Organelles I Flashcards
1
Q
[ ] allows cells to spatially organize their activities via [ ].
A
Membranes, selective permeability
2
Q
Which molecules pass through the cell membrane easier?
A
- Hydrophobic molecules: O2, CO2, N2
- Small uncharged polar molecules: H2O, glycerol, urea, ethanol
3
Q
Which type of molecules do not pass through the cell membrane very easy?
A
- Large uncharged polar molecules: glucose, sucrose
- Ions: Na+, K+, Cl-,
4
Q
What is the key building block of cell membranes?
A
Phospholipids
5
Q
Define amphipathic
A
Both polar and nonpolar qualities
6
Q
What is the hydrophilic, polar part of a phospholipid?
A
The head is polar and hydrophilic due to a phosphate group. The head also contains a glycerol.
7
Q
What is the hydrophobic, nonpolar part of a phospholipid?
A
Fatty acid chains
8
Q
In the aqueous environment of the cell, phospholipids assemble into the [. ] composed of two [. ]
A
Lipid bilayer, leaflets
9
Q
Phospholipids exhibit mobility, what actions are spontaneous versus non-spontaneous?
A
Spontaneous: rotation, lateral diffusion, flexion, rotation
Non-spontaneous: flip between bilayer leaflets
10
Q
Three major groups of membrane proteins:
A
- Receptors
- Transporters
- Enzymes
11
Q
[ ] leaflet faces the cytoplasm.
A
Cytosolic
12
Q
[ ] leaflet faces either the lumen of an organelle (if it is part of an organelle membrane) or the extra cellular environment (if it is part of the plasma membrane).
A
Non cytosolic
13
Q
The [ ] of an organelle is topologically equivalent to the outside of the cell.
A
Lumen
14
Q
What parts of a cell form an extensive bi-directional membrane flow?
A
Endoplasmic reticulum, Golgi apparatus, and lysosomes with the plasma membrane. They are all membrane bound organelles.
15
Q
Topology of membranes is maintained through [ ].
A
Transport vesicles, maintain the membrane lipid and protein orientation
16
Q
4 major types of phospholipids
A
- Phosphatidylserine
- Phosphatidylcholine
- Phosphatidylethanolamine
- Sphingomyelin
17
Q
Is phosphatidylserine mainly found in the cytosolic or non cytosolic leaflet?
What are its main functions?
A
The cytosolic due to its negative charge. functions include apoptosis and blood clotting
18
Q
[ ] is enriched in lipid rafts, can be glycosylated to form glycolipids
A
Sphingomyelin
19
Q
Sphingomyelin is concentrated on the [ ] leaflet
A
Non cytosolic leaflet (extra cellular space, outside of the cell)
20
Q
Define ganglioside
A
The most complex glycolipid formed from a Sphingomyelin phospholipid. Prominently expressed in neurons. Overaccumulation results in highly toxic neurons resulting in a number of diseases
21
Q
Cholera gets in to the cell by interacting with [ ].
A
Ganglioside GM1
22
Q
______ interacts with the fatty acid tails of phospholipids and modulates the bilayer characteristics in multiple ways. These include changes in the following membrane properties: _____ , _____ , ______ , ______.
A
Cholesterol
fluidity, thickness, compressibility, permeability, curvature.
23
Q
_______ lipids are extremely important due to their functions in cell signaling pathways and imparting organelle membrane identities.
A
Phosphatidylinositol lipids
24
Q
______ of the 3, 4, and 5 position of the inositol sugar play a central role in its function.
A
Phosphorylation
25
_____ is a unique phospholipid whose fatty acid chains present almost exclusively in _____. It facilitates the chemiosmotic events associated with oxidative phosphorylation.
Cardiolipin
Mitochondria
26
The _______ synthesizes most phospholipids. They are then modified in the _____.
Endoplasmic reticulum
Golgi apparatus
27
The enzymes that produce phospholipids are located on the _____ surface of the ER membrane.
Cytoplasmic
28
Phospholipids start in the ____ leaflet of the ER membrane and then random transfer between leaflets occur using enzymes until equilibrium is reached.
Cytosolic
29
Asymmetry of phospholipids in the membrane (higher concentration of different types on the leaflets depending on function) is due to ____ _____.
Selective translocation
30
______ randomly flip phospholipids between the leaflets
Scramblases
31
____ and ____ selectively transfer the phospholipids between leaflets.
Flippases and floppases
32
Initial equilibrium between leaflets in the ER is symmetric and is produced via _____.
Scramblases
33
_____ flip lipids in both directions randomly.
Scramblases
34
Phosphatidylserine is ____ distributed among the leaflets in the ER.
By the time it reaches the plasma membrane, almost all the Phosphatidylserine is located on the ____ leaflet. Specific triggers flip the PS to the _____ leaflet. For example when coagulation or phagocytic functions are triggered.
Equally
Cytosolic
Noncytosolic
35
The enzymes that glycosylate membrane lipids and proteins in the ER are located in the ____ of the organelle. Therefore, the sugars of glycolipids and glycoproteins are present on the _____ of the membrane. Functions of glycolipids include acting as receptors and assisting in cell to cell recognition.
Lumen
Surface
36
Glycolipids are synthesized _____ , meaning they are only present on the noncytosolic leaflet of the ER. They are then randomly distributed by scramblases
Asymmetrically
37
Different organelles have different concentrations of ____ and ____.
Lipids and proteins
38
_____ create a thicker bilayer that can trap specific proteins with longer transmembrane domains, known as a ____.
Sphingolipids
Lipid rafts
39
Another type of special membrane domain is a _____ , creating a curved membrane that plays roles in signal transduction, regulation of metabolism, cancer, and a site of endocytotic vesicle formation.
Caveolae
40
______ membrane proteins are anchored in the lipid bilayer either by having part of their polypeptide chain embedded or traverse one or both membrane leaflets or being covalently bound to a lipid that is embedded in the lipid bilayer.
Integral
41
_____ membrane proteins associate with integral membrane proteins or membrane lipids and are easier to displace.
Peripheral
42
Using the picture, which proteins are integral and peripheral?
Proteins 1 through 6 are integral (trans membrane)
proteins, seven and eight are peripheral
43
Membrane proteins are synthesized in the _____ and modified in the ____ , similar to lipids.
ER
Golgi
44
A remarkably large portion of membrane proteins are _____, which occurs in the ER and chains are modified in the Golgi.
Glycosylated
45
Functions of glycoproteins include:
Modulation of membrane surface properties, cell adhesion, and cell identification
46
This photo represents
Glycosylation of a membrane protein
47
Like glycolipids, the sugars covalently attached to membrane proteins, are also restricted to the _____ leaflet.
Non-Cytosolic
48
Define glycocalyx
Extensive oligosaccharide additions on the plasma membrane that provide protection. these structures can be found in the intestinal epithelial cells.
49
Practice question
B
50
Practice question
B
51
Practice question
E , leaflet asymmetry increases during flow from the ER to the Golgi to the plasma membrane
52
The nucleus is surrounded by a double membrane system called the ____, which disassembles during mitosis. Regulated RNAs and proteins in and out of the nucleus occurs at _____.
Nuclear envelope
Nuclear pores
53
In many cells, sites of ribosomal RNA transcription and ribosome assembly are called _____, they can be observed through differential staining properties.
Nucleoli
54
The nucleus is physically supported by the ______, a fibrous structure, hypothesized to help organize nuclear functions and by the _____, a meshwork of filaments that underlays the nuclear envelope.
Nuclear matrix
Nuclear lamina
55
More compact, less transcriptionally active regions of the nucleus are referred to as _____. Less compact more active regions are called _____.
Heterochromatin
Euchromatin
56
Each nuclear pore is composed of about 30 different pore proteins called _____. Pores are semi permeable for molecules up to about 60,000 daltons where it becomes nonpermeable and must be actively transported.
Nucleoporins
57
_____ are the major sites of energy production in the cell converting pyruvate and NADH into ATP via aerobic respiration.
Mitochondria
58
The electron transport chain in mitochondria is located on the _____ membrane. The inner membrane is folded, forming tubules called _____.
Inner
Cristae
59
In the mitochondria, where can mitochondrial DNA, ribosomes, and enzymes that facilitate beta oxidation acid cycle be found?
The inner matrix space
60
In a resting state mitochondria can be _____. In a high respiratory activity state, mitochondria form a _____. This occurs via fission and fusion.
Fragmented
Hyperfused network
61
Mitochondria generally localize where ATP is needed. Examples of this include:
1. _____
2. _____
Between muscle fibers
Wrapped around sperm flagella
62
Mitochondria contain a single circular chromosome with ____ genes. Signaling between the nucleus and the mitochondria is called ____ and from the mitochondria to the nucleus is called_____, to ensure proper gene expression. Mitochondrial inheritance is _____.
40
Anterograde
Retrograde
Maternal
63
Mutations that disrupt synthesis of the mitochondrial lipid cardiolipin lead to _____ and ____ disorders.
Cardiomyopathies
Neurodegenerative
64
The _____ endoplasmic reticulum contains ribosomes. The ER synthesizes ____ and ____.
Rough
Lipids
Proteins
65
Cells that are specialized for protein secretion tend to have a well developed _______ because they make a lot of proteins and transport then outside of the cell.
Rough ER
66
The smooth ER functions in ____, ____, ____.
Lipid synthesis, detoxification, and Ca++ signaling.
67
In the absence of an ER targeting signal, ribosomes remain _____ and release the newly formed proteins into the _____.
Free
Cytoplasm
68
In the presence of an ER targeting signal sequence, ribosomes bind to the ____ and the newly formed protein will be inserted into the ____.
ER
ER
69
The ER targeting information is contained within the ______ not the ____.
Protein
Ribosome
70
Most proteins synthesized by the ER are glycosylated by the addition of a common _______ oligosaccharide.
