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Final Exam PHGY 170 Mod 4-6 > Final Exam PHGY 170 Mod 4-6 > Flashcards

Final Exam PHGY 170 Mod 4-6 Flashcards

1
Q

Cytoskeleton

A
  • Is a network of structural proteins that are found in all cell types
  • functions such as signalling and vesicular transport
  • defines shape of cell
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2
Q

Cytoskeleton structural proteins

A

Intermediate filaments
Microtubules
Actin

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3
Q

Cytoskeleton: intermediate filaments

A

Primary purpose of intermediate filament is to add mechanical strength to cells

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4
Q

Cytoskeleton: microtubules

A

Primary purpose of microtubules is to support trafficking within cells

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5
Q

Cytoskeleton: actin

A

Primary purpose of Aston is to support cellular motility or other large scale movements like contraction

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6
Q

Three types of cytoskeleton protein function

A

Binding
Conformation
Function

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7
Q

Cytoskeleton protein function: binding

A

Bind to a target like another protein to form polymers

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8
Q

Polymers

A

Molecules made of a large number of repeating units

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9
Q

Cytoskeleton protein function: conformation

A

When cytoskeleton proteins bind they undergo conformational changes

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10
Q

Cytoskeletal protein function: function

A

Function of these proteins is defined by the number and type of cytoskeletal proteins that are bound

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11
Q

Major classes of intermediate filaments

A

Classes: 1-6

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12
Q

Intermediate filaments: class I

A

Acidic keratins
Epithelial cells
Tissue strength and integrity

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13
Q

Intermediate filaments: Class II

A

Basic keratins
Epithelial cells
Tissue strength and integrity

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14
Q

Intermediate filaments: Class III

A
  • Desmin, GFAP, vimentin, periphevin
  • muscle, glial cells, mesenchymal cells, perphevin neurons
  • sarcomere organization, integrity
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15
Q

Intermediate filaments: class IV

A
  • neurofilaments
  • neurons
  • axon organization
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16
Q

Intermediate filaments: class V

A
  • lamins
  • nucleus
  • nuclear structure and organization
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17
Q

Intermediate filaments: class VI

A
  • nestin
  • neurons
  • axon growth
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18
Q

Two most common intermediate filaments

A

Class I and class II

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19
Q

Secondary structure of intermediate filaments

A

A-helices
B-sheets

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20
Q

A-helices

A

A helix is a tight coil that forms hydrogen bonds with the backbones of every fourth amino acid

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21
Q

B-sheets

A

Planes are formed between rows of amino acids with hydrogen bonds between the backbones

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22
Q

Tertiary and quaternary structure of intermediate filaments

A

Monomer
Dimer
Tetramer

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23
Q

Monomer

A

The coiled monomer is the tertiary structural level

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24
Q

Dimer

A

Two coiled monomers form a dimer by wrapping around eachother

Allows for maximum contact between two peptides

A quaternary structure

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25
Q

Tetramer

A

Two diners assemble in an antiparallel staggered manner.

Fundamental building block of intermediate filaments

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26
Q

Intermediate filaments (tetramers) stage 1

A

The formation of what is called a unit length filament. Formed by eight tetramers coming together

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27
Q

Intermediate filaments (tetramers) stage 2

A

Unit length filaments come together to form an immature filament. These interact loosely end to end

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28
Q

Intermediate filaments (tetramers) stage 3

A

Immature filament compacts to form a mature filament.

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29
Q

Three specialized intermediate filaments

A

Lamins
Desmins
Keratins

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30
Q

Lamins

A

A type of intermediate filament found solely in the nucleus that forms the nuclear matrix a dense network to protect chromatin

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31
Q

Desmins

A

A type of intermediate filament that does not form long thin filamentous structures but more so connects different cellular structures together. It is important for muscle structural integrity

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32
Q

Keratin

A

An important intermediate filament that binds to desmosomes to form a complex. Keratin makes up hair skin and nails

