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Chapter 13 By Mrs. Pires

Proteins. Protein Synthesis. Chapter 13 By Mrs. Pires. Some background information…. Making Proteins. The human body is basically a bunch of proteins working together in a huge chemical reaction. DNA holds all the information (recipe) to make all the proteins in the body.

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Chapter 13 By Mrs. Pires

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  1. Proteins Protein Synthesis Chapter 13 By Mrs. Pires

  2. Some background information…. Making Proteins • The human body is basically a bunch of proteins working together in a huge chemical reaction. • DNA holds all the information (recipe) to make all the proteins in the body. • The DNA is located in the nucleus but the protein factory is the ribosome. • The DNA is too big and has too many responsibilities to leave the nucleus and go to the ribosomes to drop off a protein recipe. • DNA needs the help of a messenger!

  3. Some more background information…. Messenger RNA • The messenger RNA (mRNA) is like a disposable piece of DNA. • mRNA is assembled inside the nucleus from individual sugars, phosphates and bases that are floating around. • These pieces are put together in a specific order by copying a complimentary sequence of the DNA (which holds the protein recipe needed). This is called transcription.

  4. Messenger RNA continued • After the protein recipe is copied down by the mRNA, the messenger RNA leaves the nucleus and heads to the ribosome’s protein-making factory. • Proteins are made in a process called Translation.

  5. Compare - Contrast DNA and RNA

  6. Three types of RNA

  7. Here’s what the RNAs look like! mRNA:tRNA:rRNA:

  8. The DNA Code • Every 3 bases in the DNA (and mRNA) is called a codon. • Every codon codes for one amino acid. • Amino acids link together to form protein like beads on a string. • There are 23 basic amino acids in the body.

  9. DNA CODONS RNA CODONS

  10. Step 1: Transcription DNA  RNA An enzyme called RNApolymerase unwinds a section of DNA to be copied. One strand of the DNA double helix is used as a template (The template strand is also called the antisense strand) RNA polymerase binds to the “start codon” (promoter) at the beginning of a desired recipe on the DNA strand.

  11. TAC is the start codon • The START (promoter) codon is TAC on the DNA strand. • The mRNA strand copies the codons from the DNA using complementary base pairing until it gets to: • One of the STOP codons (ACT, ATT, or ATC). • These are also called repressors or terminator sequences. • The stretch of DNA that is transcribed into an RNA molecule is called a transcription unit. ACT, ATT, & ATC are the STOP codons

  12. Add the mRNA sequence:

  13. TranscriptionWatch it! • This completed mRNA migrates from the nucleus to the cytoplasm and heads to the ribosome. • The strand of mRNA is called the codon sequence (codon language). • http://youtube.com/watch?v=OtYz_3rkvPk&feature=related

  14. The Language Barrier • The mRNA gives the recipe to the ribosome to produce the protein. However, there is a problem. • The ribosome does notunderstandthe codon languagethat the recipe is written in. • Never fear…help is on the way in the form ofTransferRNA! tRNA

  15. Step 2: Translation • Transfer RNA (tRNA) is able to translate the codon language to the anticodon language so the ribosome can read it. • The ribosome binds to the mRNA at the start codon (AUG) that is recognized only by the initiator tRNA. mRNA < AUG The mRNA rolls between the two units on the ribosome.

  16. In this process, each set of 3 mRNA bases (the mRNA base triplet is called a codon) will pair with a complimentary tRNA base triplet (3 bases) called an anticodon.

  17. Translation: Watch it! • http://biology.kenyon.edu/slonc/bio3/ribo/ribo1.html • http://www.sciencenetlinks.com/interactives/protein.html

  18. Overall general protein synthesis • http://www.youtube.com/watch?v=XuUpnAz5y1g&feature=related

  19. Each tRNA is specific to an amino acid. • As tRNA's are added to the sequence, the amino acids begin to link together by peptide bonds as it grows. • The amino acid (peptide chain) will continue to grow until it reaches the stop codon on the mRNA. • Since there is no stop anticodon (tRNA) to match the stop codon, the ribosomal complex falls apart. • The amino acid chain, now called a protein chain, is release into the cell.

