PROTEIN SYNTHESIS TRANSCRIPTION AND TRANSLATION

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Justina Reed
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1 ame Biology eriod Date RTEI SYTHESIS TRSRITI D TRSLTI D is the molecule that stores the genetic information in your cells. That information is coded in the four s of D: (cytosine), (guanine), (adenine), and T (thymine). The D directs the functions of the cell on a daily basis and will also be used to pass on the genetic information to the next generation. Because of its critical role in all the functions of the cell, D is kept protected in the nucleus of your cells. D is organized in sections called genes. enes code for proteins, and it is proteins that do all the work in the cell. They function as structural proteins serving as the building blocks of cells and bodies. nd they function as enzymes directing all the chemical reactions in living organisms. roteins are made in the cytoplasm by ribosomes. Since D cannot leave the nucleus, the information from D must be transmitted from the nucleus to the cytoplasm. During transcription, each gene on the D is read and codes directly for a messenger R (mr) molecule. The mr is made by matching its complementary s,,, and (uracil) to the D s. This process is called transcription, because the message is going from one version of nucleic acid language (D code) to another version of nucleic acid language (R code), so it is like transcribing from the key of to the key of in music. Before leaving the nucleus, this primary mr transcript is modified in several ways. Introns (intervening non-coding units) are edited out and exons (expressed coding sequences) are spliced together. In addition, a T cap and a poly- tail are added to the mr to protect it from Rase enzymes in the cytoplasm. This mature mr transcript then leaves the nucleus and carries the code for making the protein from the D gene in the nucleus to the ribosome in the cytoplasm. During translation, the ribosome reads the sequence of s on the mr in sets of three the triplet codons. nother type of R transfer R (tr) brings the protein building blocks s to the ribosome as they are needed. The ribosome bonds the amino acids together to build the protein coded for by the gene back in the nucleus. This process is called translation, because the message is going from nucleic acid language (D/R code) to the completely different language (protein code), so it is like translating from English to hinese. REDRE. btain the cardstock with sections of D. ut the strips out along straight lines and tape them together to make a long one-sided D molecule. Each section is numbered. Lay them out on the desk from left (#) to right (#). See the diagram below. This will form one long strand of D and will serve as the template strand of our gene. D. We are going to use this section of our D as a gene to be transcribed and then translated into a protein the cell needs. Remember it used to be part of a double-stranded D of Developed by Kim B. Foglia

ame Biology molecule. But it has already been unzipped and now will be used as the template to build mr, one at a time. The R polymerase enzyme will do this job.

Don t forget to only start transcribing downstream from the TT box promoter sequence. s you are transcribing, tape this mr molecule along its length to simulate the covalent bonds between s.

Remember it has to leave the D in the nucleus and travel to the ribosome in the cytoplasm. Follow the diagram below. D mr. You have just made a primary transcript.

lthough we will not be simulating intron and exon splicing in this lab, you do need to add a T cap and a poly- tail to the mr to protect the mr.

2 ame Biology molecule. But it has already been unzipped and now will be used as the template to build mr, one at a time. The R polymerase enzyme will do this job.. You have also been supplied with mr nucleotides. Build a mr molecule, one at a time, from this gene by transcribing your D template. Don t forget to only start transcribing downstream from the TT box promoter sequence. s you are transcribing, tape this mr molecule along its length to simulate the covalent bonds between s. This way, it will be a stable molecule and can be moved off of the D to the ribosome for translation in the cytoplasm. Do not tape the mr to the D! Remember it has to leave the D in the nucleus and travel to the ribosome in the cytoplasm. Follow the diagram below. D mr. You have just made a primary transcript. It must be processed so it successfully travels to the ribosome in the cytoplasm. lthough we will not be simulating intron and exon splicing in this lab, you do need to add a T cap and a poly- tail to the mr to protect the mr. lthough poly- tails may be - s long, add adenine s for your simulated poly- tail.. To be ready for the mr in the cytoplasm, design a ribosome to use in your simulation. Be sure to distinguish the small and large ribosomal subunits and mark the,, and E sites of the ribosome.. To help the ribosome do its job, use a pencil to draw lines which divide your mr into triplet codons. ow obtain tr molecules and write in the complementary anticodons to match your mr codons so that the trs bring the correct to the ribosome.. Label the name of the that each tr is carrying. To help you with this, use the mr codon chart and the code chart supplied by your teacher. Start reading the mr at the STRT codon and end at the ST codon. Follow the diagram below. of Developed by Kim B. Foglia

of the ribosome covalently bonding the amino acids in a polypeptide chain.

3 ame Biology growing protein mr. s the tr molecules match the mr codons, cut off the and bond them together in a chain to simulate the action of the ribosome covalently bonding the amino acids in a polypeptide chain. ttach your D, completed mr, and polypeptide chain to this packet when it has been completed.. se your D, your mr, and your polypeptide to answer the Summary Questions. of Developed by Kim B. Foglia

4 ame Biology of Developed by Kim B. Foglia SMMRY QESTIS. Record the gene sequence (downstream from the TT box) of the D strand (from to ) that coded for your mr.. Record the sequence of the mr strand (from to ) that you built from the D in this lab.. Divide the mr sequence into the triplet codons and list them in order below.. Record the sequence that this mr coded for.. Record the tr anti-codons that carried the s to the ribosome.

