CA Lesson 3: DNA, RNA, and Protein PDF

Lesson 3 DNA, RNA, and Protein  BellRinger How is DNA and RNA involved in transcription and translation?  Learning Objectives By the end of the lesson, students will be able to  Analyze the process of Central dogma of Biology and its importance  Central Dogma of Biology- wat...

Lesson 3 DNA, RNA, and Protein  BellRinger How is DNA and RNA involved in transcription and translation?  Learning Objectives By the end of the lesson, students will be able to  Analyze the process of Central dogma of Biology and its importance  Central Dogma of Biology- watch the Video and discuss How is DNA and RNA involved in transcription and translation?  Review Vocabulary synthesis: the composition or combination of parts to form a whole  Central Dogma Geneticists accept that the basic mechanism for reading and expressing genes is from DNA to RNA to protein. This is referred to as the central dogma of biology: DNA codes for RNA, which guides the synthesis of proteins.  Central Dogma Types of RNA RNA is a nucleic acid similar to DNA, but with the sugar ribose, and with uracil instead of thymine. There are three major types of RNA (see next slide for descriptions): Messenger RNA (mRNA) Ribosomal RNA (rRNA) Transfer RNA (tRNA)  Central Dogma Comparison of Three Types of RNA Name mRNA rRNA tRNA Functio Carries genetic Associates with Transports amino n information from protein to form acids to the DNA in the the ribosome ribosome nucleus to direct protein synthesis in the cytoplasm Exampl e  Central Dogma Transcription The first step of the central dogma involves the synthesis of mRNA from DNA in a process called transcription. The enzyme RNA polymerase regulates RNA synthesis. RNA polymerase moves along the DNA strand in a 5’ to 3’ direction, synthesizing mRNA.  Central Dogma RNA is transcribed in the 5’ to 3’ direction.  Central Dogma RNA Processing In comparing DNA code with its transcribed mRNA code, scientists found that the mRNA code was much shorter. DNA sequences not found in mRNA are called introns. DNA sequences that remain in the final mRNA are called exons.  The Code Scientists hypothesized that the instructions from protein synthesis were encoded in DNA. Experiments during the 1960s demonstrated that the DNA code was a three-base code. The three-base code in DNA or mRNA is called a codon.  Video-The Code Scientists hypothesized that the instructions from protein synthesis were encoded in DNA. Experiments during the 1960s demonstrated that the DNA code was a three-base code. The three-base code in DNA or mRNA is called a codon.  The Code The figure shows a “dictionary” of the genetic code. Notice that all but three codons are specific for an amino acid; these three are stop  The Code Translation After synthesis, mRNA moves from the nucleus into the cytoplasm, where it connects at the 5’ end to a ribosome. The mRNA code is read and translated into a protein through a process called translation.  The Code Translation tRNA molecules act as the interpreters of the mRNA codon sequence. The tRNA is activated by an enzyme that attaches a specific amino acid to the 3’ end. The middle of the folded tRNA contains an anticodon, a complementary sequence to the mRNA codon.  The Code The Role of the Ribosome Ribosomes provide a site for protein synthesis. When mRNA leaves the nucleus, the two ribosomal subunits come together to hold the mRNA in place for translation. The ribosome structure has grooves that serve as tRNA sites for amino acid attachment.  One Gene – One Enzyme The Beadle and Tatum experiment showed that one gene codes for one enzyme. We now know that one gene codes for one polypeptide.  Quiz 1 Which correctly lists the changes to. eukaryotic pre-mRNA to form mRNA? A cap added, introns excised, and poly T tail added B cap added, exons excised, and poly T tail added C cap added, introns excised, CORREC and poly A tail added T D cap added, exons excised, and poly A tail added  Quiz 2 What is the mRNA. sequence for the template strand DNA sequence in the figure? A 5’ ATGTTTGATCTT C 5’ TACAAACTAGAA 3’ 3’ B 5’ D 5’ AUGUUUGAUCUU CORREC UACAAACUAGAA T 3’ 3’  Quiz 3 What is the best summary of the. hypothesis Beadle and Tatum developed based on their experiments with Neurospora? A DNA to RNA to C translation follows protein transcription B one gene-one D one codon–one enzyme CORREC anticodon T  Quiz 4 How many mRNA or DNA bases make up a. codon? A 1 B 2 C 3 CORREC T D 4  Quiz 5 Which transports amino acids to the. ribosome? A DNA B mRNA C tRNA CORREC T D rRNA