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Biochemistry > RNA > Flashcards

RNA Flashcards

1
Q

mainly seen in cytoplasm, usually 100-5000 bases

A

RNA

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2
Q

mostly inside nucleus with millions of base pairs

A

DNA

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3
Q

guanine content is not equal to cytosine and adenine is not equal to uracil

A

RNA

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4
Q

easily destroyed by alkali

A

RNA

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5
Q

alkali resistant

A

DNA

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6
Q

[RNA types] Carries the genetic instructions of a gene from the nucleus to the ribosome in the cytoplasm

A

mRNA

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7
Q

[RNA types] This constitutes about 2-5% of total RNA in the cell. They are generally degraded quickly

A

mRNA

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8
Q

[RNA types] Eukaryotic mRNA contains a ____ and a ____ and is synthesized in the nucleus

A

cap structure and a poly(A) tail

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9
Q

[RNA types] The cap consists of ______ attached to the hydroxyl group on the ribose at the 5’ end of the mRNA

A

methylated guanine triphosphate

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10
Q

[RNA types] in the mRNA cap, the ____ in the guanine is methylated

A

N7

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11
Q

[RNA types] in the mRNA cap, The _____ of the 1 and 2 ribose moieties of the mRNA may also be methylated

A

2’-hydroxyl groups

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12
Q

[RNA types] The poly(A} tail contains up to ________ attached to the hydroxyl group at the 3’ end of the mRNA

A

200 adenine (A) nucleotides

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13
Q

[RNA types] This constitutes about 80% of all RNA in the cell. Together with proteins, composes the ribosome, the organelles that are the site of protein synthesis. They are very stable.

A

Ribosomal RNA (rRNA)

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14
Q

rRNA contains many loops and extensive base-pairing. rRNA molecules differ in their _________. They associate with proteins to form ribosomes

A

sedimentation coefficients (S)

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15
Q

Prokaryotes have three types of rRNA:

A

16S, 23S, and SS rRNA

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16
Q

Eukaryotes have four types of cytosolic rRNA:

A

18S, 28S, SS, and 5.8S rRNA

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17
Q

A. The eukaryotic ribosomes have _____ different proteins

A

83

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18
Q

eukaryotic mitochondrial ribosomes are similar to

A

prokaryotic ribosome

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19
Q

[RNA types] They constitute about 15% of the total RNA in the cell. Brings the correct amino acid to the ribosome during translation. They are very stable

A

transfer RNA (tRNA)

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20
Q

[RNA types] there are about ___ different tRNA species

A

60

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21
Q

[RNA types] tRNA has a cloverleaf structure and contains _______. tRNA molecules are relatively small, containing about _______

A

modified nucleotides, 80 nucleotides

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22
Q

In eukaryotic cells, many nucleotides in tRNA are ______

A

modified

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23
Q

Modified nucleotides containing ____, ____, and ____ are present in most tRNAs.

A

pseudouridine (Ψ), dihydrouridine (D), and ribothymidine (T)

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24
Q

in tRNA molecules, the first loop from the 5’ end, the D loop, contains

A

dihydrouridine

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25
Q

in tRNA molecules, the middle loop contains the ______, which base-pairs with the codon in mRNA

A

anticodon

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26
Q

in tRNA molecules, the third loop, the TΨC loop, contains both

A

ribothymidine and pseudouridine

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27
Q

in tRNA molecules, the _____ at the 3’ end carries the amino acid

A

CCA sequence

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28
Q

RNAs involved in gene regulation and mRNA degradation

A

Small interfering RNA (siRNA), microRNA (miRNA) and small nuclear RNA (snRNA)

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29
Q

[gene expression] a DNA molecule is divided into functional units called

A

genes

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30
Q

[gene expression] During gene expression, the DNA is first copied into

A

RNA

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31
Q

[gene expression] The RNA can be ______ (transfer RNAs and ribosomal RNAs) or be the intermediate template for a protein that performs a function

A

directly functional

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32
Q

[gene expression] when RNA is said to be directly functional this means

A

it can act immediately as tRNAs or rRNAs

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33
Q

[gene expression] s the central dogma of
molecular biology

A

DNA -> RNA -> protein

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34
Q

[gene expression] One strand of the gene’s DNA is copied into RNA

A

transcription

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35
Q

[gene expression] In eukaryotes, the RNA transcript must undergo _______ in order to become a mature messenger RNA (mRNA)

A

additional processing steps

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36
Q

[gene expression] The nucleotide sequence of the mRNA is decoded to specify the amino acid sequence of a polypeptide

