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Cell and Molecular Biology > 9 > Flashcards

9 Flashcards

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1
Q

Facts about the Nucleus

Prokaryotes have no _________

A

nucleus

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2
Q

Facts about the Nucleus

Eukaryotes generally have 1 nucleus except for _______, _________, and _________

A

rbcs, osteoclasts and skeletal muscles

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3
Q

Facts about the Nucleus

_________ to be discovered

A

First organelle

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4
Q

Facts about the Nucleus

First described by ________ in 1804

A

Franz Bauer

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5
Q

Facts about the Nucleus

Presented by Scottish botanist, _________
during the 1831 meeting of the Linnaean
Society of London

A

Robert Brown

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6
Q

Overall functions of the nucleus

Storage of ___________

A

genetic material

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7
Q

Overall functions of the nucleus

Controls ___________

A

cell growth and reproduction

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8
Q

Overall functions of the nucleus

Home of essential _______ (i.e.
replication, transcription )

A

cellular processes

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9
Q

Overall functions of the nucleus

Regulates passage of materials _________ of nucleus (RNA, ions, nucleotides,aa etc)

A

in and out

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10
Q

Overall functions of the nucleus

Regulates passage of materials in and out of
nucleus (____, _____, ____, ____)

A

RNA, ions, nucleotides,aa etc

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11
Q

depending on nature
and size of molecules

A

active vs passive transport

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12
Q

Nucleus: Structure

About ________ of the cell volume

A

10%

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13
Q

Nucleus: Structure

Has a __________, two leaflets 10-50 nm apart

A

double membrane

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14
Q

Nucleus: Structure

Has a double membrane, _________ 10-50 nm apart

A

two leaflets

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15
Q

Nucleus: Structure

Has a double membrane, two leaflets 10-50 nm apart
*This forms an ___________

A

interior space

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16
Q

Nucleus: Structure

  • About 10% of the cell volume
    – Has a double membrane, two leaflets 10-50 nm apart
    *This forms an interior space
    *The space is continuous with the interior of the __________
A

rough endoplasmic reticulum

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17
Q

Parts of the Nucleus

made of phospholipid bilayer

A

Nuclear envelope

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18
Q

Parts of the Nucleus

Nuclear envelope separates?

A

cytoplasm and nucleoplasm

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19
Q

Parts of the Nucleus

Inner and outer membrane separated by __________

A

perinuclear space

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20
Q

Parts of the Nucleus

Outer nuclear membrane continuous with RER and studded with __________

A

ribosomes

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21
Q

Parts of the Nucleus

Contains 3000 ____________

A

nuclear pores

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22
Q

Parts of the Nucleus

Contains 3000 nuclear pores,
regulated by a protein structure,
the _____________

A

nuclear pore complex

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23
Q

Parts of the Nucleus

Small molecules (<mw 20,000)
can pass right through, larger
molecules are strongly
regulated.

A

nuclear pore complex

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24
Q

Parts of the Nucleus

Interior of envelope supported
by ___________ (on the
nucleoplasm side)

A

nuclear lamina

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25
Q

Parts of the Nucleus

A network of 10nm-diameter
protein fiber: __________

A

lamins

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26
Q

Parts of the Nucleus

proteins that form the nuclear lamina, a mesh-like structure that provides mechanical stability to the nuclear envelope

A

lamins

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27
Q

Parts of the Nucleus

Three (3) functions of lamins

A

(1) reinforces structure of the nucleus
(2) anchors chromatin
(3) impt in replication and transcription

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28
Q

Parts of the Nucleus

An Integral membrane

A

Nuclear Pore

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29
Q

Nucleus: Structure

Interior of the nucleus

A

nucleoplasm

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30
Q

Nucleus: Structure

analogous to cytoplasm

A

nucleoplasm

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31
Q

Nucleus: Structure

Interior of the nucleus

Includes the soluble protein
____________

A

nucleoplasmin

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32
Q

Nucleus: Structure

Interior of the nucleus

____________, sticky
fluid that supports chromosomes and nucleolus

A

Highly gelatinous

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33
Q

Nucleus: Structure

Interior of the nucleus

Highly gelatinous, sticky
fluid that supports
_____________

A

chromosomes and nucleolus

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34
Q

Nucleus: Structure

Interior of the nucleus

_____________ for
organelles inside nucleus

A

Suspension substance

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35
Q

Nucleus: Structure

Interior of the nucleus

Also dissolved are
__________________

A

nucleotides and enzymes

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36
Q

Nucleus: Parts

a network of protein fibers that support and organize the chromatin and other structures

