information in Prokaryotes vs. Eukaryotes PROKARYOTES EUKARYOTES ● In cytosol ● Transcription and translation both in cytoplasm ● DNA/RNA in cytoplasm ● RNA poly binds directly to promoter ● Transcription makes mRNA (not processed) ● No introns ● During the process it attaches to the nuclear wall and exits and attaches itself to free or attached ribosomes to make produce different things. ● Transcription in nucleus; translation in cytoplasm ● DNA in nucleus, RNA travels in/out nucleus ● RNA poly binds to TATA box & transcription factors ● Transcription makes pre-mRNA → RNA processing → final mRNA ● Exons, introns (cut out)
one gene = one RNA molecule DNA RNA ● Nucleic acid composed of nucleotides ● Double-stranded ● Deoxyribose=sugar ●
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