A

translation

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37
Q

[gene expression] in translation, arranging of the polypeptide occurs inside a ribosome and requires

A

adapter molecules ( tRNAs)

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38
Q

[transcription] one strand of the DNA that makes up a gene and acts as a template for the synthesis of a matching (complementary) RNA strand

A

non-coding strand

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39
Q

[transcription] This RNA strand is the pre-mRNA

A

matching (complementary) RNA from the non-coding strand of DNA

40
Q

[transcription] the action of synthesis of a matching complementary strand of RNA is through the enzyme

A

RNA polymerase

41
Q

[transcription] The DNA opens up to form a bubble, and the lower strand serves as a template for the synthesis of a complementary RNA strand, called the

A

template strand

42
Q

[transcription] Transcription of the template strand produces an mRNA that nearly
matches the ______ of DNA in sequence

A

coding strand

43
Q

[transcription] in eukaryotes, caps are added to the ends of the pre-mRNA, and some pieces of it may be carefully removed in a process called ______ in order to become a mature mRNA

A

splicing

44
Q

[transcription] Eukaryotic rRNA is produced by ______ as a 45S precursor

A

RNA polymerase I

45
Q

[transcription] in eukaryotic rRNA, the 45S precursor is methylated and cleaved to form 3 of the rRNAs (___, ____, ____) that appear in ribosomes

A

18S, 28S, and 5.8S

46
Q

[transcription] in eukaryotic rRNA, The 5S rRNA is produced from a separate gene by ______

A

RNA polymerase III

47
Q

[transcription] in eukaryotes, the ______ is the site of rRNA production and ribosome assembly

A

nucleolus

48
Q

[transcription] eukaryotic mRNA, produced by ______, is capped at the 5’ end and has a poly{A) tail added at the 3’ end

A

RNA polymerase Il

49
Q

[transcription] ___ are segments that do not code for protein are removed, and exons (segments that produce the mature mRNA) are spliced together

A

introns

50
Q

[transcription] Eukaryotic tRNA is produced by _____ as a precursor that is trimmed at the 5’ and 3’ ends. Introns are removed and exons are spliced together

A

RNA polymerase Ill

51
Q

[transcription] Unusual nucleotides are produced in mature tRNA by _____, and a CCA
sequence is added at the 3’ end

A

posttranscriptional modification of normal nucleotides

52
Q

[transcription] In bacteria, the pre-mRNA can _______ as a messenger RNA, or mRNA. They don’t have a nucleus, so they carry
out both transcription and translation in the cytosol

A

directly serve

53
Q

[transcription] Bacteria do not contain nuclei, so transcription and translation occur ______

A

simultaneously

54
Q

[transcription] A ______ produces mRNA, rRNA, and tRNA in bacteria

A

single RNA polymerase

55
Q

[transcription] Bacterial transcripts (e.g., those from E. coli) do not contain _____

A

introns

56
Q

[clinical corr] Compounds that inhibit _____ can be utilized as antibiotics

A

RNA synthesis

57
Q

[clinical corr] These antibiotics ____ affect bacterial function and have minimal side effects in humans, and they are usually selected to treat bacterial infections

A

selectively

58
Q

[clinical corr] inhibits the initiation of prokaryotic RNA synthesis, is used to treat tuberculosis

A

rifampicin

59
Q

[clinical corr] derived from the poisonous mushroom Amanita phalloides, inhibits eukaryotic RNA polymerases, particularly polymerase II

A

α-Amanitin

60
Q

[clinical corr] Ingestion of small amounts of α-Amanitin initially causes ______ but can rapidly result in death

A

gastrointestinal problems

61
Q

messenger RNA (mRNA) is decoded in a ribosome, to produce a specific amino acid chain, or polypeptide.

A

translation

62
Q

[translation] The polypeptide later folds into an ______ and performs its functions in the cell

A

active protein

63
Q

[translation] The ribosome will facilitate
decoding by inducing the _______ of complementary tRNA anticodon sequences to mRNA codons.

A

binding

64
Q

The _____ is the collection of codons that specify all the amino acids found in proteins.

A

genetic code

65
Q

[genetic code] A codon is 1 sequence of three bases (triplet} in mRNA (______) that specifies (corresponds to) a particular amino acids

A

5’ to 3’

66
Q

[genetic code] During translation, the successive codons in an mRNA determine ______ add to the growing polypeptide chain

A

the sequence in which amino acids

67
Q

[genetic code] Each of the 20 common amino acids has at least 1 codon; many amino acids have numerous codons.