A

nuclear matrix

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37
Q

– Active chromatin
(euchromatin) appear
lighter,
– Inactive chromatin
(heterochromatin) is darker
and located near periphery
of nucleus

A

chromatin

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38
Q

Chromatin

Active chromatin (_________) appear lighter

A

euchromatin

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39
Q

Chromatin

Inactive chromatin
(_____________) is darker
and located near periphery
of nucleus

A

heterochromatin

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40
Q

Active chromatin

A

euchromatin

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41
Q

appear lighter

A

euchromatin

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42
Q

Inactive chromatin

A

heterochromatin

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43
Q

is darker and located near periphery of nucleus

A

heterochromatin

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44
Q

a granular region

A

Nucleolus

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45
Q

site of ribosome assembly

A

Nucleolus

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46
Q

Functions of Chromatin

Chromatin determines ________

A

chromosome structure

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47
Q

Functions of Chromatin

Changes __________ associated with cell division

A

chromosome structures

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48
Q

Functions of Chromatin

Changes chromosome structures associated with __________

A

cell division

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49
Q

Functions of Chromatin

Regulates ___________

A

chromosome function

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50
Q

There are two types of heterochromatin

A

1) Constitutive heterochromatin
2) Facultative heterochromatin

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51
Q
  • Regions that are always heterochromatic
  • Permanent part of the genome and not convertible to euchromatin
  • Permanently inactive with regard to transcription
A

Constitutive heterochromatin

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52
Q

Constitutive heterochromatin

Regions that are _______ heterochromatic

A

always

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53
Q

Constitutive heterochromatin

Permanent part of the _______ and not convertible to euchromatin

A

genome

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54
Q

Constitutive heterochromatin

Permanent part of the genome and _________ to euchromatin

A

not convertible

55
Q

Constitutive heterochromatin

________ with regard to transcription

A

Permanently inactive

56
Q

**Constitutive heterochromatin*

Permanently inactive with regard to _________

A

transcription

57
Q
  • Regions that can interconvert between euchromatin and
    heterochromatin
  • Takes on staining and compactness characteristics of heterochromatin
    during some phases of development
  • Example: Barr body
A

Facultative heterochromatin

58
Q

Facultative heterochromatin

Regions that _________ between euchromatin and
heterochromatin

A

can interconvert

59
Q

Facultative heterochromatin

Regions that can interconvert between _________

A

euchromatin and heterochromatin

60
Q

Facultative heterochromatin

Takes on staining and compactness characteristics of heterochromatin
during some phases of _______

A

development

61
Q

Example: Barr body

A

Facultative heterochromatin

62
Q

In all cells of _________, one of the two X chromosomes is
permanently inactivated and
does not participate in
transcription.

A

female
individuals

63
Q

In all cells of female
individuals, __________ X
chromosomes is
permanently inactivated and
does not participate in
transcription.

A

one of the two

64
Q

In all cells of female
individuals, one of the two X
chromosomes is
____________ and
does not participate in
transcription.

A

permanently inactivated

65
Q

In all cells of female
individuals, one of the two X
chromosomes is
permanently inactivated and
does not participate in
____________.

A

transcription

66
Q

The _____________
is recognizable in epithelial
cells from the oral cavity as a
single granule called sex
chromatin (Barr body) that is
attached to the nuclear
lamina.

A

inactive X chromosome

67
Q

In __________, the sex
chromatin takes the form of a
drum stick-like appendage to
the nucleus. These
structures have been used
for gender testing.

A

neutrophils

68
Q

The Nucleolus

_________ of volume of nucleus

A

25%

69
Q

The Nucleolus

Site of __________

A

ribosome biogenesis

70
Q

The Nucleolus

Form around specific chromosome regions known as _________

A

NOR

71
Q

The Nucleolus

NOR

A

nucleolus organizer regions

72
Q

The Nucleolus

Main function: combine rRNA + protein to form _______________

A

incomplete ribosome

73
Q

The Nucleolus

Main function: combine _______ to form incomplete ribosome

A

rRNA + protein

74
Q

The Nucleolus

Uninterrupted chain from nucleoplasm to
interior of nucleolus (_________) allow
macromolecules up to 2000 kd to circulate
through organelle

