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Protein synthesis: OverviewProtein synthesis: OverviewSection 5.2, page 237
DefinitionsDefinitionsGene – A sequence of nucleotides in DNA that
performs a specific function, such as coding for a particular protein
Proteins – Complex macromolecules composed of one or more polypeptide chains◦ Functions: hormones, enzymes, membrane structure
DNA is in the nucleus
Ribosomes (which synthesize protein) are in the cytoplasmHow does the ribosome synthesize the
protein, without having access to the DNA?
The central dogma of molecular biologyThe central dogma of molecular biology
RNA is an intermediate messenger molecule
The central dogma involves two steps:
1.Transcription2.Translation
Transcription:The information in DNA
is transcribed into a complementary mRNA message.
Translation:The ribosomes read the information in RNA and translate it, in order to synthesize a protein.
RNA: A nucleic acidRNA: A nucleic acid
uracil (U) in RNA pairs with the adenine (A) in DNA
Checkpoint:Checkpoint:A coding portion of DNA is shown below.What is the sequence of complementary
RNA that will be transcribed?
DNA: 3’- T A C T T A C G A T C G -5’RNA: 5’ - -3’
Classes of RNAClasses of RNAThree types:
1.messenger RNA (mRNA)2.transfer RNA (tRNA)3.ribosomal RNA (rRNA)
HomeworkHomework
Page 241 #1-5
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