Group Activity 2 key PDF

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Group work key
Eileen Hotze instructor...

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BIO150

IN CLASS ACTIVITY #2

SPRING 2019

Group# ______ NAME:________________________________ID#__________________________________ NAME:________________________________ID#__________________________________ NAME:________________________________ID#__________________________________ NAME:________________________________ID#__________________________________ Would you rather fight one horse-sized duck or a ten duck-sized horses? To be answered by the oldest person in the group.

Groups Activity 2 Learning objectives. After completing this worksheet, students will be able to: 1. 2. 3. 4. 5.

Compare and contrast the structure of DNA and RNA. Describe how genetic information is retrieved in a cell. Explain the mechanism of transcription. Identify how RNA is post transcriptionally processed. Identify non-coding RNAs and their function in a cell.

Nucleic Acid Structure (LO1) 1. List below 4 characteristics describing the structure of DNA. a. DNA is a double stranded helix; has a major and minor groove; phosphate sugar backbone. b. DNA is a polymer composed of monomers (dNTPs) c. DNA has polarity—runs antiparallel (5’-3’) d. DNA double strands are held together by base pairing/hydrogen bonds.

2. Where on the figure below would you find the _____ i. Phosphate_A__ ii. Base__C__ iii. Hydroxyl group (OH)__B_

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BIO150

IN CLASS ACTIVITY #2

SPRING 2019

3. Compare and contrast the packaging of DNA in eukaryotes and bacteria. List at least one similarity and one difference. DNA in bacteria is typically circular where eukaryotes is linear. Eukaryotic DNA is located in a nucleus whereas bacterial is located in the cytoplasm. 4. Imagine you have discovered a new cell. To begin your investigation of this organism, you determine the percentages of adenine, thymidine, guanine, and cytosine. You discover that 20% of the organism’s DNA contains guanine. What percentage of uracil would you predict to be present? What percentage would be adenine? Since 20% is guanine then 20% is cytosine. Therefore 60% is AT. Hence, approximately 30% would be uracil (assuming all DNA is transcribed, which typically it would not).

5. In the figure below, indicate where the hydrogen bonds would form with a dashed line. Circle all of the hydrogen bond donors and box the hydrogen bond acceptors.

6. Hydrogen bonds can be broken by increasing the temperature 1°C per hydrogen bond. What would be the temperature needed to completely denature a double stranded DNA molecule with the following sequence: GGCGATTATGG. 34 degrees Celcius

Transcription (LO2/LO3) 7. Describe the usual flow of genetic information in a cell. DNA is replicated into DNA. The genetic information in DNA is transcribed into RNA. mRNA is then translated into protein. 8. DNA is transcribed into RNA by the enzyme RNA polymerase_, which is located in the nucleus_. mRNA is translated into proteins by ribosomes_ and this process occurs in the cytoplasm or rough ER_.

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BIO150

IN CLASS ACTIVITY #2

SPRING 2019

9. Using the word back below to fill out the blanks in the illustration. Some terms can be used more than once. DNA, RNA, RNA polymerase, template strand, non-template strand, 5’, 3’-OH.

a.__5’____

b.non-template

c. non-template

d.__5’_

e. __3’OH____

f. template strand

g._RNA polymerase

h.template

i.__ 5’___

j.__3’OH___

10. Identify three similarities and three differences between DNA and RNA. a. Similarities: Both are polymers of nucleotides. Both have directionality (5’-3’). Both are synthesized in 5’-3’ direction. Both use phosphodiester bonds for formation. Both use Adenine, guanine, cytosine. b. Differences: DNA uses dNTPs while RNA uses rNTPs. RNA is single stranded, not a double stranded helix like DNA. DNA is more stable. RNA incorporates uracil instead of thymine. c. 11. Sometimes the sequence of DNA gets mutated and an adenine is paired to a cytosine. Why is this interaction unstable? a. Because the phosphate groups of the two bases repel each other. b. Because an ionic bond cannot be formed between the two. c. Because the chemical groups that form hydrogen bonds are in the wrong positions. d. Because the charges on the bases repel one another.

12. Enhancer regions of the DNA act to recruit RNA polymerase to a gene. Some cancers are caused by mutations in this enhancer region. How would mutations in this region affect transcription at these genes? Mutations in the enhancer region will affect the rate of transcription from a gene. These mutations can either increase or decrease recruitment of RNA polymerase to the gene, hence affecting the amount of transcript made.

Ribonucleic Acid (LO3/ LO4) 13. Identify the three ways that the primary transcript of eukaryotes is processed and explain the purpose of these modifications. a. A 5’ cap is added to a mRNA acts to recruit ribosomes to the message. b. PolyA tail helps direct the transcript to the cytoplasm, is important for termination of transcription and helps increase resistance to RNases in the cell, hence increasing the half-life of the transcript.

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BIO150

IN CLASS ACTIVITY #2

SPRING 2019

c.

Transcripts undergo splicing events which excise exons from the message. They rid the transcript of non-translated regions of the mRNA and also offer a means of producing alternative translation products. 14. Why don’t bacterial primary transcripts get processed? Or do they? Bacterial transcripts do not get post transcriptionally processed like eukaryotes for several reasons. Transcription and translation are coupled in bacteria, meaning they occur at the same time. This is due to the fact that there isn’t a nucleus in bacteria. mRNA also have a Shine-Delgarno sequence (ribosome binding site) intrinsic in each message. Finally, no splicing occurs in bacteria. 15. The following sequence is part of a gene that encodes for a superpower. The top strand is the coding strand. 5’-AAGTGGGAGTTCACAT-3’ 3’-TTCACCCTCAAGTGTA-5’ a. Transcribe the gene below, write your answer in a 5’ to 3’ direction. 5’AAGUGGGAGUUCACAU-3’ 16. List three types of non-coding RNA and describe their functions in a cell. a. tRNAs are called transfer RNAs and they transfer amino acids to the ribosome during translation and help make proteins. b. rRNA are ribosomal RNAs and compose the majority of the ribosome structure. Additionally, they actually work to form the peptide bonds between amino acids in a protein. c. sRNAs are small nuclear RNAs that are part of the spliceosome that splices the mRNA.

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