L30: The Genetic Code
Translation of nucleotide sequence of a gene, through the medium of mRNA into the amino acid sequence of a protein. There are how many macromolecules that participate?
300 macromolecules participate
Aminoacyl-tRNA synthetases: A: "recognize" specific tRNA molecules and specific amino acids B: in conjugation with other enzymes attach the amino acid to the tRNA C: attaches a specific amino acid to any available tRNA species D: interacts directly with free ribosomes E: require GTP to activate the amino acid
A: "recognize" specific tRNA molecules and specific amino acids ***quiz question she gave***
What number base of the anticodon is the Wobble position/base? A: 1st base B: 2nd base C: 3rd base
A: 1st base bc first base of anticodon is the FIRST base of the mRNA codon
How many codons code for amino acids? A: 61 B: 43 C: 52 D: 81
A: 61
Abnormal Hemoglobin Wayne results in: A: abnormally long alpha-globin chains B: misfolded beta-globin proteins C: improper splicing of the intron/exon site D: reduced production of alpha-globin chains
A: abnormally long alpha-globin chains
Which of the following translate genetic information from mRNA into proteins? A: adaptors B: mRNA C: tiRNA D: rRNA
A: adaptors (tRNA)
The correct pairing of an amino acid residues with an appropriate tRNA is achieved by a family of enzymes called: A: aminoacyl-tRNA synthetases B: aminoacyl-tRNA synthases C: amino-tRNA synthetases D: amino-tRNA synthetases
A: aminoacyl-tRNA synthetases
If the FIRST base (wobble base) of the anticodon is CYTOSINE, it: A: can only pair with guanine B: it can pair with guanine or uracil C: it can pair with guanine or adenine D: it can pair with uracil, adenine or guanine
A: can only pair with guanine
If the FIRST base (wobble base) of the anticodon is ADENINE, it: A: can only pair with uracil B: it can pair with guanine or uracil C: it can pair with uracil or cytosine D: it can pair with uracil, cytosine or guanine
A: can only pair with uracil
Match the term with the example below: AUG coding for ONLY methionine amino acid. A: unambiguous B: degenerate C: central dogma D: the genetic map
A: unambiguous Each codon specifies only ONE AA
How many high energy bonds are expended for EACH amino acid activation? A: 1 B: 2 C: 3 D: 4
B: 2 -overall reaction of AA activation is essentially IRRESERSIVLE
If the mRNA codon is AUC, what is the tRNA anticodon sequence? A: 5'-UAG-3' B: 5'-GAU-3' C: 3'-GAU-5' D: 3'-GUU-5'
B: 5'-GAU-3' • The first base of the codon in mRNA (read in the 5' → 3' direction) pairs with the third base of the anticodon.
What mRNA codon would the tRNA 5'-UAC-3' be able to form a codon-anticodon bp interaction? A: 5'-AUG-3' B: 5'-GUA-3' C: 5'-UAC-3' D: 5'-CAU-3' E: 5'-GAU-3'
B: 5'-GUA-3'
What is the byproduct(s) of amino acid charging? A: ADP + Pi + aminoacyl-tRNA B: AMP + 2Pi + aminoacyl-tRNA C: GDP + Pi + aminoacyl-tRNA D: GMP + 2Pi + aminoacyl-tRNA
B: AMP + 2Pi + aminoacyl-tRNA
AUG is typically the initiator codon in eukaryotes, but what other codon is occasionally used as an initiator codon for methionine in eukaryotes? A: AUC B: CUG C: GUC D: AUU E: UGA
B: CUG
The cloverleaf of tRNA undergoes further folding to form a compact ____________ structure held together by __________ bonds. A: s-shaped; hydrogen B: L-shaped; hydrogen C: s-shaped; covalent D: L-shaped; covalent
B: L-shaped; hydrogen
Most tRNAs have what at the 5' end? A: the trinucleotide sequence CAA B: a guanylate reside (pG) C: a UGG sequence D: an RNA primer
B: a guanylate reside (pG)
Nucleotide triplets are read in ____________ fashion. A: an overlapping B: a non-overlapping C: concerted D: repeated
B: a non-overlapping
Amino acids are attached to tRNAs by what type of linkage? A: a phosphodiester link B: an ester link C: an ether link D: hydrogen bonding
B: an ester link
Where does the amino acid bind to the tRNA? A: at the ACC trinucleotide sequence at the 5' end of the tRNA molecule B: at the CCA trinucleotide sequence at the 3' end of the tRNA molecule C: at the ACC trinucleotide sequence at the 3' end of the tRNA molecule D: at the CCA trinucleotide sequence at the 5' end of the tRNA molecule
B: at the CCA trinucleotide sequence at the 3' end of the tRNA molecule
Match the term with the example below: GUU and GUC codons BOTH code for the same amino acid, valine. A: unambiguous B: degenerate C: central dogma D: the genetic map E: non-uniform degeneracy
B: degenerate • An amino acid may be specified by more than one codon- Degenerate
Abnormal Hemoglobin Wayne is caused by: A: insertion of uracil in the codon (UCU) for serine in the alpha-globin sequence, causing a frameshift mutation B: deletion of uracil in the codon (UCU) for serine in the alpha-globin sequence, causing a frameshift mutation C: deletion of cytosine in the codon (UCU) for serine in the alpha-globin sequence, causing a frameshift mutation D: deletion of cytosine in the codon (UCU) for serine in the beta-globin sequence, causing a frameshift mutation E: deletion of uracil in the codon (UCU) for serine in the beta-globin sequence, causing a frameshift mutation
