MCM Functions and Dysfunctions of Protein Processing - Kinde Flashcards Preview

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Flashcards in MCM Functions and Dysfunctions of Protein Processing - Kinde Deck (49):

Correlation Box – Sickle Cell Anemia (p351) What are the two variants? 7

Changes a hydrophilic (negatively charged) Glu to a hydrophobic Val

Glu --> Val (in one allele) and Glu --> Lys in the other allele


Where does the mutation occur in sickle cell anemia? 37

There is a mutation in the gene for human β-globin altering the conformation of wild type HbA


Correlation Box – Duchenne Muscular Dystrophy (p352) 7

A large out-of-frame shift to dystrophin gene

The larger the frame shift the greater the effects

In-frame shifts give rise to Beckers Muscular Dystrophy (less severe)


What are the three sites of a Ribosomal complex 12, 15

Acceptor (A) Site – First, where the mRNA accepts the anti-codon

Peptidyl (P) Site – Second, where the aminoacyl tRNA becomes bonded to the growing peptide chain

Empty (E) Site – Third, where the tRNA leaves the ribosome


Before translation can begin what does mRNA need to have during the Initiation Step of Translation 16, 17

5’ cap
3’ poly A tail
Kozak sequence
An ATP-dependent mRNA scan


Why is the initiation step of translation so crucial? 17

Because it determines the reading frame for the whole length of the mRNA


What are the different sequences involved in initiation for prokaryotes and eukaryotes? 17

Prokaryoytes – Shine-Dalgarno sequence (SDG) AGGAGG

Eukaryotes – Kozak sequence


What does the initiation complex during translation look like? 18

Initiator tRNA bound by GTP containing an amino acid attached to methionine (MET)
i. The tRNA binds to the p site

Initiator factor --> eIF*


Describe the Elongation Step of Translation 14

an elongation factor (EF) bound by GTP is attached to the tRNA

in order to load, the GTP is hydrolyzed


What catalyzes amino acid bond formation between the A and P site? 19

Peptidyl transferase


How is each codon translocated to the next codon? 19

By GTP hydrolysis


What are the prokaryotic elongation inhibitors? Briefly, what do they inhibit? 21

Tetracycline: binds 30S subunit, blocking tRNA entry

Chloramphenical: inhibits peptidyl transferase

Clindamycin/erythromycin: binds 50S subunit, blocking translocation of ribosome


What are the eukaryotic elongation inhibitors? Briefly, what do they inhibit? 22

Cycloheximide: inhibits peptidyl transferase

Diptheria toxin: inactivates GTP-eEF-2

Shiga Toxin/Ricin: binds 60S subunit, blocking tRNA entry


Describe the Cytoplasmic Pathway 27, 29

Synthesis begins and ends in the cytoplasm, has no translocation signal


What is defective in I-Cell disease? 29, 33

The lysosomal mitochondrial localization signal: Mannose 6-phosphate signal group is unable to be applied to the lysosome*


How is a protein imported into the mitochondria? What does the signal look like? (figure 19.7) 30

Signal N-terminus, hydrophobic and positively charged

Protein is guided by HSP70 ensuring the integrity of the protein

TOM complex brings the protein through the outer membrane

TIM complex brings the protein through the inner membrane

Peptidase on the inner membrane cuts off the signal


What are three kinds of Covalent modifications 42

1. Glycosylation
2. Phosphorylation
3. Disulfide bond formation


Describe the deficiency and the result of that deficiency in Alzheimer’s disease (β-amyloid) 37

A mutated gene that produces amyloid precursor protein (APP) formation of neuritic plaques

supplementation with lys may help


Describe Creutzfeldt-Jakob/Kuru/Mad Cow disease (prion proteins) 38

Introduction of prions (misfolded proteins) that induce the same formation in their counterparts


Describe Huntington Disease (poly-glutamine repeat diseases) 38

Protein aggregations in the brain CAG repeats = polyglutamine tracts (polyQ tract)

The abnormal Huntington protein (mHTT) forms intramolecular hydrogen bonds and aggregates


Describe the deficiency and outcome in Parkinson’s disease (α-synuclein) 31

mutated α-synuclein results in aggregates that form lewy bodies

Function form is an α-helix while the fibrile form is β-sheet

Results in neuronal death of the midbrain and a lack of available dopamine


What are the combinations of transcription factors that can be used to induce iPS? 46

