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86 Cards in this Set
- Front
- Back
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Polypeptides are strings of amino acids that are assembled by what? |
Ribosomes |
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tRNAs (with amino acids attached) used during translation are ___ (charged/uncharged) |
Charged |
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What substances transport amino acids to the ribosome? |
tRNAs |
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During translation, complementary base pairing takes place between the mRNA ___ (codon/anticodon) and the tRNA ___ (codon/anticodon) |
mRNA codon, tRNA anticodon |
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One of the boundaries of translation is the start codon which corresponds to the ___ (N-/C-) or ___ (amino/carboxyl) terminus |
N- or amino terminus |
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One of the boundaries of translation is the stop codon which corresponds to the ___ (N-/C-) or ___ (amino/carboxyl) terminus |
C- or carboxyl terminus |
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What are the 2 ends of a polypeptide? |
Amino and carboxyl |
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In translation, the 5' UTR and 3' UTR are segments of the mRNA ___ (outside/inside) the translated regions |
Outside |
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The basic functions of ribosomes in eukaryotes and prokaryotes are ___ (the same/different) |
The same |
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One function of ribosomes is to: Bind ___ (DNA/mRNA) and identify the ___ (start/stop) codon, which is where translation begins |
Bind mRNA and identify the start codon |
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One function of ribosomes is to: ___ (Prohibit/Facilitate) complementary base pairing of mRNA codons and the corresponding tRNA anticodons |
Facilitate |
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One function of ribosomes is to: Catalyze formation of ___ (hydrogen/phosphodiester/peptide) bonds between amino acids on the growing polypeptide chain |
Peptide bonds |
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What 2 components make up ribosomes? |
rRNAs and proteins |
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The ___ (A/P/E)-site of a ribosome binds a new tRNA molecule containing an amino acid to be added to the growing polypeptide chain |
A-site |
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The ___ (A/P/E)-site of a ribosome holds the tRNA to which the polypeptide is attached |
P-site |
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The ___ (A/P/E)-site of a ribosome provides an avenue for exit of the tRNA after its amino acid has been added to the chain |
E-site |
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Between what 2 areas is the P-site located? |
A-site and E-site |
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The first step in bacterial translation is the formation of what complex? |
Pre-initiation complex |
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What 3 components make up the pre-initiation complex in bacterial translation? |
Small ribosomal subunit, mRNA, and IF3 |
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In bacterial translation, IF3 binds to the ribosome near the ___ (5'/3') end of the mRNA, and together with the ribosome, looks for a special sequence in the mRNA called the ___ (Shine-Dalgarno/TATA) sequence |
5' end, Shine-Dalgarno sequence |
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The binding of the Shine-Dalgarno sequence with the 16S ___ (rRNA/tRNA) in the ribosome positions the start codon in the ___ (A/P/E)-site of the small subunit |
rRNA, P-site |
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In bacterial translation, the first charged tRNA is a modified methionine called what? |
fMet |
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In bacterial translation, after the pre-initiation complex is formed, what happens next? |
The start codon is bound with its transfer RNA (fMet) |
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In bacterial translation, what compounds assist the fMet in binding to the start codon and prevent the large subunit from attaching? |
Initiation factors |
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In bacterial translation, after the start codon is bound with its transfer RNA, what happens next? |
The large subunit joins the small subunit to form the functional ribosome |
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In bacterial translation, after the functional ribosome is formed, the initiation factors ___ (stay/dissociate) and the ___ (A/P/E)-site is occupied by ___ (transcription factors/fMet) |
initiation factors dissociate, P-site is occupied by fMet |
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In eukaryotic translation, the small ribosomal subunit complexes with what 2 components to form the pre-initiation complex? |
Eukaryotic initiation factor (eIF) and a charged tRNAmet |
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In eukaryotic translation, the pre-initiation complex is recruited to the ___ (5'/3') cap region of the mRNA |
5' cap region |
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In eukaryotic translation, the pre-initiation complex joins a group of at least four ___ (tRNA/eIF4) proteins that assembles at the 5' cap of the mRNA to form the initiation complex |
eIF4 proteins |
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In eukaryotic translation, once the ___ (pre-initiation/initiation) complex is formed, it scans to move the small subunit along the ___ (5'/3') UTR in search of the ___ (start/stop) codon |
Initiation complex, 5' UTR, start codon
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In eukaryotic translation, the correct start codon can be located because it is embedded in a consensus sequence called what? |
Kozak sequence |
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In eukaryotic translation, location of the start codon leads to recruitment of the large subunit using energy from what? |
GTP hydrolysis |
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In eukaryotic translation, when then large subunit is added to the complex, what components dissociate? |
eIFs |
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In translation, elongation begins with the recruitment of ___ (transcription/elongation) factor proteins that use energy of ___ (H2O/GTP) hydrolysis to recruited charged tRNAs to the ___ (A/P/E)-site |
Elongation factor proteins, GTP hydrolysis, A-site |
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What enzyme catalyzes peptide bonds between amino acids at the P- and A- sites? |
Peptidyl transferase |
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___ (Transcription/Elongation) actors help form peptide bonds using peptidyl transferase |
Elongation |
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In translation, the first step in forming the peptide bond is breaking the bond between what 2 components? |
fMet and its tRNA |
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___(Transcription/Elongation) factors translocate the ribosome |
Elongation |
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Translocation of the ribosome moves the tRNA in the A-site into the ___ (P/E)-site and opens a new ___ (A/P/E)-site |
P-site, A-site |
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In translation, bacteria and eukaryotes both use ___ (termination/release) factors to bind a ___ (start/stop) codon in the ___ (A/P/E)-site |
Release factors, stop codon, A-site |
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Ribosomes account for what percentage of the mass of a bacterial cell? |
25% |
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What is the name of structures the contain groups of ribosomes that all actively translate the same mRNA? |
