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BLA Biology ( ) June 6th 2017
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Ch. 11 & 12 Test, Wednesday Jun 7th 2017
COPY DATE, TOPIC & OBJECTIVE ON PG Date: Ch. 12. Gene Action Ch. 11 & 12 Test, Wednesday Jun 7th 2017 Topic(s) – Gene Expression: RNA, Transcription, Translation & Protein Synthesis (Day 2) Objective: SWBAT 1) Learn translation and protein synthesis using animation, notes and power point lecture; 2) Compare transcription and translation; and 3) Learn about mutation COPY HW, COPY& ANS.DO-NOW; COPY & ANS. EXIT TICKET ON PG. 67 HW: Organize your science journal, Unfinished CW/HW (if any), ET Complete Transcription & Translation Wksht. Work on Study Guide & Study for test Do Now (Refer to slip): None! Refer to the power point pkts CW: Gene Expression – Translation ( Transcription vs. translation ( Exit Ticket**: Refer to slip! Body of Lesson: (DO NOT HAVE TO COPY) 1) DN & DN Debrief ) Gene Expression 3) ET
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Pathway to Making a Protein
DNA mRNA tRNA (ribosomes) Protein
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The Genetic Code A codon consists of 3 nucleotides and it designates an amino acid An amino acid may have more than one codon There are 20 amino acids, but 64 possible codons Some codons tell the ribosome to stop translating
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The Genetic Code Use the code by reading from the center to the outside Example: AUG codes for Methionine
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Name the Amino Acids GGG? UCA? CAU? GCA? AAA?
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Codons and Anticodons Codon: Sequence of 3 bases
Anticodon: Sequence of 3 bases complementary to a codon Example: Codon ACU Anticodon UGA UGA ACU
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Remember the Complementary Bases
On DNA: On RNA: A-T A-U C-G C-G
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Protein Synthesis The production or synthesis of polypeptide chains (proteins) Two phases: Transcription & Translation mRNA must be processed before it leaves the nucleus of eukaryotic cells
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DNA RNA Protein Eukaryotic Cell DNA NUCLEUS Pre-mRNA mRNA
Nuclear membrane Transcription RNA Processing Translation DNA Pre-mRNA mRNA Ribosome Protein NUCLEUS Eukaryotic Cell CYTOPLASM
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Transcription vs. Translation
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Transcription The process of copying the sequence of one strand of DNA, the template strand mRNA copies the template strand Requires the enzyme RNA Polymerase
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Template Strand Complementary RNA strand for the following DNA sequence DNA 3’-GCGTATG-5’ RNA 5’-CGCAUAC-3’
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Transcription During transcription, RNA polymerase binds to DNA and separates the DNA strands RNA Polymerase then uses one strand of DNA as a template to assemble nucleotides into RNA
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Transcription Promoters are regions on DNA that show where RNA Polymerase must bind to begin the Transcription of RNA Called the TATA box Specific base sequences act as signals to stop Called the termination signal
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RNA Polymerase
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mRNA Transcript mRNA leaves the nucleus through its pores and goes to the ribosomes
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Translation Translation is the process of decoding the mRNA into a polypeptide chain Ribosomes read mRNA three bases or 1 codon at a time and construct the proteins
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Transcription Translation
Transcription occurs when DNA acts as a template for mRNA synthesis. Translation occurs when the sequence of the mRNA codons determines the sequence of amino acids in a protein. Translation
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Ribosomes Made of a large and small subunit
Composed of rRNA (40%) and proteins (60%) Have two sites for tRNA attachment --- P and A
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Step 1- Initiation mRNA transcript start codon AUG attaches to the small ribosomal subunit Small subunit attaches to large ribosomal subunit mRNA transcript
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Ribosomes Large subunit P Site A Site mRNA A U G C Small subunit
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Step 2 - Elongation As ribosome moves, two tRNA with their amino acids move into site A and P of the ribosome Peptide bonds join the amino acids
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Initiation G aa2 A U U A C aa1 A U G C U A C U U C G A codon hydrogen
2-tRNA G aa2 A U 1-tRNA U A C aa1 anticodon A U G C U A C U U C G A hydrogen bonds codon mRNA
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Elongation G A aa3 peptide bond aa1 aa2 U A C G A U A U G C U A C U U
3-tRNA G A aa3 peptide bond aa1 aa2 1-tRNA 2-tRNA anticodon U A C G A U A U G C U A C U U C G A hydrogen bonds codon mRNA
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Ribosomes move over one codon
aa1 peptide bond 3-tRNA G A aa3 aa2 1-tRNA U A C (leaves) 2-tRNA G A U A U G C U A C U U C G A mRNA Ribosomes move over one codon
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peptide bonds G C U aa4 aa1 aa2 aa3 G A U G A A A U G C U A C U U C G
4-tRNA G C U aa4 aa1 aa2 aa3 2-tRNA 3-tRNA G A U G A A A U G C U A C U U C G A A C U mRNA
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Ribosomes move over one codon
peptide bonds 4-tRNA G C U aa4 aa1 aa2 aa3 2-tRNA G A U (leaves) 3-tRNA G A A A U G C U A C U U C G A A C U mRNA Ribosomes move over one codon
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peptide bonds U G A aa5 aa1 aa2 aa4 aa3 G A A G C U G C U A C U U C G
5-tRNA aa5 aa1 aa2 aa4 aa3 3-tRNA 4-tRNA G A A G C U G C U A C U U C G A A C U mRNA
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Ribosomes move over one codon
peptide bonds U G A 5-tRNA aa5 aa1 aa2 aa3 aa4 3-tRNA G A A 4-tRNA G C U G C U A C U U C G A A C U mRNA Ribosomes move over one codon
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Termination aa5 aa4 aa3 primary structure of a protein aa2 aa1 A C U C
terminator or stop codon 200-tRNA A C U C A U G U U U A G mRNA
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End Product –The Protein!
