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Biotechnology Mid Term > CH3 | PTMs (2/2) > Flashcards

CH3 | PTMs (2/2) Flashcards

1
Q

Post-translational modifications (PTMs) are…

A

alterations in the amino acid sequence of a protein after its synthesis.

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2
Q

PTMs may involve modifying…

A

the amino acid side chain, terminal amino, or carboxyl group.

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3
Q

PTMs are achieved through…

A

covalent or enzymatic means.

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4
Q

PTMs influence…

A

protein structure, stability, activity, cellular localization, or substrate specificity.

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5
Q

PTMs provide…

A

complexity to the proteome for diverse functions with a limited number of genes.

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6
Q

PTMs can occur…

A

at any step in the “life cycle” of a protein.

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7
Q

PTMs that occur shortly after translation mediate…

A

proper protein folding/stability or direct the nascent protein to distinct cellular compartments.

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8
Q

PTMs that occur after folding and localization…

A

activate/inactivate catalytic activity or influence the biological activity of the protein.

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9
Q

PTMs can also be used to…

A

get rid of defective proteins or end-of-life proteins.

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10
Q

The human genome comprises approximately…

A

21,000 genes.

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11
Q

The human proteome is estimated to contain over…

A

1 million proteins.

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12
Q

The difference in numbers between the genome and proteome demonstrates…

A

proteome complexity.

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13
Q

The human genome has ~22,000 genes, while the transcriptome has…

A

~200,000 transcripts.

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14
Q

The increase in numbers from the genome to the transcriptome is due to…

A

alternative promoters, alternative splicing, and mRNA editing.

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15
Q

The increase in numbers from the transcriptome to the proteome is due to…

A

post-translational modifications.

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16
Q

How many different types of PTMs are there?

A

More than 400.

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17
Q

PTMs that involve the addition of chemical groups are…

A

reversible.

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18
Q

Examples of PTMs that involve the addition of chemical groups include…

A

hydroxylation, phosphorylation, acetylation, and methylation.

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19
Q

PTMs that involve amino acid modification are…

A

irreversible.

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20
Q

Examples of PTMs that involve amino acid modification include…

A

deamidation and eliminylation.

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21
Q

PTMs that involve the addition of complex molecules are…

A

reversible.

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22
Q

Examples of PTMs that involve the addition of complex molecules include…

A

AMPylation, ADP-ribosylation, glycosylation, and prenylation.

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23
Q

PTMs that involve the addition of polypeptides are…

A

reversible.

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24
Q

Examples of PTMs that involve the addition of polypeptides include…

A

ubiquitylation and UBL-protein conjugation (e.g., SUMO).

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25
Q

PTMs that involve cleavage are…

A

irreversible.

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26
Q

An example of a PTM that involves cleavage is…

A

proteolysis.

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27
Q

Phosphorylation involves the addition of…

A

a phosphate group on serine, threonine, or tyrosine residues.

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28
Q

Phosphorylation converts an uncharged pocket of a protein into…

A

a negatively charged and hydrophilic protein.

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29
Q

Phosphorylation and dephosphorylation can switch proteins…

A

on or off.

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30
Q

Phosphorylation has implications in cellular processes such as…

A

cell cycle, growth, apoptosis, and signal transduction pathways.

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31
Q

The enzyme that adds a phosphate group is called…

A

kinase.

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32
Q

The enzyme that removes a phosphate group is called…

A

phosphatase.

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33
Q

Phosphorylation requires what molecule as a phosphate source…

A

ATP.

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34
Q

Dephosphorylation releases what molecule…

A

Pi (inorganic phosphate).

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35
Q

Acetylation involves the addition of…

A

an acetyl group (C2H3O) to a lysine residue.

36
Q

Acetylation is carried out by enzymes called…

A

acetyltransferases.

37
Q

Acetylation neutralizes…

A

the positive charge on the amino acid residue.

38
Q

Acetylated proteins cannot be…

A

ubiquitinated, making them more stable.

39
Q

Acetylation and deacetylation of histones are a critical part of…

A

gene regulation.

40
Q

Histone acetylation causes DNA to become…

A

accessible, activating the gene.

41
Q

Deacetylation of histones causes DNA to become…

A

inaccessible, silencing the gene.

42
Q

Hydroxylation involves the addition of…

A

a hydroxyl group (-OH) to proline, lysine, and asparagine.

43
Q

Hydroxylation is catalyzed by enzymes called…

A

hydroxylases.

44
Q

Hydroxylation aids in converting…

A

hydrophobic compounds into hydrophilic compounds.

