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BIO1339 - Cell > Mammalian Cell Biology > Flashcards

Mammalian Cell Biology Flashcards

1
Q

What contains specific proteins, lipids and sugars?

A

Plasm membranes

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2
Q

What are does plasma membranes surround?

A

A cell

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3
Q

What can you word can be used to describe phospholipids?

A

Amphipathic

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4
Q

What is Amphipathic?

A

Having hydrophobic and hydrophilic parts

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5
Q

What makes the bio-membrane?

A

Phospholipids

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6
Q

What occurs to phospholipids in the presence of water?

A

Lipid bilayer

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7
Q

Are plasma membranes fluid or solid?

A

Fluid

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8
Q

What do steroids serve as?

A

Hormones

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9
Q

What is the source for sex hormones?

A

Cholesterol

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10
Q

What do steroids affect?

A

Membrane fluidity

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11
Q

What model represents the phospholipid bilayers?

A

Fluid Mosaic Model

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12
Q

What is the Fluid Mosaic Model?

A

-Applies to all membrane
-Membranes are fluid and flexible
-Proteins embedded in liquid environment
-

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13
Q

How thick is a plasma membrane?

A

4nm

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14
Q

Is the plasma membrane organised by itself or by other factors?

A

Itself

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15
Q

How does plasma membranes self organise?

A

Due to interaction between the hydrophilic and hydrophobic parts the membrane with water and lipids in the cytoplasm

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16
Q

What structural difference allows the identification of organelles?

A

Membranes differ in their lipid composition

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17
Q

Do membranes contain particles?

A

Yes

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18
Q

Using a microscope, what difference can you visualise when observing an exoplasmic extracellular membrane and the cytoplasmic face?

A

Less proteins embedded in the extracellular membrane

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19
Q

What do fibres of cytoskeleton interact with on the plasma membrane

A

Proteins

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20
Q

What are lipid rafts?

A

Membrane regions that assemble specialised lipids and proteins to preform a certain task

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21
Q

What is an example of a lipid raft?

A

Sites of uptake in plasma membranes are rich in cholesterol and sphingolipids an receptors

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22
Q

Why would use use Fluorescent Recovery After Photobleaching (FRAP)?

A

To investigate differences in membrane fluidity and protein mobility

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23
Q

What are the various functions of a protein in plasma membrane?

A
  • Anchorage with cytoplasm
  • Communication with cytoplasm
  • Anchorage at extracellular matrix
  • Transport over membranes
  • Cell-cell communication
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24
Q

What are different types or proteins embedded in membranes?

A
  • Transporters
  • Enzymes
  • Receptors
  • Cell-cell recognition
  • Intracellular joining
  • Attachment to the extracellular matrix an intracellular cytoskeleton
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25
Q

Are biomembranes permeable, semi-permeable or impermeable?

A

Semi-permeable

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26
Q

What can passively pass through a bio-membrane?

A

Uncharges, small, hydrophobic molecule

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27
Q

What do channels mediate?

A

Communication and exchange of small molecules and ions

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28
Q

What are the difference between pumps and channels?

A

Pumps require/consume ATP

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29
Q

What does gating of ion channels control?

A

Permeability of ion channels

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30
Q

When are gates normal open or closed?

A

In response to stimuli

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31
Q

What are the different types of channels?

A
  • Voltage gated channel
  • Mechanically gated channel
  • Temperature gated channel
  • Ligand-gated channel
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32
Q

What do channels rely on whether closed or opened?

A

Depend on concentration gradient

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33
Q

Does facilitated glucose transport require ATP?

A

No

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34
Q

How much of E.coli plasma membrane covered by transporters?

A

2%

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35
Q

How do channels form a membrane potential over their plasma membrane?

A

Having an asymmetry of ionic charges over there membranes

  • More positive charge outside
  • More negative charge inside
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36
Q

What are cell called if they do not change their membrane potential?

A

Non-excitable cells

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37
Q

What is an example of non-excitable cells?

A

Epithelial cells

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38
Q

What is an example of excitable cells?

A

Muscle cells, neurones

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39
Q

What are excitable cells?

A

Membrane potential can dramatically change

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40
Q

What is required for a membrane potential?

A
  • Difference in ion permeability of plasma membrane

- Activity of ATO-dependent ion pumps

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41
Q

How do you establish a resting membrane potential?

A
  • Na+ enter pump and bind
  • ATP comes along changing the conformation of the pump
  • Pump is a phosphorylated ADP + Pi produced, ATP leaves
  • Na+ diffuse out of cell
  • Inside more negative than outside
  • K+ binds to K+/Na+ pump, Pi leaves
  • K+ ion enters cell
  • K+ ion higher concentration gradient inside so K+ leaves via K+ leakage pump
  • Resting membrane potential reached
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42
Q

What is established in epithelium cells?

A

Tight lateral and basal contact

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43
Q

In epithelium cells what are the function of tight junctions?

A

Cells hold so tightly together there is no diffusion between the cells, have a high field of interacting proteins

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44
Q

Where can you find tight junctions?

A

In the blood brain barrier

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45
Q

What type of barrier do tight junctions act like?

A

Diffusion barrier

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46
Q

What are structures you can find in the epithelium cells which help establish high lateral and basal contact?

A
  • Tight junctions
  • Adherens junctions
  • Gap junctions
  • Desmosomes
  • Hemidesmosomes
  • Extracellular matrix
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47
Q

What is the function of adherents junctions?

A

Involved in controlling actin organisation

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48
Q

What do adherents junctions consist of?

A

Cadherins and catenin

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49
Q

Why do adherents contain cadherins?

A

To from cadherins bright between cells

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50
Q

Why do adherents contain catenin?

A

Catenins link to the actin cytoskeleton

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51
Q

What is the role of gap junctions in epithelium cells?

A

Supports exchange between the cytoplasm of adjacent cells

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52
Q

What makes up gap junctions?

A

A field of connecting channels, each made up of connexins

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53
Q

What do the channels of hap junctions allow the passage of?

A

Ions and small molecules

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54
Q

What is the function of desmosomes in epithelium cells?

A

Resist shear force in epithelia and in muscle

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55
Q

What do desmosomes consist of?

A

Specialised Catherine proteins that interact with each other and with intermediate filaments

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56
Q

Why are filaments important fibres?

A

Resist shared force

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57
Q

What is the function of hemidesmosome in epithelium cells?

A

Anchor the epithelia cell to basal lamina and involved in signalling

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58
Q

What do hemidesmosome consists of?

A

Many proteins (including ingrains) that interact with extracellular matrix

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59
Q

Where can you find hemidesmosomes structures?

A

In skin epithelial cells

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60
Q

What is the function of the extracellular matrix in epithelium cells?

A

-Holds tissues together, provides strength, directing cell migration

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61
Q

What is the extracellular matrix consistent of?