  20. Using the chart to figure out the amino acid from the mRNA

  21. Protein synthesis

  22. tRNA anticodon matches up with the 1st codon sequence of the mRNA.

  23. Name____________________________Date ____________Period _____Interactive: Protein synthesisReview and Practice 1. Type in the link below: www.wiley.com/legacy/college/boyer/0470003790/structure/tRNA/trna_intro.htm 2. Scroll down to page 2 where you will find the diagram below. 3. Click on “protein synthesis animation” under the diagram online. 4. Go through the Overview and Basic tutorials. 5. Complete the first two interactive activities dealing with the mRNA/amino acid chart. Put your answers on the back of this paper.

  24. TRY THIS!

  25. DO NOW! Using your mRNA/amino acid chart, DETERMINE THE AMINO ACID SEQUENCE OF THE DNA STRAND BELOW. • DNA: TAC GGA TCT GTA CTT ACG ACT • mRNA: ___ ____ ___ ____ ___ ____ ___ • tRNA: ___ ____ ___ ____ ___ ____ ___ • a.a.: ___-____ -___ -____-____-____-___ * Remember: the chart is based on mRNA.

  26. Mutations: • Are heritable changes in genetic information • Two types: • Gene mutations (a.k.a. Point mutations) • Chromosomal Mutations

  27. DNA engineering video clip with scenes from GATACCA http://www.pbs.org/wgbh/nova/genome/media/2809_q056_13.html

  28. Gene Mutations a.k.a. Point Mutations • Include: • 1. Substitutions (one base is changed into another) 2. Insertion results in a frameshift 3. Deletion

  29. Chromosomal Mutations: • Four main types: • Deletion • Duplication • Inversion • Translocation • Lets take a look---------------------

  30. Inversion • Some or all of the genes on a chromosome become reversed. • THE CAT ATE THE FAT RAT could become…. • THE TACETA EHTTAF RAT

  31. Deletion • Some or all of the genes on a chromosome are deleted. • THE CAT ATE THE FAT RAT could become…. • THE CAT RAT

  32. DuplicationDuplication • Some or all of the genes on a chromosome are doubled. • THE CAT ATE THE FAT RAT could become…. THE CAT CAT ATE THE FAT FAT RAT

  33. Translocation • Some or all of the genes on two different chromosomes either switch places like this: 1)THE CAT ATE THE FAT RAT 2)THE RAT ATE THE HAT could become…. • THE RAT ATE THE HAT RAT 2) THE CAT ATE THE FAT

  34. Translocation continued or some genes from one chromosome transfer to another like this: • THE CAT ATE THE FAT RAT • THE RAT ATE THE HAT could become…. 1) THE CAT ATE THE… 2) THE RAT ATE THE HAT FAT RAT

  35. Mutation Video animation Brac 1 • Brac 1: http://www.youtube.com/watch?v=4bGkUQBw1Rs • Sickle Cell and Malaria: • http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html

  36. CHNOPS Lab Gene A • DNA: ACC GGT TAT • mRNA: • tRNA: • A.A sequ: • Trait: In this lab, the chart is basd on tRNA not mRNA

  37. MY CHNOPS

  38. DO NOW! Using your mRNA/amino acid chart, DETERMINE THE AMINO ACID SEQUENCE OF THE DNA STRAND BELOW. • DNA: TAC GGA TCT GTA CTT ACG ACT • mRNA: ___ ____ ___ ____ ___ ____ ___ • tRNA: ___ ____ ___ ____ ___ ____ ___ • a.a.: ___-____ -___ -____-____-____-___ * Remember: the chart is based on mRNA.

  39. Making Synthetic Life4 video shorts (last 2 are best) • http://science.discovery.com/videos/creating-synthetic-life/

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