Chapter 15 - Intracellular Compartments And Transport Flashcards
1
Q
Invagination
A
Bending inward
2
Q
What members does invagination
A
ER, golgi, endosomes, lysosomes
3
Q
What are the two proposed mechanism of evolution of membrane enclosed organelles
A
Membrane invagination
Endosymbiosis
4
Q
Nuclear membranes and the ER are believed to have evolved from invagination from where
A
Plasma membrane
5
Q
Mitochondria and chloroplast have through
A
Endosymbiosis
6
Q
Mitochondria and chloroplast replicate by
A
Binary fission
7
Q
Virtually all proteins are synthesized by ________ in the _____, then transported to their final destination
A
Ribosomes, cytosol
8
Q
Sorting signal (signal sequence)
A
Directs the protein to the organelle in which it is required
9
Q
Proteins destined to the ER posses what
A
N terminal signal sequence that directs them to ER
10
Q
What happens if no signal sequence what happens to proteins
A
They remain in the cytosol
11
Q
What are three different mechanisms of protein import into the organelles
A
Transport through nuclear pores
Transport across membranes
Transport vesicles
12
Q
How does molecules move in and out of nucleus
A
Nuclear pores
13
Q
What moves out of the nuclear pores
A
MRNAs and ribosomal subunits move out
14
Q
What moves in nuclear protein, and what is needed for this to happen
A
Nuclear protein
A signal sequence
15
Q
What can you say about water and nuclear pores
A
Water moves freely
16
Q
What is needed to transport into the nucleus
A
Nuclear localization signal
Nuclear import receptor
17
Q
Nuclear localization signal
A
Directs proteins from the cytosol into the nucleus
18
Q
Nuclear import receptor
A
Directs the new protein through the nuclear pore
This is recycled and used for later use
19
Q
What drives nuclear transport
A
Energy supplied by GTP hydrolysis
20
Q
Ran GTP
A
GTP binding protein
21
Q
What is unique about proteins passing through nuclear pores
A
They don’t need to unfold to pass through
22
Q
Ran GTP
A
Is active
23
Q
Ran GDP
A
Is inactive
24
Q
Ran GAP
A
Triggers conversion of ran GTP to Ran GDP
25
Signal sequence of proteins targeted to the mitochondria and chloroplast binds to what
Receptor in the outer membrane
26
Complex of the receptor, protein, and protein translocator diffuses ________ in the outmembrane until it encounters _____ _____ in the _________
Laterally
Second protein translocator
Inner membrane
27
What happens when’s two protein translocator transport the protein across both membranes
The protein unfolds in the process
28
How does chaperons help with transporting proteins into the mitochondria and chloroplast
They are inside the organelle help pull the protein through and then refold it
29
Once a protein is transported in the mitochondria and chloroplast, what happens to the signal sequence
Cleaved off by signal peptidase
30
Proteins with multiple destinations first enter where
The ER
31
Examples with proteins with multiple destinations
ER proteins, Golgi proteins, endosomes proteins, lysosome proteins, and cell surface proteins
32
Once proteins enter the ER, they are ALWAYS what
Contained in the membrane enclosed organelle or compartment (endomembrane system)
33
What are the two types of proteins that enter the ER
Water soluble proteins
Transmembrane proteins
34
Water soluble proteins pass through what? And transport to where?
Pass completely through the ER membrane into the lumen, then transported into lumen of specific organelle or secreted to extracellular space
35
Transmembrane proteins transported though and transported where
Are PARTYLY transported through ER membrane and embedded to keep from transporting into lumen
36
Another name for cytosolic ribosomes
Free ribosomes
37
Cytosolic ribosomes
Ribosomes that are fee in the cytosol
38
Free ribosomes make what type of proteins and the proteins are destined where
Cytosolic proteins, proteins destined to the mitochondrial, nucleus, chloroplast and peroxisomes
39
ER bound ribosomes
Attached to the cytosolic side of the ER
40
Polyribosome
Many ribosomes bind to each mRNA
41
ER Signal sequence
On the polypeptide directs the ribosome translating the polypeptide to bind the cytosolic side of the ER
42
Polyribosomes are beneficial because
Allows a large number of polypeptides to be made from a single mRNA within a short period of time
43
What components help ribosome bind to the ER membrane
Signal recognition particle
SRP receptor
44
SRP or signal recognition protein
Binds to the ER signal sequence and ribosome
Slowing down polypeptide synthesis
45
SRP receptor
Binds to the SRP complex
Polypeptide passes through protein translocator into the ER lumen, speeding up polypeptide synthesis
46
Protein translocator opens up upon binding to what
Signal sequence
47
Where are water soluble proteins found? N and C termini
ER Lumen, The termini is found in the lumen too
48
Single pass transmembrane protein is kept in the ER by
Stop transfer sequence
49
When a protein pass through the translocator, who does it know when to stop?
Stop transfer sequence binds to the translocator
50
Where is the N and C termini during a single pass transmembrane
N terminus in the ER lumen and the C terminus in the cytosol
51
Multi-pass transmembrane proteins are kept in the ER by what
Combination of start and stop transfer sequences
52
What is true about multi pass transmembrane proteins stop sequence enters the translocator
Both the sequences are discharged and neither the start and stop sequence is cleaved off, leaving the entire polypeptide anchored in the membrane
53
Multi transmembrane protein that pass membrane 3x has what
2 start and 1 stop transfer sequence
54
Where is multi-pass transmembrane that has an even number of transfer sequences in the membrane, N and C termini found?
