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MCBG TEST 2!!! > 8-15 Protein Synthesis > Flashcards

8-15 Protein Synthesis Flashcards

1
Q

What are 4 MAIN DIFFERENCES between prokaryote vs. EUKARYOTE Protein synthesis

A
  1. prokaryotes use F-MET as Starting AA while EUKARYOTES have only MET
  2. prokaryotes ribosomes are 50s+30s->70S
    • ***** EUKARYOTES: 60s+40s—> 80s
  3. prokaryotes are fully polycistronic
    EUKARYOTES ARE MONOCISTRONIC
  4. prokaryotes: 3 rRNAs //// EUKARYOTES: 4 rRNAs
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2
Q

What are the Elongation Factors of translation for prokaryotic cells?

A

EF-Tu , EF-G

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3
Q

[T or F] prokaryotic cells undergo mRNA processing Just like Eukaryotic Cells

A

FAALSE!!!! PROKARYOTIC CELLS DO NOOOT AT ALL UNDERGO mRNA PROCESSING!!!

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4
Q

What are the translation “initiation” factors for Prokaryotes specifically?

A

IF2 and IF3

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5
Q

Prokaryotes use _____Polyermase during protein synthesis/translation

A

Prokaryotes ONLY USE RNA POL 1! During protein synthesis/translation

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6
Q

In regards to [aminoacyl tRNA synthetase] what is the difference between Prokaryotes and EUKARYOTES?

A

prokaryotes may use ONLY 1 aminoacyl tRNA synthetase to bring different types of AA to their corresponding tRNA

**EUKARYOTES HAVE A DIFFERENT SYNTHETASE FOR EACH AA WHEN BINDING THEM TO THEIR tRNA

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7
Q

What’s the relationship between a DNA template and the protein sequences it ultimately codes for?

A

DNA Template(daughter strand) is THE SAME SEQ./Co-linear with the Protein AA seq.

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8
Q

THe Genetic Code is “____” which means =….

A

Genetic code is DEGENERATE!–>this means Multiple codons will possibly encode for the same AA

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9
Q

Genetic Code

A

Code where each AA is represented by at least 1 codon. Note: Some AA can be made by multiple codons[degenerate]

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10
Q

1: What codon (___) produces the START Amino Acid (____)
2: What 3 codons (____, _____ or ______) produces the stoppp amino acids

A
  1. START codon (AUG) = Methionine AA

2. UAA, UAG or UGA codons = stoppp AA

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11
Q

1) What makes tRNAs?

2) What does tRNAs contribute to protein synthesis other than AA?

A

1) tRNAs are made by RNA POL 3

2) tRNA binding to AA by synthetases INC fidelity of the process –> good thing!

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12
Q

What parts of the EUKARYOTIC tRNA allows it to be “distinguished” from other tRNAs when binding to its correct aminoacetyl tRNA synthetase?

A

tRNAS have specific:
1-anticodon loop
2-acceptor stem
3-specific aminoacetyl-tRNA that it binds to only[EUKRYTOC}

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13
Q

Describe the rxn by which AA are actually covalently attached to tRNAs? [2]

A

Aminoactyl tRNA synthetase activates AA with ATP hydrolysis –>
AA is then ESTER bonded to (OH) of 3’ on tRNA

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14
Q

How do Aminoactyl-tRNA synthetase ensure the CORRECT AA is being ester bonded to tRNA

A

Hydrolytic Editing of the Aminoactyl-tRNA synthetase removes its own coupling errors by rejecting wrong AA at the “editing site” [CORRECT AA should NOT be able to fit into this editing site!]

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15
Q

Which base of the codon contributes MOST to Degeneracy??

A

THe WOBBLE BASE “3rd Base” allows for multiple codon seq. to sometimes code for the SAME AA = DEGENERACY

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16
Q

What may prevent the wrong reading frame from being used in translation

A

frequent premature STOP codons

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17
Q

[T or F] the first 2 bases of a codon have to have STRICT MATCHING while the 3rd can have variability

A

TRUE!

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18
Q

Describe the Process of prokaryote Translation? [4]

A

1) 16s sRibosomal[brought by IF-3] subunit binds to upstream Shine-Delgarno sequence
2) Ribosome assembles at Trnsltion start site with Psite right on point! [due to SD sequence]

3) binds to ]—>Placed @ P site
4) IF-2 is hydrolyzed by large ribosome so that initiation factors can DETACH from the initiating tRNA

19
Q

When does the Lrge ribosomal subunit during EUKARYOTIC translation actually bind to the mRNA?

A

Large ribosomal unit binds to mRNA AFTER eIF2(carrying the tRNA and GTP) is HYDROLYZED and initiator MET is in P-site!

20
Q

Describe the process of Translation ELONGATION?

A

1) EFTU (with an attached GTP) binds to a floating tRNA*with its Amino Acid attached and hooks it up with the GROWING CHAIN!–>2 lags occur when EFTU GTP is hydrolyzed and EFTU is released= which allow for correctness check
2) EFG then comes and binds to ribosome w/GTP and is hydrolyzed to ACTUALLY SHIFT the Ribosome downward

21
Q

How is translation Terminated? [3]

A

STOP Codon—->Release factor (looks similar to tRNA) binding to A site————–>water is added to end of chain which releases polypep chain and disassembles ribosome!

22
Q

What are the 4 Fidenlity/Check Points for ensuring Amino Acids are paired correctly?

A

1) Aminoactyl-tRNA synthetase has to recognize correct tRNA with correct AA [Hydrolytic editing]
2) mRNA has to be fully processed[5’cap/3’polyA tail]
3: Codon and ANTI-codon matched correctly produces stronger affinity. THey have to match !