Polyribosomes |
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Each polypeptide-producing gene in eukaryotes produces ___ (monocistronic/polycistronic) mRNA |
Monocistronic |
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___ (Monocistronic/Polycistronic) mRNA is an RNA molecule that directs synthesis of a single kind of polypeptide |
Monocistronic |
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___ (Monocistronic/Polycistronic) mRNA is an RNA molecule that leads to the synthesis of several different proteins |
Polycistronic |
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In bacteria, ___ (monocistronic/polycistronic) mRNAs are produced |
Polycistronic |
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What is the name for the groups of bacterial genes that share a single promoter and produce polycistronic mRNA? |
Operons |
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The genetic code contains ___ (more/less) codons than common amino acids, leading to ___ (conspiracy/redundancy) |
More, redundancy |
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What two amino acids are the only amino acids not specified by at least two codons? |
Methionine and tryptophan |
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All amino acids, besides 2, are specified by at least two codons called ___ (repetitive/synonymous) codons |
Synonymous |
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tRNA molecules with different anticodons for the same amino acid are called what? |
Iso-accepting tRNAs |
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What is the name for the relaxation of the strict complementary base-pairing rules at the third base of a codon? |
Third-base wobble |
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Pairs of synonymous codons either both carry a ___ (purine/thymine) or both carry a ___ (adenine/pyrimidine) |
Purine, pyrimidine |
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Most synonymous codons can be grouped into pairs that differ only in the ___ (1st/2nd/3rd) base |
3rd base |
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Third-base wobble occurs through flexible pairing at the 3'-most nucleotide of the ___ (codon/anticodon) and the 5'-most nucleotide of the ___ (codon/anticodon) |
3'-most nucleotide of the codon, 5'-most nucleotide of the anticodon |
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True or false: In third-base wobble, a pyrimidine must still-base pair with a purine |
True |
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An overlapping genetic code ___ (is/is not) possible because the sequence of one codon would ___ (limit/free up) the possible sequences for the two ___ (subsequent/previous) codons |
Is not possible, limit the possible sequences for the two subsequent codons |
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What is the name of the type of mutation that alters the reading frame of a sequence? |
Frameshift mutations |
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With a frameshift mutation, all the codons ___ (before/after) the addition or deletion will specify the wrong amino acids |
After |
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What is the term that refers to the specific codon sequence as determined by the start codon? |
Reading frame |
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___ (Protein sorting/Post-translational polypeptide processing) modifies polypeptides into functional proteins by folding the polypeptide chains and by removal or chemical alteration of amino acids |
Post-translational polypeptide processing |
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What type of enzymes carry out phosphorylation? |
Protein kinases |
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What is the name of the most common amino acid modifications that can activate or inactivate a protein? |
Phosphorylation |
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True or false: Some proteins only become functional once amino acids are removed or chemically altered after translation |
True |
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What is the name of the proteins that assist in the folding of polypeptides, prevent unproductive folding, and undo incorrect folding? |
Chaperones |
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___ (Protein sorting/Post-translational polypeptide processing) uses signal sequences/leader sequences to direct proteins to their cellular desinations |
Protein sorting |
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What is the name of the sequences that protein sorting uses to direct proteins to their cellular destinations? |
Signal or leader sequences |
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The signal sequence directs proteins to the ___ (endoplasmic reticulum/Golgi apparatus), where they are sorted for their specific destinations |
Endoplasmic reticulum |
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Polypeptides destined for secretion are produced at the ___ (rough/smooth) ER |
Rough |
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As translation begins, polypeptides with a signal sequence have their ___ (C/N) terminal pushed into the cisternal space of the rough ER thru receptors on the ER surface |
N terminal |
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Once inside the rough ER, polypeptides have their ___ (coding/signal) sequence removed and are glycosylated and packaged into a ___ (larger protein/vesicle) for transport to the ___ (smooth ER/Golgi apparatus) |
Signal sequence, vesicle, Golgi apparatus |
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In the Golgi apparatus, further ___ (polyadenylation/glycosylation) of proteins determines their ultimate locations |
Glycosylation |
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Glycosylated proteins bind to different/specific receptors for packaging into ___ (ribosomal/transport) vesicles |
Transport vesicles |
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Vesicles bud off of the Golgi apparatus ___ (cytoplasm/membrane) and transport proteins to their destinations |
Membrane |
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Proteins that cannot fold properly are irreversibly bound to ___ (rough ER/chaperones) that are sequestered and ___ (maintained/destroyed) |
Chaperones, destroyed |
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What type of diseases result when large amounts of mutant proteins accumulate without being destroyed? |
Conformational diseases |
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What are 3 examples of conformational diseases? |
Alzheimers, a form of Parkinsons, and Huntington disease |
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Attachment of an amino acid to tRNA occurs in the ___ (ribosomes/rough ER/cytoplasm) |
Cytoplasm |
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Translation of cytoplasmic proteins occurs in the ___ (ribosomes/rough ER/cytoplasm) |
Ribosomes |
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Translation of secreted proteins occurs in the ___ (ribosomes/rough ER/cytoplasm) |
Rough ER |
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Are RNA primers used in protein synthesis? |
No |
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What is the equation for finding the minimum size of a codon? |
# of bases in DNA ^ minimum amount of bases per codon = amino acids |
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What enzyme can identify a mismatched nucleotide and remove it? |
DNA polymerase |
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What enzyme catalyzes bond formation between nucleotide base pairs? |
DNA polymerase |
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Topoisomerase breaks ___ (hydrogen/covalent) bonds in the DNA backbone |
Covalent |
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SSBs prevent ___ (hydrogen/covalent) bonds between bases |
Hydrogen |