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33
Q

Intermediate filament assembly order

A

Monomers
Dimers
Tetramer
Unit length filament
Immature filament
Mature filament

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34
Q

Microtubules

A

Cellular trafficking, vesicles, cellular organelles within the cytoplasm

Not random they define how things move throughout

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35
Q

Microtubule organizing centre

A

Microtuble assembly here they require many proteins

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36
Q

Tubulins

A

Composed of dimerized proteins

Very large family of cellular proteins

Two specific tubulins: a-tubulin and B-tubulin

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37
Q

Steps of microtubule polymerization

A

Dimers form polymers
Polymer growth
Protofilament tubes
Assembly/disassembly

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38
Q

Dimers form polymers

A

Dimers will spontaneously assemble into unstable polymers that can quickly fall apart

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39
Q

Polymer growth

A

Once a polymer of at least six dimer subunits forms it is more stable and it may grow laterally and longitudinally. This forms protofilament

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40
Q

Protofilament tubes

A

Will form a sheet and will assemble into a tube of 13 Protofilament. This is the nucleation site for microtubles elongation.

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41
Q

Assembly/disassembly

A

At the ends of microtuble dimers continue to come and go. If the rate of assembly is greater than disassembly the microtubules grows if slow rate it disassemblies

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42
Q

Microtubles assembly

A

When GTP is bound to b-tubulin dimer polymerization is favoured and the diners will attach to eachother

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43
Q

Microtubule disassembly

A

When b-tubulin GTP is hydrolysed to GDP, the dimer undergoes a conformational change that promotes depolumerization

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44
Q

Microtuble polarity

A

Microtuble formed by end to end polymerization of dimers, ends are polarity. One end is plus the other minus. Growth occurs at both ends but at different rates extending faster from the plus end

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45
Q

Microtubule dynamic instability

A

Microtubule are very responsive and have the ability to grow and shrink or change directions to respond to changes in cellular environment

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46
Q

Microtubule catastrophe

A

GTP is converted to GDP on the tubulin dimers fall off resulting in rapid depolyerization to tubulin dimers at the plus end resulting in shortening of Microtuble

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47
Q

Measures against microtubule catastrophe

A

Capping
Rescue

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48
Q

Catastrophe aversion capping

A

Once a microtuble is of desired length the plus end can be bound by capping proteins. Which add tremendous stability and will keep them polymerized

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49
Q

Catastrophe reversal rescue

A

Occur spontaneously if there are enough GTP bound dimers present thus halting catastrophe

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50
Q

Motor proteins

A

Control trafficking by binding to cargo then bind to microtubule and walk along them

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51
Q

Two common types of microtubule motor proteins

A

Kinesin
Dynein

Kinesin walks towards plus end of microtubule well dynein moves to the minus end

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52
Q

Structure of dynein

A

Microtubule binding domains
Stalk
Head
Stem
Tail

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53
Q

Structure of Kinesin

A

Microtubule binding domains
Head
Stalk (coiled)
Tail

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54
Q

Walking motor proteins step 1

A

Head 1 is bound to the microtubule and head 2 is bound to ADP

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55
Q

Walking motor proteins step 2

A

The walking movement is initiated by ATP binding to head 1 which causes a conformational change that includes head 2 swinging around

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56
Q

Walking motor proteins step 3

A

Once head 2 is over binding site it binds to the microtubule and releases the ADP

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57
Q

Walking motor proteins step 4

A

The ATP at head 1 then undergoes hydrolysis so it is now ADP bound to head 1 which causes it to release from the microtubule

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58
Q

Walking motor proteins step 5

A

The entire process is then repeated but with ATP now binding to head 2 causing head 1 to swing around

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59
Q

Composition of actin and microtubules

A

Both are composed of globular proteins

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60
Q

Movement of actin and microtubules

A

Motor proteins are used to initiate movement along both cytoskeletal proteins

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61
Q

Actin monomers

A

Basic building block
Long thin filaments
Have high tensile strength

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62
Q

Tensile strength

A

Resistance to breaking under tension

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63
Q

Actin polymerization

A

The binding of ATP promotes assembly aka polymerization. Where the binding of ADP discourages polymerization which may lead to disassembly

