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Cell And Molec > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

What is the function of tRNA?

A

Transfer RNAs; central to protein synthesis as adaptors between mRNA and amino acids

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2
Q

What is the function of siRNA?

A

Small interfering RNAs; turn off gene expression by directing the degradation of selective mRNAs and the establishment of compact chromatin structures

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3
Q

What is the function of miRNA?

A

MicroRNAs; regulate gene expression by blocking translation of mRNAs and cause their degradation

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4
Q

What is the function of piRNA?

A

Piwi interacting RNAs; bind to piwi-proteins and protect the germ line from transposable elements

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5
Q

The 5’ cap of mRNAs is generated by which enzymes?

A

Phosphatase, a guanyl transferase, a methyl transferase

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6
Q

RNA is?

A

Composed of 4 nucleotides connected by a phosphodiester backbone (same as DNA)

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7
Q

RNA is less what than DNA?

A

Less hydrophobic, less stable than DNA

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8
Q

Uracil can?

A

Base pair with adenine

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9
Q

What synthesizes RNA from a DNA template?

A

RNA polymerase

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10
Q

Describe initiation of transcription of a eukaryotic gene by RNA polymerase 2.

A

Through TBP subunit, TF2D binds TATA box. TF2B is recruited next. RNA polymerase 2 recruited next. Phoshporylation of CTD releases RNA polymerase next

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11
Q

RNA polymerase 2 is an RNA factory involved in?

A

Transcription of DNA and processing of the mRNA it produces

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12
Q

CTD is key for?

A

mRNA processing by binding proteins required

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13
Q

mRNA splicing does what?

A

Removes introns and joins exons

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14
Q

What are two types of splicing error?

A

Exon skipping and cryptic splice site selection

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15
Q

RNA splicing is performed by the?

A

Spliceosome

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16
Q

SR proteins do what?

A

Bind and mark exons

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17
Q

SR proteins contain?

A

Serine and arginine domains

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18
Q

hnRNPs bind to?

A

Introns

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19
Q

B thalassemia is what and what causes it?

A

It is anemia with aberrant hemoglobin synthesis caused by abnormal splicing of the b-globin primary transcript

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20
Q

Some major steps in generating the 3’ end are?

A

CPSF; a cleavage and polyadenylation specificity factor
CstF; a cleavage stimulation factor
PAP; a poly-A polymerase
Poly-A-binding proteins

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21
Q

What is the role of the RNA polymerase 2 CTD and how does its modification affect the activity of the enzyme?

A

It serves as a scaffold for mRNA processing by binding the proteins required; it is dephosphorylated before starting transcription again

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22
Q

The purpose of the 5’ cap of mRNAs is to?

A

Distinguish mRNA from other RNA

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23
Q

What are consequences of errors in splicing?

A

B thalassemia, cystic fibrosis, Parkinsons, retinitis pigmentosa, cancer

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24
Q

What is translation?

A

The conversion of the genetic information in mRNA to an amino acid sequence within a protein

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25
Q

What are codons?

A

Three consecutive nucleotides in mRNA that specify which amino acid should be utilized

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26
Q

What acts as stop codons?

A

UAA
UAG
UGA

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27
Q

What acts as the start codon?

A

AUG

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28
Q

Inosine is what?

A

A non-standard nucleotide that makes codon base pairing more flexible if it is pairing in the wobble position

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29
Q

What is a ribosome?

A

A large protein/RNA complex containing 2/3 rRNA

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30
Q

What do eukaryotic initiation factors (elFs) do?

A

Assess mRNA quality

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31
Q

What does the Kozak sequence do?

A

Helps the small subunit correctly identify the start codon

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32
Q

What does elF4G do?

A

Binds to the 5’ cap and polyA binding proteins

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33
Q

What do proteins called release factors do?

A

They bind the A site thus releasing COOH the completed polypeptide chain and then dissassembly of the ribosome

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34
Q

What is a polyribosome?

A

Multiple ribosomes actively translating a single mRNA

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35
Q

Exon junction complexes (EJCs) do what?

A

Mark successful splicing events

36
Q

Upf proteins do what?

A

Bind to EJCs and target defective mRNAs for degradation

37
Q

Chaperones including the heat shock proteins do what?

A

Help to guide protein folding

38
Q

HSP70 proteins do what?

A

They fold new proteins

39
Q

What is a proteasome?

A

An ATP dependent protease in the cytosol and nucleus that digests proteins down into fragments

40
Q

What are two ways of inducing protein degradation?

A

Ubiquitin ligases or degradation signals

41
Q

Degrons do what?

A

Stimulate polyubiquination of proteins which targets it for proteasomal degradation

42
Q

Helps to position the RNA polymerase correctly at the promoter, to aid in pulling apart the two strands of DNA to allow transcription to begin, and to release RNA polymerase from the promoter into the elongation mode once transcription has begun.

A

General transcription factor

43
Q

Small RNA molecules that are complexed with proteins to form the ribo-nucleoprotein particles involved in RNA splicing.

A

snRNA (small nuclear RNA)

44
Q

Nucleotide sequence in DNA to which RNA polymerase binds to begin transcription.

A

Promoter

45
Q

A large protein complex containing multiple 3’ to 5’ RNA exonucleases that degrade improperly processed mRNAs, introns, and other RNA debris retained in the nucleus

A

Exosome

46
Q

The enzyme that carries out transcription.