B: deletion of uracil in the codon (UCU) for serine in the alpha-globin sequence, causing a frameshift mutation
The genetic code is unambiguous. What is meant by this? A: each protein has specific codons that code for it B: each codon specifies only one amino acid C: each protein has only one codon that specifies it D: an amino acid may be specified by more than one codon
B: each codon specifies only one amino acid like AUG [codon] codes for methionine [amino acid]
If the FIRST base (wobble base) of the anticodon is GUANINE, it: A: can only pair with cytosine B: it can pair with cytosine or uracil C: it can pair with cytosine or adenine D: it can pair with uracil, adenine or cytosine
B: it can pair with cytosine or uracil [Girls ,Ugly Cry = for when G FIRST]
Which of the following carries the genetic information transcribed from DNA? A: adaptors B: mRNA C: tiRNA D: rRNA
B: mRNA
What are open reading frames? A: open reading frames contain multiple codons in the mRNA that code for amino acids B: open reading frames contain a series of triplets without any termination codon C: open reading frames are the codons in the entire mRNA transcript
B: open reading frames contain a series of triplets without any termination codon
Abnormal Hemoglobin Wayne results in: A: producing a lysine amino acid where an asparagine amino should be produced B: producing an asparagine amino acid, when lysine should be produced C: producing a threonine amino acid, when serine should be produced D: producing a serine amino acid, when a threonine should be produced
B: producing an asparagine amino acid, when lysine should be produced
The four code letters of DNA (A, T, G and C) in groups of two can yield how many different combinations? A: 8 B: 24 C: 16 D: 64
C: 16 -The four code letters of DNA (A, T, G and C) in groups of two can yield only 4^2 = 16 different combinations, insufficient to encode 20 amino acids.
The aminoacyl-tRNA synthetases esterify how many amino acids to their corresponding tRNAs? A: 10 B: 15 C: 20 D: 21
C: 20
There are how many amino acids and how many possible codons? A: 20 amino acids; 60 possible codons B: 21 amino acids; 61 possible codons C: 20 amino acids; 61 possible codons D: 20 amino acids; 62 possible codons
C: 20 amino acids; 61 possible codons
ANY ssDNA/mRNA has how many possible reading frames? A: 1 B: 2 C: 3 D: 4
C: 3
The following are all the possible codons for Leucine [assume in 5'-3' order]: UUA UUG CUU CUC CUA CUG What MUST be the tRNA anticodon sequence that can pair with these 6 codons? A: 3'-AAG-5' B: 3'-IAG-5' C: 5'-IAG-3' D: 5'-GAI-3'
C: 5'-IAG-3'
What percentage of chemical energy used by a cell in biosynthetic reactions is involved in protein synthesis? A: 50% B: 75% C: 90% D: 80%
C: 90%
Mutations: A: are always inherited B: always result in dysfunctional proteins C: are changes in the base sequence of DNA that produce a change in the base sequence of mRNA, resulting in the possibility of an altered protein D: are changes in the mRNA sequence that result in incorrect reading frames
C: are changes in the base sequence of DNA that produce a change in the base sequence of mRNA, resulting in the possibility of an altered protein
Match the term with the example below: A certain strand of mRNA has the nucleotide sequence AUG-UUU-UCU, which till be translated into a AUG codon, a UUU codon and a UCU codon that codes for the amino acids methionine, phenylalanine and serine, respectively . A: unambiguous B: degenerate C: central dogma D: the genetic degeneracy E: non-uniform degeneracy
C: central dogma
Why is tRNA shaped like a clover leaf? A: cyclical torsion strain causes the conformation B: phosphodiester bonds in the backbone pair with other pentose sugars to create a clover-leaf-like structure C: complementary base-pairing of 4 segments with single-stranded open loop regions produce clover leaf-like structures D: hydrophobic structures in the middle of the tRNA cause the clover leaf conformation
C: complementary base-pairing of 4 segments with single-stranded open loop regions produce clover leaf-like structures
If the FIRST base (wobble base) of the anticodon is URACIL, it: A: can only pair with guanine B: it can pair with guanine or uracil C: it can pair with guanine or adenine D: it can pair with uracil, adenine or guanine
C: it can pair with guanine or adenine [U A God = U first]
Aminoacyl-tRNA synthetases: A: esterify 10 amino acids to their corresponding tRNAs B: participate in "charging tRNA" which is an exothermic process C: must be specific for BOTH the amino acid and the tRNA D: must be specific for BOTH the mRNA and tRNA