A

nucleolar passages

75
Q

A Single Set of Human DNA is > __________

A

1 Meter in Length

76
Q

CHROMATIN CONDENSATION

Results from ________ of chromatin

A

packaging

77
Q

CHROMATIN CONDENSATION

________ stops

A

Transcription

78
Q

CHROMATIN CONDENSATION

Chromosomes visible in ____

A

microscopy

79
Q

CHROMATIN CONDENSATION

Separation of _______ sets occurs in nuclear division

A

haploid chromosome

80
Q

CHROMATIN CONDENSATION

Separation of haploid
chromosome sets occurs in
_____________

A

nuclear division

81
Q

CHROMATIN CONDENSATION

Packaging ratio about _________

A

10000:1

82
Q

Importance of Folded DNA Structures

a. for storage in the _______ of the nucleus

A

limited size

83
Q

Importance of Folded DNA Structures

b. during ___________, it allows for neat segregation into newly formed cells

A

mitosis and meiosis

84
Q

Importance of Folded DNA Structures

b. during mitosis and meiosis, it allows for neat segregation into _________

A

newly formed cells

85
Q

Importance of Folded DNA Structures

c. manner of folding determines _________ in a cell

A

activity of genes

86
Q

basic structural unit of eukaryotic chromosome

A

Nucleosome

87
Q

Nucleosome

  • an octamer composed of two each of _________ histone proteins
A

H2A, H2B, H3 and H4

88
Q

Nucleosome

DNA wrapped around _______ and H1 stabilizes association of
nucleosomes to form solenoid

A

octamer

89
Q

Nucleosome

DNA wrapped around octamer and ________ stabilizes association of nucleosomes to form solenoid

A

H1

90
Q

Nucleosome

DNA wrapped around octamer and H1 stabilizes association of
nucleosomes to form __________

A

solenoid

91
Q

is a complex of a histone and 146 nucleotide pairs

A

a nucleosome

92
Q

All histone proteins have a large positive charge; between 20
and 30% of their sequences consist of the basic _________

A

amino acids, lysine and arginine.

93
Q

Histones will bind very strongly to the ___________ in forming chromatin.

A

negatively charged DNA

94
Q

-highly conserved sequences (universality in eukaryotes)
- H3, H4 first to form, tightly bound, most conserved
- H2A, H2B, well conserved with species-specific variation
-H1 divergent, absent in S. cerevesiae

A

Histones

95
Q

first to form, tightly bound, most conserved

A

H3, H4

96
Q

well conserved with species-specific variation

A

H2A, H2B,

97
Q

The compaction of linear DNA in eukaryotic chromosomes
involves interactions between _________

A

DNA and various proteins

98
Q

Proteins bound to DNA are subject to change during the life ofthe cell
* These changes affect the _______

A

degree of chromatin compaction

99
Q

how the cell moves molecules into and out of the nucleus

A

Nuclear Pores

100
Q

At the nuclear pore, the inner and outer membranes come
together forming an _______

A

opening

101
Q

Nuclear pores is lined with _____

A

protein

102
Q

It is lined with protein
– at least ________ proteins

A

100 nucleoporin

103
Q

It is lined with protein
– at least 100 nucleoporin proteins
– Including ___________, extending to the cytoplasm

A

cytoplasmic filaments

104
Q

It is lined with protein
– at least 100 nucleoporin proteins
– Including cytoplasmic filaments, extending to the _________

A

cytoplasm

105
Q
  • Proteins are brought into the ___________
    – and can be sent out too
A

nucleus from the cytoplasm

106
Q

RNAs (_____________)
are all transported out of the nucleus
– but only when they are completed

A

messenger RNA, ribosomal RNA and transfer RNAs

107
Q
  • a specific amino acid sequence marks protein for
    nuclear entry (Laskey, 1982)
    – a series of positively charged amino acids in specific
    sequence:
  • pro – lys – lys – lys – arg – lys – val –
A

Nuclear Location Signal (NLS)

108
Q

a specific amino acid sequence marks protein for
nuclear entry

A

(Laskey, 1982)

109
Q

a series of positively charged amino acids in specific
sequence:

A

pro – lys – lys – lys – arg – lys – val –

110
Q

NLS

A

Nuclear Location Signal

111
Q

how do we know the function of the NLS?