A

Fibres of secreted protein (collagen, matrix proteins and glycoproteins)

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62
Q

What can cells sense and react too?

A

Its environment

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63
Q

What are the two major intracellular signalling mechanisms ?

A
  • Phosphorylation of protein

- Signalling by GTP-binding protein

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64
Q

What proteins are involved in intracellular signalling pathway?

A
  • Receptor protein
  • Intracellular signalling proteins
  • Effector proteins
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65
Q

What do metabolic enzymes alter?

A

Metabolism

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66
Q

What do gene regulatory proteins alter?

A

Gene expression

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67
Q

What do cytoskeletal protein alter?

A

Cell shape or movement

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68
Q

What are G-proteins?

A

Molecular switches

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69
Q

What are G-proteins activated by?

A

Guanine nucleotide exchange factor (GEF)

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70
Q

What are G-proteins inactivated by?

A

GTPase-activating protein (GAP)

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71
Q

Describe small monomeric G-proteins:

A

Receive signals from many receptors

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72
Q

What is an example of small monomeric G-proteins?

A

Rab-GTPase

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73
Q

Describe large trimeric G-proteins:

A

Interact with G-protein coupled receptors

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74
Q

What is an example of large trimeric G-proteins?

A

G-proteins that activate adenylyl cyclase

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75
Q

What a kinases often forming?

A

A signalling cascade

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76
Q

What can control the activity of effector protein?

A

Phosphorylated kinase or phosphatases

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77
Q

Does protein kinases and phosphatases have a specific or broad roles in control protein activity and cellular processes?

A

Broad role in control protein activity and cellular processes

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78
Q

What is kinase?

A

An enzyme that transfers phosphate groups from high-energy donor molecules to specific substrates (Phosphorylation)

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79
Q

What is phosphatase?

A

An enzyme that removes a phosphate group from a protein (dephosphorylation)

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80
Q

Is phosphorylation the adding or taking phosphates?

A

Adding phosphates

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81
Q

Is dephosphorylation the adding or taking phosphates?

A

Taking phosphates

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82
Q

What percentage of all human proteins carry a phosphate group?

A

30%

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83
Q

How many kinases does the human genome contain?

A

520

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84
Q

How many protein phosphatase does the human genome contain?

A

150

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85
Q

What can kinases act as?

A

Microchips

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86
Q

What can kinase act as microchips?

A

Can integrate information

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87
Q

What does cdk kinase control?

A

Control of cell progression

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88
Q

What does src-type kinase control?

A

Control of regulate various biological functions

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89
Q

What motion do particles and molecules undergo?

A

Brownian motion

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90
Q

What is Brownian motion?

A

Diffusional motion, random motion of particles

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91
Q

What does diffusion depend on?

A

The size of the molecule/organelle

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92
Q

Does the molecule have to be smaller or bigger in order to diffuse quicker?

A

Smaller

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93
Q

What is diffusion restricted by?

A

Crowded cytoplasms

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94
Q

How many subunits make up a ribosome?

A

2

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95
Q

What subunits make up prokaryotes 70S ribosome?

A

50S

30S

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96
Q

What subunits make up eukaryotes 80S ribosome?

A

60S

40S

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97
Q

What does the S stand for?

A

The Svedberg unit

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98
Q

What does the Scedberg unit describe?

A

The sedimentation behaviour of particles

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99
Q

What did Scedberg develop?

A

The technique of analytical ultracentrifugation

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100
Q

What factors determine the S value?

A

A particle is mass, density and shape

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101
Q

What does 50S of prokaryotic ribosome contain?

A

5S rRNA
23S rRNA
24 Proteins

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102
Q

What does 30S of prokaryotic ribosome contain?

A

16S rRNA

21 protein

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103
Q

What does 60S of eukaryotic ribosome contain?

A

5S rRNA
28S rRNA
49 Proteins

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104
Q

What does 40S of eukaryotic ribosome contain?

A

18S rRNA

33 Proteins

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105
Q

What are the subunits of ribosomes made up of?

A

Proteins and rRNA

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106
Q

Where can you find ribosomes?

A

In the cytoplasm

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107
Q

What is the role of ribosomes?

A

Translate information from mRNA to proteins

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108
Q

Describe protein translation:

A
  • Matching tRNA to mRNA
  • Release of elongation factor TU
  • Formation of peptide bound
  • Elongation factor G triggers a forward movement of ribosomes
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109
Q

What is a polysome?

A

Numerous ribosome operate along a single mRNA molecule

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110
Q

What is the largest organelle?

A

Nucleus

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111
Q

What is the average size of the nucleus in comparison to cell volume?

A

10% of cell volume

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112
Q

What makes up the nucleus?

A
  • Euchromatin
  • Heterochromatin
  • Lamina
  • Nuclear pore
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113
Q

How many membranes does the nucleus have?

A

two

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114
Q

What is the inner membrane of a nucleus?

A

Phospholipid bilayer

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115
Q

What is the outer membrane of a nucleus?

A

Lumen around nucleus (aka nuclear envelope)

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116
Q

What acts as gates controlling transport in and out of the nucleus?

A

Nuclear pores

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117
Q

What makes up the nuclear lamina?

A

Net work of fibres

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118
Q

What is the role of nuclear lamina?

A

Protects nucleus from damage, organises the distribution of nuclear pores and arranges interphase chromosomes

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119
Q

What happens if no lamina in the nuclear membrane?

A

Nuclear pores cluster

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120
Q

What happens to the nuclear envelope and nuclear lamina during mitosis?

A

Disassembles

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121
Q

Are nuclear pores highly organised or disorganised multi-protein complexes?

A

Highly organised

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122
Q

What do nuclear pore complexed composed of?

A
  • 8-fold symmetry

- Numerous proteins build pore

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123
Q

What are nucleoporines?

A

Proteins that make up a nuclear pore

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124
Q

How many different nucleoporins make up a pore?

A

30 nucleoporins

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125
Q

What structure does the inner pore of a nuclear pore have?

A

Cage-like structure

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126
Q

What structure does the outside pore of a nuclear pore have?

A

Extensions toward cytoplasm

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127
Q

What molecules can simple diffuse?

A

Small and uncharged

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128
Q

What molecules require active transport?

A

Large and charged

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129
Q

What does nuclear transport depend on?

A
  • Smal GTPase

- Soluble import/export receptors (aka helper proteins)

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130
Q

What can target specific organelles by localisation signals?

A

Fluorescent proteins

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131
Q

What does the nuclease realise during mitosis?

A

Its content = has to re-import nuclear proteins

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132
Q

What does nucleolus form?

A

Ribosome

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133
Q

What is the structure of a nucleolus?

A
  • Granular components
  • Fibrillar centres
  • Heterochromatin
  • Euchromatin
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134
Q

What is the function of granular component?

