The Paradigm of Differential Gene Expression Flashcards

1
Q

approximately how many protein encoding genes are present in humans?

A

25,000

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2
Q

at what 4 steps can regulation occur for the selective expression of gene products?

A
  1. differential gene transcription
  2. selective nuclear RNA processing
  3. selective mRNA translation
  4. differential protein modification
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3
Q

differential gene expression refers to

A

which genes are allowed to be transcribed within the nucleus

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4
Q

selective nuclear RNA processing refers to

A

which transcribed RNA sequences will make it to the cytoplasm

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5
Q

selective mRNA translation refers to

A

which mRNA is translated into proteins

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6
Q

differential protein modification refers to the determination of

A

which proteins are activated/functional

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7
Q

chromatin is a form of

A

DNA unique to eukaryotic cells

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8
Q

is chromatin found in prokaryotic cells?

A

NO

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9
Q

define nucleosome

A

basic unit of chromatin which contains the genetic information

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10
Q

the nucleosome structure is comprised of

A

histone subunits

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11
Q

the histone subunits of nucleosomes are encased with

A

2 bands of 147 DNA base pairs

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12
Q

histones are

A

octamer protein subunits

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13
Q

linker proteins contain _________ base pairs that link…

A

60-80

adjacent nucleosomes

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14
Q

what is the primary type of histone bound to the linker section?

A

histone H1

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15
Q

what prevents uncoiling of nucleosomes?

A

tightly joined nucleosomes linked together

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16
Q

the tight linkage between nucleosomes allows for

A

polymerase enzymes to bind & transcription proceeds

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17
Q

H1 represses or regulates the…

A

transcription of DNA to mRNA

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18
Q

what prevents the uncoiling of nucleosomes and DNA?

A

acetylation of histones

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19
Q

what represses or prevents the uncoiling of nucleosome units?

A

methylation

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20
Q

define exons

A

regions of the DNA which code for a protein

21
Q

define introns

A

regions of DNA not expressed in the final amino acid sequence of a protein

22
Q

promotor sites are the binding location for

A

RNA polymerase enzymes on DNA

23
Q

promoter sites allow for transcription of

A

DNA to mRNA

24
Q

initial nuclear RNA consists of

A
  • promotor site
  • cap sequence
  • tail sequence
25
the cap sequence is found at what end of RNA?
5'
26
poly A tail is found at the
3' end of RNA
27
enhancers are
DNA sequences which control the efficiency and rate of transcription from a promoter region
28
negative enhancer prevent the
premature formation of proteins and cells
29
negative enhancers can maintain the proper sequnce of
morphogenesis & organogenesis
30
transcription factors bind to the
enhancer/promoter regions to activate/repress transcription of a gene
31
transcription factors recruit
acetyl transferases methyltransferases
32
acetyl transferases loosen the... methyltransferases tighten the
histones and nucleosomes for transcription to occur histone complex to repress transcription
33
transcription factors can form bridges to form a loop of DNA this causes
enhancer/promoter region to be closer together causing more efficient transcription
34
why are totipotent stems cells still capable of forming all cell types?
ICM has not undergone methylation
35
censorship refers to different cell types represented by the
processing of specific nuclear RNA transcripts into mRNA
36
differential splicing leads to an
assortment of various combinations of exons
37
due to differential splicing for humans one gene produces
multiple polypeptides or proteins
38
due to differential splicing for prokaryotes one gene produces
only ONE polypeptide or protein
39
what is the downside of having 1 gene producing many polypeptides?
a single gene mutation can lead to abnormalities of multiple proteins
40
what are spliceosomes?
a modified form of RNA which binds to nRNA strand to excise and ligate
41
spliceosomes are capable of
removing a mutated segment of RNA so transcription can proceed normally
42
what protects the mRNA from rapid enzymatic degradation in the cytoplasm?
the poly-A-tail
43
the maintenance and stabilization of the mRNA allows for more
efficient synthesis of its protein product
44
an mRNA strand w/o a tail or cap would be
degraded before translation at ribosomes can occur
45
the oocyte/egg stores some mRNAs that will be used ONLY
after fertilization
46
the mRNAs stored in the oocyte code for proteins that are needed for
- cleavage - actin and cytoskeleton strands - cyclin proteins
47
cyclin proteins are used to
regulate the timing of cell division
48
a polypeptide is a
non-function protein precursor