A

degenerate (redundant)

68
Q

[genetic code] each nucleotide is used only once, beginning with a start codon (AUG)
near the 5’ end of the mRNA and ending with a termination (stop) codon (UGA. UAG, or UAA) near the 3’ end

A

s non overlapping

69
Q

[genetic code] there are no breaks or markers to distinguish one codon from the next

A

comma-less

70
Q

[genetic code] The same codon specifies the same amino acid in almost all species studied;
however, some differences have been found in the codons used in mitochondria

A

nearly universal

71
Q

[genetic code] Mitochondrion, has its own circular

A

DNA chromosome and protein biosynthetic apparatus

72
Q

[genetic code] Only a small number of mitochondrial proteins are encoded by the

A

mitochondrial genome

73
Q

[genetic code] The start codon ____ determines the reading frame. Subsequent nucleotides are read in sets or three,
sequentially following this codon

A

(AUG)

74
Q

[effects of mutation on proteins] Mutations in DNA are_______ into mRNA and can thus cause changes in the encoded protein

A

transcribed

75
Q

[effects of mutation on proteins] occur when one base in DNA is replaced by another, altering the codon in mRNA

A

Point mutations

76
Q

[effects of mutation on proteins] type of point mutation that do not affect the amino acid sequence of a protein (e.g., CGA to CGG causes no change, since both codons specify arginine)

A

Silent mutations

77
Q

[effects of mutation on proteins] type of point mutation that result in one amino acid being replaced by another (e.g., CGA to CCA causes
arginine to be replaced by proline)

A

Missense mutations

78
Q

[effects of mutation on proteins] type of point mutation that result in a premature termination or the growing polypeptide chain (e.g., CGA to UGA causes arginine to be replaced by a stop codon)

A

Nonsense mutations

79
Q

[effects of mutation on proteins] type of mutation that occur when a base or a number or bases are added to DNA. They can result in a protein with more amino acids than normal

A

insertions

80
Q

[effects of mutation on proteins] type of mutation that occur when a base or a number of bases are removed from the DNA. They can result in a protein with fewer amino acids than normal

A

deletions

81
Q

[effects of mutation on proteins] type of mutation that occur when the number of bases added or deleted is not a multiple of three. The reading frame is shifted so that completely different sets of codons are read beyond the point where the mutation starts

A

frameshift mutations

82
Q

[clinical corr] results from a point mutation (GAG to GTG) that causes valine to replace
glutamate at position 6 in the β-globin chain

A

sickle cell anemia

83
Q

[clinical corr] in sickle cell anemia, hydrophobic interactions between these valine residues on different hemoglobin molecules cause _______, which alters the shape of the red blood cells and results in hemolysis

A

polymerization of sickle cell hemoglobin (HbS)

84
Q

[clinical corr] is due to a point mutation, also in position 6 of the β-globin chain, which
causes a lysine to replace glutamate at this position causing anemia

A

Hemoglobin C (HbC)

85
Q

[clinical corr] a group of hemolytic anemias, mutations can affect all steps of RNA metabolism. This is also an imbalance in the synthesis of the globin proteins

A

Thalassemias

86
Q

[clinical corr] type of thalassemia that is an excess of α subunits

A

a β-thalassemia

87
Q

[clinical corr] type of thalassemia that is an excess of β subunits

A

α-thalassemia

88
Q

translation proceeds in 3 phases, namely:

A

initiation, elongation, termination

89
Q

[translation phase] The ribosome assembles around the target mRNA. The first tRNA is attached at the start codon

A

initiation

90
Q

[translation phase] The last tRNA validated by the small ribosomal subunit (_______) transfers the amino acid it carries to the large ribosomal subunit which binds it to the one of the precedingly admitted tRNA (_____). The ribosome then moves to the next mRNA codon to continue the process
(_____________), creating an amino acid chain

A

elongation, accommodation, transpeptidation, translocation

91
Q

[translation phase] When a stop codon is reached, the ribosome releases the polypeptide

A

termination

92
Q

The process in cells by which an enzyme makes a copy of DNA from RNA

A

reverse transcription

93
Q

Synthesis of DNA from an RNA temp late is catalyzed by reverse _______

A

transcriptase

94
Q

Retroviruses contain RNA as their genetic material. The retroviral RNA serves as a ______ for the synthesis of DNA by reverse transcriptase

A

template

95
Q

in viruses, the DNA that is generated from reverse transcription can be inserted into the _____ of the host cell and be expressed

A

genome (chromosomes)

Biochemistry (5 decks)

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