A

Ribosome assembly site

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135
Q

What is the function of fibrillar centres?

A

rRNA transcription

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136
Q

What is heterochromatin?

A

Remain packed after mitosis, transcriptional inactive, 10% of DNA

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137
Q

What is euchromatin?

A

Transcriptional active

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138
Q

Is chromosome DNA much bigger than the nucleus?

A

Yes 1000x

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139
Q

What must the chromosome be to fit into the nucleus?

A

highly folded

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140
Q

What is chromatin?

A

Interaction of structural proteins to fold chromosomes

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141
Q

Why is DNA tightly packed during mitosis?

A
  • Takes least amount of space
  • Best protected by protein
  • Suitable for inheritance during mitosis
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142
Q

What is the size of DNA?

A

2nm diamete

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143
Q

Is DNA negatively or positively charged?

A

Negatively charged

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144
Q

Are histones negatively or positively charged?

A

Positively charged proteins

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145
Q

How many types of histones are there?

A

4 types

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146
Q

What are the 4 types of histones?

A

H2A, H2B, H3, H4

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147
Q

Histones are considered as small proteins. How many amino acids is that approximately?

A

100 amino acids

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148
Q

Where is DNA normally organised in?

A

Nucleosomes

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149
Q

Do nucleosomes tighten or loosen during transcription?

A

Loosen

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150
Q

What is the average size of nucleosomes?

A

30 nm

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151
Q

How is a 30nm fibre formed chromatin?

A

Interaction between DNA and histones = higher degrees of package

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152
Q

What is 200nm fibre of chromatin?

A

DNA is further packed around a scaffold that contains specialised proteins

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153
Q

Is there transcription during metaphase?

A

No

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154
Q

Why is there no transcription during metaphase?

A

A chromosome is tightly packed

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155
Q

What is the main process in nucleus?

A

Transcription

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156
Q

What is transcription?

A

Process of transcribing DNA nucleotide sequence information into RNA sequence information

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157
Q

What are the types of RNA polymerase in eukaryotes ?

A
  • RNA polymerase I : ribosomal RNA
  • RNA polymerase II: messenger RNA
  • RNA polymerase III: transfer RNA
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158
Q

What is the RNA polymerase revenant to plants?

A

RNA polymerase IV: siRNAs, required for heterochromatin formation

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159
Q

How many types of RNA polymerase are there in prokaryotic cells?

A

1

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160
Q

Is linker DNA transcribed?

A

No

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161
Q

Describe the basic principle or transcription:

A
  1. Numerous transcription factors bind to the TATA box in the promoter
  2. RNA polymerase binds to the template strand and synthesis an exact copy of the coding stand
  3. RNA is release, further processed and released from the nucleus (bound to RNA-binding proteins)
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162
Q

Where does transcription occur in prokaryotes?

A

Cytoplasm

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163
Q

Where does transcription occur in eukaryotes?

A

Nucleus

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164
Q

What is the difference of mRNA in prokaryotes and eukaryotes?

A

Prokaryotes: use mRNA directly
Eukaryotes: Pre-mRNA modified to mRNA where mRNA and RNA binding protein exposed via nuclear pores

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165
Q

Does translation occur immediately in cytoplasm of prokaryotes?

A

Yes

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166
Q

Which sentence is relevant to prokaryotes:
A. Many genes on one mRNA
B. One mRNA for one gene

A

A

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167
Q

Which sentence is relevant to eukaryotes:
A. Many genes on one mRNA
B. One mRNA for one gene

A

B

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168
Q

What does the endomebrane system contain?

A
  • Nucleus
  • Endoplasmic reticulum
  • Golgi apparatus
  • Lysosome/Vacuole
  • Endosomal compartments
  • Transport vesicles
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169
Q

What are compartments of endomembrane system connected by?

A

Transport vesicles

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170
Q

What is a cellular compartment?

A

Membrane-surronded space in the cell

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171
Q

What do you call a cellular compartment which has a specialised function?

A

Organelle

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172
Q

Are transport vesicles organelles?

A

No

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173
Q

Does the endoplasmic reticulum communicate directly or indirectly to the Golgi-apparatus?

A

Directly

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174
Q

What does the Golgi apparatus communicate with?

A

Late/early endosomal compartments

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175
Q

What doe endosomal compartment communicate with?

A

Lysosomes

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176
Q

How are communication between all compartments mediated?

A

Via transport vesicles

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177
Q

What is membrane trafficking?

A

Motors move transport vesicles and organelles within the cell

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178
Q

What are molecular motors?

A

Enzymes that use ATP to move along the cytoskeleton

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179
Q

What is secretion?

A

Transport from the interior to plasma membrane for release in to the environment

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180
Q

What do vesicles mediate?

A

Exchange of material between the cell and the environment

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181
Q

What is exocytosis?

A

Vesicles fusing with cell membrane to release material

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182
Q

What is endocytosis?

A

Vesicles forming at the membrane to transport material into the cell

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183
Q

What are the three types of trading pathways?

A
  1. Secretory pathway (biosythesis)
  2. Endocytic pathway
  3. Retrieval-recycling pathway
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184
Q

What is secretory pathway?

A

Material from inside cell transported to outside cell

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185
Q

What is endocytic pathway?

A

Material from outside side transported to inside cell

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186
Q

How many secretory vesicles does a single human beta cell have?

A

10,000

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187
Q

What is the endoplasmic reticulum in contact with?

A

The nuclear envelope

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188
Q

What is endoplasmic reticulum?

A

Membranous synthesis and transport organelle that is an extension of the nuclear envelope

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189
Q

What makes up the endoplasmic reticulum?

A

Membrane sacs and bracnched tubules

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190
Q

What makes up 50% of all membranes of the cell?

A

Membrane sacs and branched tubules

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191
Q

Are the tubules of the endoplasmic reticulum motile or fixed?

A

Motile

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192
Q

What are the two types of endoplasmic reticulum?

A
  • Smooth endoplasmic reticulum

- Rough endoplasmic reticulum

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193
Q

What is the purpose of smooth endoplasmic reticulum?

A
  • Calcium storage for cell signalling
  • Lipid synthesis
  • Detoxification of drugs/poisons
  • Metabolism of carbohydrates
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194
Q

What is the purpose of rough endoplasmic reticulum?

A

Processing of secretory proteins

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195
Q

What can you visualise of rough endoplasmic reticulum using a microscope?

A

more organised and has dots representing ribosome on the surface of them

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196
Q

What can you visualise of smooth endoplasmic reticulum using a microscope?

