Chp. 10 (pp. 189-210)
I.
II.
III.
IV.
Gene expression?
a. DNA used as a template to begin protein production
b. Transcription- (10.2)
i. copies part of the DNA sequence into a complimentary RNA molecule
ii. occurs in the nucleus
c. Translation- (10.14 &10.15)
i. manufacture of specific proteins
ii. aligning and joining amino acids
iii. occurs in the cytoplasm on a ribosome
iv. translates nucleotide language to protein language
d. Gene Expressioni. overall events of transcription and translation
e. genetic code- (Table 10.4)- YOU WILL USE THIS TABLE
i. relationship between gene (boss) and protein (worker)
Transcription
a. Relationship between DNA and RNA
i. One side of the DNA is copied- Template Strand
ii. One side is not copied – Coding Strand
iii. RNA Polymerase- enzyme that assists transcription (moves 3’ to 5’ direction)
b. RNA Structure and Types
i. RNA contains one nitrogenous base different than DNA- Uracil
1. no Thymine in RNA
ii. RNA folds into shapes called Conformations - allow the RNA to stay single stranded
iii. mRNA (Messenger RNA)- carries information from nucleus to ribosome
1. Condon- 3 mRNA bases in a row that specify a certain protein
2. mRNA are all different lengths depending on what they code for
iv. rRNA (Ribosomal RNA)- Structural support and catalyze formation of bonds between
amino acids
v. tRNA (Transfer RNA)- “connectors” bind mRNA codons at with specific amino acids
1. “carry” the amino acids
2. Anticodon- 3 bases within tRNA
c. Transcription Factors- initiate transcription at specific sites (~ 2000 different ones known)
d. Steps (Fig 10.7)
i. Initiation- transcription begins
1. Promoter- a special sequence in the DNA that starts transcription (TATA)
ii. Elongation- mRNA strand gets longer 5’ to 3’ direction
iii. Termination- transcription stops at the terminator sequence
e. RNA Processing - RNA is altered before it enters protein synthesis
Translation
a. Deciphering the genetic code - Use table 10.4
i. 3 bases within the mRNA code for an amino acid (Fig. 10.9)
b. Building a protein
i. Translation Initiation –
1. mRNA, tRNA, rRNA, ATP, amino acids come together
2. 1st mRNA codon is always AUG which codes for met (Methionine)
ii. Translation Elongation - Polypeptide formed (long amino acid chain)
iii. Translation Termination – stop codon is reached (UGA, UAG, UAA)
c. Protein folding – conformation leads to further specialization
The Human Genome – 3.2 billion DNA base pairs
a. Only 1.5 % encodes 100,000 – 200,000 different proteins
b. Proteomics – study the entire collection of proteins