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Protein Synthesis
University of Glasgow
20
Biology
Undergraduate 1
04/11/2013

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Term
gene expression
Definition
the process by which DNA directs the synthesis of proteins.
Term
base pairing
Definition
A=T (2 hydrogen bonds) C=G (3 hydrogen bonds)
Term
codon
Definition
triplet of nucleotides
Term
Purines
Definition
A and G. 2 organic rings
Term
Pyrimidines
Definition
T and C. 1 organic ring
Term
tRNA
Definition
transfer amino acids from cytoplasmic pool to ribosomes
Term
anticodon
Definition
nucleotide triplet which base-pairs with the complementary codon on the mRNA
Term
Explain the process of Transcription
Definition
1) RNA Polymerase (II) binds to promoter region on DNA
2) Transcription Initiation Complex formed : TATA Box
*Elongation*
3) RNA Polymerase unwinds and moves along DNA template strand 5' -> 3'
*Termination*
4) RNA Polymerase transcribes a POLYADENYLATION SIGNAL on DNA, this tells it to detach
Term
Polyadenylation Signal
Definition
The signal on DNA that tells RNA Polymerase (II) to detach
Term
Post Transcription, what happens?
Definition
RNA Splicing (Introns removed, Exons expressed) , Poly-A-Tail is attached to the 3' end and a 5' cap is attached to the 5' end, this completes the mRNA ready for translation
Term
Poly-A-Tail
Definition
the cap that goes onto the 3' end after transcription and splicing
Term
5' cap tail
Definition
the cap that goes to the 5' end of the mRNA after splicing
Term
Aminoacyl-tRNA synthetase
Definition
protein that matches the correct A.A. to tRNA in the cytoplasm , it bings the A.A. to tRNA via hydrolysis of ATP
Term
wobble
Definition
the ability of the 3rd codon to be different and still be read by tRNA/mRNA so it can code for an A.A.
Term
ribosome
Definition
produces proteins
Term
characteristics of ribosome
Definition
-small and large subunit
- made in nucleus by rRNA and proteins
- the few proteins that make up ribosomes come from the cytoplasm, transported from there to the nucleus
- 3 Binding sites
*E-Site : Exit site
*P-Site : peptidyl-tRNA binding site
*A-site : aminoacyl-tRNA binding site
Term
Explain the process of Translation
Definition
*Initiation*
1) Initiator codon AUG on the mRNA
2) large subunit binds to the small subunit, the mRNA shifts and the A site is ready for next tRNA anticodon
*Elongation*
3) A.A. added one by one to C' terminus
4) Elongation factor proteins help out
5) anti-codon binds to A-site, hydrolysis of GTP increases efficiency
6) Peptide bond formed between amino group and carboxyl end at the P-site
7) Peptide being formed (A.A. chain) attaches to A site so the tRNA molecule in the P site can shift over to the E-site
*Termination*
8) Stop codon UAG, UAA, UGA on mRNA stop the action
9) Release factor stops the codon at A site
10) addition of water (H2O) to the polypeptide chain so it breaks off and releases itself through the Exit tunnel
Term
Post Translation
Definition
the primary structure of the polypeptide chain fold itself , sugars, phosphates and lipids attach to it to aid its structure=function
- free ribosomes produce proteins that stay in cytosol
- bound ribosomes attach to rER
- signal peptides address proteins to cellular organelles or secretion
Term
point mutations
Definition
change in single pair nucleotide
Term
sickle cell disease
Definition
differ in one pair of nuclotides, instead CTT, its CAT, causing valine to be created making sickle cell hemoglobin to be produced
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