A

Highly disorganised

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197
Q

Describe cotranslation translocation into the endoplasmic reticulum:

A
  1. Ribosome assembles and binds mRNA
  2. If polypeptide contains a signal sequence,
    the ribosome is targeted to the ER membrane; If not it stays in the cytosol
  3. The signal peptide is cleaved off and the protein is translated into the ER lumen where it is folded and further processed
  4. Cytosolic proteins can contain signal sequences that target them to other organelles
    (nucleus, mitochondria, peroxisomes, chloroplasts)
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198
Q

When are integral membrane proteins inserted at the endoplasmic reticulum?

A

During translation

199
Q

What are many membrane receptors?

A

Type I, II and IV

200
Q

What are the different types of transmembrane receptors?

A 
Type I
Type II
Type III
Type IV
GPI-linked
201
Q

What is transmembrane domain?

A

Consists of number of hydrophobic amino acids will integrate and stain in membrane

202
Q

What are Golgi apparatus?

A

Disc-shaped stack of membranes

203
Q

Describe the organisation of Golgi apparatus (cis face to trans face):

A
  • Cis face
  • Cis Golgi network
  • Golgi stack (Cis cisterna -> medial cisterna -> trans cisterna)
  • Trans Golgi network
  • Trans face
204
Q

What are glycoproteins?

A

Membrane contain proteins that are linked to sugar residues

205
Q

What is the function of oligosaccharide?

A
  • Provide protection against pathogens
  • Serves in cell-cell recognition and signalling
  • Marks progression of the protein
  • Helps folding and interaction with other proteins
206
Q

Where are oligosaccharides processed?

A

In the Golgi

207
Q

Where are proteoglycans assembles?

A

In the Golgi

208
Q

What do most proteins that arrive at Cis Golgi from endoplasmic reticulum contain?

A

N-linked oligosaccharide

209
Q

Describe the process of oligosaccharide chains in the Golgi:

A
  • Cis Golgi network: phosphorylation of oligosaccharide on lysosomal proteins
  • Cis cisterna: Removal of Man
  • Medial cisterna: removal of Man, addiction of GlcNAc
  • Trans cisterna: Addition of Gal, addition of NANA
  • Trans Golgi network: Sulfation of tyrosine and carbohydrates
210
Q

What do oligosaccharide undergo in the Golgi?

A

Several glycosylation steps

211
Q

What is glycosylation?

A

Adding and modifying sugar residues on protein

212
Q

In what two ways can oligosaccharide be linked proteins?

A
  • N-linked

- O-linked

213
Q

Where are N-linked oligosaccharide largely occur?

A

In endoplasmic reticulum

214
Q

Where are O-linked oligosaccharide largely occur?

A

In Golgi apparatus

215
Q

How many of all eukaryotic proteins glycosylated?

A

50%

216
Q

What are the serval different types of endosomes?

A
  • Late endosomes
  • Early endosomes
  • Recycling endosomes
217
Q

What are the three types of endocytosis?

A

Phagocytosis
Pinocytosis
Receptor-mediate endocytosis

218
Q

What is phagocytosis?

A

Large particles taken up in large vesicles

219
Q

What are pinocytosis?

A

Small/liquid particles which are dissolved in liquid

220
Q

What are receptor-mediate endocytosis?

A

Receptors are exposed and bind to specific molecules goths a coated pit (a vesicle formed with protein) and surrounded by coated proteins on the outside

221
Q

Describe the membrane trafficking along the endocytic pathway:

A

1.Formation of a vesicle
at the plasma membrane (pH of cytosol 7)
2.Fusion of vesicle with early endosome (pH of cytosol 6.5)
3.Decision: degradation or recycling of receptors in vesicles to plasma membrane or recycling via endosome
4.Maturation of early endosome to late endosome (Internal pH 5.5 to 4.5)
5. Specific enzyme can become active due to low pH where enzymes digest molecules to small pieces
6.Recycling from late endosome to Golgi
7.Maturation of late endosome into lysosome
8.Majorityly of material ends in lysine (internal pH 4.5)

222
Q

What is the last compartment of the endocytotic pathway?

A

Lysosomes

223
Q

What is the equivalent of lysosome (which is present in animal cells) in a plant cell?

A

Vacule

224
Q

What does phagocytosis fo in macrophages?

A

Cleans the body from invading pathogens and damaged cells

225
Q

What can occur in phagocytosis which is a major problem?

A

Some pathogens stop the process and escape the phagosome to infect the host cell

226
Q

What does incomplete phagocytosis underlies?

A

The endosymbiont hypothesis

227
Q

What is endocytosis?

A

Uptake of material into the cell

228
Q

What is autophagy?

A

Membrane vesicles fuse and form autophagosome which engulfs organelles which fuse with lysosome

229
Q

Do organelles have a limited life time?

A

Yes

230
Q

What do autophagy do to those organelles that have a limited life time?

A

Recycles organels

231
Q

What do lysosomes serve as?

A

Disposal containers

232
Q

Why do lysosomes serve as disposal containers?

A
  • Low pH acid hydrolase have optimum activity

- Degrade to fundamental structures to be transported out of lysosome and reused

233
Q

What do transport vesicles do?

A

Deliver their content to compartments and to/from from the plasma membrane

234
Q

What is the size of transport vesicles?

A

About 25-200 nm

235
Q

Are transport vesicles moving around by diffusion?

A

No actively moving in the cell

236
Q

What do transport vesicles carry various of?

A

Cargo

237
Q

How many type of integral proteins are there in synaptic vesicles?

A

50

238
Q

How many phospholipids are there in synaptic vesicles?

A

7000

239
Q

How many cholesterol molecules are there in synaptic vesicles?

A

5700

240
Q

What provides membrane specificity?

A

SNARE receptors

241
Q

How do SNARE receptors provide membrane specificity?

A
  • vSNARE forms a complex with tSNARE

- Fusion of a vesicle with a target membrane

242
Q

How does fusion of a vesicle with a target membrane occur?

A
  1. Tethering
  2. Docking
  3. Fusion
243
Q

What occurs in step 1. tethering of how does fusion of a vesicle with a target membrane occur?

A

Rab-binding tethering factor at target membrane binds the RAB-GTP vesicles (loosely links)

244
Q

What occurs in step 2. docking of how does fusion of a vesicle with a target membrane occur?

A

vSNARE interacts with tSNARE (brings vesicle more closely to membrane)/interaction overcome replying forces

245
Q

What occurs in step 3. fusion of how does fusion of a vesicle with a target membrane occur?

A

pH drops, ligand is release (some parts are recycled) a v-SNARE-tSNARE complex is formed

246
Q

What are many vesicles coated in?

A
  • Clathrin
  • COPI
  • COPII
247
Q

What do vesicles coats do?

A
  • Coat concentration specific proteins in patches

- Coat holds the forming vesicles

248
Q

Are coats generalised or specific for particular places in the endocytic and the exocytic pathway?

A

Specific

249
Q

What coats are found on Golgi apparatus?

