Lecture 12 - Lecture 12 Transcription and RNA Processing We...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 12 Transcription and RNA Processing
Background image of page 1

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

View Full DocumentRight Arrow Icon
We have seen already that genes contain exons (expressed regions) and introns (intervening regions). Genes (DNA) are transcribed into RNA. RNA is processed to remove introns by the splicosome. Alternative splicing allows for the production (translation) of more than 100, 000 proteins from about 25, 000 genes. DNA mRNA protein DNA rRNA or tRNA r = ribosomal t = transfer
Background image of page 2
Eukaryotic mRNA moves from nucleus to cytoplasm 32 P labeled uridine UTP is not incorporated into DNA
Background image of page 3

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

View Full DocumentRight Arrow Icon
RNA is usually single stranded nucleotide chain (not a double helix) RNA is more flexible than DNA and can form a range of complex 3-D shapes (structural conformation) stabilized by intramolecular pairing. RNA has ribose sugar rather than deoxyribose found in DNA. The two sugars differ in the presence of a hydroxyl group (OH) on the 2’ carbon; DNA has only hydrogen atom in this position (the deoxy part of its name). Sugar-phosphate linkages are made at the 5’ and 3’ positions of the sugar, just like DNA so that RNA chains also have 5’ and 3’ ends. RNA contains Uracil (U) in place of Thymine. U pairs (forms H-bonds) with A but can also pair with G in a weaker interaction RNA can catalyze reactions: Ribozymes
Background image of page 4
Unnumbered figure pg 297 Thymidine H 3 C RNA versus DNA
Background image of page 5

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

View Full DocumentRight Arrow Icon
The four ribonucleotides found in RNA Figure 8-2
Background image of page 6
Several classes of RNA 1. Messenger RNA (mRNA) transcribed from protein coding genes, translated into protein… 1. Functional RNA – gene-encoded but never translated into polypeptides. The main types are involved in the conversion of information from DNA to protein. . Transfer RNA (tRNA) : bring amino acids to the ribosomal complex for addition to the growing polypeptide Ribosomal RNA (rRNA) : comprise the major constituent of the ribosome that assemble amino acid chains
Background image of page 7

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

View Full DocumentRight Arrow Icon
Other functional RNAs include small nuclear RNAs (snRNAs) – involved in transcript processing micro RNAs (miRNAs) – involved in regulation of gene expression small interfering RNAs (siRNAs) – prevent viral advance and control spread of transposable elements. These 3 classes are found only in eukaryotes
Background image of page 8
Opposite DNA strands can serve as template for RNA For any given gene only one strand carries the gene sequence, the other strand carries the template for transcription. The same strand is always used as the template.
Background image of page 9

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

View Full DocumentRight Arrow Icon
Overview of transcription Local opening in the helix and binding of the RNA polymerase and associated factors initiates transcription of the target sequence. The template strand is transcribed as ribonucleotides are added with RNA polymerization proceeding in the 5’ to 3’ direction.
Background image of page 10
Many RNAs can be simultaneously transcribed from a gene Figure 8-5
Background image of page 11

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

View Full DocumentRight Arrow Icon
antiparallel complementarity directs the addition of ribonucleotides to the growing RNA molecule…
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 33

Lecture 12 - Lecture 12 Transcription and RNA Processing We...

This preview shows document pages 1 - 13. Sign up to view the full document.

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