C: must be specific for BOTH the amino acid and the tRNA
A 4-year-old girl Annie was diagnosed with beta-thalassemia. Genetic analysis revealed that codon 17 of beta-globin gene has been changed from UGG to UGA. What type of mutation was detected in Annie's beta-globin gene? A: silent mutation B: missense mutation C: nonsense mutation D: frameshift mutation
C: nonsense mutation **quiz question she gave***
Which of the following decodes mRNA? A: adaptor proteins B: miRNA C: tRNA D: rRNA
C: tRNA
What establishes the reading frame? A: the mRNA transcript's linear sequence B: the AUG start codon in the mRNA C: the first mRNA codon D: the last mRNA codon
C: the first mRNA codon
What is the idea of the "second genetic code?" A: the idea that RNA can be interconverted to DNA through the use of viral vectors, reverse transcriptase and cDNA B: all of the genetic information stored in the mitochondrial DNA that participates in protein synthesis C: the interaction between aminoacyl-tRNA synthetases and tRNAs D: the ability to interconvert multiple types of RNA
C: the interaction between aminoacyl-tRNA synthetases and tRNAs
In the synthesis of a charged tRNA: A: there is only one aminoacyl-tRNA synthetase for all tRNAs B: each AA is added via an ester linkage to the 5' end of the tRNA C: there is a separate aminoacyl-tRNA synthetase for every amino acid D: ADP + Pi are included in the products formed E: the selection of the AA to be added is based exclusively on the anticodon sequence of the tRNA
C: there is a separate aminoacyl-tRNA synthetase for every amino acid ***quiz question she gave in class***
If a tRNA has the sequence 5'-CAU-3', what codon would it recognize (ignore wobble bp)? A: 3'-UAC-5' B: 3'-AUG-5' C: 5'-ATG-3' D: 5'-AUG-3' E: 5'-AUC-3'
D: 5'-AUG-3' ** quiz question she gave***
Groups of 3 can produce how many different combinations? A: 8 different combinations B: 24 different combinations C: 16 different combinations D: 64 different combinations
D: 64 different combinations 4^3 = 64
What is the start codon? A: UAA B: UGA C: UAG D: AUG E: GUA
D: AUG
Abnormal Hemoglobin Wayne is caused by: A: a point mutation B: a missense mutation C: a nonsense mutation D: a frameshift mutation
D: a frameshift mutation
mRNA codons are: A: a set of 3 genes that specify a particular protein B: a set of 3 amino acids that specify a particular protein C: a set of 3 amino acids that specify a particular nucleotide D: a set of 3 nucleotides that specify a particular amino acid
D: a set of 3 nucleotides that specify a particular amino acid
The coding sequence (CS)-1 is the normal coding strand of the gene. A mutation has occurred in CS-1 resulting in CS-2. The reading frame begins with the first NTs shown in the sequences below. CS-1: 5'- G A T T C A T G T T C G G A C T G G T G T A T-3' CS-2: 5'-G A T T C A T G T T C G G A C T G G A T-3' What is the consequence of the mutation shown by CS-2? A: a single AA is added in the coding sequence 2 B: a single AA is replaced by another AA C: this is a nonsense mutation that results in premature chain termination D: a single AA is missing in the coding sequence 2 E: splicing of the transcript is abnormal
D: a single AA is missing in the coding sequence 2 -there is 3NTs missing = a codon (TGT missing) ***quiz question she gave in class***
Which of the following is NOT a feature of the genetic code? A: triplet B: degenerate C: non-overlapping D: ambiguous
D: ambiguous **quiz question she gave***
The genetic code is DEGENERATE. What is meant by this? A: each protein has specific codons that code for it B: each codon specifies only one amino acid C: each protein has only one codon that specifies it D: an amino acid may be specified by more than one codon
D: an amino acid may be specified by more than one codon like GUA and GUU both might code for phenylalanine
The __________ of the tRNA molecule recognizes appropriate codons by complementary base pairing. A: complementary loop B: trinucleotide loop C: guanylate residue (pG) D: anticodon loop
D: anticodon loop
tRNA: A: translate genetic information from mRNA into proteins B: molecules have a adenylate residue at the 5' end C: molecules have a trinucleotide CAA at the 3' end where the amino acid binds D: is a ssRNA chain
D: is a ssRNA chain A: translate genetic information from mRNA into proteins -this is an adaptor B: molecules have a adenylate residue at the 5' end -guanylate residue** C: molecules have a trinucleotide CAA at the 3' end where the amino acid binds -CCA ***
The genetic code: A: is special sequences of the genome, stored in the nucleus and translated in the cytoplasm B: is the relationship between DNA and RNA C: is the relationship between DNA sequences and the process of how information is stored in the nucleus D: is the relationship between the sequence of bases in the DNA or mRNA and the sequence of amino acids in proteins.
