Nucleic Acids
- Created by: R214116
- Created on: 02-03-20 09:06
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- Nucleic Acids
- DNA
- Structure
- Nucleotides
- A pentose sugar - deoxyribose
- A phosphate group
- 5'
- A nitrogenous base
- Pyrimidines
- Single C ring
- T and C
- Single C ring
- Purines
- Double C ring
- A and G
- Double C ring
- A forms 2H bonds with T
- G forms 3H bonds with C
- Pyrimidines
- Phosphodiester bonds
- Phosphate on 5' and OH on 3'
- Antiparallel
- Double helix
- Nucleotides
- Replication
- Semi-conservative replication
- 1. DNA helicase separates strands
- 2. Free nucleotides attracted to complementary bases
- 3. Once lined up, nucleotides joined by DNA Polymerase
- New DNA has one parent strand, one new strand
- Discontinuous Replication
- Unzipped from 5'
- Continuous replication
- Unzipped from 3'
- Evidence
- 1. Meselson and Stahl grew E.coli on medium with N15
- 2. Transferred to N14 for 1, 2 or 3 gens
- 3. Density centrifrugation
- 4. UV light
- RESULT - density decreased
- Conservative replication
- Completely new double stranded DNA made
- Parent DNA remains the same
- Semi-conservative replication
- Triplet code
- 3 base pairs are a codon
- Code for one AA
- A set of codons create a gene
- Introns
- Degenerate code
- 64 combinations, only 20 AAs
- Methionine
- Non overlapping
- Stop codons
- Non overlapping
- 3 base pairs are a codon
- Structure
- RNA
- Nucleotides
- Phosphate group
- A pentose sugar - ribose
- A nitrogenous base
- T replaced with U
- Nucleotides
- Protein Synthesis
- Transcription
- 1. DNA helicase unwinds DNA
- 2. Free RNA nucleotides complementary base pair
- Antisense strand 3'-5'
- 3. RNA polymerase catalyses phosphodiester bonds
- 4. At stop codon, transcription stops - mRNA formed
- 5. mRNA detaches from antisense and exits
- 6. Double helix reforms
- DNA polymerase
- Translation
- Ribosomes
- Large and small subunit
- Composed of protein and rRNA
- rRNA maintains structure and catalyses reactions
- tRNA
- One RNA strand folded
- Anticodon
- Complementary to a codon
- Carries AA that anticodon is complementary to
- 1. mRNA binds to small subunit of DNA at start codon
- 2. tRNA with complementary anticodon binds to mRNA start codon
- 3. tRNA lines up with next codon
- 4. Peptidyl transferase catalyses peptide bond between AAs
- 5. tRNA detaches and ribosome moves along strand until a stop codon
- Ribosomes
- Transcription
- DNA
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