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64
Q

Three stages of actin polymerization

A

Stage 1: nucleation
Stage 2: elongation
Stage 3: steady state

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65
Q

Actin polymerization: stage 1 nucleation

A

Two actin monomers can dimerize but nucleation occurs when a third actin monomer binds to the dimer forming a nucleus trimer

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66
Q

Actin polymerization: stage 2 elongation

A

Additional actin monomers added to nucleus. Actin elongates occurring in both directions

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67
Q

Actin polymerization: stage 3 steady state

A

Eventually the rate of assembly equals the rate of disassembly and net actin elongation ceases

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68
Q

Actin treadmilling

A

Same rate of removal and addition to the ends of actin

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69
Q

Actin binding proteins

A

Monomer binding proteins
Nucleating proteins
Capping proteins
Severing and depolymerization proteins
Cross linking proteins
Membrane proteins
Actin binding motor proteins

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70
Q

Actin binding proteins

A

Monomer binding proteins
Nucleating proteins
Capping proteins
Severing and depolymerization proteins
Cross linking proteins
Membrane proteins
Actin binding motor proteins

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71
Q

Actin binding proteins: monomer binding

A

Proteins that bind directly to the actin monomers and influence polymerization

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72
Q

Actin binding proteins: nucleating protein

A

Proteins that bind to actin polymers to increase their stability and can allow for growth of a new branch

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73
Q

Actin binding proteins: capping proteins

A

Proteins the bind to the plus or minus end and can stabilize the polymers to prevent disassembly and further assembly

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74
Q

Actin binding proteins: severing and deploymerizatiin proteins

A

Proteins that can bind to the actin polymer and sever or induce disassembly respectively

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75
Q

Actin binding proteins: cross linking proteins

A

Proteins that allow the side to side linkage of actin polymers to form bundles of actin filaments

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76
Q

Actin binding proteins: membrane anchors

A

These link actin filament to nonactin structural proteins

77
Q

Actin binding proteins:actin binding motor proteins

A

Proteins that bind to the actin filament and allow movement.

78
Q

Myosin

A

Most studied actin binding protein

18 different families of myosin broken into subunits called light chain or heavy chain

Have three different domains motor, regulatory, tail domains

79
Q

Myosin: motor domain

A

Formed by heavy chain binds to the actin filament and ATP

80
Q

Myosin: regulatory domain

A

Formed by a heavy chain and two light chains moves back and forth as the myosin moves along an actin filament

81
Q

Myosin: tail domain

A

Binds to other cellular proteins or other myosin

82
Q

Hydrolysis movement of actin binding protein

A

With ATP bound to the motor domain, the myosin is unbound to the actin filament. Hydrolysis of ATP to ADP and inorganic phosphate cause a conformational shift in the regulatory domain swing like a lever

83
Q

Actin binds movement of actin binding. Motor protein

A
  • Motor domain then binds to the actin filament.
  • The inorganic phosphate is released from myosin causing another conformation all change and pulling the myosin along the actin filament
  • ADP is then released and the binding of new ATP causes myosin to unbind from actin
84
Q

Movement of myosin

A

Moves toward the plus end of actin

85
Q

Three types of actin filaments responsible for cellular migration

A

Filopodia
Lamellipodia
Stress fibres

86
Q

Filopodia

A

Are thin parallel bundles of filaments. All have same polarity with plus end facing membrane. They extend in the direction of the intended movement

87
Q

Lamellipodia

A

Are large sheet like bundles of actin filaments. Are polar with plus end towards plasma membrane. Form broader structures

88
Q

Stress fibres

A

Forms around integrins. Plus end towards the cytosol. Rich in motor proteins and anchored to the integrins

89
Q

Two overarching phases of the cell cycle

A

Interphase
Mitosis

90
Q

Interphase cell cycle

A

Made up three phase G1, S and G2.
Most of cells life in G1
They are actively living or preparing to divide

91
Q

Mitosis cell cycle

A

Cells dividing

92
Q

Cell cycle phase

A

G1 phase
G0 phase
G1/S checkpoint
S phase
S/G2 checkpoint
G2 phase
G2/M checkpoint
M phase
Mitotic spindle checkpoint