A

RNA polymerase

47
Q

RNA molecule that specifies the amino acid sequence of a protein.

A

mRNA (messenger RNA)

48
Q

Process in which intron sequences are excised from RNA transcripts in the nucleus during the formation of messenger and other RNAs.

A

RNA splicing

49
Q

Signal in bacterial DNA that halts transcription

A

Terminator

50
Q

Segment of a eukaryotic gene consisting of a sequence of nucleotides that will be represented in mRNA or other functional RNAs.

A

Exon

51
Q

Large multiprotein structure forming a channel through the nuclear envelope that allows selected molecules to move between nucleus and cytoplasm.

A

Nuclear pore complex

52
Q

Large protein complex in the cytosol and nucleus with proteolytic activity that is responsible for degrading the proteins marked for destruction.

A

Proteasome

53
Q

Set of rules specifying the correspondence between nucleotide triplets in DNA or RNA and amino acids in proteins

A

Genetic code

54
Q

Special tRNA that carries methionine and is used to begin translation

A

Initiator tRNA

55
Q

Sequence of three nucleotides in a tRNA that is complementary to a three nucleotide sequence in an mRNA molecule

A

Anticodon

56
Q

RNA molecule with catalytic activity

A

Ribozyme

57
Q

Surveillance system in eukaryotes that eliminates defective mRNAs before they can be translated into protein.

A

Nonsense mediated mRNA decay

58
Q

The three-nucleotide phase in which nucleotides in an mRNA are translated into amino acids in a protein.

A

Reading frame

59
Q

Enzyme that attaches the correct amino acid to a tRNA molecule to form the activated intermediate used in protein synthesis.

A

Aminoacyl-tRNA synthetase

60
Q

Protein that helps other proteins fold correctly.

A

Molecular chaperone

61
Q

Regulates which RNAs are exported from the nucleus

A

RNA transport control

62
Q

Regulates when and how often a given gene sequence is made into RNA

A

Transcriptional control

63
Q

Regulates which mRNA molecules are selectively destabilized in the cytoplasm

A

mRNA degradation control

64
Q

Regulates which mRNAs are selected to be used for protein synthesis by ribosomes

A

Translational control

65
Q

Regulates the splicing and modification of RNA transcripts

A

RNA processing control

66
Q

Nucleotide sequence in DNA to which RNA polymerase binds to begin transcription

A

Promoter

67
Q

The whole expanse of DNA involved in regulating and initiating transcription of a gene

A

Gene control region

68
Q

The segment of DNA that is transcribed into RNA

A

Gene

69
Q

Cell derived from a fibroblast, by artificial expression of specific transcription regulators, that looks and behaves like an embryonic stem cell

A

Induced pluripotent stem cell

70
Q

The property that allows a proliferating cell to maintain its identity through subsequent cell divisions

A

Cell memory

71
Q

Antibody secreted by a hybridoma cell line

A

Monoclonal antibody

72
Q

Cell line used in the production of monoclonal antibodies; obtained by fusing antibody secreting B cells with cells of a lymphocyte tumor

A

Hybridoma

73
Q

General term for purification technique in which a mixture of proteins is passed through a cylinder containing a porous solid matrix

A

Column chromatography

74
Q

Type of chromatography that uses columns packed with special chromatography resins composed of tiny spheres that attain a high degree of resolution, even at very fast flow rates

A

High performance liquid chromatography

75
Q

Artificial product generated by linking the coding sequences for two different proteins, or protein segments, and expressing the hybrid gene in cells

A

Fusion protein

76
Q

Technique for protein separation in which the protein mixture is run first in one direction and then in a direction at right angles to the first

A

Two dimensional gel electrophoresis

77
Q

Technique in which a protein mixture is separated by running it through a gel containing a detergent that binds to and unfolds the proteins

A

SDS polyacrylamide-gel electrophoresis

78
Q

The main technique that has been used to discover the three dimensional structure of molecules, including proteins, at atomic resolution

A

X-ray crystallography

79
Q

Technique by which proteins are separated by electrophoresis, immobilized on a paper sheet, and then analyzed, usually by means of a labeled antibody

A

Western blotting (immunoblotting)

80
Q

Fluorescent protein (from a jellyfish) that is widely used as a marker for monitoring the movements of proteins in living cells

A

Green fluorescent protein

81
Q

The minimal separation between two objects at which they appear distinct

A

Limit of resolution

82
Q

The normal light microscope in which the image is obtained by simple transmission of light through the object being viewed

A

Bright field microscope

83
Q

Computer treatment of images gained from microscopy that reveals information not immediately visible to the eye

A

Image processing

84
Q

Similar to a light microscope but the illuminating light is passed through one set of filters before the specimen, to select those wavelengths that excite the dye, and through another set of filters before it reaches the eye, to select only those wavelengths emitted when the dye fluoresces

A

Fluorescence microscope

85
Q

Type of light microscope that produces a clear image of a given plane within a solid object. It uses a laser beam as a pinpoint source of illumination and scans across the plane to produce a two dimensional optical section

A

Confocal microscope

86
Q

Technique for monitoring the closeness of two fluorescently labeled molecules in cells

A

Fluorescence resonance energy transfer

87
Q

Piece of fine glass tubing, pulled to an even finer tip, that is used to inject electric current into cells

A

Microelectrode

Cell And Molec (5 decks)

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