Lecture 11 Translation

Question 1

What are some characteristics of the genetic code

Answer 1

-specific
-universal
-degenerative
-continuous
-non overlapping

Question 2

What does AUG codon do

Answer 2

It is the start codon and it does methionine

Question 3

What are some of the stop codons

Answer 3

UAA
UAG
UGA

Question 4

What is a nonsense mutation

Answer 4

change in one nucleotide results in a stop codon

Question 5

What is a missense mutation

Answer 5

change in one nucleotide that results in a different protein

Question 6

What is a silent mutation

Answer 6

Change in one nucleotide that does not change the protein that is produced

Question 7

What is a point mutation

Answer 7

a change in one nucleotide

Question 8

What are some examples of a frameshift mutation

Answer 8

addition of a base and deletion of a base

Question 9

_________________________:
✓ 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

Answer 9

Huntington disease

Question 10

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

Answer 10

glutamine residues

Question 11

_________________
✓ 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.

Answer 11

Mytonic dystrophy type 1

Question 12

______________________
✓ 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

Answer 12

Fragile X Syndrome

Question 13

___________________ 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.

Answer 13

The Wobble Hypothesis

Question 14

In prokaryotes what initiates Elongation

Answer 14

Shino delgarno sequence
3 initiation factors IF
Formulation MET

Question 15

In Eukaryotes what directs binding

Answer 15

5’ cap directs binding, many initiation factors

Question 16

What is required for protein folding

Answer 16

-many proteins
-requires suitable physiological conditions
-chaperone assisted

Question 17

What is required for polypeptide synthesis

Answer 17

polysomes

Question 18

-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

Answer 18

Protein Misfolding Diseases

Question 19

What is occurring during amyloidosis?

Answer 19

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

Question 20

What are some Protein post translational modifications

Answer 20

-carbohydrate addition
-lipid addition
-mannose 6 P

Question 21

___________________ 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

Answer 21

I cell disease

Question 22

__________________ ✓Selectively degrade damaged or short-lived proteins
✓Uses ubiquitin modification to target proteins for degradation
✓Energy-dependent (requires ATP)

Answer 22

proteasomal degradation

Question 23

_______________:
✓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)

Answer 23

lysosomal degradation

Question 24

What are the steps of protein degradation

Answer 24

1. Protein sequence selected for degradation is tagged with ubiquitin
2. Ubiquinated proteins are recognized and transported to the proteolytic core
3. Peptide fragments produced by the proteasome are degraded to amino acids in the cytosol