{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

MICRO CH8 - Chapter 8 Transcription Translation and...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 8- Transcription, Translation, and Bioinformatics RNA Synthesis Transcription- making an RNA copy of part of a DNA strand Differences between DNA & RNA: DNA- made of deoxyribonucleotides Double stranded Nitrogen base thymine found in DNA but not RNA Sugar- deoxyribose RNA- made of ribonucleotides Single stranded Uracil instead of thymine Sugar- ribose 3 main types of RNA: 1. Messenger RNA (mRNA) - Encode proteins - Average 1000-1500 bases long 2. Transfer RNA (tRNA) - Carries amino acids to the ribosome to build a protein during translation 3. Ribosomal RNA (rRNA) - Component of ribosomes (site of protein synthesis) Template strand- DNA strand that is being copied into complementary mRNA RNA polymerase Enzyme that transcribes DNA into RNA by adding ribonucleotides onto 3’ end of growing RNA chain Needs no primer Recognizes specific start sequence on DNA called the promoter & starts transcribing DNA into RNA at that site Bacterial RNA polymerase - 4 subunits: alpha (2), beta, beta prime, and sigma - σ function is to help core enzyme locate promoter (beginning of gene) Multiple sigma factors   (over 100 known so far from numerous species) Sigma 70 “housekeeping” sigma factor used for most essential genes 1
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Sigma 32 Active when cell is stressed by heat (heat-shock response) Process of transcription 3 phases: 1. Initiation 2. Elongation 3. Termination Transcription Initiation Sigma factor binds core RNA polymerase Forms RNA polymerase holoenzyme RNA polymerase binds promoter Sequence on DNA 10 and 35 bases upstream of start site (on DNA before transcription site starts Polymerase unwinds DNA at promoter Open complex 1 st ribonucleotide base pairs to DNA at +1 position Transcription Elongation Sigma dissociates after about 9 bases have been joined Core RNA polymerase moves down the template DNA strand RNA strand is made 5’ to 3’( ribonucleotides added to 3’ end ) about 45 bases/second- complementary to the DNA Transcription Termination When RNA polymerase reaches terminator, transcription stops and RNA chain is released 2 known transcription termination sequences in bacteria : Rho-dependent termination Rho ( r ) factor binds to mRNA Slides along mRNA to polymerase breaks polymerase & mRNA off of DNA Rho independent termination Series of uracils downstream of pause site (
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern