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MOL. BIO LEC > MB PRELIM LEC 3: RNA TRANSCRIPTION > Flashcards

MB PRELIM LEC 3: RNA TRANSCRIPTION Flashcards

1
Q

Copying of 1 strand of DNA into RNA
mRNA carries the information in DNA to the ribosomes, where it is translated into protein

A

TRANSCRIPTION

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2
Q

DNA can only store information. How will this information be used?
____________
- It is the production of RNA and protein using a DNA template

A

GENE EXPRESSION

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3
Q

Setting the stage for transcription to begin:
DNA must be released locally from histones & the helix unwound, involve the participation of:

A

DNA BINDING PROTEINS
TRANSCRIPTION FACTORS
HISTONE MODIFICATION ENZYMES
RNA POLYMERASE

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4
Q

RNA polymerase & its supporting accessory proteins assemble on DNA at a specific site (promoter)

A

TRANSCRIPTION INITIATION

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5
Q

PROKARYOTE:
_____________: assembly of large & small subunits of RNA polymerase & additional sigma factors at the promoter

A

BASAL TRANSCRIPTION COMPLEX

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6
Q

EUKARYOTES:
_________: assembly of RNA polymerase & up to 20 additional factors for accurate initiation

A

TRANSCRIPTION COMPLEX

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7
Q

how many bases/sec can RNA polymerase build?

A

50 - 100 bases/sec

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8
Q

how many bases/sec can DNA polymerase build?

A

1,000 bases/sec

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9
Q

Some are responsive to protein products; HIGH LEVEL OF GENE PRODUCT induce termination of its own synthesis.

TERMINATION IN?

A

PROKARYOTES

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10
Q

LARGEST COMPONENT of cellular RNA (80%-90% of the total cellular RNA)
- Various types are named for their sedimentation coefficient (S) in density-gradient centrifugation
- Important in structural & functional part of the ribosomes

A

RIBOSOMAL RNA

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11
Q

Initial connection between the information stored in DNA & the translation apparatus that will ultimately produce the protein products responsible for the phenotype

A

MESSENGER RNA

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12
Q

MESSENGER RNA IN __________ are:
- Synthesized & simultaneously translated into protein
- Sometimes POLYCISTRONIC (1 mRNA codes for more than 1 protein)

A

PROKARYOTES

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13
Q

MESSENGER RNA IN __________ are:
- MONOCISTRONIC (having only 1 protein per mRNA)
- Can produce different proteins from the same DNA sequences by:
- starting the RNA synthesis in different places or
- by processing the mRNA differently

A

EUKARYOTES

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14
Q

EUKARYOTES mRNA
messages are transcribed CONSTANTLY & are relatively abundant in the cell

A

CONSTITUTIVE TRANSCRIPTION

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15
Q

EUKARYOTES mRNA
messages are transcribed only a CERTAIN TIMES during the cell cycle under particular conditions

A

INDUCIBLE/REGULATORY TRANSCRIPTION

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16
Q

Addition of adenosines to the 3’ end of mRNA

A

POLYADENYLATION

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17
Q

is the enzyme responsible for adding the adenines to the end of the subscript

A

POLYADENYLATE POLYMERASE

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18
Q
  • A structure (5’-5’ pyrophosphate linkage of 7-methyl guanosine to either 2’ O-methyl adenine of the mRNA) that BLOCKS THE EUKARYOTIC mRNA at the 5’ terminus
  • Confers a protective function & serves as a recognition signal for the translational apparatus
A

CAP

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19
Q

Removal of intron sequences from mRNA

A

SPLICING

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20
Q

noncoding (intervening) sequences, does not code for amino acids

A

INTRONS

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21
Q

Remaining sequences that code for the protein product

A

EXONS

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22
Q

newly transcribed mRNA, much larger than mature RNA because it contains introns

A

HETERONUCLEAR RNA (hnRNA)

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23
Q

Splicing Mechanism:
Special sequences of RNA that are able to splice themselves

A

SELF - SPLICING

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24
Q

Splicing Mechanism:
Nuclear macromolecule complex within which splicing reactions occur to remove introns from pre-mRNAs

A

SPLICEOSOME

25
- Removal of introns from RNA USING DIFFERENT BREAKPOINTS - Exons from the same gene are joined in different combinations, leading to different, but related, mRNA transcripts - Modifies products of gene by ALTERNATE INSERTION OF DIFFERENT EXONS - Has been found in over 40 different genes
ALTERNATIVE SPLICING
26
Some of the diseases resulting from abnormalities in splicing process: - mutations in the splice recognition sequences of the ẞ-globin genes
ẞ-THALASSEMIAS
27
Some of the diseases resulting from abnormalities in splicing process: - production of antibodies to RNA- protein complexes
CERTAIN AUTOIMMUNE CONDITIONS
28
- FUNCTIONS IN SPLICING IN EUKARYOTES, allowing for precise alignment and correct excision of introns - Stays in the nucleus after its transcription by RNA polymerase I or III
SMALL NUCLEAR RNA (snRNA)
29
- ADAPTOR MOLECULES during the translation process - Relatively short, single-stranded polynucleotides of 73-93 bases in length, MW 24,000-31,000 - At least 1 tRNA for each amino acid CCA at the 3' end: amino acid will be covalently attached to the tRNA
TRANSFER RNA (tRNA)
30
the end of tRNA to which an amino acid becomes bound
ACCEPTOR ARM
31
tRNA loops:
TψC loop ANTICODON LOOP VARIABLE LOOP D LOOP
32
TψC loop ( stands for the modified pseudouridine), seven-base loop, contains the sequence _________-
5' - TTCG - 3'
33
SPECIAL RECOGNITION SITE FOR THE RIBOSOME to allow a tRNA-ribosome complex to form during the process of protein synthesis
TψC loop
34
Larger in longer tRNAs, HELPS IN RECOGNITION OF THE tRNA molecule
VARIABLE LOOP
35
- 8- to 12-base loop, relatively rich in dihydrouridine (modified nucleotide), plays an important role in STABILIZING RNA STRUCTURE
D LOOP
36
solved the 1st tRNA sequence (alanine tRNA of yeast = 76 bases long & 10 of these are modified)
ROBERT HOLLEY & COLLEAGUES AT CORNELL UNIV. 1964
37
OTHER RNA'S FUNCTIONS: - RNA synthesis & processing - Influence numerous cellular processes such as?
- PLASMID REPLICATION - BACTERIOPHAGE DEVELOPMENT - CHROMOSOME STRUCTURE AND DEVELOPMENT
38
- It refers to any events in the life cycle of RNA molecules: ● Transcription ● Folding/unfolding ● Modification ● Processing ● Degradation
RNA METABOLISM
39
OTHER RNA-METABOLIZING ENZYMES - Ubiquitous, stable enzymes that degrade all types of RNA
RIBONUCLEASES
40
OTHER RNA-METABOLIZING ENZYMES - Required in RNA synthesis & processing to catalyze the UNWINDING of dsRNA - Have been characterized in prokaryotes & eukaryotes - Some work exclusively on RNA, others on DNA (RNA heteroduplexes & DNA substrates - Involved in removal of proteins from RNA-protein complexes
RNA HELICASES
41
- Production of RNA and protein using a DNA template - Key determinant of phenotype - Some genes (products are in continual use by the cell), gene expression is constant (constitutive) - Other genes, gene expression is tightly regulated throughout the life of the cell
GENE EXPRESSION
42
Most immediate & well-studied level of control of gene expression:
TRANSCRIPTION INITIATION
43
Regulation of mRNA Synthesis at Initiation 2 FACTORS RESPONSIBLE:
CIS FACTORS & TRANS FACTORS
44
DNA sequences that MARK PLACES ON DNA involved in the initiation & control of RNA synthesis
CIS FACTORS
45
Proteins that BIND TO THE CIS SEQUENCES & direct the assembly of transcription complexes at the proper gene
TRANS FACTORS
46
SERIES OF STRUCTURAL GENES transcribed together on 1 mRNA & subsequently separated into individual proteins
OPERON
47
LOCATION OF CIS REGULATORY ELEMENTS: - closer to the gene (proximal elements only) PROKARYOTES OR EUKARYOTES?
PROKARYOTES
48
LOCATION OF CIS REGULATORY ELEMENTS: - thousands of base pairs away from the genes they control (distal elements) - in or around the genes they control (proximal elements) PROKARYOTES OR EUKARYOTES?
EUKARYOTES
49
REPRESSOR PROTEIN BINDS TO THE OPERATOR SEQUENCE & prevents transcription of the operon
LAC OPERON IN THE ABSENCE OF LACTOSE
50
LACTOSE BINDS TO REPRESSOR PROTEIN & changes its conformation & lowers its affinity to bind the operator sequence, resulting in the expression of the operon
LAC OPERON IN THE PRESENCE OF LACTOSE
51
MODE OF REGULATION IN PROKARYOTES
- ENZYME INDUCTION - ENZYME REPRESSION - ACTIVATION
52
MODE OF REGULATION IN PROKARYOTES - inducer prevents the repressor from binding the operator to turn on expression EX: found in lac operon
ENZYME INDUCTION
53
MODE OF REGULATION IN PROKARYOTES - corepressors must bind to a repressor to turn off expression EX: found in arg operon
ENZYME REPRESSION
54
MODE OF REGULATION IN PROKARYOTES - activator binds with RNA polymerase to turn on transcription EX: found in mal operon
ACTIVATION
55
- Another mechanism of control in bacteria - FORMATION OF STEMS & LOOPS IN THE RNA TRANSCRIPT by intrastrand - H bonding of complementary bases (allow/prevent transcription)
ATTENUATION
56
Several factors affecting the stability of the RNA transcript:
- RNA STRUCTURE - PRESENCE OF EXONUCLEASE & ENDONUCLEASE THAT DIGESTS RNA
57
POST - TRANSCRIPTIONAL REGULATION - enzymatic & structural alterations in RNA interfere with its processing - alternate splicing in combination with protein factors is responsible for many tissue- & development-specific gene expression patterns (hematopoiesis) EUKARYOTES OR PROKARYOTES?
EUKARYOTES
58
POST - TRANSCRIPTIONAL REGULATION - RNA transcription & translation are CONCURRENT, protecting the RNA from the processing & exogenous factors - RNA stability is affected by secondary structure (folding of the RNA molecule) & polyadenylation of 3' end of the transcripts - codon usage & cofactor availability may alter translation speed EUKARYOTES OR PROKARYOTES?
PROKARYOTES

MOL. BIO LEC (15 decks)

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