The end products of protein synthesis is a primary structure of a protein A sequence of amino acid bonded together by peptide bonds aa1 aa2 aa3 aa4 aa5 aa200 aa199
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Messenger RNA (mRNA) Primary structure of a protein A U G C mRNA start
codon codon 2 codon 3 codon 4 codon 5 codon 6 codon 7 codon 1 methionine glycine serine isoleucine alanine stop codon protein Primary structure of a protein aa1 aa2 aa3 aa4 aa5 aa6 peptide bonds
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Summarizing Protein Synthesis
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DNA Replication vs. Protein Synthesis
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Hallmarks of Genetic Code
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Mutations Mutations are essential to evolution; they are the raw materials of genetic variation. Without mutation, evolution could not occur.
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(Agents that cause mutation)
Mutagens (Agents that cause mutation) Physical Factors 1. High Temperature 2. Radiation (X-rays, UV radiation, Ionization radiation-Alpha, Beta & Gamma Rays, Cosmic Radiation Chemical Factors 1. pH Changes 2. Chemicals a. Aflatoxins (produced by mold) b. Pesticides c. Colchicine d. Ozone
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Mutations Chromosomal Mutation Gene Mutation
Involves change in the structure or number of chromosomes Gene Mutation Involves change in one or more of the nucleotides in a strand of DNA (Gene)
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Point Mutation Sickle Cell disease is the result of one nucleotide substitution Occurs in the hemoglobin gene Autosomal recessive trait (Chromosome 11)
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Point mutations in our lives!
-Sickle cell anemia is a blood disease caused by a point mutation. -A single nucleotide is changed from “A” to “T” which causes the amino acid to change from glutamic acid to valine: Normal: ACT CCT GAG GAG Amino Acids: Thr – Pro – Glu – Glu Sickle cell: ACT CCT GTG GAG Amino acids:Thr – Pro – Val – Glu
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Point mutations in our lives!
-People with sickle cell anemia often experience a lot of pain and swelling and have trouble exercising. Sickle cells do not move smoothly through blood vessels like normal cells do. Sickle cells get stuck and cause blood clots. Sickle cells also can’t carry Oxygen as effectively as normal Cells.
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A case study of the effects of mutation: Sickle Cell Anemia
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A case study of the effects of mutation: Sickle Cell Anemia (Contd…)
3. Effects at cellular level 4. Negative effects at the whole organism level 5. Positive effect at the whole organism level: Resistant to malaria
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Mutation – A chain of causation
What happens at the DNA level propagates up to the level of the organism. Single mutation can have a large effect (both negative & positive in case of sickle cell disease). Changes at the DNA level propagate up to the phenotype.
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Stages of Mitosis (Onion Root Tip)
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Differences between Mitosis & Meiosis
1. Results in two identical diploid somatic cells 1. Results in four different haploid gametic cells 2. No laws apply 2. Both law of segregation & law of independent assortment apply 3. No crossing over takes place 3. Crossing over takes place 4. PMAT happens only once 4.PMAT happens twice: PMAT – I and PMAT – II 5. No pairing of homologous chromosomes 5. Homologous chromosomes pair 6. Involved in growth & repair of damaged tissues 6. Involved in reproduction 7. Asexual 7. Sexual
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