4: EFTU introduces 2 lags as time for tRNA to be corrected* happens when EFTU GTP is hydrolyzed and EFTU released

23
Q

How can less than 64 tRNAs recognize ALL 64 codons??

A

WOBBLE pairing of the 3rd base allows a small group of tRNAs to still be able to recognize MULTIPLE codons

24
Q

Prokaryotic Tx and TL occur in which compartment?

A

Prokaryotic Tx and TL BOTH occur in the SAME Compartment!

25
Q

Eukaryotes are MONOcistronic!

A

Eukaryotes are MONOcistronic [1 protein message per mRNA strand] due to the tedious task of having to scan for AUG start codon during TL initiation!

26
Q

Puromycin

A

Mimics tyrosyl-tRNA with “Molecular Mimicry” and binds to

(A site) of Lrge ribosome STOPPING any further peptide bond growth because it LACKS [OH] for protein chain growth

27
Q

Why don’t abx that affect ribosomal sites of Bacteria affect us as Eukaryotes as well?

A

Ribosomes between Bact and Eukaryote Are Different in Size! [Eukaryotes= 60s + 40s–>80s]

28
Q

What Eukaryotic Organisms CAN be possibly affected by abx?

A

Ribosomes of Mitochondria/Chloroplast resemble Bacteria and are sensitive to Rbsme inhibitors
deleterious effect on human mitochondria

29
Q

When and WHY does folding of a protein occur?

A

Protein folding occurs AS Polypeptide Chain is being MADe due to hydrophobic AA folding inward to protect themselves from aqueous environment of blood

30
Q

Why when eIF2 is Phosphorylated eIF2B is unable to do its job?

A

When eIF2 is phosphorylated “[eIF2P]” then eIF2B WILL BIND IRREVERSIBLY to [eIF2P] and not be able to help other regular eIF2 become recharged!

31
Q

1) What does the AP1 element of a gene do?

2) Explain the ENTIRE PROCESS of the AP1 gene activation?

A

1)AP1 element of a gene INDUCES CANCER METASTASIS

2) A: URK phosphorylates Fos and Junk phosphorylates Jun
B: Jun-P, Fos-P and ETS tx factor all bind to AP1 element
C: AP1 element gene is activated!

32
Q

WHat does PERK do in the Endoplasmic Reticulum ?

A

After BIP leaves from PERKs side..PERK STOPS TRANSLATION! in order to prevent any more misfolded proteins from happening while the ER problem is reprimanded!

33
Q

The intermembrane space of the mitochondria is _____

[+ / - ] .WHat does this have to do with cargo proteins?

A

mitochondrial intermembrane space is [+]!! and Cargo protein that’s mitochondria bound will electrophoresis across this [+] space to eventually get to TIM for the matrix

34
Q

During Translation, mRNA molecules are read_____

A

mRNA molecules during Translation are read 5’–>3’

35
Q

Which site of the tRNA is responsible for the initial attachment of an AA for delivery to a protein?

A

3’ end ACCEPTOR STEM on tRNA grabs the AA so that it can be delivered

36
Q

Second Genetic Code

A

Refers to the recognizing of a tRNA by its appropriate aminoacyl-tRNA synthetase

37
Q

The Shine-Dalgarno box is a ___-rich sequences in _______ that’s located ____nucleotides upstream of initiator [___ or ____]. Shine-Dalgarno box sequence is complementary to what part of the incoming Prokaryote ribosome?

A

*Shine-Dalgarno box is a PURINE-rich sequence in PROKARYOTES located 10 nucleotides upstream of initiator [AUG or GUG]

**Shine-Dalgarno box sequence is complementary and pairs to the
3’ end of the 16s-ribosomalRNA THAT’S APART OF the Prokaryotic 30s Ribosomal subunit

38
Q

eIF4F?

2)What is eIF4F job during translation?

A

eIF4F= (eIF4E cap binding protein) + (eIF4G) and (eIF4A helicase used for AUG scanning by mRNA unwinding)
2)eIF4F includes the cap binding protein that is needed to

39
Q

During Protein Synthesis mRNA transcripts are read by ribosomes from ____—->___ and the __-terminal end of the protein is the end the new amino acid is added to

A

During Protein Synthesis mRNA transcripts are READ from 5—->3 and the C-TERMINAL end is the protein end AA will be added to.
{n-terminal is the end made first}

40
Q

How does Translation Elongation MOVEMENT FORWARD occur

A

Upon contact w/ribosome, EF-G GTPase ability is activated and the GTP hydrolysis causes a confirmational change in EF-G that moves an “in the middle” A/P tRNA FULLY into the P-site.–>This moves the previous P site-tRNA into the
E site

41
Q

When does the tRNA occupying the E-site of Lrge ribosome actually get pushed off??

A

E-site tRNA is ejected when the next aminoacyl-tRNA is delivered to the A site and is pushed fully into that A site from the dissociation of EF-Tu*GDP

42
Q

Why exactly are Bacteria/Prokaryotes Polycistronic

A

in Eukaryotes our ribosomes HAVE to bind near the
1 5’end cap and scan for the AUG but Prokaryotes have a 5’end cap that is NOT significant so Prokary.Ribosomes can bind to multiple site/SD and start codons

43
Q

What are some common post-translational modifications

A

Most frequent post-TL modifications are covalent Glycosylation, phosphorylation and acetylation

44
Q

When does Protein Folding occur and what is it for?

A

Proteins are FOLDED while they’re MADE!=
Co-translationally fold with N-terminal folding first.
2)Proteins FOLD are important for a mature functional state

MCBG TEST 2!!! (13 decks)

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