Protein Synthesis Transcription and Translation

8.4 and 8.5Protein SynthesisTranscription and TranslationBell Work1. A structure in the nucleus of the cell consisting of one long strand of DNA that is tightly coiled2. Provides blueprint for synthesis of proteins 3. A specific location on a chromosome, consisting of segments of DNA, that codes for a specific protein4. List two nucleic acids.5. List the three parts of a nucleotide.6. Which sugar does RNA contain?7. Which sugar does DNA contain?8. List the four bases that RNA has.9. List the four bases that DNA has.10. Which molecule has the shape of a double helix?11. What happens during DNA replication?12. When does DNA replication occur? Focus QuestionsWhat is protein synthesis?Define transcription and explain the process.What is the function of mRNA?

What is protein synthesis?Protein synthesis -Making proteins

RNA carries DNAs instructions. The central dogma states that information flows in one direction from DNA to RNA to proteins. The central dogma includes three processes.RNA is a link between DNA and proteins.

replicationtranscriptiontranslation Replication Transcription TranslationWhat is transcription?The process by which the DNA is copied to make a strand of RNAThrough this process the DNA code is transferred out of the nucleus to the ribosomeTranscription- How does it happen?An enzyme attaches to the exact location on the DNA molecule where the gene is found, causing the two strands of DNA to separate at that location.

start sitenucleotidestranscription complexTranscriptionComplementary RNA nucleotide bases bond to the bases on one of the separated DNA strands.DNA RNA A bonds with U T bonds with A C bonds with G G bonds with C

DNATranscriptionNucleotides of RNA bond together, forming a single-stranded molecule of RNA that peels away from the DNA strand and the two DNA strands rejoin. This is called messenger RNA (mRNA).

DNATranscriptionThe messenger RNA leaves the nucleus

Try This: Transcribe the messageUse the DNA code to make a complementary strand of mRNA.TAC GGG ATT TCC GAG CCA ATC CAG CCA ACT

Questions1. What is made during transcription? 2. Where does the mRNA go after transcription?

More Practice with transcriptionGo to class web page.Click on link for Build a Protein. Make the mRNA.Get signature of teacher in lab notebook.Stop for now. 8.5 Focus Questions1. Define translation.2. How is messenger RNA involved in translation? What is a codon? Distinguish start and stop codons. How are the codons related to the amino acids?3. How is transfer RNA involved in translation? What is an anticodon? Draw a diagram and label the parts of tRNA.4. Summarize the steps of translation. Amino acids are coded by mRNA base sequences. Translation is the process of interpreting the genetic message and building proteins.Describe the messenger RNA (mRNA)Carries the genetic message to the ribosomeA codon is a sequence of three nucleotides Each codon specifies a specific amino acid that will be placed in a chain to build a protein.The sequence of mRNA nucleotides determines the order of amino acids and which protein is produced

codon formethionine (Met)codon forleucine (Leu)The genetic code matches each codon to its amino acid or function.three stop codonsone start codon, codes for methionine

The genetic code matches each RNA codon with its amino acid or function.Transfer RNA (tRNA)tRNA transfers the amino acid into the correct sequenceThere are 20 different types of tRNA (one for each amino acid)At one end is the anticodon site that is complementary to mRNA codonAt the other end is the specific amino acid

Describe the transfer RNA (tRNA)

How are Ribosomes involved?Translation begins when the mRNA attaches to the ribosome.The ribosomes contain proteins and ribosomal RNA (rRNA)Ribosomes consist of two subunits.The large subunit has three binding sites for tRNA.The small subunit binds to mRNA.

The tRNA binds to a start codon and signals the ribosome to assemble.A complementary tRNA molecule binds to the next exposed codon, bringing its amino acid close to the first amino acid.

The ribosome helps form a polypeptide bond between the amino acids and the chain begins to form

The now empty tRNA molecule exits the ribosome to pick up another amino acid.

A complementary tRNA molecule binds to the next exposed codon.The process ends once the stop codon is reached.Compare the processesProcessOccurs in ProducesReplicationTranscriptionTranslation