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M1 > Gene Expression and Regulation > Flashcards

Gene Expression and Regulation Flashcards

1
Q

Inhibitors to know!!!

A
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2
Q

process by which an enzyme system converts the genetic information in dsDNA into an RNA strand with a complementary base sequence

A

trancription

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3
Q

RNA synthesis does not require

A

a primer

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4
Q

mRNA in eukaryotes is synthesized by

A

RNA polymerase II

two or more upstream activating sequences

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5
Q

rho-independent terminators:

A

have a self-complementary region that forms a hairpin

have a conserved string of three A residues that are transcribed into U residues near the 3′ end of the hairpin

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6
Q

an array of proteins that work with Pol II form the active transcription complex

A

transcription factors

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7
Q

those required at every Pol II promoter

A

general transcription factors

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8
Q

Transcription factors are: (specificity)

A

tissue specific

gene specific

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9
Q

Enhancer Sequences

A
  • may be long distances upstream or downstream of the start site
  • must be on the same strand as the gene
  • can be found within introns
  • can affect transcription regardless of its orientation
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10
Q

Transcription Factor 3A protein has the motif

A

Zinc finger protein motif

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11
Q

= responsible for the synthesis of a transcript called pre-ribosomal RNA (or pre-rRNA)

A

RNA polymerase I (Pol I)

pre-rRNA contains the precursor for the 18S, 5.8S, and 28S rRNAs

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12
Q

RNA polymerase II needs to have

A

TATA box binding protein and TFIID to transcribe

In Eukaryotes, the TATA box is necessary but not sufficient for strong promoter activity. Additional elements are located between -40 and -110

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13
Q

Termination of transcription in eukaryotes requires a

A

poly-a-addition signal (AAUAAA)

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14
Q

Processes and Possible Regulation

A
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15
Q

nucleotidal transferase

A

does not require a template

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16
Q

Always present in constant amounts regardless of the metabolic state of the organism

A

Constitutive enzymes

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17
Q

Usually found in low amounts and can increase when their substrates are present

A

induced enzymes

18
Q

Enzymes are not synthesized if not needed

A

Enzyme repression

19
Q

Describes the complete regulatory unit of a set of cluster genes; it includes adjacent structural genes that code for related enzymes or associated proteins and control element

A

operon

20
Q

genes for products that are required at all times and are expressed continuously

examples: enzymes of central metabolic pathways

cellular concentrations of the proteins encoded vary

A

housekeeping genes

21
Q

= expression of a gene at approximately constant levels

A

constitutive gene expression

22
Q

The RNA polymerase-promoter interaction strongly influences the rate of

A

transcription initiation

23
Q

The lac Operon is subject to ________ regulation

A

negative

24
Q

lactose (lac) operon includes the genes for:

A
  • β-galactosidase (Z)
  • galactoside permease (Y)
  • thiogalactoside transacetylase (A) = modifies toxic galactosides to facilitate their removal

the lac operon is repressed in the absence of lactose

repression is not absolute

25
Q

an inducer of the lac operon

A

allolactose, an isomer of lactose

binding of allolactose to the Lac repressor causes a conformational change and dissociation

results in expression of lac operon genes

26
Q

phosphodiesterase cleaves

A

cAMP in the presense of glucose

27
Q
A
28
Q

process in which a particular exon may or may not be incorporated into the mature mRNA transcript

A

alternative splicing

occurs in > 95% of human genes

29
Q
A
30
Q

REQUIREMENTS FOR RNA BIOSYNTHESIS

A
  • A double-stranded (ds) DNA template
  • DNA-dependent RNA polymerases
  • 4 nucleoside triphosphates
  • Mg++ for optimal activity
  • Transcription occurs in the 5’à3’ direction
  • Only 1 strand of the DNA molecule serves as the template in a given region

NO PRIMER NEEDED UNLIKE DNA SYNTHESIS

31
Q
A
32
Q

Prokaryotic Subunits of RNA Polymerase from E. coli

A
  • Subunit # Role
  • α 2 Binds regulatory sequences
  • β 1 Forms phosphodiester bonds
  • β’ 1 Binds DNA template
  • w (omega)1 conformation maintenance & recruitment of the b’ subunit
  • σ70 1 Recognizes promoter & initiates synthesis
  • The core enzyme is composed of all the subunits except the sigma subunit.
  • The holoenzyme is composed of all the subunits, including the sigma subunit. ​
33
Q

Eukaryotic RNA Polymerases

A
34
Q

Initiation begins with the recognition of the _______ by the _______component of _______

A

TATA box; TATA box binding protein (TBP); TFIID

35
Q

Differences between transcription in eukaryotes and prokaryotes

A
  • One type of RNA polymerase in prokaryotes and three in eukaryotes
  • Prokaryotes make POLYCISTRONIC mRNA and eukaryotes make MONOCISTRONIC mRNA.
  • Prokaryotic mRNA undergoes very little modifications while eukaryotic mRNA undergoes multiple modifications.
  • This is because mRNA from prokaryotes can be co-transcriptionally translated while eukaryotic mRNA cannot and need modification to increase molecular stability as well as protect against degradation.
36
Q

The base sequence of an intron begins with _______ and the exon ends with _______.

A

GU; AG

37
Q

Important internal site located 20 to 50 nucleotides upstream of the 3’ splice site in introns

A

branch site

38
Q

Amino acids are activated and attached to their corresponding tRNA by

A

aminoacyl-tRNA synthetase

39
Q

Formation of aminoacyl-transfer RNAs ( tRNAs)

A
  1. An amino acid first reacts with adenosine triphosphate (ATP), forming an activated amino acid (aminoacyl-adenosine monophosphate [AMP]) and pyrophosphate, which is cleaved to two inorganic phosphates (Pi).
  2. The aminoacyl-AMP then forms an ester with the 20-or30-hydroxyl of a tRNA specific for that amino acid, producing an aminoacyl-tRNA and AMP.
  3. Once an amino acid is attached to a tRNA, insertion of the amino acid into a growing polypeptide chain depends on the codon–anticodon interaction
40
Q

Steps of Translation

A
  1. Initiation: Involves the assembly of an active ribosomal complex
  2. Elongation & Translocation: New amino acids are brought to the ribosome according to the codon sequence and translocated to a growing polypeptide chain
  3. Termination: At certain “stop” codons, translation is ended.
  4. Release : The newly formed polypeptide is released

Note that translation occurs from the amino terminal to the carboxy terminal and mRNA is read in the 5’ to 3’ direction

41
Q

40s ribosomal subunit associates with eIF3 to physically block 40s & 60s subunit association

A

anti-association factor

M1 (48 decks)

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