A

COPI

250
Q

What coats are found on early endosomes, endocytic pathway?

A

Clathrin

251
Q

When are coats formed?

A

Formed around emerging vesicles

252
Q

What are involved in the molecular organisation of a Cathrin coat?

A
  • Adaptin = which binds the receptor
  • Clathrin coat = binds to adaption, shape vesicles
  • Clathrin = subunits consists of triskelion structure of three heavy chain and three light chain of Cathrin proteins
253
Q

Describe formation of a clathrin-coated vesicles:

A
  • Receptors bind to cargo, more receptors binding more recognising
  • More triskelion structure recruited (self assemble)
  • Specificity is provided by adaptor-receptor interaction
  • Self assemble bends the membrane forms the vesicles
  • Coat formation curves the membrane and shapes the vesicles
  • Coat is readily lost and vesicles interacts with the cytoskeleton for intracellular transport
254
Q

Can coatings of vesicles be reused?

A

Yes

255
Q

What delivers deeper into the cell coated or naked transport vesicles?

A

Naked transport vesicles

256
Q

What are extracellular vesicles?

A

Transport vesicles which are released from cells

257
Q

Where do you find extracellular vesicles?

A

In body fluids

258
Q

What are examples of body fluids?

A

Fluids around brain and spinal chord, urine, blood

259
Q

What do extracellular vesicles contain?

A

RNAs, porteins

260
Q

What provides the RNAs and protein in extracellular vesicles?

A

Donor cells

261
Q

Where do extracellular vesicles deliver their content to?

A

Recipient cells

262
Q

What is an example of an extracellular vesicles in cell-cell communication?

A

Microvesicles

Exosomes

263
Q

What is another name for microvesicles?

A

Ectosomes

264
Q

Describe cell-cell communication via microvesicles:

A
  • Formation at donors plasma membrane
  • Transfer proteins, mRNAs and miRNAs
  • Uptake via fusion with plasma membrane
265
Q

Describe cell-cell communication via exosomes:

A
  • Formed at early endosomes, released from late endosomes
  • Transfer protein, mRNAs and miRNAs
  • Uptake via endocytosis or fusion with recipient’s plasma membrane
266
Q

What is the role of exosomes and microvesicles?

A
  • In immunology
  • In blood
  • In CNS
  • In bone
267
Q

What can spread cancer?

A

Extracellular vesicles

268
Q

What does cytoskeleton provide?

A

Tracks that link the region of the cell

269
Q

What are the three different filaments that make up the cell?

A
  • F-actin
  • Microtubules
  • Intermediate filaments
270
Q

What is the size of F-actin?

A

7-9nm

271
Q

Is F-actin short or long range communication?

A

Short range communication

272
Q

Is microtubules short or long range communication?

A

Long range communication

273
Q

What does intermediate filaments add to the cell?

A

Mechanical strength

274
Q

What is the cytoskeleton?

A

Consists of filaments bio-polymers and of associated proteins that are modulating the activity, dynamics or organisation of the cytoskeleton

275
Q

What is the role of the cytoskeleton?

A
  • Connects all parts of the cell
  • Support motility
  • Helps spatial organisation
276
Q

What does the cytoskeleton provide for intracellular trafficking?

A

Tracks

277
Q

What is essential for cell function?

A

Exchange of material and information

278
Q

Does the cytoskeleton provide stability for the cell?

A

Yes

279
Q

What is structure of F-actin?

A
  • Subunits G-actin (binds ATP in the centre)

- Two pear strings twisted around each other (Two protofilaments)

280
Q

Where is actin found?

A

In animal cells

281
Q

What modifies actin organisation?

A

Actin-binding proteins

282
Q

What are different types of actin-binding modifications?

A
  • Sequestering/Recycling
  • Capping
  • Branching/Nucleating
  • Depolymerising
  • Nucleating/Polymerising
  • Cross-linking
  • Moving
  • Severing
  • Bunding
  • Stabilising
283
Q

How different types of actin-binding proteins are there?

A

+160

284
Q

What is an example of ordered bunding?

A

Microvilli

285
Q

What do actin form?

A

Cellular protrusions

286
Q

Where does polymerisation occur at microtubules?

A

N plus end

287
Q

What is the structure of microtubules?

A
  • Dimers coasting of a-tubulin and B-tubulin
  • Bind to a GTP
  • B-tubulin = GTP hydrolysed to GDP
288
Q

How many protofilaments to make up a microtubule?

A

13 protofilaments

289
Q

Where are microtubules made and extended to?

A

Made at centrosome and sent towards periphery cell

290
Q

What modifies microtubule organisation and function?

A

Microtubule-binding proteins

291
Q

What are different types of microtubule-binding modifications?

A
  • Nucleating
  • Capping
  • Cross-linking
  • Depolymerising
  • Attaching
  • Moving
  • Severing
  • Stabilising
  • Bunding
  • Polymerising
  • Sequestering
292
Q

What does helioza from?

A

Microtubule-supported protrusions

293
Q

What are helioza?

A
  • Projection contain highly organised microtubules

- Serves in capturing food, sensation, movement and attachement

294
Q

How does polymerisation of microtubules work?

A

Plus-end binding proteins control dynamics of microtubules and participate in intracellular motility?

295
Q

What happens at plus-end of microtubules?

A
  • Attachment of microtubules to cell periphery
  • Control of microtubule dynamic behaviour
  • Control of intracellular trafficking by regulating dynein
296
Q

What do microtubules nucleating from?

A

Microtubule organising centre near the nucleus

297
Q

What do animal centromeres contain?

A

Centrioles

298
Q

What do centrioles mainly consist of?

A

Microtubule

299
Q

What do centrioles become of flagella and cilia?

A

Basal body

300
Q

What does the centrioles organise?

A

Pericentriolar material together and ensures it inheritance

301
Q

What does not have centrioles?

A

Fungi and plants

302
Q

What do fungi and plants have instead of centrioles?

A

Gamma-tubulin

303
Q

Do centrioles replicate during cell cycle?

A

Yes

304
Q

What does peri-centriolar material contain?

A

Gamma-tubulin

305
Q

What do tubules exists as?

A

Dimers and as polymers

306
Q

What subunits build tubules?

A

a-tubulin

B-tubulin

307
Q

What does adding of tubules subunits do to microtubules?

A

Elongate it

308
Q

What does subtracting of tubules subunits do to microtubules?

