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Molecular Biology > Chapter 2: Gene Expression and Epigenetics > Flashcards

Chapter 2: Gene Expression and Epigenetics Flashcards

1
Q

genetic mutation where a single base pair substitution results in a changed amino acid

A

missense mutation

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2
Q

genetic mutation where a single base pair substitution changes a codon to code for a stop codon resulting in early termination and non functional protein

A

nonsense mutation

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3
Q

deletion or jnsertion of mucleotides that lead to misreading of all nucleotides downstream

A

frameshift mutation

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4
Q

results in changed amino acid but the amino acid has similar chemical characteristics as the original

A

conservative missense

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5
Q

nucleotide sequence is changed but amino acid is similar

A

silent mutation

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6
Q

two types of factors responsible for regulation of mRNA synthesis

A

cis and trans factors

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7
Q

DNA sequences that mark places on the DNA involved in the initiation anf control of RNA synthesis

A

cis factors

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8
Q

proteins that bind to the cis sequences and direct assembly of transcription complexes at the proper gene

A

trans factors

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9
Q

a series of structural genes transcribed together on one mRNA and separated into individual proteins

A

operon

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10
Q

bring about corrdinated expression of proteins required at the same time

A

operons

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11
Q

three structural genes in the lac operon

A

lac Z
lac Y
lac A

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12
Q

gene product of lac Z

A

Beta-galactosidase (hydrolyzes lactose into glucose and galactose)

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13
Q

gene product of lac Y

A

lactose permease (transports lactose into the cell)

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14
Q

lacA gene product

A

thiogalactoside transacetylase

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15
Q

cis factor of lac operon

A

lac O

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16
Q

where RNA polymerase binds in lac operon

A

lac P

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17
Q

encodes the protein repressor that binds to lac O

A

lac I

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18
Q

what happens to the operon if lactose is present

A

lactose binds to repressor protein, changing conformation and decreasing affinity for lac O

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19
Q

mode of regulation of lac operon where a binding protein activates transcription

A

induction

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20
Q

mode of regulation of arg operon where binding protein binds to repressor protein turning off the transcription

A

repression

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21
Q

protein binds with RNA polymerase to turn on transcription like in mal operon

A

activation

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22
Q

formation of stems and loops in RNA transcript by intrastran hybridization of complementary bases such as in trp regulation

A

attenuation

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23
Q

True or False: Eukaryotes have operons

A

False, synchronous expression is brought about ny combinatorial control

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24
Q

examples of distal regulatory elements of eukaryotes

A

engancers amd silencers

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25
Q

a developent phenomenon that allowed cells to differentiate without changes in the genetic structure

A

epigenetics

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26
Q

nuclear DNA and its asscociated proteins

A

chromatin

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27
Q

about 150 bases of DNA wrapped around a complex of 8 histones

A

nucleosome

28
Q

8 histones that compose a nucleosome

A

2 H2A
2 H2B
2 H3
2 H4

29
Q

regulate access of trans factors and RNA polymerase to DNA helix

A

histones

30
Q

lowers the positive charge of histones, decreasing binding strength to DNA , making DNA more available for interaction and transcription factors

A

histone acetylation

31
Q

causes open chromatin

A

histone acetylation

32
Q

attracts enzymes that further methylate DNA resulting decreased gene expression

A

DNA methylation

33
Q

causes closed chromatin

A

Histone methylation

34
Q

H2A acetylation

A

activation

35
Q

H2B acetylation

A

activation

36
Q

H3 methylation

A

silencing or activation

37
Q

H3 acetylation

A

activation/histone positioning

38
Q

H4 methylation

A

silencing or activation

39
Q

H4 acetylation

A

DNA repair
histone positioning

40
Q

occurs in cytosine guanine rich sequences in the DNA (CpG islands)

A

DNA methylation

41
Q

regions of more than 200 bp length with CpG occurence ratio of greater than 0.6

A

CpG islands

42
Q

CpG islands are found mostly on

A

the first exons
promoter regions
3’ end of genes

43
Q

DNA methylation mechanism of cancer

A

methylation of cytosine residues in promoter regions of tumor suppresor genes

44
Q

stage and gamete specific silencing of genes

A

genomic imprinting

45
Q

selective methylation of homologous genes occurs in

A

gametogenesis

46
Q

maintenance emzyme that mainly methylates cytosines that are methylated on one strand but not the other

A

DNA methyltransferase 1

47
Q

de novo methylase that methylates ummethylated DNA establishing newly methylated regions

A

DNA methyltransferase 3

48
Q

nonfucntional beacuse of non exitsent catalytic site but regulates activity of DNMT3A and 3B by occupying binding sites

A

DNMT3L

49
Q

True or false: Euchromatin has more acetylated histones and less methylated histones than heterochromatin

A

True, Euchromatins are transcriptionally active and therefore have open chromatin

50
Q

reversal of DNA methylation

A

DNA demethylation

51
Q

DNA demethylation is catalyzed by

A

Ten Eleven Transferase

52
Q

histone and nucleic acids modifications are classified into

A

writers
erasers

53
Q

another classification system of epigenetics particularly in cancer cells

A

modulators
modifiers
mediators

54
Q

activities that activate epigenetic process

A

modulators

55
Q

writers and erasers that maintain the chromatin structure

A

nodifiers

56
Q

carry out their function as RNA and transcribed but not translated to protein

A

noncoding RNAs

57
Q

17 to 27 nts long regulatory RNAs that control gene expression by hybridizing with the 3’ end of imperfectly complementary sequences to inhibit translation

A

micro RNAs

58
Q

associated with cancer

A

miRNA dysregulation

59
Q

miRNAs promote the tumor cell phenotype called

A

oncomirs

60
Q

functional intermediates of RNA interference

A

small interfering RNAs

61
Q

defense of eukaryotic cells against viral invasion

A

RNA interference

62
Q

responsible for generation of siRNA and microRNA

A

ribonuclease III enzyme

63
Q

used in the laboratory to artificially turn off the expression of specific genes

A

siRNA

64
Q

miRNA and siRNA have similar regulatory mechanisms but differ in

A

siRNA is foreign
miRNA are encoded in the cell DNA

65
Q

uses associated siRNA to bind and degrade mRNA with sequences exactly complementary to the siRNA

A

RNA-induced silencing complex

66
Q

200 to 100,000 base RNA that regulate chromatin structure affecting gene expression and chromatin structure

A

lncRNA

67
Q

lncRNA functions

A
  1. bind protein that normally bind to cis sequences
  2. hairpin structures scaffold to bring proteins together
  3. may connect trans factors to enhancer regions
  4. bind small ligands
  5. interact with mRNA in RISC
  6. form troples structures woth double stranded DNA
  7. further processd into small RNA fragments

Molecular Biology (12 decks)

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