Mechanisms to correct damaged DNA.
Replication errors that have escaped the proof-reading process.
Damage that may occur in non-replicating DNA
Mismatch repair
Excision repair
Recombination(post-replication) repair
S.O.S. repair
2. DNA repair
Mechanisms to correct damaged DNA.
A. Replication errors that have escaped the proof-reading process.
B. Damage that may occur in non-replicating DNA
1. Mismatch repair
2. Excision repair
3. Recombination(post-replication) repair
4. S.O.S. repair
15. Transcription (Overall)
• One strand of DNA used as a template to
make a complimentary strand of mRNA
• Promoter/RNA polymerase/termination
site/5’ to 3’
• Ways in which RNA & DNA differ:
RNA is ss
RNA sugar is ribose
Base pairing-A-U
17. Types of RNA(important now!)
• Three types:
mRNA: messenger RNA
Contains 3 bases ( codon)
rRNA: ribosomal RNA
Comprises the 70 S ribosome
tRNA: transfer RNA
Transfers amino acids to ribosomes for protein
synthesis
Contains the anticodon (3 base sequence that is
complimentary to codon on mRNA)
18. Genetic code
• DNA: triplet code
• mRNA: codon (complimentary to
triplet code of DNA)
• tRNA: anticodon (complimentary to
codon)
20. Genetic code
• Codons: code for the production of a
specific amino acid
• 20 amino acids
• 3 base code
• Degenerative: more than 1 codon codes
for an amino acid
• Universal: in all living organisms
24. Translation
• Three parts:
Initiation-start codon (AUG)
Elongation-ribosome moves along mRNA
Termination: stop codon reached/polypeptide
released and new protein forms.
• rRNA=subunits that form the 70 S ribosomes
(protein synthesis occurs here)
• tRNA=transfers amino acids to ribosomes for
protein synthesis)