A

Shorten it

309
Q

Describe the polymerisation and depolymerisation of microtubules:

A
  1. Polymerisations
    - B-tubulin is GTPase
    - GTP bound tubules dimer gets added to “plus end”
    - cap of GTP-tubulin stabilises growing molecule
  2. Pausing
    - If low amount of GTP-tubulin available process is paused and hydrolysis ‘eats’ the GTP-cap
    - Tubulin hydrolyse bound GTP while microtubules polymerises
    - When polymerisation slows down, the GTP-cap disappears
  3. Depolymerisation
    - Without GTP-cap, microtubule becomes unstable and depolymerises
    - Moment of transition is called a catastrophe
  4. Polymerisation
    - GTP-tubulin can bind the shrinking microtubule and establish new cap
    - Moment of transition is called a rescue event
310
Q

What is dynamic instability of microtubules?

A

Microtubules constantly switch between growth and shrinkage

311
Q

Describe the process of F-actin formation:

A 
G-actin
to
Nucleation seed formation
to 
F-actin
312
Q

What does existing actin filaments show?

A

Treadmilling

313
Q

What is treadmilling in actin filaments?

A
  • Plus-end ATP bound G-actin can be added
  • Minus-end ADP bound G-actin can be released
  • Overal length is NOT changed
314
Q

Where can you locate intermediate filaments?

A

Around the cell

They have contact with desmosomes and other cytoskeleton

315
Q

Is intermediate filaments less or more organised than the other filaments?

A

Less organised

316
Q

What does intermediate filaments provide to the cell?

A

Mechanical strength

317
Q

Intermediate filaments can be put into groups. What is the group on based on?

A

Central rod domain amino acid sequences, net acidic charge and secondary structure

318
Q

Can several intermediate filaments xo-exist in the same cell?

A

Yes

319
Q

What is the general function of intermediate filaments?

A
  • Mechanical strength
  • Organising cytoplasm
  • Signalling
  • Regulating transcription
320
Q

What is shared by all types of intermediate filaments?

A

Domain structure

321
Q

What does the coiled-coil of intermediate filaments consist of?

A

Alpha helices (around 2-3) wind around each other

322
Q

What are the a helices often structures as?

A

Amphiphatic

323
Q

What does a-helices in intermediate filaments being amphiphatic mean?

A

Protein interaction

324
Q

Does intermediate filaments require ATP or GTP for assembly?

A

No

325
Q

How does intermediate filaments assemble?

A

Self assemble into an apolar filament

326
Q

What makes the nuclear lamina?

A

Intermediate filaments

327
Q

What is the function of all lamina?

A

-Stabillity
-Organise
The nucleus

328
Q

What occurs to intermediate filaments to able to reorganise?

A

intermediate filaments can disassemble into subunits to allow cell movement

329
Q

What filaments make skin associated structures?

A

intermediate filaments

330
Q

What skin like structure does B-keratin make?

A

Nails, scales and claws or reptiles, feathers, beaks

331
Q

What skin like structure does a-keraton make?

A

Hair, horns and hooves of mammals

332
Q

What is filament is a crucial part of you eye lens?

A

intermediate filaments

333
Q

What does eye lens consist of that degrade their organelles?

A

Cells

334
Q

How many types of intermediate filaments participate in development and function of vertebrate eye lens?

A

7

335
Q

What do intermediate filaments determine in eye lens?

A

Optical properties

336
Q

Does actin, microtubules or intermediate filaments consist of protein subunits?

A

Yes

337
Q

Does intermediate filaments have more that one type of subunit?

A

Yes

338
Q

Does actin, microtubules or intermediate filaments present in all eukaryotes?

A

Actin and microtubules

339
Q

What eukaryotic cell is intermediate filaments present in?

A

Animal cell

340
Q

Which filament actin, microtubules or intermediate filaments polymerise and depolymerise?

A

ALL

341
Q

Which filament actin, microtubules or intermediate filaments cleave nucleoside triphosphate to control dynamics?

A

Actin and microtubules

342
Q

Which filament actin, microtubules or intermediate filaments use phosphorylation to control dynamic?

A

Intermediate filaments

343
Q

Which filament actin, microtubules or intermediate filaments provides stability?

A

All

344
Q

Which filament actin, microtubules or intermediate filaments supports cell motility?

A

Actin and microtubules

345
Q

Which filament actin, microtubules or intermediate filaments forms extracellular structures?

A

Intermediate filaments

346
Q

What is another name for molecular motor?

A

Mechano enzymes

347
Q

What is the purpose of molecular motor?

A

Transport vesicles and organ eels through cell

348
Q

What are molecular motors?

A

Molecular scale of dimers or large proteins consistent of heavy and light chains

349
Q

What does molecular motor utilise to walk along cytoskeleton?

A

ATP

350
Q

How are molecular motor organised?

A
  • Motor domain (2 heavy chains)
  • Stalk (connects motor and cargo)
  • Cargo-binding (light chains modify activity)
351
Q

What are two different types of molecular motors?

A
  • Microtubule - associated

- Actin - associated

352
Q

Give an example of microtubule-associated molecular protein:

A

Kinesin/Dynein

353
Q

Give an example of actin-associated molecular protein:

A

Myosin

354
Q

How can one prove that motors are mechanical-enzymes?

A
  • Purified myosin molecules flushed underneath coverslips
  • equally distributed, someone molecules attached to coverslip
  • wash the solution to remove the molecules which are not attached
  • add label actin filament (fluorescently labelled)
  • actin filament interact with myosin
  • Addition of ATP, actin motor protein walks along the actin filament
355
Q

What direction do molecular motors move in?

A

Relative to charge

356
Q

What direction does dynein move in?

A

Towards minus end

357
Q

What direction does kinesis/myosin move in?

A

Towards plus end

358
Q

Hoe can motor be grouped in to families?

A

By diverse functions

359
Q

How may motor groups are there?

A

More than 25

360
Q

How does kinesis walk along a microtubule?

A
  • ATP interaction with motor head
  • ATP binding leads to conformational change allowing other head forwards
  • Head binds tightly to next tubules dimer ATP is cleaved
  • New ATP comes along and head swings forwards
361
Q

How are kinesis or dynein recycled?

A

Bind to cargo and actively or passively transported back

362
Q

Can motors use more than one motor?

A

Yes

363
Q

What does having more that one motor allow?

A

Allows long distance transport of vesicle

364
Q

How do kinesis and dynein move to avoid collision?

A

Move differently
Dynein uses several filaments
Kinesin stays on same protofilamenst and moves in straight line

365
Q

Does the nucleus move within the cell?

A

Yes

366
Q

How does the colour of fish skin change?

A

Melanosome motility

Dispersal and concentration depends on kinesis, dynein that move along the microtubule

367
Q

What shapes endoplasmic reticulum?

A

Motors

368
Q

How does endoplasmic reticulum reach nucleus to cell periphery?

A

Microtubules and kinesin organisation

Kinesis goes to plus end

369
Q

How does Golgi apparatus stay concentrated at the nucleus?

A

Microtubules and dynein

Dynein goes to minus end

370
Q

How does neurones cope with long distance?