N-linked
71
Describe what is occurring in this picture
A sugar is preassembled on a lipid called dolichol and is then transferred to the polypeptide by oligosaccharyl transferases. The transferase active sites are located in the ER lumen, thus the sugar groups are always located on the non cytosolic side of membranes
72
Protein folding in the ER is carefully monitored and regulated via _____ proteins. Misfolded proteins are dangerous and can cause diseases.
Chaperone
73
What is the ER-Associated protein Degradation (ERAD) pathway?
Proteins that cannot be correctly folded are translocated into the cytoplasm, and then de-glycosylated, ubiquitinated, and targeted by proteasomes for destruction
74
ATF6, IRE1, and PERK are 3 different pathways that monitor protein _____ problems in the ____.
Folding
ER
75
When BiP (chaperone protein) is bound to ATF6, the degradation pathway is ______. Misfolded proteins pull BiP away and _____ the degradation pathway.
Inactive
Activates
76
If protein misfolding isn’t corrected the ____ ____ ____ activates the signaling pathways that prime cells for ____.
Unfolded Protein Response (UPR)
Apoptosis
77
The _____ ER is associated with steroid synthesis and metabolism.
Smooth
78
Calcium is an important signaling molecule and is stored in the ____. The calcium concentration in the cytoplasm stays very low due to ____ in the ER lumen.
ER
Ca2+ pumps
79
Define malignant hyperthermia
Mutations of calcium pumps lead to energy expenditure due to pumping calcium out of the cytoplasm which raises body temperature to potentially fatal levels
80
Most detoxification occurs in the ____ ER, carried out by ____ family of enzymes. Important in liver cells.
Smooth
cytochrome p450
81
The ___ face of the Golgi apparatus receives vesicles from the ER. The ____ face of the Golgi packages products after modification. Most common modification is _____.
Cis
Trans
Glycosylation
82
N linked Glycosylation occurs in the ____. The ____ modifies N linked glycoproteins received from the ER.
ER
Golgi
83
As proteins move from the sis, medial, trans cisternae of the Golgi they encounter a highly ordered set of processing enzymes that catalyze specific reactions, adding and removing specific ____ groups to Nlinked and Olinked oligosaccharides.
Sugar
84
Genetic defects in Golgi enzymes results in _________, a group of over 100 monogenic human diseases with deficits in the synthesis of oligosaccharides
Congenital Disorders of Glycosylation (CDG)
85
The ______ is a cellular sorting station.
Golgi
86
If a protein is sent to a _____, the protein will be digested. Degradative enzymes that requires a pH of 5 is called ____ _____, enzymes will not function in the cytoplasm. ______ maintains the acidity of a lysosome by pumping H+ into the lysosome.
Lysosome
Acid hydrolases
Vacuolar H+ ATPas (vATPase)
87
In long-lived cells, lysosomes can accumulate non degradable material giving rise to a yellowish pigment called _____.
Lipofuscin
88
______ refers to the uptake of extracellular material via invagination of the plasma membrane.
Endocytosis
89
______ refers to the nonselective uptake of soluble molecules and fluid
Pinocytosis
90
______ involves the engulfment of large particles, dead cells and debris
Phagocytosis
91
______ _____ ______ allows selective uptake of specific molecules
Receptor mediated endocytosis
92
Lysosomes can also digest a cells own macromolecules and organelles through the process of ____.
Autophagy
93
The best understood form of autophagy involves formation of a double membrane vesicle called a _____, which engulfs, cytoplasmic material, and then fuses with the lysosome.
Autophagosome
94
_____ _____ _____ are caused by genetic defects that affect one or more lysosomal hydrolases. Most often affect the nervous system. In ____ ____ ____ the enzyme missing in an LSD is injected or infused, and makes its way to the lysosome via endocytosis.
Lysosomal storage diseases (LSD’s)
Enzyme replacement therapy
95
All pathways to the lysosome pass first through the ____, and organelle that sorts cargo to different destinations in the cell. This includes endocytic and phagocytic vesicles.
Endosome
96
As the endosome matures, the pH _____, and the endosome forms ______ that are delivered to the lysosome.
Decreases
Multivesicular bodies
97
______ is an organelle that is involved in detoxification reactions, including the production and removal of hydrogen peroxide. It also breaks down long fatty acid chains.
Peroxisomes
98
The _____ is the term for the main non-organelle compartment of the cell. It contains soluble ions and enzymes.
Cytosol
99
The ____ is responsible for translation of mRNA into a protein
Ribosome
100
______ a sight of protein degradation specific for proteins that are tagged with poly-ubiquitin chains. Found in the cytosol.
Proteasomes
101
Major classes of cytoskeleton proteins include ____ , ____, _____ and are found in the ____.
Actin, microtubules and intermediate filaments
cytosol
102
Practice question
A, exchange lipids and proteins
103
Practice question
C
104
Practice question
E, ribosomes are assembled in the nuclei
105
Practice question
See picture