A

Experiment 1:
– modify the amino acid sequence (by site-directed-mutagenesis)
* “SV40 virus t-antigen” a protein molecule, M.W. 90,000
* normally enters the nucleus if injected into cytoplasm.
* normally accumulates in the nucleus (one-way)
* experimentally visualize the location of the protein
– using a fluorescent tag which glows under UV light
– Set up a microscope with ultraviolet light source
* An experimental alteration of the sequence (pro-lys-thr-lys-arglys-val-) completely prevents accumulation in the nucleus.

112
Q

what happens when we alter the NLS?

A

Altering the nuclear localization signal (NLS) can disrupt the transport of proteins into the nucleus, potentially leading to a loss of function or misregulation of cellular processes. This change may affect gene expression, signaling pathways, and overall cellular homeostasis.

113
Q

What happens when we use recombinant DNA techniques to add the NLS to a dummy protein?

A

Adding a nuclear localization signal (NLS) to a dummy protein using recombinant DNA techniques allows that protein to be transported into the nucleus of cells. This modification can enable the protein to interact with nuclear targets, influencing various cellular processes such as gene regulation or signaling.

114
Q
  • What happens when we use recombinant DNA techniques
    to add the NLS to a dummy protein?
  • Normal or modified ________ (NLS added)
    and injected to the cytoplasm
A

Bovine Serum Albumin

115
Q

family of proteins
associated with the
nuclear pore
complex

A

nuclear transport
receptors

116
Q

recognize
the NLS and bring
proteins in

A

Importins

117
Q

Another set of
proteins, the
_________, work in the
opposite direction
– These recognize
other signals

A

exportins

118
Q

mechanism of protein import through nuclear pore complex

(1) Protein binds to a two-protein complex (______________)
- Importin a is a receptor for the NLS portion of the
protein
i.e. it recognizes and sticks to this region.
(2) Complex and protein stick to cytoplasmic filament
- mediated by importin b

A

(importin a and
importin b

119
Q

mechanism of protein import through nuclear pore complex

is a receptor for the NLS portion of the
protein

A
  • Importin a
120
Q

mechanism of protein import through nuclear pore complex

(2) Complex and protein stick to cytoplasmic filament
- mediated by ____________

A

importin b

121
Q

mechanism of protein import through nuclear pore complex

(3) Complex moves into nucleoplasm
- Not an energy consuming step, it can go back at this
point unless captured by the _______ in next step:

A

RanGTP

122
Q

mechanism of protein import through nuclear pore complex

(4) Complex binds to another protein (Ran-GTP)
- After binding, ________
- importin b ______ on the Ran-GTP

A

complex dissociates
stays

123
Q

mechanism of protein import through nuclear pore complex

(5) _________ - importin b complex moves back to the cytoplasm,
down a concentration gradient

A

Ran-GTP

124
Q

mechanism of protein import through nuclear pore complex

(5) Ran-GTP - importin b complex moves back to the cytoplasm,
________________

A

down a concentration gradient

125
Q

mechanism of protein import through nuclear pore complex

(6) Two things happen now:
– (1) the Ran-GTP is converted to Ran-GDP + Pi by the enzyme
________. This causes it to loosen from importin b

A

RANGAP

126
Q

mechanism of protein import through nuclear pore complex

an _________ molecule binds to importin a, setting it up for
transport out of the nucleus

A

exportin

127
Q

mechanism of protein import through nuclear pore complex

(7) Ran-GDP _______ back to the nucleus (1)
– (down its concentration gradient, I.e. from high to low
concentration)
– Exportin carries importin a out of the nucleus (2)

A

diffuses

128
Q

mechanism of protein import through nuclear pore complex

(8) Restoration to initial state
– The importin a and importin b complex reforms.
– Enzyme _________ re-forms Ran-GDP to RanGTP

A

RCC1

129
Q

_________ is an energy source and controls
the process

A

GDP to GTP conversion

130
Q

Molecules always diffuse from high to low concentration, so
if the gradient is maintained, it can be used to bring __________ back to the cytoplasm

A

importin b

131
Q

RCC1 occurs only in the ________

A

nucleoplasm

132
Q

RANGAP occurs in _________

A

cytoplasm

133
Q

RCC1 occurs only in the nucleoplasm, RANGAP in cytoplasm
- By breaking down Ran-GTP and thereby removing it,
RANGAP _______ the concn gradient. It can take the
other molecule out with it.

A

maintains

134
Q

By changing Ran-GDP back to Ran-GTP, RCC1 maintains
the gradient helping Ran-GDP to diffuse back into the
______

A

nucleus

Cell and Molecular Biology (10 decks)

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