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Biol 243 Midterm > 2C > Flashcards

2C Flashcards

1
Q

Translational regulation of gene expression brief overview

A

.mRNA-> polypeptide/protein

  1. Initiation
  2. Élongation
  3. Termination
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2
Q

Translation

A

Assembly of a.a. Into polypeptides

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3
Q

Amino acid components

A

Amino + carboxyl group (bonded to central carbon with hydrogen and R group)

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4
Q

R group? And role in a.a.

A

Its variable and determine unique character of a.a.

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5
Q

Bond between 2 a.a.?

A

Covalent peptide bond between amino and carboxyl in dehydration rxn (produce H2O by taking it out of a.a.)

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6
Q

Peptide bond

A

C-N

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7
Q

Polypeptide

A

Linear chain of a.a. Linked by peptide bond

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8
Q

Nonpolar a.a.

A

R group has -CH2 or -CH3

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9
Q

Uncharged polar a.a.

A

R group has -O or -OH

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10
Q

Charged a.a.

A

R group has acid or base that can ionize

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11
Q

Aromatic a.a.

A

R group has carbon. Ring with alternating single and double bond

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12
Q

Special fxnal a.a.

A
  1. Methionine: first a.a. In polypeptide
  2. Proline: kink in polypeptide chain
  3. Cysteine (S-S): disulfide bridge contributes to structure of polypeptide
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13
Q

Primary protein

A

A.a.sequence

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14
Q

Secondary structure

A

H-bonding in polypeptide backbone (alpha helix and beta sheet)

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15
Q

Tertiary structure

A

3-D structure of single polypeptide and made of interactions between a.a. Side chains

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16
Q

Quaternary structure

A

Interaction between more than 1 polypeptide=multisubunit protein like hemoglobin

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17
Q

What disrupts protein folding

A

Dénaturation (heat and chemicals/ mutations that change a.a. Sequence)

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18
Q

Chaperone??

A

Fxn: protect slow-folding/denatured protein and prevent aggregation

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19
Q

.tRNA

A

Adaptor between codon (mRNA) and a.a.

2D and 3D RNA from self complimentarity
Acceptor stem (a.a. Attaches here) has 5’-CCA-3’ at 3’ end of tRNA

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20
Q

Where is the anticodon in the 2D RNA cloverleaf for tRNA

A

Bottom loop of cloverleaf and has 3 nucleotide sequence and recognize codon by base pairing with mRNA

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21
Q

Aminoacyl-tRNA (charging)

A

Adding a.a. To tRNA

Aminoacyl tRNA synthase adds a.a. To acceptor stem of tRNA

Each a.a. Has a different and unique aminoacyltRNA synthétase

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22
Q

Charging rxn (aminoacylation)

A

A.a.+ tRNA+ ATP-> aminoacyl-tRNA+ AMP+ PPi

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23
Q

Genetic code

A

Multiple of the sense codons+ a.a.

24
Q

Initiation/ start codon

A

AUG

25
Q

Termination/stop codon

A

UAA/UAG/UGA… DO NOT code for a.a. (.tRNA doesn’t bind to these)

26
Q

How are codons written

A

5’->3’ likemRNA

27
Q

Rules of genetic code

A

1.codons of mRNA read in 5’->3”
2.codons non overlapping and no gaps
3. Message translating in fixed reading frame set by start codon (AUG)

28
Q

Wobble in tRNA anticodon

A

Base of 5’ end of anticodon form H-bond with more than 1 type of base at 3’ end of codon
Pairing of other 2 nucleotides in anticodon… codon is precise (no wobble)

29
Q

Pair combination with wobbling

If A (1,2,3,4,5-anticodon) then B (codon)

  1. G
  2. C
  3. A
  4. U
  5. INOSINE
A
  1. U/C
  2. G
  3. U
  4. A/G
    5.A/U/C
30
Q

Ribosome (prokaryote): protein synthesis machinery

A

2 subunits:
1. Large subunit (5OS): S+ S rRNA+ proteins that have peptides transféras E center for formation of peptide bonds
2.small subunit (3OS)L S rRNA+ protein+ decoding center where charged tRNA read and decode codon of mRNA

31
Q

S???

