Chapter 6:
DNA (complemental strand) -> RNA -> Protein
The amount of the need of the protein in the cell determines the amount of RNA is made.
Uracil -> instead of thymine -> cheaper
RNA is single-stranded, because the OH-group is energetic unfavorable to form hydrogen
bonds.
In some regions double-stranded RNA is possible -> secondary structure of RNA ->
complementary groups of RNA form base pairs.
Types of RNA:
- mRNA -> messenger RNA -> code for proteins
- rRNA -> forms peptide bonds between amino acids
- tRNA -> the adaptor between mRNA and amino acids -> transport
- snRNA -> function in nuclear processes -> splicing pre mRNA
- snoRNA -> chemically modify rRNA’s
The template strand is 3’ till 5’ way, translated to RNA in 5’ till 3’ way.
Sigma factor -> complex together with the RNA polymerase -> bind at promoter -> make
RNA -> promoter clearance and sigma factor release -> RNA polymerase release -> RNA free
The sigma factor binds to the TATA-box (-10 place bases TATA)
RNA polymerase stops when reaching the stop codon. RNA complementary groups making
hydrogen bonds, which form a loop by binding.
Types of polymerases:
- Type I -> genes including rRNA genes
- Type II -> most important -> all protein-coding genes, snoRNA, miRNA for example
- Type III -> tRNA genes, some rRNA genes and some snRNA genes
RNA polymerase recognizes the TATA box and will bind -> when he sees the start codon
transcription starts
Factors needed for transcription initiation:
- TFIID -> has different subunits -> TBP (recognizes the TATA box) and TAF (recognizes
the start point of the DNA)
- TFIIB -> recognizes BRE element in promoters
- Some others but not necessary to know
, Some proteins needed for transcription:
- The TATA box binding protein unwinds the DNA and causes bonds.
- The activator protein binds with a loop from a distance to the RNA polymerase and
initiate the transcription.
- Histone-modifying enzyme -> it
- Chromatin remodeling complex
After transcription some stuff must be done to the RNA strand -> a 5’ RNA cap is placed -> a
3’ poly-A tail is placed -> these are necessary for export to the cytoplasm
Splicing -> an intron sequence contains an active base (mostly A) -> it can
do a nucleophilic attack at the 5’ exon place -> cuts it off -> another
attack at the 3’ exon place takes place -> cuts it off -> the intron is now
released.
The spliceosome does the splicing. RNA molecule is working as an
enzyme here.
Snurps (snRNA) binds and causes the loop, which facilitate the
nucleophilic attack.
Splicing mistakes:
- Sometimes exon skipping takes place.
- Only a portion of an exon is spliced.
o Cryptic splicing signals
- An extra exon is inserted
Dystrophin -> protein important for muscles -> when an exon is missing no dystrophin will be
made -> when another exon is missing altered dystrophin is produced.
CstF and CPSF are factors
Many PAP’s (poly-A binding Protein) cover the poly-A tail.
The mRNA molecule must undergo some changes/adding before transport to the cytosol.
Noncoding RNAs, like rRNA, are also synthesized. Some parts are removed just like the
intron splicing.
Methylation -> a methyl-group is added.
The nucleolus -> ribosome-producing factory -> ribosomal RNA is made here.
Cell-division:
- G2-phase -> preparation for mitosis
- Mitosis -> pro-, meta-, ana- and telophase
- G1-phase -> preparation for DNA replication
- S-phase -> DNA replication
DNA (complemental strand) -> RNA -> Protein
The amount of the need of the protein in the cell determines the amount of RNA is made.
Uracil -> instead of thymine -> cheaper
RNA is single-stranded, because the OH-group is energetic unfavorable to form hydrogen
bonds.
In some regions double-stranded RNA is possible -> secondary structure of RNA ->
complementary groups of RNA form base pairs.
Types of RNA:
- mRNA -> messenger RNA -> code for proteins
- rRNA -> forms peptide bonds between amino acids
- tRNA -> the adaptor between mRNA and amino acids -> transport
- snRNA -> function in nuclear processes -> splicing pre mRNA
- snoRNA -> chemically modify rRNA’s
The template strand is 3’ till 5’ way, translated to RNA in 5’ till 3’ way.
Sigma factor -> complex together with the RNA polymerase -> bind at promoter -> make
RNA -> promoter clearance and sigma factor release -> RNA polymerase release -> RNA free
The sigma factor binds to the TATA-box (-10 place bases TATA)
RNA polymerase stops when reaching the stop codon. RNA complementary groups making
hydrogen bonds, which form a loop by binding.
Types of polymerases:
- Type I -> genes including rRNA genes
- Type II -> most important -> all protein-coding genes, snoRNA, miRNA for example
- Type III -> tRNA genes, some rRNA genes and some snRNA genes
RNA polymerase recognizes the TATA box and will bind -> when he sees the start codon
transcription starts
Factors needed for transcription initiation:
- TFIID -> has different subunits -> TBP (recognizes the TATA box) and TAF (recognizes
the start point of the DNA)
- TFIIB -> recognizes BRE element in promoters
- Some others but not necessary to know
, Some proteins needed for transcription:
- The TATA box binding protein unwinds the DNA and causes bonds.
- The activator protein binds with a loop from a distance to the RNA polymerase and
initiate the transcription.
- Histone-modifying enzyme -> it
- Chromatin remodeling complex
After transcription some stuff must be done to the RNA strand -> a 5’ RNA cap is placed -> a
3’ poly-A tail is placed -> these are necessary for export to the cytoplasm
Splicing -> an intron sequence contains an active base (mostly A) -> it can
do a nucleophilic attack at the 5’ exon place -> cuts it off -> another
attack at the 3’ exon place takes place -> cuts it off -> the intron is now
released.
The spliceosome does the splicing. RNA molecule is working as an
enzyme here.
Snurps (snRNA) binds and causes the loop, which facilitate the
nucleophilic attack.
Splicing mistakes:
- Sometimes exon skipping takes place.
- Only a portion of an exon is spliced.
o Cryptic splicing signals
- An extra exon is inserted
Dystrophin -> protein important for muscles -> when an exon is missing no dystrophin will be
made -> when another exon is missing altered dystrophin is produced.
CstF and CPSF are factors
Many PAP’s (poly-A binding Protein) cover the poly-A tail.
The mRNA molecule must undergo some changes/adding before transport to the cytosol.
Noncoding RNAs, like rRNA, are also synthesized. Some parts are removed just like the
intron splicing.
Methylation -> a methyl-group is added.
The nucleolus -> ribosome-producing factory -> ribosomal RNA is made here.
Cell-division:
- G2-phase -> preparation for mitosis
- Mitosis -> pro-, meta-, ana- and telophase
- G1-phase -> preparation for DNA replication
- S-phase -> DNA replication