93
Q

Cell cycle G1 phase

A

Cells are not actively dividing
G1 cells are active and growing but pass through check point to start cell division

94
Q

Cell cycle G0 phase

A

Resting state found in nerve and muscle cells

95
Q

Cell cycle G1/S checkpoint

A

Cell proteins check for DNA damage before the cell can move to S phase

Known as start point, activates a range of signals to allow cells to divide

96
Q

Cell cycle S phase

A

Synthesis, the cell replicates its entire genome for division

The centrosome is duplicated

97
Q

Cell cycle S/G2 checkpoint

A

DNA integrity is checked before the cell moves to G2

98
Q

Cell cycle G2 phase

A

Last chance for cells to grow before division cytoplasm and endomembrane system increased

99
Q

Cell cycle G2/M checkpoint

A

Triggers large scale rearrangement to the structure of the cell which facilitates mitosis. Increase in cell volume

100
Q

Cell cycle M phase

A

Mitosis occurs

101
Q

Cell cycle mitotic spindle checkpoint

A

Ensures all chromosomes are properly separated

102
Q

P53 protein

A

Is a tumour suppressor protein that ensures cells with damaged DNA done divide

103
Q

P53 protein

A

Is a tumour suppressor protein that ensures cells with damaged DNA dont divide

104
Q

LFS

A

Genetic condition that gives individuals a greater risk of developing cancer.

Often have a mutation in the gene that codes p53

105
Q

Mitosis

A

When a parent cell divides into two daughter cells

106
Q

Mitosis phases

A

Prophase
Prometaphase
Metaphase
Anaphase
Telophase

107
Q

Mitosis: interphase

A

G1, S, G2 all occur in interphase
At this time cells are not dividing they are growing and preparing to divide

DNA replication occurs

108
Q

Mitosis: prophase (chromosome condensation)

A
  • chromosomes densely packed into chromatids
  • each chromosome has been replicated (sister chromatids)
  • connected structural point called centromere
  • transcription is shut down, endo system dissolves and mitochondria distribute to give each daughter cells the organelles to live
109
Q

Mitosis: prophase (after condensation)

A
  • nuclear envelope dissolves, releasing chromosomes into cytosol
  • centrosomes are moved to opposite ends of the cell by tubulin and motor proteins
110
Q

Chromatid

A

One of two identical copies of DNA making a duplicated chromosome which are joined at their centromeres for cell division

111
Q

Centromere

A

Region in the chromosome that holds sister chromatids together

112
Q

Kinetichore

A

Typically located near the centromere it is the location of attachment of spindles during cell division

113
Q

Mitosis: prometaphase

A
  • each pair will have two kinetochore which binds to chromatids of centromere
  • kinetochores use ATP to polymerize and depolarize microtubule spindle fibres allowing chromosomes to move within cell
  • eventually moving to centre of cell for next stage metaphase
114
Q

Mitosis: Metaphase

A
  • chromosomes have arrived at spindle equator
  • chromosomes have attached to kinetochore microtubules pulling equally in both directions
115
Q

Mitosis: Anaphase

A
  • proteins that bind sister chromatids are cleaved dividing each chromosome into two
  • reaching final step for cell division and reformation of nucleus
116
Q

Mitosis: telophase

A
  • reorganization of cell, nuclear membrane is reformed around chromosomes
  • cytoskeleton reform
  • endo system reform
117
Q

Mitosis: cytokinesis

A
  • contractile ring forms where spindle equator was located
  • ring tightens cell is divided roughly in half
118
Q

Extracellular communication

A

Is communication that occurs when a signal is received from outside the cell itself

119
Q

Intracellular communication

A

To collect info from multiple sources, synthesize this information then make decision on how to respond to the info

