Test 4 Flashcards
Initiation (replication)
- Replication starts at the origin of replication (unique DNA sequence)
- DNA helicase binds at each origin and separates the 2 stands (“melting” DNA)
- Get replication “bubble”
Elongation (replication)
- Primer
- Short Piece of DNA
- DNA primase
- DNA polymerase III
Termination (replication)
- DNA polymerase I removes RNA primers and replaces with DNA
- DNA ligase makes new phosphodiester bonds between all DNA fragments
DNA Damage and Repair
- Replication export
- UV, xrays
- Carcinogens
- Chemicals
- Metabolism
- Mismatch Repair (Bacteria)
- Nucleotide excision repair (animals) and BER
- Photolyase (plant)
Beadle and Tatum
One gene/one protein hypothesis
Gene Structure
-DNA gyrase removes supercoils to allow forks to continue and for replication to complete
Transcription Mechanism
- RNA polymerase
- Transcription factors (Ch.11)
- 3 Stages
- Initiation
- RNA poly binds at the promoter and melts the DNA, forming a transcription bubble
- Initiation
- Elongation
- Termination
- RNA poly continues elongation until it hits a termination signal (not a stop codon)
- Falls off DNA and releases RNA polymer
RNA Modifications
- 5’-cap added
- 3’-poly A tail
- Introns are removed and exons “spliced” together
- Done by the spliceosomes
- Can lead to alternative splicing to increase diversity of proteins
Translation
Players:
- mRNA-coding region
- tRNA-transfer RNA
- Bring amino acids to ribosomes
- rRNA-ribosomal RNA
- Ribosome-collection of proteins and rRNA
- Amino Acids
Mechanism-3 Phases
- Synthesize enzymes, connect tRNA and amino acids (Charging tRNA)
- Small subunit of the ribosome binds to the mRNA and the first charged tRNA
Monomers
amino acids
polymers
polypeptide
polypeptides are connected by what type of bond?
Peptide
Primary structure:
Order that the amino acids are put together in polymer
Secondary structure:
Stabilized by hydrogen bonds
Tertiary structure
- final folded form of protein (globular, 3-D form)
- stabilized by hydrogen bonding and other molecular interactions
Quaternary Structure:
- Protein has more than 1 subunit
- Not all proteins have a Quaternary structure
