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38 Cards in this Set
- Front
- Back
- 3rd side (hint)
Relates information in the sequence of bases in DNA and RNA to the structure (amino acid sequence) of a protein
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Genetic code
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Carries the code in the form of codons (words)
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mRNA
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Interprets the code from the mRNA into amino acids, uses anticodons
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tRNA
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The machine that catalyzes deconding and peptide bond formation; translation
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ribosome
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Work with the ribosome, mRNA and tRNA to start, maintain and end the process
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Translation factors
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80-90% of the cellular energy is used for protein biosynthesis
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Uses GTP and ATP
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The ribosome, mRNA and charged tRNA's (each carrying an amino acid) must come together
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Ribosome must 'read' its way down the mRNA (5' to 3' only)
Uses tRNA's to translate nucleotide sequence into amino acid sequence |
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Does the ribosome have reparative functions?
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Nope
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1. Correct mRNA sequence
2. Correct charginig of tRNA 3. Correct ribosome processivity 4. Correct start and stop |
Four determinants of fidelity.
Charging is responsible for most of the fidelity in RNA |
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This RNA subunit has:
- a finger and thumb - Palm position has peptidyl transferase activity. |
The large ribosomal subunit
Peptidyl transferase is a translocation domain. - Information is read by tRNA's |
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Symptoms:
- Reduced rate of RBC production - Normochromatic macrocytic anemia - Absence of erythroid precursors in normal marrow - Elevated RBC Ad deaminase (eADA) and HbF |
Diamond Blackfan anemia
Craniofacial, hand, heart and urinary tract development defects. Fetal/infant growth retardatio in severe (~40%) cases |
Null mutation in genes coding for L5 or L11 (RPL5, RPL11)
L5 and L11 are large ribosomal subunits. Increases incidence of cleft palate and thumb abnormalities |
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1. Three tRNA binding sites
2. mRNA binding 'groove' between 40 S and 60 S 3. one active site (peptidyl transferase) in 60 S 4. Peptidyl trasnfer catalyzed by rRNA (ribozyme) 5. Adjacent tRNA sites lock into place the reading frame (in register) |
The functional architecture of the ribosome
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Amino acyl site (A) binding site on ribosome:
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Accepts tRNA
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Peptidyl (P) binding site on ribosome:
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Peptide bond is formed
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Exit binding site on ribosome:
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Penultimate tRNA bonds here.
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On the ribosome, mRNA binds on the groove between _____ S and the 60 S
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40
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The peptidyl transferase in ____ S possesses one active site
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60
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What enzyme is a ribozyme, not a protein?
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Peptidyl transferase
Large 28 S subunit |
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Viral and bacterial mRNA's stall or nudge the ribosome to slip forward or back one or two nucleotides.
Causes frameshifting. What does this allow the virus/bacteria to do? |
Allows for it to make two different proteins from one coding region.
Used by retroviruses (ie, HIV) to make gag-pol protein (viral replication) |
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Which structure in gag-pol is synthesized by the viral genome?
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Pol
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Which structure in gag-pol is responsible for structure?
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Gag
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Not every nucleotide will be the same.
Overriden by majority |
Consensus
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Translation proceeds ___' to ___3'
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5'-3'
N to C |
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Untranslated regions often bind proteins that regulate ________
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translation
If it is found on the 5' side, it is called the 5' UTR (also known as the Leader Sequence), or if it is found on the 3' side, it is called the 3' UTR. |
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- Use periods or spaces to separate codons in an OFR
- Untrasnlated regions and unused reading frames are not 'punctuated' - Punctation does not occur in native mRNA's - Punctation changes with insertions, deletions and stop codons |
Introns normally have stop codons inside of the coding region (aka ORF)
UAA UAG UGA |
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If the first position in anticodon is inosine, this allows for pairing with what nucleotides?
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U:I
C:I A:I |
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Wobbly 3rd base allows for both __:U and ___:U pairing
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A:U
G:U |
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Some amino acids are encoded by more than one codon
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Degenerate genetic code
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Genetic code is considered universal, same in most prokaryotes and eukaryotes
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However, mitochondrial code is slightly different.
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Mutations:
Nucleotide change does not alter protein sequence |
Silent mutation
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Mutations:
Nucleotide change alters the protein sequence by one AA |
Missence mutation
Little effect on protein function in most cases |
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Mutations:
Nucleotdie change converts a sense codon to a stop codon |
Nonsense mutation
Truncates protein prematurely, loss of function |
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Mutations:
Nucleotide change converts a stop codon to a sense codon |
Read-through mutation
Fusion protein (extension) Effect depends on position of the next stop codon |
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Mutations:
Insertion or deletion of 1, 2, 4, or 5 nucleotide changes in the reading frame |
Frameshift mutation
Incoherent protein sequence, truncates prematurely Loss of function |
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- Lipoprotein lipase deficiency (familial chylomicronemia)
- Severe unmanageable type V hyperlipoproteinemia - Episodes of abdominal pain following high fat meals - Obese heterozygotes may show fasting hypertriglyceridemia |
Frameshift mutation disease
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Sickle cell disease
Phenylketonuria |
Missense mutations
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B-thalassemia
Phenylketonuria (milder) |
Nonsense mutations
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Humans use RNA editing to introduce a nonsense codon. Give an example:
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Apo B48
In the intestine, deamination of C (into a U)in the middle of the mRNA creates a stop codon. UAA |
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