UMD BSCI 330 exam 2 Questions and Answers with complete solution
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Course
UMD BSCI 330
Institution
UMD BSCI 330
How does translation terminate? - ️️-stop codon (UAA, UAG,UGA)
-instead of tRNA, release factor binds to ribosome, causing hydrolysis of the peptidyl
tRNA, releasing the completed protein
-ribosome dissociates into its subunits, releasing mRNA, release factor, and tRNA
mRNA and protein synt...
UMD BSCI 330 exam 2
How does translation terminate? - ✔️✔️-stop codon (UAA, UAG,UGA)
-instead of tRNA, release factor binds to ribosome, causing hydrolysis of the peptidyl
tRNA, releasing the completed protein
-ribosome dissociates into its subunits, releasing mRNA, release factor, and tRNA
mRNA and protein synthesis are very energetically - ✔️✔️adding each subunit requires
the conversion of an NTP to an NMP, equivalent to hydrolyzing 2 ATPS to ADP
-elongation step consume multiple ATP/GTP
-splicing and proofreading use up even more ATP/GTP molecules
codon - ✔️✔️set of 3 nucleotides
-most amino acids have multiple corresponding codons
tRNA - ✔️✔️matches amino acids with codons
-amino acid is covalently attached to the 3' end of the tRNA
-contains loop with an anticodon that is complementary to the appropriate amino acids
codon
Amino acid activation - ✔️✔️-first activated by conjugation to AMP (energetically
expensive) then the aa is transferred to tRNA, resulting in a high energy bond
Proofreads translation - ✔️✔️Synthetase, each aa has a distinct synthetase which
proofreads for accuracy
ribsozyme - ✔️✔️rRNAs make up the structural and catalytic core
Ribosome function - ✔️✔️reads mRNA from 5 to 3, reading 3 bases at a time
-ribosome chooses one of three potential rwading frames
How does translation begin? - ✔️✔️codon AUG (Met)- which uses a special initiator
tRNA that differs from the Met tRNA used for the rest of translation
Elongation Factors - ✔️✔️-prokaryotes- EF-tu/EF-g
euk- EF1/2
- use GTPase activity to allow proofreading and to speed up ribosome translation
Protein Translation - ✔️✔️20 different amino acids
-triple nucleotide code= 64 different combinations
, polyribosome - ✔️✔️-a single mRNA may thus have several ribosomes translating
simultaneously
Antibiotics and protein synthesis - ✔️✔️-protein synthesis inhibitors
-most effect only prokaryotes, but sometimes can also affect ribosomes in mitochondria
and chloroplasts
The 3D structure of a protein determines its _________ - ✔️✔️function
describe the structure of primary proteins - ✔️✔️-linear sequence of amino acid residue
-determined by mRNA code
the structure of primary amino acids is dependent on? - ✔️✔️-covalent binds b/t amino
acids in linear sequence
-determines secondary tertiary and quaternary structures in combination with proteins
environment
describe structure of secondary proteins - ✔️✔️-folding & twisting of peptide backbone
-NO amino acid side chain interactions
_R groups stick out from backbone
the structure of secondary protein is dependent on? - ✔️✔️weak H-bonds b/t C=O
carbonyl & N-H amine groups in backbone
- NOT SIDE CHAINS
What are two well known structures of secondary proteins? - ✔️✔️-alpha helices
-beta sheets
describe the structure of alpha helix - ✔️✔️-rigid cylindrical structure
-coils clockwise down the length of the chain
the structure of alpha helix is dependent on? - ✔️✔️H-bonding between C=O & N-H
that are 4 amino acids apart ON BACKBONE
4 amino acids = ___ helix turns - ✔️✔️ONE
describe the structure of beta sheet's - ✔️✔️-flat, sheet-like structure
-perpendicular interactions
the structure of beta sheet's is dependent on? - ✔️✔️H-bonding is between C=O & N-H
on ADJACENT polypeptide chains
in beta sheet's, adjacent polypeptide chains can be
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