I.
Protein Synthesis:
Chp. 10 pp. 204-223
From DNA to proteins a.
Making mRNA from DNA i.
RNA stands for ribonucleic acid ii.
RNA is nucleic acid just like DNA iii.
RNA differs from DNA in the following ways
1.
Contain ribose instead of deoxyribose
2.
Contains the nitrogen base uracil (U) rather than thymine (T) a.
Uracil is complementary to adenine (A) b.
RNA follows base pairing rules for DNA except U pairs with A rather than T
3.
RNA is a single strand of nucleotides instead of 2 like DNA iv.
Transcription - DNA mRNA, has 3 steps (fig. 10-2) mRNA - Messenger RNA carries the instructions from the gene to the ribosome
1.
RNA polymerase binds to gene’s promoter - a “start” signal
2.
RNA polymerase unwinds and separates the 2 strands of double helix (DNA)
3.
RNA polymerase adds and then links the complimentary RNA nucleotide to the
DNA until it reaches a “stop” signal which releases the mRNA b.
Making proteins from mRNA (fig. 10-5) i.
Translation – mRNA tRNA amino acid
Instructions are read on the mRNA molecule and put together amino acids that make up the protein. ii.
RNA instructions are written in a series of 3-nucleotide sequences on the mRNA called codons . iii.
Each codon corresponds to a specific amino acid. iv.
Genetic Code - the amino acids and “start” and “stop” signals that are coded for by each codon (see fig. 10-4) v.
tRNA -a single strand of RNA that temporarily carries the amino acid to the mRNA
1.
Contains an anticodon which is a 3-nucleotide sequence complimentary a mRNA codon vi.
Translation occurs on the ribosome c.
rRNA -ribosomal RNA molecules which are part of the structure of ribosomes