D: is the relationship between the sequence of bases in the DNA or mRNA and the sequence of amino acids in proteins.
If the FIRST base (wobble base) of the anticodon is INOSINATE (I), it: A: can only pair with guanine B: it can pair with guanine or uracil C: it can pair with guanine or adenine D: it can pair with uracil, adenine or cytosine
D: it can pair with uracil, adenine or cytosine [I Always Come Unhinged --> when I first]
The phenylalanine (Phe) residue of Phe-tRNA was chemically converted to tyrosine (Tyr). When Try-tRNA was mixed with components of the protein synthesis machinery where will the Try from Try-tRNA be incorporated during the protein synthesis? A: it cannot be incorporated anywhere in the protein B: it will be incorporated where Tyr normally occurs C: it will be incorporated randomly where either Tyr or Phe occurs D: it will be incorporated where Phe normally occurs E: it will cause premature termination of the protein
D: it will be incorporated where Phe normally occurs ***quiz question she gave in class***
The genetic code is said to be degenerate because: A: it is non-overlapping and without punctuation. B: three amino acids in the protein are specified by each codon C: the same codon may specify more than one amino acid D: several different codons may specify the same amino acid E: when several different codons specify a single amino acid, the third base at the 3' end is always similar
D: several different codons may specify the same amino acid **quiz question she gave***
The aminoacyl group is esterified to: A: the 5' position of the terminal guanylate residue B: the 5' position of the terminal adenylate residue C: the 3' position of the terminal guanylate residue D: the 3' position of the terminal adenylate residue
D: the 3' position of the terminal adenylate residue
Charging of a tRNA molecule with the correct amino acid is dependent on: A: the anticodon loop B: the variable loop C: the codon of the mRNA D: the aminoacyl synthetase specific for that tRNA
D: the aminoacyl synthetase specific for that tRNA ***quiz question she gave***
Which is true of mRNA/tRNA interactions? A: tRNA base pairs with mRNA through the codon loop B: amino acids will get attached to the ACC sequence at the 3' end C: the first two bases of the mRNA codon form weak base pairs with the corresponding bases of the tRNA anticodon D: the first base of the codon in the mRNA pairs with the third base of the anticodon in the tRNA
D: the first base of the codon in the mRNA pairs with the third base of the anticodon in the tRNA
What happens if an incorrect amino acid is attached to a tRNA? A: RNA poly II will detect the incorrect amino acid and repair the mistake B: RNA repair enzymes after translation will detect the error and exchange the incorrect amino acid with the correct one C: chaperone proteins involved in proper protein folding will detect the incorrect amino acid and recruit peptidases and peptidyl transferases in order to remove the incorrect amino acid and replace it with the correct one D: the incorrect amino acid will be incorporated into a protein because there is no mechanism during translation to detect incorrect amino acids
D: the incorrect amino acid will be incorporated into a protein because there is no mechanism during translation to detect incorrect amino acids
What determines the linear sequence of amino acids in the protein? A: the order of the anticodons in the tRNA B: intron/exon splicing in DNA C: the order or nucleotides in the DNA D: the order of codons in the mRNA
D: the order of codons in the mRNA
Match the term with the example below: AUG is the only code for methionine and UGG is the only code for tryptophan, BUT there are 6 codons that code for the same amino acids arginine, leucine and serine . A: unambiguous B: degenerate C: central dogma D: the genetic map E: non-uniform degeneracy
E: non-uniform degeneracy
True or False: Amino acid tRNA activation is reversible.
False • Two high-energy phosphate bonds are expended for each amino acid activation. Thus, the overall reaction of amino acid activation is essentially irreversible.
True or False: A codon is a triplet of nucleotides that code for a specific amino acid and is universally seen in prokaryotes, eukaryotes and plant kingdom.
True
A __________ is a triplet of nucleotides that code for a specific amino acid.
codon -universal thru PRO/EUK and plant kingdom
True or False: The clover-shaped tRNA molecule goes under further folding to form a compact L-shaped structure, which is required for tRNA to fit into ribosomes.
true
