To be successful today 1 Set up Cornell
To be successful today… 1) Set up Cornell Notes for Protein Synthesis 2) New Semester & Expectations 3) New Spiral Notebook (8. 5 x 11 in) by TUES 1/16 BYOD Color of the day is Phones are in put away in backpacks
Essential Question: How is a protein made using the code of nucleotides from DNA?
G 1: Normal Cell Function
Recall… Where does protein synthesis occur? Where is DNA located?
RNA : Ribonucleic Acid
Turn to a Partner List all the similarities and differences with DNA and RNA
1) 2) 3) 4) 5) Single- stranded Ribose sugar Uracil replaces thymine Can leave nucleus with DNA’s instructions 3 types ~ m. RNA, r. RNA, t. RNA
Function of RNA Carries out DNA instructions by building proteins
3 Types of RNA 1. Messenger RNA (m. RNA) Carry copies of instructions for building a protein from nucleus to ribosome
2. Ribosomal RNA (r. RNA) Structural component of ribosomes
3. Transfer RNA (t. RNA) Transfers an amino acid to the ribosome to be added to the protein.
Talk to a Partner List the 3 types of RNA & their functions
Central Dogma of Biology
Protein synthesis occurs in two steps: 1. Transcription 2. Translation
Protein Synthesis in Prokaryotes Replication, transcription & translation occur in the cytoplasm at the same time
Protein Synthesis in Eukaryotes Replication, transcription & translation are separated by time and location
Transcription Process of copying a specific portion of DNA (gene), producing a complimentary strand of m. RNA acts like an intermediate link between DNA in the nucleus and protein synthesis in the cytoplasm Think of m. RNA as a temporary copy of DNA that is used and then destroyed
Steps of Transcription 1. RNA polymerase attaches to a promoter site, part of the DNA strand that codes for a gene, and separates that section of the DNA strand
Steps of Transcription 2. RNA polymerase uses one DNA strand as a template to assemble nucleotides into a complementary strand of m. RNA. This follows the base pairing rules for DNA replication except that in RNA, uracil rather than thymine, pairs with adenine.
Talk to a Partner…
Steps of Transcription continued 3. Once polymerase reaches the terminator site (end of the gene), m. RNA separates from the DNA strand & leaves the nucleus. DNA strands rejoin or zip closed.
Transcription Animation
Talk to a Partner Explain the process of transcription
Translation RNA to PROTEIN
Translation into a Proteins are made by joining amino acids with a peptide bond into long chains called polypeptides. Each polypeptide contains a combination of any or all of the 20 different amino acids.
The genetic code is read three letters at a time, so that each “word” of the coded message is three m. RNA bases long. This 3 -letter “word” is known as a codon. Each codon corresponds to a particular amino acid (the anti-codon on t. RNA).
Translation Animation
Steps to Translation
1. m. RNA leaves the nucleus and attaches to a ribosome 2. The t. RNA molecule with the correct anticodon attaches to the m. RNA codon.
3. The AA is released from the t. RNA. Peptide bond is formed between AA. 4. The m. RNA slides through the ribosome. The next t. RNA attaches to the m. RNA codon. 5. This process continues until a STOP codon is reached.
Talk to a Partner Translation: RNA to PROTEIN
Because there are 4 different bases, there are 64 possible 3 -base codons. 61 of them code for amino acids and 3 of them are “stop codons” that signal the end of the protein. There is also one codon that specifies methionine which serves as the “start” codon for protein synthesis.
Decoding codons into amino acids
Decoding codons into amino acids
DNA: TAC TGG CCT TCG ACT m. RNA: AUG ACC GGA AGC UGA t. RNA: UAC UGG CCU UCG ACU Amino Acids: Met-Thr-Gly-Ser
Talk to a partner… Which amino acids do the following m. RNA codons code for? UCU UCC UCA UCG AGU AGC This is known as redundancy in the genetic code….
Proteins Code for Traits The properties of proteins are determined by the number, order, and arrangement of amino acids joined together. Proteins provide the shape, structure, and pigment within your cells that you see as your physical traits Each m. RNA codes for a different protein & different proteins mean different traits
Proteins Code for Traits
To sum it all up:
m. RNA requires EDITING before use Pre-m. RNA transcribed in nucleus – not all bases will be translated into a protein Exons – DNA bases that are transcribed into m. RNA and eventually code for amino acids in proteins (=expressed genes) Introns – DNA basesthat are found btwn exons & are not translated into a protein (=interrupted genes)
m. RNA EDITING Image by Riedell
RNA editing continued Exons are spliced together by enzymes to create mature m. RNA that will become a protein Animation – no sound google chrome http: //www. dnalc. org/resources/ani mations/
Cornell Summary
Protein Synthesis
How does RNA POLYMERASE know where a gene starts and stops? Enzyme binds to places with specific DNA PROMOTERS sequences called ________. RNA POLYMERASE PROMOTERS tell _________ where to start. Signals at the end of the gene code cause transcription to _____ stop. http: //images 2. clinicaltools. com/images/gene/dna_versus_rna_reversed. jpg
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