A
  • Axonal transports mediates motility in neurons
  • Anterograde transport = negative end to positive end mediated by kinesin
  • Retrograde transport = positive end to negative end mediated by dynein
371
Q

What are the motor in muscle function?

A

Myosin motors

372
Q

What % of you body is muscle?

A

40%

373
Q

How much of muscle is protein?

A

20%

374
Q

What does skeletal muscle mainly consist of?

A

Myosin and F-actin

375
Q

How are muscles built?

A

Sarcomere -> muscle fibrille -> muscle cell -> muscle

376
Q

What makes up a sarcomere?

A

Z-disc
Thin filament
Thick filament

377
Q

What makes up a dark band of sarcomere?

A

Thick filament

378
Q

What makes up a light band of sarcomere?

A

Z-disc

Thin filament

379
Q

What does thick filaments consist of?

A

Myosin II

380
Q

What does thin filament consist of?

A

F-acton

381
Q

When relaxed is there interaction between myosin and actin filaments?

A

No interaction

382
Q

How is contraction controlled?

A
  • Stimulus from neurons first over the plasma membrane of muscle cells
  • Depolarisation of membrane release calcium from endoplasmic reticulum into cytoplasm
  • Binding of calcium to tropic complex releases the block of myosin binding site on actin
  • Myosin binds actin and walks towards Z-disc
  • Calcium is removed by calcium pumps and myosin releases actin filaments
  • Myosin releases actin and slide back (relaxation)
383
Q

What does cardiac myocytes from?

A

Another type of straight muscle

384
Q

How many times does the heart muscle contract over the course of a human lifetime?

A

3 billion

385
Q

Is cardiac muscle organised?

A

No

386
Q

What types of contractions do cardiac myocytes undergo?

A

Spontaneous contractions

387
Q

Are flagella and cilia stationary or motile structures?

A

Motile

388
Q

Do flagellum have a few or many per cell?

A

Few

389
Q

Do cilium have few or many per cell?

A

Many

390
Q

What do flagellum function in fluid/particle transport or cell locomotion?

A

Cell locomotions

391
Q

What do cilium function in fluid/particle transport or cell locomotion?

A

Fluid and particle transport

392
Q

What are cilia used for?

A

To move liquid within the body

393
Q

What is the motion of flagellum?

A

Propeller-like motion

394
Q

What is the motion of cilium?

A

Back and forth beating

395
Q

How many beats per second do cilia beat?

A

12-30

396
Q

How many beats per second do flagella beat?

A

10-40

397
Q

What structural similarities do cilium and flagellum share?

A
  • Axoneme (Core made of microtubules)

- Basal body anchors structure at cell

398
Q

What forms basal body of flagella?

A

Centrioles

399
Q

What fo centrioles participate in?

A

Microtubule formation in interphase

400
Q

What supports the formation and function of the cilium?

A

Intraflagellar transport

401
Q

What travels along the axoneme?

A

Rafts

402
Q

What drive bidirectional transport of rafts?

A

Kinesin and dynen

403
Q

What is the ultrastructure of the standard cilium?

A
  • 9x2 microtubules (next to each other)
  • +2 microtubes in middle
  • Outer arm dynein
  • Inner arm dynein
  • Radical spoke
404
Q

Do dynein slide microtubules for or against each other?

A

Against

405
Q

What occurs due to dynein sliding microtubule against each other?

A

Motor activity against protein bridges causes bending

406
Q

Do most cells form motile or non-motile primary cilium?

A

Non-motile

407
Q

How many primary cilium do many endothelial cells have?

A

One

408
Q

What do primary cilium detect?

A

Signals that govern cell proliferation

409
Q

Wha do primary cilium sense?

A

Flow and bending - triggering various regulation pathways

410
Q

What are primary cilia essential for?

A

Developmental processes

411
Q

Where can you find non-motile cilia in the human body?

A
  • Inner ear
  • Kidney
  • Bile duct
  • Pancreas
  • Bone
  • Eye
412
Q

What is the main function of motile cilia?

A

Generating flow, cleaning surfaces

413
Q

What is the main function of non-motile cilia?

A

Sensing environmental cues

414
Q

How do motile and non-motile primary cilia differ?

A
  • Motility

- Number of microtubules pair

415
Q

What sensing functions fo non motile cilia have?

A
  • Chemosensation
  • Mechanosensation
  • Thermosensation
416
Q

What does a stimulus result in?

A

Membrane depolarisation

417
Q

What are found in eye retina?

A

Rods and cones

418
Q

What are found in cilium in relation to the eye?

A

Rhodopsin discs

419
Q

What are photo-receptor in the eye?

A

Specialised cilium

420
Q

Do cones see in black and white or colour ?

A

Colour

421
Q

How many cones do you have per retina?

A

4.5-6.5 million

422
Q

How many rods do you have per retina?

A

110-130 million

423
Q

Do rods seas in black and white or colour?

A

Black and white

424
Q

Are actin dynamics involved in cell migration?

A

Yes

425
Q

Where do you find a high concentration of actin?

A

At the tip of the cell

426
Q

What are the stress fibres in a fibroblast like?

A

Contractile bundle

427
Q

What are the cell cortex in a fibroblast like?

A

Gel-like network

428
Q

What are filopdoium in a fibroblast like?

A

Tight parallel bundle

429
Q

Where does treadmilling of actin occur?

A

At cell periphery

430
Q

How do actin and actin-binding proteins move a cell?

A
  1. Extension - Lamellipodium at leading edge moves forwards
  2. Adhesion - new adhesion sites must established to move forwards
  3. Translocation - causes contraction, end tail detaches (myosin interacts with actin moving against each other)
  4. De-adhesion - adhesion site at rear gets dissolved
431
Q

What helps healing wounds?

A

cell motility

432
Q

What phase is mitosis of the cell cycle?

A

M Phase

433
Q

What are the two different stages in M phase?

A
  1. Mitosis (nuclei division)

2. Cytokinesis (cytoplasmic division)

434
Q

What are inherited during mitosis?

A

Chromosomes

435
Q

What are the different phases in mitosis?

A 
Interphase
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
436
Q

What occurs at prophase?

A
  • Chromosome condense
  • Nuclear envelope disrupts
  • Spindle is formed
437
Q

What occurs at metaphases?

A
  • Microtubules make contact with chromosomes

- Chromosomes are position in one plane

438
Q

What occurs at anaphase?

A
  • Microtubules and motors pull on chromosomes
  • Chromatids move to poles
  • Rapid elongation of spindle fibres
  • Formation of contractile ring
439
Q

What occurs at telophase?

A
  • Cell middle contact and separates (cytokinesis)
  • Chromosomes decondense
  • Nuclear envelope is formed
440
Q

What distinct step do M phase occur?

A
  • Chromosome alignment
  • Chromosome separation
  • Cell division
441
Q

Why does the cell cycle have checkpoints?