5 ame Biology MTTIS Sometimes when D is copied (replicated) errors occur. We call these mutations. When these mutations occur in gametes, they have the potential of being passed on to offspring and therefore will affect the next generation. Sometimes mutations cause only minor changes to a gene and therefore make only minor changes in the protein produced from that gene. These types of mutations may cause only minor effects to the phenotype of an organism. But sometimes mutations can cause great changes to the gene and therefore greatly alter the protein that is made from that gene. This will likely have great effects on the organism, since the protein will not be able to perform its normal function. This may lead to the inheritance of a genetic disease.. IT MTTI : ne mutation is called a point mutation where only one in the D is copied incorrectly during D replication. Here is your original D sequence from this lab and the sequence that was translated from it: T T T T T T T T T T T MET THR R LE S VL SER L R LY HIS ILE ST a. Let s simulate a point mutation at the th. It was accidentally changed during replication from a to a. ow transcribe this new D strand into mr, and then translate it into its sequence. T T T T T T T T T T T b. Did this change in the D sequence cause any significant change to the protein produced? Explain. of Developed by Kim B. Foglia

6 ame Biology of Developed by Kim B. Foglia c. What is the name of this type of point mutation and why is it referred to by this terminology?. IT MTTI : Here is your original D sequence from this lab and the sequence that was translated from it: T T T T T T T T T T T MET THR R LE S VL SER L R LY HIS ILE ST a. ow, let s simulate a point mutation at the th. It was accidentally changed during replication from a to an. ow transcribe this new D strand into mr, and then translate it into its sequence. T T T T T T T T T T T b. Did this change in the D sequence cause any significant change to the protein produced? Explain.

7 ame Biology of Developed by Kim B. Foglia c. What is the name of this type of point mutation and why is it referred to by this terminology?. IT MTTI : Here is your original D sequence from this lab and the sequence that was translated from it: T T T T T T T T T T MET THR R LE S VL SER L R LY HIS ILE ST a. Finally, let s simulate a point mutation at the st. It was accidentally changed during replication from a to an T. ow transcribe this new D strand into mr, and then translate it into its sequence. T T T T T T T T T T T T b. Did this change in the D sequence cause any significant change to the protein produced? Explain.

8 ame Biology c. What is the name of this type of point mutation and why is it referred to by this terminology? d. Why could a mutation in a gamete have more profound biological consequences than a mutation in a somatic cell?. Sickle cell anemia is an example of a genetic disease caused by a point mutation. a. Describe the specific D changes that produce the abnormal sickle cell hemoglobin. b. Explain the structural effect that this point mutation has on the hemoglobin protein. c. Explain why the sickle cell mutation is selected for in certain areas of the world. of Developed by Kim B. Foglia

9 ame Biology. FRMESHIFT MTTI : nother group of mutations is called frameshift mutations where at least one is either added to or deleted from the D as it is copied during D replication. Let s investigate the effects of these. a. Here is your original D sequence from this lab and the sequence that was translated from it: T T T T T T T T T T T MET THR R LE S VL SER L R LY HIS ILE ST b. Let s simulate a frameshift mutation by adding an additional between the th & th s. The was accidentally added to the sequence of the gene. ow transcribe this new D strand into mr, and then also translate it into its sequence. T T T T T T T T T T T c. Did this change in the D sequence cause any significant change to the protein produced? Explain. d. Why are insertions and deletions called frameshift mutations, and what is meant by the reading frame of a gene? of Developed by Kim B. Foglia

10 ame Biology of Developed by Kim B. Foglia FRMESHIFT MTTI : Here is your original D sequence from this lab and the sequence that was translated from it: T T T T T T T T T T T MET THR R LE S VL SER L R LY HIS ILE ST a. ow let s simulate a frameshift mutation by deleting the th. ow transcribe this new D strand into mr, and then also translate it into its sequence. T T T T T T T T T T b. Did this change in the D sequence cause any significant change to the protein produced? Explain. c. Which do you think would cause a more profound biological impact: () a deletion/insertion near the beginning of a gene, or () a deletion/insertion towards the end of a gene? Explain.

11 ame Biology. ystic fibrosis is an example of a genetic disease caused by a frameshift mutation. a. Describe the specific D changes that produce the abnormal cystic fibrosis protein (the delta F mutation). b. Explain the structural and functional effects that this frameshift mutation has on lung cells. c. Explain why cystic fibrosis shortens life span.. re mutations always deleterious? What is the evolutionary value of mutations? Explain. of Developed by Kim B. Foglia

12 T T T T T T T T T T T T T

18 tr tr tr tr tr tr tr tr tr tr tr tr

19 ame Ms Foglia Biology eriod Date mr DS of -

20 ame Biology eriod Date MI ID DES lanine L ysteine YS D sparticcid S E lutamiccid L F henylalanine HE lycine LY H Histidine HIS I Isoleucine ILE K Lysine LYS L Leucine LE M Methionine MET sparagine S roline R Q lutamine L R rginine R S Serine SER T Threonine THR V Valine VL W Tryptophan TR Y Tyrosine TYR of

Create a model to simulate the process by which a protein is produced, and how a mutation can impact a protein s function.

HASPI Medical Biology Lab 0 Purpose Create a model to simulate the process by which a protein is produced, and how a mutation can impact a protein s function. Background http://mssdbio.weebly.com/uploads/1//7/6/17618/970_orig.jpg