1. Oct3/4, Sox2, c-Myc, Klf4

2. Oct3/4, Sox2, Klf4

3. Oct3/4, Sox2, N-myc,

4. Oct3/4, Sox2, Lin28, Nanog


What is somatic cell nuclear transfer (SCNT), what is the process? 43

Produces cells that aren’t rejected using cloning methods with ES technology

Remove the nucleus from an egg cell and fuse the SCNT cell containing the SCNT nucleus and eventually extract the ICM to produce pluripotent cells


Describe hematopoietic and stromal stem cell differentiation 32

Hematopoietic (HSC) --> Blood components

Stromal Stem Cell (MSC) --> Connective tissue and other tissue


What would cause the differentiation of ES cells into a neuron? 25

Retinoic acid


What would cause the differentiation of ES cells into an adipocyte? 25

Retinoic acid + insulin + thyroid hormone


What transcription factors are essential for maintenance of pluripotent cells? 29






Correlation box – Induced pluripotent stem cells. What is the potency of a zygote? Of the ICM? What can induce ES-like characteristics in adult stem cells?

Zygote --> totipotent

ICM of blastocyst --> Pluripotent

Oct4, Sox2, Nanog, and Lin28 --> can induce adult differentiated to become ES-like


What is the definition of mutation? 8

Any permanent, heritable change in the DNA sequence


What is a silent mutation and its effect on a protein? 8

new codon, but same amino acid product

effect --> no change in function


What is a missense mutation and its effect on a protein? 8

new codon, with a different amino acid product

effect --> multiple effects possible


What is a nonsense mutation and its effect on a protein? 8

Instead of a new codon, a stop codon is incorporated

Effect on Protein --> protein becomes nonfunctional


What is a frameshift mutation and its effect on a protein? 8

One or more nucleotides is skipped, inserted or deleted

Effect on Protein --> Protein becomes nonfunctional


What part of the amino acid chain is added to during translation? 3, 14

Ribosomes grab mRNA and add amino acids to the C terminus of the growing chain


How does the structure of ribosomes differ for prokaryotic and eukaryotic ribosomes? 14

Prokaryote Ribosomes – (50s/30s) 70s

Eukaryotic Ribosomes – (60s/40s) 80s

Differences allow for antibiotic targeting


What occurs to turn pre-mRNA into mRNA? 10

Removal of introns (non-coding) (no introns in prokaryotes)

Addition of 5’ cap

Addition of poly A tail


How many amino acids can tRNAs transport? 11

Each tRNA carries only one kind of amino acid


What facilitates amino acid activation? 10, 11

Aminoacyl-tRNA Synthetase utilizing 2* ATP

One Aminoacyl-tRNA Synthetase for each kind of tRNA


What antibiotic is commonly used to treat pertussis? 21



How is puromycin able to cause premature chain termination in both eukaryotes and prokaryotes? 23

Because of its identical structure to Tyrosyl-tRNA

Puromycin contains an amine group while tyrosyl-tRNA contains an oxygen at the same location


What occurs during the Termination Step of Translation 14, 21

Occurs when a stop codon enters the A site

Releasing factor (RF) is loaded onto the A site causing peptidyl transferase to cleave the ester bond of the tRNA in the P site


Where does synthesis begin and end in the Secretory Pathway? 31

Synthesis begins on a ribosome, but ends in the ER 15 – 60 aa peptide signal of mostly Lys and Arg


During the secretory pathway how does translation throught the ER happen? 32

SRP (signal recognition particle) wraps itself around mRNA-ribosome complex and plugs into the ER lumen


What are Chaperonins 28

Barrel shaped compartments the take in unfolded proteins and use ATP to facilitate folding


What requires Chaperonins? 28

Larger proteins need help folding and require chaperonins


What is the goal of proteolytic cleavage? Give an example 41

convert precursor to active enzymes by cleavage

Ex. trypsinogen and chymotrypsinogen to trypsin and chymotrypsin


What disease result in over glycosylation? 44

Diabetes more free-floating glucose means more glycosylation

Can result in eye problems


What type of Glycosylation is most common 35?

N-linked glycosylation


What falls under O glycosylation? 45

OH groups of Ser and Thr