A

Quality control

442
Q

What are checkpoints?

A

Biological processes that recognise the status of the cell and control the transition from between cell cycle phases

443
Q

What form the mitotic spindle?

A

Microtubules

444
Q

What structures are involved in the organisation of the mitotic spindle?

A
  • Centrosomes
  • Kinetochor microtubules
  • Polar microtubules
  • Astral microtubules
445
Q

What is formed when polar microtubules overlap?

A

Midzone

446
Q

What interferes with the ability of microtubules?

A

Nocodazole

447
Q

Do microtubules support chromosome serration in mitosis?

A

Yes, provide the force for chromosome segreafation

448
Q

What is nocodazole?

A

A specific anti-microtubule drug

449
Q

What mechanisms help microtubules provide the force for chromosome segregation?

A

Mechanism 1: De/polymerisation of microtubules
Exert force on attached chromosome
Mechanism 2: Molecular motors that act on the microtubules

450
Q

What are the different motors in the spindle?

A
  • Dynein
  • Kinesin-14
  • Kinesin-5
  • Kinesin-4
  • Kinesin-10
451
Q

What does pulling on chromosomes exert?

A

Polar ejection force

452
Q

What forms at the area of constrictions during mitosis?

A

Contractile ring

453
Q

What is the contractile ring?

A
  • Forms near the cortex at the end of anaphase

- Contains myosin, actin, regulators and actin-binding proteins

454
Q

At what stage of mitosis does the contractile ring form?

A

End of anaphase

455
Q

What inhibits myosin II?

A

Blebbistatin

456
Q

What does the inhibition of myosin II stop?

A

Cytokinesis

457
Q

What does bebbistatin disturb?

A

Organisation of actomyosin ring

458
Q

How does myosin II and actin make the contractile ring?

A

During early anaphase:
-Actin formed in middle of cell
-Actin is polymerised with plus end joined to plasma membrane
During late anaphase:
-Actin filaments recruits myosin II for local constriction
-Cell constricts until two cells are split in half

459
Q

What are peroxisomes?

A
  • Single-membrane bound organelles that contains man enzymes (crystalline core)
  • Major sites of oxygen utilisation
  • Scattered in the cell
460
Q

Describe the model for peroxisome genesis:

A

-Site of formation at endoplasmic reticulum
-Precursor vesicle is formed acquiring cytoplasmic proteins and lipids by peroxisomal signal protein
-Fission splits structure into two
-

461
Q

What are peroxisomes associated with?

A

Lipid droplets

462
Q

How many different enzymes are contained in mammalian peroxisomes?

A

More than 50

463
Q

How many peroxins are there on mammalian peroxisomes?

A

Over 20

464
Q

What is detoxification in peroxisomes?

A

Generation of hydrogen peroxide which is degraded by catalase

465
Q

What do peroxisomes play an important role in?

A

Lipid metabolism

466
Q

What organelle plays a role in biosynthesis of cholesterol and break down of very ling chain fatty acids?

A

Peroxisomes

467
Q

What converts fats into sugars in plant seeds?

A

Glyoxysomes

468
Q

What are lipid droplets?

A
  • Fat storage
  • Vary in size and enclosed by a monolayer
  • Organelles surrounded with membrane and protein involved metabolism in lipid droplets
469
Q

What are nucleomorph?

A

DNA-containing relict of an engulfed eukaryote

470
Q

Does algae contain nucleomorph?

A

Yes

471
Q

Where are lipid droplets formed?

A

Endoplasmic reticulum

472
Q

How are lipid droplets formed?

A
  • Bilayer of smooth endoplasmic reticulum surrounds fatty acid
  • Membrane formed and surrounded with proteins
473
Q

What are fat-acid-binding protein?

A
  • Makes fatty acid water soluble

- Shield fatty acid by binding it in a hydrophobic pocket

474
Q

What makes up 5% of all protein in liver cells?

A

Fat-acid-binding protein

475
Q

What is a mitochondria?

A
  • Double-membrane with an inner membrane fold

- Produces ATP

476
Q

What is the inner membrane fold called in mitochondria?

A

Cristae

477
Q

What does mitochondria use to make ATP?

A

Sugars, fats, oxygen

478
Q

What are essential functions of mitochondria?

A
  • Producing ATP
  • Fatty acid metabolism
  • Control of programmed cell death/apoptosis
479
Q

Why is ATP synthesised in the mitochondria?

A

Electrochemical garden over the inner mitochondrial membrane

480
Q

How proposed the chemiosmotic hypothesis?

A

Peter D. Mitchell

481
Q

Where is ATP synthesised?

A

Inner mitochondrial membrane

482
Q

What does the breakdown of fatty acid and glucose result in?

A

NADH and FADH2

483
Q

What does ATP synthase convert?

A

Energy of proton gradient into chemical-bond energy

484
Q

Describe the steps in cellular respiration (OXIDATIVE PHOSPHORYLATION):

A
  • NADH reaches complex I/FADH2 reaches complex II
  • NADH –> NAD+ + H+ + e- / FADH2 –> FAD+ + 2H+ + e-
  • Electron transferred into complex I or complex II ends up in CoQ
  • Electron goes through complex II with the transfer of H+ to the inter membrane space then to CytoC
  • Electron transferred to complex IV whilst again H+ pumped into intermembrane space creating a gradient of proton over membrane is formed
  • 2H+ + O- –> H2O
  • Protons flow through complex V to mitochondria matrix and ATP is formed
485
Q

What is term for programmed cell death?

A

Apoptosis

486
Q

What do mitochondria produce in low amounts of highly reactive molecules?

A

Reactive oxygen species (ROS)

487
Q

How is ROS produced?

A

In mitochondria electrons not processed via complexes

  • Stay in mitochondria matrix
  • Electrons react with oxygen and produce ROS
488
Q

What is ROS involved in?

A

Cell signalling that controls a broad range of cellular processes

489
Q

What does a high quantity of ROS induce?

A

Apoptosis

490
Q

What is apoptosis?

A
  • In multi-cellular organisms

- Mechanism by which cells die in a controlled way (building blocks recycled)

491
Q

Why can apoptosis be advantages?

A

Separation of fingers and toes in a developing human embryo

492
Q

How many cells on average die each day due to apoptosis?

A

50 and 70 billion cells

493
Q

Describe the process of apoptosis:

A
  • Stress triggers “apoptotic signalling”
  • Apoptotic proteins cause damage to mitochondria which releases factors that activate atopic enzymes
  • Enzymes cause blebbing and nucleus condenses
  • Nucleus and DNA fragmentises
  • Phagocytosis of apoptotic bodies by phagocytes
494
Q

What is blebbing?

A

Myosin II process forming protrusions

BIO1339 - Cell (9 decks)

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