In they cytosol
55
Where is multi-pass transmembrane that has an odd number of transfer sequences in the membrane, N and C termini found
N terminus will be found in cytosol and C terminus in the ER lumen
56
Another name for exocytosis
Secretion
57
In exocytosis, the cell does what in size
Increase
58
With endocytosis, the cell does what in size
Decrease
59
When transport vesicles bud off from one location, what is distinct depending on their direction of transport
Protein coat
60
Why is the protein coat important
Helps shape the membrane into budding vesicles and to capture molecules for transport
61
Protein coat is released when
Budding is complete
62
Why is clathrin coated vesicles needed
Formation of vesicles
63
Clathrin coated vesicles: what is needed to form this vesicles
Cargo molecules binds to cargo receptors ( in the membrane)
Adaptin proteins bind to cargo receptors to clathrins
Dynamin is needed to pinch off from membrane
64
What causes dynamin protein to pinch off from membrane
Hydrolyzing GTP
65
Dynamin is an example of what type of protein
GTP Binding
66
When the clathrin coated vesicles are formed, what is released
Clathrins and adaptins
67
Clathrin coated vesicles bud off from what locations
Plasma membrane and Golgi apparatus
68
COP-coated protein (coat protein) transport molecules from what locations
From the ER to the golgi
Through the golgi
From the golgi to the ER
69
What is needed to dock the transport vesicle
Receptor proteins:
v-SNAREs
t-SNAREs
70
V-SNAREs
Receptor proteins on the vesicle
71
T-SNAREs
Receptor protein on the target membrane
72
What provides the initial recognition between vesicles and its target membrane
Rab and tethering proteins
73
For membrane fusion, what is needed
V-snares and T-snares to wrap around each other
74
Secretory proteins follow the pathway to be released from cell
Exocytic
75
What is the secretory pathway
ER —-> Golgi ——> plasma membrane
76
Where are proteins folded and modified
Rough ER
77
What bonds are form between cysteines
Disulfide bonds
78
What are attached to proteins that coverts them to glycoproteins
Short oligosaccharides
79
Glycosylation
Proteins beginning converted then to glycoproteins
80
Why are short oligosaccharides important for proteins
Protect protein from degradation, keep protein in ER for further folding, and guide protein into appropriate transport vesicle
81
Dolichol
Large oligosaccharides is linked to lipid and is transferred over to the amino group (NH2) on asaragine in the polypeptide
82
Only ________ folded proteins will be released from the ER transport
Correctly
83
What happens if misfolded proteins fail to refolded in their ER, what happens?
Transported back to the cytosol, where they are degraded
84
UPR (unfolded proteins response)
Triggered by accumulation of misfolded proteins in the ER
85
How do transport vesicles move from the ER to the golgi
Cis to trans face
86
Oligosaccharides that are added to proteins in the ER undergo further modification where
In the golgi
87
Constitutive secretion
Many soluble proteins continually secreted from all the cells by constitutive secretion which operates in all cells regardless of external signals
88
Regulated secretion
Operates only in cells that are specialized for secretion
89
What is different about regulated secretion vs constitutive secretion
Specialized secretory cells produce large quantity of products which are stored in secretory vesicles where proteins are concentrated and stored until extracellular signal stimulates their secretion
One needs a signal, one doesn’t
90
What are three types of endocytosis
Phagocytosis
Pinocytosis
Receptor mediated endocytosis
91
Does exocytosis requires energy
Yes
92
Does endocytosis require energy
Yes
93
Phagocytosis
Cellular eating
Ingestion of large particles; such as microorganisms and cell debris
94
Phagocytosis has large vesicles such as
Phagosomes
95
Phagocytosis is used by
Protist and our immune cells
96
Which cells in our bodies uses phagocytosis
Immune cells such as macrophages and neutrophils
97
How does phagocytosis gets rid of cell debris and microorgansims
They fuse with lysosomes
98
Pinocytosis
Cellular drinking and bend inward or invagination
Uptake fluids containing small molecules
99
Cells us what to “sample” their extracellular environment
Pinocytosis
100
How does pinocytosis gets rid of their waste
Form endocytic vesicles that fuses with endosomes, which fuse with lysosomes
101
All cells carry out what endocytosis
Pinocytosis
102
What endocytosis is indiscriminate
Pinocytosis
103
Receptor mediated endocytosis
Means to endocytosis specific molecules
104
Receptor mediated endocytosis what causes the formation of endocytic vesicle
Ligand binding to the receptor
105
Receptor mediated endocytosis uses what type of vesicle
Clathrin coated
106
Receptor mediated endocytosis is used for both
Pinocytosis and phagocytosis
107
LDL
Low density lipoproteins, bad cholestrol
More cholestrol than proteins
108
HDL
High density lipoprotein
More protein than cholestrol
109
Endosomes
Serve as holding dock for endocytosed molecules
110
Early endosomes has a pH of what
~6
111
Late endosomes has a pH of
~5.5
112
Endosomes has a low pH that is maintained by
ATP driven H pump
113
Why are endosomes have acidic environment
Breaks apart most receptor and ligand pairs
114
Endosomes can have 3 outcomes
Recycled to the same location
Transcytosis (receptors recycles to a different location)
Degradation - receptors transported to lysosomes
115
Lysosomes contains what that allows it to function at a low pH
Hydrolytic enzymes or acid hydrolases
116
Acid hydrolases
Hydrolytic enzymes
117
Lysosomes works best at what pH
Under 5
118
Lumen of the lysosome is maintained at low pH by what
H+ ATPase in the membrane
119
Lysomes receives materials from where
Phagosomes and endocytic vesicles via endosomes
But also auto phagosomes
120
Autophagosomes
Double membrane lipid forms because of autophagy
121
Autophagy
Involves degradation of unnecessary or dysfunctional cellular components through the actions of lysosomes
