The pathway of protein synthesis is called-
translation
each 3-base codon recognizes specific __________
amino acids
tRNA does what?
brings amino acids
What is an anti-codon
a sequence of three nucleotides in tRNA that binds to a corresponding in an mRNA sequence
a codon is composed of how many nucleotide bases?
3
Nucleotides in RNA are
uracil (U), adenine (A), guanine (G), and cytosine (C)
nucleotide sequences are always written from-
the 5' end to the 3' end
amino acids are coded by an-
mRNA sequence
What is the mRNA start codon?
AUG
What are the stop codons?
UAG, UGA, UAA
UAG, UGA, and UAA are not amino acids but they are-
termination codons
what are the characteristics of the genetic code?
specificity, universality, degeneracy, nonoverlapping and commaless
what is specificity?
each codon is specific to each amino acid
what is universality?
all mammas have the same genetic code
what is degeneracy?
multiple codons code for the same amino acids (redundant)
what is nonoverlapping and commaless?
codons are read in the same direction, in order, 3 codons at a time
What are the types of mutations?
silent, missense, nonsense, tri-nucleotide repeat expansion, splice site mutations, frameshift mutations
What is a silent mutation?
when a base is altered, but still codes for the same amino acid
What is a missense mutation?
when a base is altered and codes for a different amino acid
What is a nonsense mutation?
when a base is altered and codes for a termination codon
Which mutations can alter the amount or structure of the protein produced by translation?
trinucleotide repeat expansion, splice site, and frameshift
What is trinucleotide repeat expansion?
occurs when a sequence of 3 bases that is repeated in tandem will become amplified in number, which results in too many copies of the triplet
What is splice site mutation?
mutations that can alter how introns are removed from pre-mRNA. produce aberrant proteins
What is a frameshift mutation?
when 1 or 2 nucleotides are deleted/added to the coding region of a sequence. alters the reading frame.
what components are required for translation?
all amino acids are found in the finished product, mRNA to be translated, tRNA, functional ribosomes, energy sources, enzymes, and protein factors for initiation, elongation, and termination.
what is the function of tRNA?
carries a specific mRNA
How many species of tRNA are there in humans?
50
Where is the amino acid attachment site of tRNA?
3' end
What does the anticodon of tRNA do?
a three-base nucleotide sequence that recognizes a certain codon on the mRNA
What are aminoacyl-tRNA synthetases?
a group of enzymes that are required for the attachment of amino acids to their corresponding tRNA
Ribosomes consists of how many subunits?
2 (60S and 40S to form 80S) (weird ass math)
The large subunit does what
catalyzes the formation of peptide bonds that link amino acid residues in a protein
The small subunit does what
binds mRNA and is responsible for the accuracy of translation by ensuring correct base-paring between codons in mRNA and the anticodon of the tRNA
What happens at the A site?
binds an incoming aminoacyl tRNA as directed by the codon currently occupying the site (elongation)
What happens at the P site?
a peptide is bound between the amino acids
What happens at the E site?
occupied by the empty tRNA and exits the ribosome
RER associated ribosomes synthesize proteins that can become integrated into the-
plasma, ER, Golgi membranes, lysosomes
cytosolic ribosomes synthesize proteins that are needed in-
the cytosol, nucleus, mitochondria, and peroxisomes
what factors are needed for translation (protein synthesis)
initiation, elongation, and termination
cleavage of ______________________ is required for the addition of one amino acid to the growing polypeptide chain
4 high energy bonds
mRNA is translated from the _____end to the ______ end
5',3'
Proteins are synthesized from the ____________ terminal to its ___________ terminal end
amino, carboxyl
What does a polyribosome consist of?
several ribosomes simultaneously translating one mRNA
elF-2 needs to be ______________ to activate
dephosphorylated