L13 GRQs Flow of Genetic information I PDF

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Guide reading questions for lecture 13...

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Flow of Genetic information I Guided Reading Qs (Reading 10.2-10.14) Reading Objectives:  Draw how the monomers of DNA are put together to form polynucleotides.  Explain how four nucleotides create so much variation.  Describe how specific DNA nucleotides encode specific protein sequences and how mutations in DNA affect proteins.  Name all the components of transcription, and how they function.  Name all the components of translation and how they function. Compare and contrast the processes and outcomes of DNA replication, transcription, and translation. 1. What makes up a nucleotide? How do the four nucleotides differ from each other? A sugar molecule, a nitrogenous base, and a phosphate group. Thymine and Cytosine are pyrimidines while Adenine and Guanine are purines. 2. What kind of bonds hold a nucleotides together in a polynucleotide? Are they strong? Covalent bonds. Yes. 3. What kind of bonds hold two polynucleotides together (what holds the double helix together)? Are they strong? Hydrogen bonds, and they are strong. 4. Draw a simple picture of a DNA polynucleotide (one half of the double helix), showing sugars, phosphates, bases.

5. Who was Rosalind Franklin? What did she contribute to the discovery of DNA’s structure? She produced the X-ray image of DNA. The image enabled Watson to deduce the basic shape of DNA.

6. What did Watson and Crick do to solve the structure? They imagined that the bases paired like with like, but soon they realized that the chemical structures of the bases dictated the pairings even more specifically. 7. What is the Watson-Crick pairing rule? A on one of DNA’s polynucleotide chains always pairs with T on the other polynucleotide chain, and G on one chain pairs only with C on the other chain.

8. If a DNA molecule was made of 20% A, what percent of the DNA would be T? And what % would consist of G? C? 20% T, and G and C are 30% separately. 9. Which 3 scientists won the Nobel Prize for the discovery of the structure of DNA? Watson, Crick, and Wilkins Why didn’t Rosalind Franklin win the prize? Rosalind Franklin died before the award ceremony of Nobel. 10. Where does the variation of DNA sequences come from? That is, you and an emu and an elephant and a bacterium all possess DNA, but how is your DNA different? The pairing of complementary bases accounts for the ability of DNA to be copied. We won’t go into much about how DNA replication occurs, so answer these next questions to get an overview: Describe figure 10.4A: A parental molecule of DNA separate and serve as templates. Then, the two identical daughter molecules of DNA are formed. Where does DNA replication occur in the cell? _nucleus____ What enzyme links DNA polymers together? ____DNA polymerases_________ 11. Think about the overview of what you are about to learn and put these words in order in a simple diagram: Translation, RNA, DNA, transcription, protein. RNA is synthesized by the direction of DNA through transcription, and protein is synthesized by the direction of RNA through translation. 12. What is the relationship between codons and amino acids? The RNA condons are translated into amino acids that form a polypeptides. 13. What does amino acid is coded by the mRNA sequence CAU? Histidine

What is the codon(s) for the amino acid valine (Val)? GUG GUA GUC GUU 14. In a few sentences that are your own, describe the process of transcription. Be sure to explain where it occurs in the eukaryotic cell, how it starts, what the enzyme does, and how it ends. Be sure to include these terms in your description: RNA polymerase, template strand, promoter, RNA nucleotides, terminator, and pre-RNA transcript. The DNA strands separate into two, one for the template of forming new RNA and one for unused. Then, the RNA polymerase move along the gene. The promoter determines where the transcription takes place and signals the start of transcription. In the end, terminator DNA is formed by the combination of RNA polymerase and RNA nuleotides. 15. How is transcription different from DNA replication?

Template(s)? Enzyme?

DNA Replication Both DNA strands DNA helicase & DNA polymerase

Nucleotides incorporated? ACGT End result?

2 daughter DNA

Transcription Single DNA strand Transcriptase, RNA polymerase ACGU

mRNA, tRNA, rRNA and non-coding RNA

16. What are the difference between a pre-mRNA and a mature mRNA? Pre-mRNA is an exact copy of the gene; The "mature" mRNA contains only exons 17. What are the two important sites that every tRNA has? (Draw a cartoon tRNA). Anticodon and amino acid attachment site

18. Ribosomes bring together what players in the process of translation? mRNA and tRNA. 19. Why is it significant that there are structural differences between prokaryotic and eukaryotic ribosomes? Certain antibiotic drugs can inactivate bacteria; ribosomes while leaving eukaryotic ribosomes unaffected. 20. What is the goal of translation? mRNA is decoded in a ribosome Where does translation occur? cytoplasm

How does translation begin? An mRNA molecule binds to a small ribosomal subunit. 21. If a tRNA had an anticodon of AAA, what codon would it recognize? The elongation will not stop. What amino acid would this same tRNA be carrying? Met 22. How does translation end? The stop codon reach the ribosome’s site 23. The bonds between amino acids are called _peptide_ bonds. They form during translation but are not catalyzed by an enzyme. What catalyzes this reaction? Ribosome....