120
Q

Four types of extracellular communication

A

Autocrine
Paracrine
Endocrine
Neurotransmitters

121
Q

Autocrine

A

Substances are released by a cell and have an effect on the same cell

122
Q

Paracrine

A

Substances are released by a cell and have an effect in nearby cells

123
Q

Endocrine

A

Substances are released by a cell and have effect in distant cells

124
Q

Neurotransmitter

A

Substances are released by a nerve terminal into the synapse

125
Q

Nerve terminal

A

The end of a nerve cell

126
Q

Components of signalling pathway: intracellular

A

The signal
The receptors
Signalling protein
Second messengers

127
Q

Intracellular signalling pathway: the signal

A

Can be either membrane permeable or membrane impermeable

128
Q

Intracellular signalling pathway: the receptors

A

Interact with the signal

129
Q

Intracellular signalling pathway: signalling proteins

A

Are proteins that help conduct the signal intracellularly

130
Q

Intracellular signalling pathway: second messengers

A

Are non protein that help conduct the signal intracellularly

131
Q

Structure of a signalling pathway

A

Membrane permeable signal molecule
Membrane impermeable signal molecule
Signalling proteins and second messengers
Cytoplasmic effects
Nuclear effectors

132
Q

Membrane permeable signal molecule

A

Molecules bind to receptor protein in the cytosol

133
Q

Membrane impermeable signal molecule

A

Bind to transmembrane cell surface receptor proteins which then activate second messengers

134
Q

Signalling proteins and second messengers

A

Amplify process and distribute incoming signals from both classes of signal receptor proteins

135
Q

Cytoplasmic effectors

A

Some signals are sent to effector proteins in the cytosol typically a fast short lived response to the activation of signalling pathway

136
Q

Nuclear effectors

A

Some signalling pathways terminate at effectors in the nucleus. These effectors are transcription factors that control gene expression. Results in slower more prolonged response

137
Q

Signal transduction

A

Is a signal activating a receptor that can be linear, convergent, divergent or multi branched

138
Q

Linear

A

One receptor interacts with one signalling protein or second messenger

139
Q

Convergent

A

Several receptors will share common signalling proteins or second messengers

140
Q

Divergent

A

A single receptor can interact with multiple signalling proteins or second messengers

141
Q

Multi branched

A

A combination of convergence and divergence may be happening all at the same time

142
Q

Stages of signal transduction

A

Signal (ligands)
Receptors
Signalling proteins
Second messengers

143
Q

Signal (ligands)

A

Arise from extracellular space must bind to sensor
A substance that forms complex bio molecules

144
Q

Three types of signals

A

Membrane impermeable
Membrane permeable
Physical signals

145
Q

Signal: membrane impermeable

A

Majority of molecules/ligands are impermeable
Are molecules that cannot penetrate membrane bind to receptor proteins on cell surface

146
Q

Signal: membrane permeable

A

Signal molecules/ligands are mainly steroids
Able to penetrate membrane
Not limited to membrane receptors and interact with cytosolic receptors

147
Q

Signal: physical

A

Pressure
Temp
Light

148
Q

Receptors

A

Often found on the plasma membrane but can be found in cytoplasm of cell

149
Q

Types of receptors

A

G-protein coupled receptors
Ion channels
Guanylate Cyclase
Protein kinase receptors
Transmembrane scaffolds
Nuclear receptors

150
Q

G protein coupled receptors

A
  • Role in cellular transduction
  • Located on cell surface
  • Respond to hormones, neurotransmitters
  • immune responses and metabolism
151
Q

Ion channels

A
  • select specific ions
  • key role in nerve impulse and muscle contraction
  • sodium and potassium channels
152
Q

Guanylate cyclase

A
  • conversion of GTP
  • vasodilation, neuronal signaling, cardiac function
153
Q

Protein kinase receptors

A
  • Cellular surfeit receptors that assist with external signals that activate intracellular pathways
  • 2 types tyrosine and threonine/serine kinase
  • help with cell growth and metabolism
154
Q

Transmembrane scaffolds

A
  • proteins throughout the cell membrane that form clusters of receptors
  • role in organization of signaling pathways
155
Q

Nuclear receptors

A

Located In the cytosil of cells bind to DNa to help gene expression

156
Q

Mobility

A
  • Signalling proteins are highly mobile
  • diffuse rapidly through the cytosol and move rapidly within plasma membrane
157
Q

Catalysis

A

Signalling proteins are either enzymes that can catalyze chemical reactions for signal amplification or they are capable of binding to enzymes

