Lecture 11 Translation Flashcards
What are some characteristics of the genetic code
-specific
-universal
-degenerative
-continuous
-non overlapping
What does AUG codon do
It is the start codon and it does methionine
What are some of the stop codons
UAA
UAG
UGA
What is a nonsense mutation
change in one nucleotide results in a stop codon
What is a missense mutation
change in one nucleotide that results in a different protein
What is a silent mutation
Change in one nucleotide that does not change the protein that is produced
What is a point mutation
a change in one nucleotide
What are some examples of a frameshift mutation
addition of a base and deletion of a base
_________________________:
✓ CAG codon expansion in the HTT gene encoding the
huntingtin protein
✓Inherited in an autosomal dominant pattern.
✓Leads to the insertion of many extra glutamine
residues in the protein resulting in an abnormally long
protein that is cleaved, producing toxic fragments
that aggregate in neurons causing the
neurodegenerative disorder
✓Symptoms include progressive neurodegeneration
characterized by chorea, psychiatric problems, and
dementia and usually begin insidiously
✓Age of onset ranges from childhood to the eighth
decade, but is most common in mid-life
Huntington disease
In hunnginton disease: there is an insertion of many extra _______________in the protein resulting in an abnormally long
protein that is cleaved, producing toxic fragments
that aggregate in neurons causing the
neurodegenerative disorder
glutamine residues
_________________
✓ CUG codon expansion in the 3’-UTR of the dystrophia myotonica protein kinase (DMPK)
gene which is is transcribed into RNA but is not translated
✓Autosomal dominant inheritance
✓Multisystem disorder characterized by skeletal muscle weakness and myotonia, cardiac
conduction abnormalities, cataracts, and others.
Mytonic dystrophy type 1
______________________
✓ CGG codon expansion leading to a loss-of-function variant in
the fragile X messenger ribonucleoprotein 1 (FMR1) gene that results in decreased or absent levels of the respective protein
✓X-linked inherited disorder
✓The most common inherited cause of intellectual
disability.Often associated with neurobehavioral disabilities
Fragile X Syndrome
___________________ explains why multiple codons can code for a single amino acid. One tRNA molecule can recognize and bind to more than one codon, due to the less-precise base pairs that can arise between the 3rd base of the codon and the base at the 1st position on the anticodon.
The Wobble Hypothesis
In prokaryotes what initiates Elongation
Shino delgarno sequence
3 initiation factors IF
Formulation MET
In Eukaryotes what directs binding
5’ cap directs binding, many initiation factors
What is required for protein folding
-many proteins
-requires suitable physiological conditions
-chaperone assisted
What is required for polypeptide synthesis
polysomes
-Misfolded proteins may spontaneously assemble into insoluble amyloid fibrils
‣ In the brain their accumulation is associated with slow degeneration
‣ Examples: Alzheimer disease, Parkinson disease , transmissible spongiform
encephalopathies (such as “mad cow disease”), and polyglutamine expansion
diseases (Huntington disease), amyloidosis
Protein Misfolding Diseases
What is occurring during amyloidosis?
Protein misfiling disease
‣ Amyloid deposition may occur in other organs such as the endocrine pancreas in Type
II diabetes
‣ Some, but not all, amyloids are intrinsically toxic to cells
‣ Some amyloid precursors are more toxic than the fibrils themselves
What are some Protein post translational modifications
-carbohydrate addition
-lipid addition
-mannose 6 P
___________________ caused by a deficiency in the enzyme that phosphorylates mannose at C6. It is characterized by skeletal abnormalities, restricted joint movement, coarse fascial features and severe psychomotor impairment. Dease is sally occurring in early childhood, autosomal recessive
I cell disease
__________________ ✓Selectively degrade damaged or short-lived proteins
✓Uses ubiquitin modification to target proteins for degradation
✓Energy-dependent (requires ATP)
proteasomal degradation
_______________:
✓Use acid hydrolases to nonselectively degrade:
‣ intracellular proteins via autophagy
‣ extracellular proteins such as plasma proteins that are taken
into the cell by endocytosis (heterophagy)
lysosomal degradation
What are the steps of protein degradation
- Protein sequence selected for degradation is tagged with ubiquitin
- Ubiquinated proteins are recognized and transported to the proteolytic core
- Peptide fragments produced by the proteasome are degraded to amino acids in the cytosol
