ch369_f09_transc_notes

ch369_f09_transc_notes - Vocabulary Prokaryotes. The...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Vocabulary Prokaryotes . The single-cell organisms that lack a cell nucleus. The prokaryotes include the bacteria and archaea, which are actually separate branches on the tree of life. Eukaryotes . Organisms with cells that have nuclei. Includes people & yeast. An example of a bacterial cell from Wikipedia.
Background image of page 1

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

View Full DocumentRight Arrow Icon
“Transcription and RNA” - Chapter 19 Replication: DNA ============> copied DNA Transcription: DNA ============> mRNA, rRNA, tRNA, other RNA Translation: mRNA ==============> protein DNA polymerase Ribosome RNA polymerase
Background image of page 2
In transcription , an enzyme (RNA pol.) reads a DNA sequence and synthesizes an RNA with the same sequence as the DNA top strand (and complementary to the DNA bottom strand), except with U in place of T. Transcription: DNA =============> RNA RNA polymerase Example of transcription:
Background image of page 3

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

View Full DocumentRight Arrow Icon
Not all of an organism’s DNA is transcribed into RNA. “gene” = section of a DNA sequence that is transcribed into RNA by RNA pol. Only a fraction of the human DNA genome is transcribed into RNA. (in human genome, maybe 25% of DNA is transcribed to RNA) RNAs that are transcribed include: mRNA (messenger RNA) - codes for protein tRNA (transfer RNA) - delivers amino acids to ribosome in protein synthesis rRNA (ribosomal RNA) - component of the ribosome miRNA (micro RNA) - involved in regulation of gene expression.
Background image of page 4
Bacterial mRNA - relatively simple: RNA polymerase makes mRNA, which is translated to protein.
Background image of page 5

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

View Full DocumentRight Arrow Icon
mRNA production in eukaryotes is more complicated. transcriptio n Transcription, splicing and capping happen in the nucleus, mature mRNA is exported to cytosol.
Background image of page 6
In eukayotes, pre-mRNA is made in the cell nucleus, and then “spliced” by the “spliceosome” to remove “introns”. Introns ” and “ exons ”. Exons are the protein-coding segments of mRNA. Introns are the part of pre-mRNA that needs to be removed before it becomes a mature mRNA that encodes protein. A typical human mRNA may have 10 exons of 150 nt each, separated by 9 introns of 3000 nt each ! Bacterial mRNA does not contain introns. Most eukaryotic mRNAs do contain introns. RNA splicing ” refers to the process of removing introns from pre-mRNA to make mature mRNA that can be translated into protein by the ribosome.
Background image of page 7

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

View Full DocumentRight Arrow Icon
Splicing of introns from eukaryotic mRNA Introns are removed by a complex apparatus called the spliceosome . The spliceosome contains several RNAs and dozens of protein components (the RNAs are called the U1, U2, U4, U5, U6 RNAs).
Background image of page 8
E. coli - Has about 4000 DNA genes, for 4000 E. coli proteins.
Background image of page 9

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

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 34

ch369_f09_transc_notes - Vocabulary Prokaryotes. The...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online