45
Q

Hydroxyproline in collagen plays an important role in…

A

stabilizing the triple-helix structure of collagen by forming hydrogen bonds.

46
Q

The hydrogen bonds formed by hydroxyproline in collagen contribute to…

A

the tensile strength of connective tissues.

47
Q

Mutations in collagen can lead to connective tissue disorders such as…

A

Ehlers-Danlos syndrome.

48
Q

Methylation involves the addition of…

A

a methyl group to lysine and arginine residues of a protein.

49
Q

Methylation is achieved by enzymes called…

A

methyltransferases.

50
Q

Methylation increases…

A

the hydrophobicity of the protein.

51
Q

Methylation can neutralize…

A

a negative amino acid charge.

52
Q

Methylation plays a major role in…

A

gene expression control and cancer by silencing tumor suppressors.

53
Q

Methylation of DNA and histones causes…

A

nucleosomes to pack tightly together, making DNA inaccessible and the gene inactive.

54
Q

DNA methylation…

A

silences genes.

55
Q

Demethylation of DNA…

A

activates genes.

56
Q

In a normal cell, tumor suppressor genes (TSG) are…

A

expressed (active transcription).

57
Q

In a tumor cell, tumor suppressor genes (TSG) are…

A

silenced (blocked transcription) due to focal hypermethylation.

58
Q

In a normal cell, oncogenes are…

A

silenced (blocked transcription).

59
Q

In a tumor cell, oncogenes are…

A

expressed (active transcription) due to global hypomethylation.

60
Q

Glycosylation involves the addition of…

A

an oligosaccharide ‘glycan’ to either a nitrogen atom (N-linked) or an oxygen atom (O-linked) of asparagine, serine, or threonine residues.

61
Q

Erythropoietin (EPO) is a glycoprotein hormone that…

A

stimulates the production of red blood cells.

62
Q

Glycosylation affects EPO’s…

A

stability, activity, pharmacokinetics, and pharmacodynamics.

63
Q

Glycosylation can prolong…

A

the half-life of EPO in the bloodstream.

64
Q

Glycosylation can enhance…

A

EPO’s binding affinity to its receptor.

65
Q

Differences in the glycosylation pattern of EPO can affect…

A

its immunogenicity and therapeutic efficacy, with implications for the development of biologic drugs.

66
Q

Ubiquitination involves the addition of…

A

a protein - ubiquitin - to the lysine residue of a substrate.

67
Q

Ubiquitination plays a role in protein degradation by…

A

targeting the protein to the proteasome for degradation into small peptides.

68
Q

Ubiquitination plays a role in protein trafficking by…

A

targeting proteins to specific subcellular compartments, such as targeting membrane proteins for internalization and lysosomal degradation or cytoplasmic proteins for transport to the nucleus.

69
Q

Ubiquitination plays a role in protein signaling by…

A

activating or inhibiting the enzymatic activity of some proteins or promoting their interaction with other proteins.

70
Q

Ubiquitination is involved in cellular processes such as…

A

DNA repair, cell cycle regulation, and immune response.

71
Q

Ubiquitination is involved in the regulation of…

A

the tumor suppressor protein p53.

72
Q

Proteolysis can remove…

A

regulatory proteins when they are not needed.

73
Q

Proteolysis can transform proteins…

A

from the dormant into the biologically active state.

74
Q

An example of a protein that undergoes proteolysis to become active is…

A

insulin.

75
Q

The first step in insulin processing involves…

A

the removal of the signal sequence from preproinsulin to produce proinsulin.

76
Q

Proinsulin contains…

A

an A chain, a B chain, and a C-peptide.

77
Q

The second step in insulin processing involves…

A

the removal of the C-peptide from proinsulin to produce insulin.

78
Q

The active form of insulin contains…

A

an A chain and a B chain linked by disulfide bonds.

79
Q

The cleavage site for insulin processing critically includes…

A

a lysine residue.

80
Q

Deamidation involves the removal of…

A

amide groups in asparagine or glutamine, converting them to aspartic or glutamic acid.

81
Q

Deamidation is catalyzed by enzymes called…

A

deamidases.

82
Q

α-crystallin, a small protein in the eye’s lens, aids in…

A

proper protein folding and shape maintenance.

83
Q

α-crystallin contains several asparagine residues that are susceptible to…

A

deamidation over time, particularly in the aging lens.

84
Q

Deamidation of α-crystallin can affect…

A

its structure and function.

85
Q

Deamidation of α-crystallin has been linked to…

A

the formation of cataracts, a common age-related eye disorder.

Biotechnology Mid Term (9 decks)

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