9.8 The Genetic Code and Translation Flashcards
________ is the process through which genetic information is converted to protein products
translation
how many bases are there per codon?
3
the code is _________ (redundant), some amino acids are coded by more than one _______
degenerate
codon
_____ are proteins that read the codons and attach the right amino acid. They have non-standard __________ that are essential for enzymes to recognize which protein they are dealing with and attach the right aa.
t-RNAs
nucleotides
what enzyme attaches the correct amino acid to the correct tRNA?
amino acyl-tRNA synthetase
how many amino acyl-tRNA synthetases are there?
20, one for each amino acid
amino acyl-tRNA synthetases are completely specific for both the _____ and _______
tRNA and amino acid
The _____________ recognizes specific modified nucleotides within individual tRNAs, allowing correct addition of amino acids.
amino acyl tRNA synthetase
are there the same amount of tRNAs as codons? (there are 61 codons not including stop codons). If not, how many tRNAs are there?
no. there are 48 tRNAs.
some tRNAs need to recognize more than 1 codon. The non-standard base pairing between the third base of the codon and the corresponding anticodon in the tRNA is called:
wobble
the most important modified nucleotide is _____ (closely related to guanine). Is is a purine or pyrimidine? What can it pair with?
inosine
purine
C, A, U
a mutation in the mitochondrial gene encoding leucine tRNA causes _______, a human genetic disease that has mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like symptoms.
MELAS
in MELAS, a mutation prevents the efficient recognition of the _____ by the appropriate ____________ and therefore interferes with synthesis of mitochondrial proteins.
tRNA
leucyl-tRNA synthetase
___________________ disease is a common genetics disease that results in peripheral neuropathy. Associated with mutations in the gene encoding for glycyl-tRNA synthetase.
Charcot-Marie-Tooth disease
Charcot-Marie-Tooth disease is caused by a mutation in the ____________, the _______ that attaches _____ to its appropriate _____.
glycyl-tRNA sythetase
amino acyl tRNA synthetase
glycine to its appropriate tRNA
the ______ is the fundamental machinery for translation
ribosome
translation always starts at the start codon ____, which codes for _____
AUG
methionine
in order to begin translation, an initiation complex is formed from the following factors:
- tRNAmet
- GTP
- small subunit of ribosome
- initiation factors (ex. eIF-2)
the initiation complex for translation recognizes the ____ structure at the 5’ end of an mRNA
cap
after binding the cap structure at the 5’ end of an mRNA, the initiation complex moves along the mRNA until it comes in contact with the first ____ sequence. ____ provides unwinding for secondary structures in the mRNA
AUG
eIF-2
In the process of translation: When the first AUG is located, ____ is hydrolyzed and ____ leaves the initiation complex. The large ribosomal subunit joins the complex and translation occurs.
GTP
eIF-2
What is the enzyme that catalyzes peptide bond formation on the ribosome? (between P and A sites on the large ribosome)
peptidyl transferase
a single mRNA translated by multiple ribosomes at the same time.
polysome
what are the three stop codons?
UAA
UGA
UAG
stop codons are not recognized by ____, thus when a stop codon is in vacant A site, a protein called a ___________ binds to the site. What does it do?
tRNA
release factor
attaches a water molecule to the end of the polypeptide chain - severing it.