158
Q

Two types of signalling proteins

A

Monomeric G-proteins
Heterotrumeric G proteins

159
Q

Monomeric G proteins

A

Are single polypeptides that contain at least two different binding sites in GTP or GDP

160
Q

Heterotrumeric G proteins

A

Contain three polypeptides similar function to Monomeric G proteins

161
Q

Four step to activate G proteins

A

Binding
Separation
Propagate
Cleave and reform

162
Q

G protein activation: binding

A
  • Heterotrimer containing alpha and beta subunits is bound to GDP
  • when ligand binds the receptor changes to interact with hetero G protein
163
Q

G protein activation: separation

A
  • the receptor protein causes exchange of GDP with GTP on alpha subunit
  • hetero separates alpha and beta
  • G proteins active
164
Q

G protein activation: propagate

A
  • while separated the alpha and beta bind downstream to targets
165
Q

G protein activation: cleave and reform

A
  • alpha subunit cleaves GTP to form GDP
  • alpha and beta bind to reform heterotrimer
166
Q

Five signalling proteins

A

Calcium binding
Adenylyl cyclase
Protein kinases
Lipid kinases
Adaptor proteins

167
Q

Signalling protein: calcium binding

A

Ion on cell kept in low intracellular concentrations
- results in downstream signalling

168
Q

Signalling protein: adenylyl cyclase

A

Binds to alpha subunit of hetero G protein

Converting ATP to cAMP

169
Q

Signalling protein: protein kinases

A

Enzymes that phosphorylation proteins resulting in activation of downstream signalling

170
Q

Signalling protein: lipid kinases

A

Phosphorylation phospholipids in the cytoplasmic leaflets of the membrane

171
Q

Signalling protein: adaptor proteins

A

Allow cascades to be associated in the right space and turn to fulfill their task when and where they are needed

172
Q

Second messengers

A

Non protein ions and molecules which relay signalling info from signalling proteins to cellular targets

173
Q

Heterotrimeric G protein signalling cascade

A

GPCRS
cAMP
PKA
CREB

174
Q

Heterotrimeric G protein signalling cascade: GPCRS

A
  • Is initiated by the binding of ligand to GPCR
  • receptor allows receptor protein to interact with Hetero G protein
175
Q

Heterotrimeric G protein signalling cascade: CAMP

A
  • ligand bound receptor stimulates the replacement of GDP for GTP
  • G protein dissociate from receptor and leave beta and alpha subunit
176
Q

Heterotrimeric G protein signalling cascade: PKA

A

ligand bind yet to another signalling pathway
- causes protein to dissociate and release the active catalytic subunit

177
Q

Heterotrimeric G protein signalling cascade: CREB

A
  • once PKA, CREB binds with CBP the two proteins can interact with DNA to initiate transcription
178
Q

Three types of cells to handle dangerous cargo

A

Lysosomes
Proteasomes
Perixisomes

179
Q

Lysosomes

A

Are organelles that break down misfolded and damaged organelles nucleic acids and lipids

180
Q

Proteasomes

A

Are protein complexes that specifically break down damaged and misfolded proteins in the nucleus and cytosol

181
Q

Peroxisomes

A

Small membrane enclosed organelles that handle dangerous free radicals

182
Q

Two forms of cell death

A

Apoptosis
Necrosis

183
Q

Apoptosis

A

Programmed cell death used to protect the body from damaged cells that no longer function properly

184
Q

Necrosis

A

Accidental cell death

185
Q

Mechanism of necrosis’s

A

Damage
Swelling
Destruction

186
Q

Mechanism of necrosis: damaged

A

Cells are damaged beyond repair from toxins, radiation, freezing, trauma

187
Q

Mechanism of necrosis: swelling

A

Organelles begin to lose their structures and swell DNA is degraded

188
Q

Mechanism of necrosis: destruction

A

Cell membrane and remaining organelles lose structural integrity, contents spill out of cell causing inflammation. Near by cells exposed causing apoptosis of those cells

Final Exam PHGY 170 Mod 4-6 (1 decks)

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