3.4.2- DNA and protein synthesis Flashcards
Genetic code- features (3)
- Universal (same triplet codes for same AA in all organisms)
- Non-overlapping (each codon read separately)
- Degenerate (more than 1 triplet of bases can code for same AA)
introns vs exons
I= sections of DNA that DO NOT code for PP E= sequences of DNA that do code for AA
start & stop codon
start= three bases at start of every gene that initiates TRANSLATION
stop= 3 bases at end of every gene that causes ribosomes to detach & stop translation
Genome=
- organisms complete set of genes in a cell
- never changes
Proteome=
- full range of proteins a cell is able to produce
- constantly changing depending on which proteins are currently needed
2 stages of protein synthesis=
- Transcription (complementary mRNA of 1 gene produced)
2. Translation (mRNA> protein)
tRNA structure=
- carries a AA
- each tRNA specific to 1 AA
- A single polynucleotide strand folded> 3 loops, held together by H bonds
- Has an anticodon
Transcription process (5)
1) DNA double helix unzipped by helicase; H bonds broken
2) RNA nucleotides align next to complementary bases on TS; forming H bonds
3) RNA polymerase joins adjacent nucleotides (via C); forming phosphodiester bonds
4) when RNA p reaches stop codon, pre-mRNA detaches from DNA
5) mRNA leaves nucleus via nuclear pore
Post- T modification (In eukaryotes)
Splicing out of introns in mRNA, leaving behind just exons (coding regions)
translation process (6)
1) mRNA attaches to ribosome (on RER) in cytoplasm (at SC)
2) tRNA anticodon binds to complementary mRNA codon
3) tRNA brings specific AA
4) ribosome moves along one codon to allow another tRNA to attach to next codon
5) two AA joined by peptide bonds, using energy from ATP
6) tRNA detaches & R moves along mRNA strand to next codon to form the PP
