lecture 20, plant DNA part 1 Flashcards
define genome
all genetic material of an organism (coding and non-coding)
what is the molecular structure of DNA
- double helix
- each nucleotide has a: phosphate group, a deoxyribose sugar, and a purine/pyrimidine base
- 5’ - 3’ direction
- strands are anti-parallel
- H bonds
what is the difference between RNA and DNA, chemically?
- sugar has an extra oxygen atom
- uracil instead of thymine
- single-stranded, does not form a regular helix
if 1 nucleotide “coded” for 1 amino acid:
we would only have 4 amino acids
if 2 nucleotides ‘coded’ for 1 amino acid:
4 (nucleotides) x 4 (combinations) = 16
if 3 nucleotides ‘coded’ for 1 amino acid:
64 amino acids
what direction does DNA run in?
5’ to 3’
what direction does RNA run in?
3’ to 5’
what is tRNA?
- 80 nucleotides
- amino acid attaches to 3’ end
- anticodon section: binds to mRNA codon
- 60 different tRNA molecules
ribosomes:
- 2 subunits; large and small
- rRNA and protein molecules
- mRNA binds to smaller subunit
- large subunit, 3 sites: aminoacyl, peptidyl, exit; binding sites for tRNA
initiator tRNA has the …
methionine, binds to AUG initiation code
what does the 2nd tRNA do?
binds to A site and its anticodon binds to mRNA; peptide bond formed between amino acids
when the ribosome reaches the termination codon (UGA), what site does the release factor occupy?
the A site
a string of amino acids = …
a polypeptide
what two pathways can a 30aa sequence enter?
- endomembrane
- cytosolic
