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Medical biology and genetics > Chapter 7 > Flashcards

Chapter 7 Flashcards

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1
Q

Which of the following is true?
A. DNA synthesize proteins itself
B. Gene expression starts with copying the
nucleotide sequence of that gene into RNA
C. The process of converting DNA to RNA is called translation
D. All

A

B

  • DNA does not synthesize proteins itself, but it acts as a manager, delegating the various tasks to a team of workers.
  • The process of converting DNA to RNA is called transcription
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2
Q

Which of the following is not a trait that RNA share with DNA
A. linked together by phosphodiester bonds
B. consists of four different nucleotide subunits
C. contains the sugar ribose
D. is a linear polymer
E. All

A

C

DNA contains deoxyribose while RNA contains ribose

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3
Q

What makes RNA polymerization different from DNA polymerization?

A
  • RNA strand does not remain hydrogen-bonded to the DNA template strand.
  • RNA molecules are single-stranded.
  • RNA molecules are much shorter than DNA molecules
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4
Q

Which of the following is true about RNA polymerase?
I. RNA strand is released immediately from the DNA as it is synthesized
II. RNA polymerases make more errors
III. RNA polymerases can start an RNA chain without a primer
IV. Many RNA copies can be made at the same time from the same gene in a short time
V. RNA polymerase catalyzes ribonucleotides links, not deoxyribonucleotides
A. I, II, III, IV
B. II, III, IV, V
C. I, II, III, IV, V
D. I, III, IV, V

A

C

All are true

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5
Q

Which enzyme do the following functions?

  1. code for protein
  2. regulate gene expression
  3. serve as an adopter between mRNA and amino acid during synthesis
  4. form the core of the ribosome’s structure and catalyze protein synthesis
A
  1. mRNA
  2. miRNA
  3. tRNA
  4. rRNA
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6
Q

Terminator is part of the RNA transcript while

the promoter is not

A

True

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7
Q

Bacteria contain a single type of RNA polymerase while

Eukaryotic cells contain three types.

A

True

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8
Q

what are the genes transcribed by the following RNA polymerases

  1. RNA polymerase I
  2. RNA polymerase II
  3. RNA polymerase III
A
  1. rRNA
  2. all protein-coding genes
    miRNA
  3. tRNA
    5S rRNA
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9
Q

which one of the two RNA polymerases can initiate transcription on its own
A. Bacteria RNA polymerase
B. Eukaryotic RNA polymerase

A

A

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10
Q

Only the dephosphorylated form of ………. can initiate RNA synthesis.

A

RNA polymerase II

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11
Q

What are the RNA processing steps?

A

capping
splicing
polyadenylation

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12
Q

which of the two RNA processing steps occur only on RNA transcripts destined to become mRNA molecules?

A

Capping and polyadenylation

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13
Q

What is the reason for capping and polyadenylation of a Eukaryotic
mRNA?
A. Increases the stability
B. Facilitates export from the nucleus to the cytoplasm
C. takes place as protein is being synthesized
D. Marks the RNA molecule as an mRNA.
E. All except B
F All except C

A

F

takes place as RNA is being synthesized

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14
Q

Protein-Coding genes are interrupted by Noncoding sequences Called ….. in Eukaryotic cells

A

introns

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15
Q

classify the following as bacterial or eukaryotic gene

  1. coding sequences are interrupted by long, noncoding sequences
  2. Proteins are encoded by an uninterrupted stretch of DNA
  3. Translated into protein (without any further processing)
  4. Coding sequences are expressed sequences or exons while non-coding sequences are intervening sequences called introns
A

bacterial gene- 2, 3

eukaryotic gene- 1,4

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16
Q

Introns Are removed from pre-mRNAs by RNA………….

A

spilicing

17
Q

what is snRNP (small nuclear ribonucleoprotein)?

A
  • form the core of the spliceosome
  • recognize splice-site sequences through complementary,
  • they participate in splicing
18
Q

What is the benefit of splicing?

A

RNA splicing enables eukaryotes to increase the already enormous coding potential of their genomes

19
Q

How can the cell distinguish between the relatively rare mature mRNA molecules it needs to export to the cytosol and the overwhelming amount of debris generated by RNA processing?

A

by using nuclear pore complexes that connect the nucleoplasm with the cytosol
and control which macromolecules can enter or leave the nucleus.

20
Q

For an mRNA to be exported from the nucleus it should contain three basic components. what are they?

A
  • poly-A–binding proteins
  • a cap-binding complex
  • proteins that bind to mRNAs that have been appropriately spliced.
21
Q

What happens to the waste RNAs left in the nucleus?

A

The “waste RNAs”, remain in the nucleus and are degraded and the nucleotides recycled

22
Q

Each mRNA molecule is eventually degraded into nucleotides by ….. present in the cytosol

A

ribonucleases (RNAses)

23
Q

A mRNA molecule can be translated many times depending on
A. how long mRNA molecule persists
B. nucleotide sequence and the type of cell
C. RNA called the 3′ untranslated region
D. All

A

D

24
Q

before cells containing DNA and proteins appeared, what was the role of RNA?

A
  • RNA stored genetic information

- RNA catalyzed chemical reactions in primitive cells.

25
Q

what are the two worlds of RNA?

A
  • Primordial RNA world (Hypothetical era)

- Today’s biological systems (non-Hypothetical era)

26
Q

What can RNA do by itself?

A

=Riboswitches-They can bind specifically to small metabolites and use this binding energy to switch from one RNA structure to another.
=Self-cleavage
=Self-Splicing-Group I and II introns perform splicing similar to the spliceosome without requiring any protein.

27
Q

Which of the following is false?
A. Without catalysts, polymer formation is slow, error-prone, and inefficient.
B.Complementary base-pairing enables one
nucleic acid to act as a template for the
formation of another
C. nucleotide polymerization is catalyzed by protein enzymes (DNA and RNA polymerases)
D. A single strand of RNA or DNA can’t specify the sequence of the original molecule

A

D

A single strand of RNA or DNA can specify the sequence of the original molecule

28
Q

How could complementary base pairing be

catalyzed before proteins with the appropriate catalytic ability existed?

A

RNA molecules themselves can act as catalysts and information carriers.

Medical biology and genetics (4 decks)

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