PRACTICE EXAM #3 Flashcards

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1
Q

Allolactose induces the synthesis of the enzyme lactase. An E. coli cell is presented for the first time with the sugar lactose (containing allolactose) as a potential food source. Which of the following occurs when the lactose enters the cell?

A

Allolactose binds to the repressor protein.

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2
Q

true or false: A ribosome binds one tRNA at a time.

A

false

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3
Q

true or false: Ubiquitin is a small protein that is covalently attached to proteins to mark them for delivery to the proteasome.

A

true

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4
Q

Examples of a pair of codons expected to be read by the same tRNA because the Wobble effect areCAA and _______________

A

CAU
CAG
CAC

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5
Q

Which level control in eukaryotic gene activity involves changes in the polypeptide chain before it becomes functional such as adding phosphate groups?

A

Posttranslational

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6
Q

If mature eukaryotic mRNA is hybridized with its corresponding DNA coding strand (heteroduplex analysis) and visualized by electron microscopy, looping strands of nucleic acid are seen. What do these structure represent?

A

introns

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7
Q

Which level of of control in gene expression regulation is very comon in both prokariotes and eukaryotes?

A

transcriptional like using activators and repressors

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8
Q

true or false: Ribosomes are large RNA structures composed solely of rRNA.

A

false

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9
Q

Which of the classes of RNA molecules is linked with proteins in forming the large and small subunits of a cytoplasmic structure?

A

ribosomal RNA

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10
Q

While prokaryotes are polycystronic, they also have a _______ sequence to bind to the ribosome upstream form the AUG starting code.

A

Shine-Dalgarno sequence

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11
Q

PAP and poly-A binding protiens are related with:

A

the 3’ terminal of the mRNA

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12
Q

With your expert opinion, what do you think it would happen if snRNA are produced but are mutated?

A

no formation of splisosomes

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13
Q

A transcriptional regulator that decreases transcription of a gene from a vast distance is known as a(n)

A

repressor-silencer.

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14
Q

Ribozymes catalyze the reactions ________________, _____________

A
  • splicing

- translation

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15
Q

true or false: Ribosomes can start translating an mRNA molecule before transcription is complete.

A

true

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16
Q

If glucose is available in the environment of E. coli, the cell responds with very low concentration of cAMP. When the cAMP increases in concentration, it binds to CAP. Which of the following would you expect would then be a measurable effect?

A

increased concentrations of sugars such as arabinose in the cell

17
Q

true or false: tRNA bind only one type of amino acid.

A

false

18
Q

Which is most directly responsible for the sequence of amino acids in a protein?

A

the sequence of codons in mRNA

19
Q

true or false: A single procaryotic mRNA molecule can be translated into several proteins.

A

true

20
Q

How does active CAP induce expression of the genes of the lactose operon?

A

It stimulates the binding of RNA polymerase to the promoter.

21
Q

Which amino acid would you expect a tRNA with the anticodon 5′-CUU-3′ to carry?

A

lysine

22
Q

In prokaryotes, mRNA molecules commonly contain coding sequences for several different polypeptide chains; such a molecule is called a __________.

A

Polycistronic mRNA

23
Q

True or false: enhancer-binds to the repressor plus ligand protein

A

false

24
Q

true or false: genetic code is exactly the same in all organisms.

A

false

25
Q

THe exons joint together, from a primary transcript, carry the genetic information from the nucleus to the cytosol as it is needed for the construction of a protein as

A

messenger RNA

26
Q

In polypeptide Met-Phe-Leu, what amino acid has a free carboxyl group?

A

Leu

27
Q

Altering patterns of gene expression in prokaryotes would most likely serve the organism’s survival in which of the following ways?

A

allowing the organism to adjust to changes in environmental conditions