A

Svedberg unit

Measure mass…each subunit exist separately in cytoplasm (small and large subunit) but join on mRNA

32
Q

.tRNA binding sites of ribosomes

A
  1. P site (peptidyl): bind to tRNA attached to growing peptide chain
  2. A site (aminoacyl): bind to tRNA carrying next a.a. To be added
    3.E site (exit): bind to tRNA where previous a.a. Was added
33
Q

Translation initiation (eukaryotes)

A

Initiation complex (ribosome+mRNA+initiator tRNA bound to methionine)

  1. Initiator tRNA met brought to P-site of small ribosome subunit (need GTP)
    2.complex of initiator tRNA met and small ribosomalunit added to capped 5’end (mRNA) and scan mRNA in 5->3 till 5-AUG-3 (start codon)
  2. Complementary base pairing… between anticodon of initiator tRNA met and start codon of mRNA
  3. Large ribosomal subunit bind small subunit= intitiation complex… ready to accept first tRNA in A site
  4. GTP hydrolysée to GDP and translation begin
34
Q

Translation elongation (growth of polypeptide)-eukaryote

A

1.aminoacyl tRNA added to A site (elongation factor GTP) (tRNA anticodon is complementary to mRNA codon in A-site)
2. Peptidyl transferase (large subunit)= peptide bond between carboxyl group of polypeptide and a. Group of a.a. In A site (tRNA in P site is uncharged)
3. Ribosome translocates (tRNA shift from A->P site and uncharged tRNA from P->E site then ejected)
4.next codon of mRNA is in A site and next aminoacyl tRNA loaded by EF-GTP

35
Q

Termination (eukaryotes)- release completed polypeptide from ribosome

A

3 stop/termination codon at end of protein coding sequence in mRNA (UAA,UAG, UGA)… recognized by release factors

Ribosome reaches stop codon and release factorbinds the A-site and stimulates peptidyl transferase to leave polypeptide from P-site tRNA

Ribosome subunit separate and detach frommRNA and empty tRNA and release factor separate

36
Q

Posttranslational regulation of gene brief overview

A

Mod. Of proteins with chemical groups for activity and degradation

  1. Phosphorylation: add phosphate to protein by kinase (activate or inhibit activity)
    2.ubiquitination (add ubiquities molecule to protein target them for destruction by proteasome)
  2. Proteolysis (specific cleavage of protein induce activity)
37
Q

Postranslational regulation of proteins steps and example using spline les assembly

A

1.phosphorylation: CDK1 (cyclin dependent kinase)phosphorylates and activates MAP (microtubule associated protein) thus promote spindle assembly and mitotic entry
2. Ubiquination: cyclin (CycB) is destroyed at end of mitosis= inactivate CDK 1
3. Proteolysis (Proteolysis of viral envelope glycoprotein triggers maturation of HIV)

38
Q

Epigenetics

A

Postranslational mod of histones affect transcription

39
Q

Change in gene transcription affect DNA sequence??

A

W/o change in DNA sequence

40
Q

What affects transcription of genes/histone code

A

Mod to lysine on histone tail

Histone acetyl transféras E (HATs) add acetyl group (CH3CO-) to histone tail= increase gene transcription and loosen DNA binding

41
Q

Methylation of histone tail??

A

Posttranslational mod and activates and repress transcription of genes

DNA methylated @ CPG islands close to promoter repressing transcription

42
Q

Chromatin remodeling complex??

A

Displace nucleosome from promoter region (ATP dependent) activating transcription

43
Q

Is heterochromatin active or inactive

A

Inactive

44
Q

Is euchromatin active or inactive

A

Active

45
Q

Acetylation by histone acetyltransferase… ____->_____

A

Heterochromatin->euchromatin

46
Q

Deacetylation by histone deacetylase… ____->_____

A

Euchromatin->heterochromatin

47
Q

Translational regulation

A

Control protein synthesis (rate of translation intitiation/formation of initiation complex)

48
Q

Postranslational regulation

A

Control protein abundance and activity (availability of fxnal protein)

49
Q

Abundance of protein depend on…

A

Postranslational mod (phosphorylation)
Processing (cleavage)

50
Q

Levels of eukaryotic gene regulation brief overview

A
  1. Epigenetics (chromatin remodelling)
  2. Transcriptional (mRNA synthesis)
  3. Post transcription (mRNA processing)
  4. Translation (protein synthesis)
  5. Post-translation. (Protein processing)
51
Q

Epigenetics (chromatin remodelling

A

-Postranslational mod of histones
-DNA methylation

52
Q

Transcriptional (mRNA synthesis)

A

-initiation elongation termination
-transcription factors promotes enhancers

53
Q

Posttranscription (mRNA processing)

A

-5’capping
-3’ polyadenylation
-splicing
-mRNA degradation (exoribonucleases and siRNA)

54
Q

Translation (protein synthesis)

A

-initiation
-elongation
-termination
-microRNA

55
Q

Posttranslation (protein processing)

A

-Postranslational mod: phosphorylation,acetylation, methylation, ubiqutination
-protein degradation

56
Q

What would happen if you made changes at a level of eukaryotic gene regulation

A

Potentially alter protein expression and cause variation in phenotype

Biol 243 Midterm (8 decks)

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