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Cell Lecture > Exam 3 - Ch 12 through Ch 15 > Flashcards

Exam 3 - Ch 12 through Ch 15 Flashcards

(85 cards)

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1
Q

components of the endomembrane system

A

ER
Golgi apparatus
Endosomes
Lysosomes

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2
Q

endoplasmic reticulum

A

continuous network of flattened sacs and cisternae filled with lumen

roughER + smoothER

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3
Q

what are cisternae

A

tubules of the ER

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4
Q

function of the rough ER

A

site of protein synthesis

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5
Q

functions of the smooth ER

A

drug detox, carb metabolism, calcium storage, steroid synthesis

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6
Q

function of the golgi apparatus

A

processing and sorting of proteins

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7
Q

function of endosomes

A

carry material brought into cell

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8
Q

function of lysosomes

A

digestion of material

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9
Q

where are ribosomes held on the rER

A

on the cytosolic side by receptor proteins

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10
Q

signal peptide sequence

A

determines the fate of protein transportation

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11
Q

what events happen for a protein that enters the lumen of the rER

A
  1. signal recognition particle (SRP) recognizes and binds to signal peptide sequence and the SRP receptor on the ER membrane
  2. Pore opens with energy from GTP
  3. Signal peptide sequence is cleaved by signal peptidase
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12
Q

what are the different forms that integral membrane proteins can have (3)

A
  1. bulk outside due to stop-transfer sequences
  2. bulk inside due to start-transfer sequences
  3. even due to alternating stop and start transfer sequences
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13
Q

what are the different pathways of post-translational import

A
  1. into ER lumen
  2. into mitochondria/chloroplast membranes
  3. into mitochondria/chloroplast matrix/stroma
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14
Q

what do chaperone proteins do

A

associated with protein synthesis in the cytosol to keep it unfolded and then pulling the polypeptide into the ER lumen and folding them

also do so for the chloroplasts/mitochondria

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15
Q

where are most of the proteins used in the mitochondria/chloroplasts coded

A

nuclear genes

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16
Q

when are polypeptides known to be sent to mitochondria and chloroplasts

A

when they are synthesized on free ribosomes and have a transit sequence

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17
Q

what does transit peptidase do

A

cleave the transit sequence once its threaded through the pore of the mitochondria/chloroplast

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18
Q

how do chaperone proteins fold the polypeptides once in the lumen/matrix/stroma

A

by binding to the hydrophobic regions of the polypeptide and folding them internally

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19
Q

what is ER-associated degradation

A

when improperly folded or modified proteins are exported from the ER and degraded in the cytosol by proteasomes

the proteasomes look for the ubiquitin tag to know what to degrade

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20
Q

ER stress

A

When too many unfolded/mid folded proteins accumulate

There are diseases associated with this

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21
Q

What is a cell’s response to ER stress

A

Destroying the proteins

Trying to refold the proteins

Commit apoptosis

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22
Q

Where is smooth ER that focuses on drug detox and carbohydrate metabolism

A

In hepatocytes

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23
Q

Where is smooth ER that focuses on calcium storage

A

Muscle cells

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24
Q

How does the smooth ER detox drugs

A

Enzymes perform hydroxylation

This makes the molecule more soluble

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25
How does the smooth ER breakdown glycogen stores
1. Glycosidic bonds broken 2. Glucose phosphorylation 3. Phosphate removed by glucose-6-phosphatase 4. Glucose leaves via GLUT2
26
How does the ER play a role in biosynthesis of membranes
Phospholipids from the ER are moved by phospholipid exchange proteins to other membrane organelles and the plasma membrane
27
What is the Golgi apparatus composed of
Cisternae are stacked disk-shaped sacs of flattened membrane
28
What are the two sides of the golgi
1. Cis-golgi network: toward the ER side receives vesicles from the ER 2. Trans-golgi network: away from ER side and where vesicles leave
29
movement through the golgi (two ways)
1. stationary cisternae model: vesicles move between each cisternae as they remain stationary 2. cisternal maturation model: cisternae move themselves from CGN toward TGN
30
Glycosylation
starts in the ER and finished in Golgi 1. N-linked glycosylation: add oligosaccharide to the nitrogen on the terminal amino group of asparagine residues 2. O-linked glycosylation: add oligosaccharide to the oxygen on the hydroxyl group of serine or threonine residues
31
KDEL sequence
protein tag that keeps soluble proteins in the ER
32
what does mannose-6-phosphate do in protein trafficking
send proteins to lysosomes
33
Secretory pathways (3)
1. Constitutive 2. Regulated 3. Polarized
34
constitutive secretion definition and example
when secretory vesicles move directly from TGN to plasma membrane; continuous and unregulated mucous secretion in intestines
35
regulated secretion
when secretory vesicles accumulate in cell before fusing w/plasma membrane; need extracellular signal to fuse and release contents insulin
36
polarized secretion
secretory vesicles release proteins only on one side of the cell nerve cells and their neurotransmitters
37
signaling in exocytosis
1. specific extracellular signal binds to cell surface receptor 2. second messenger released (usually Ca2+) 3. [second messenger] signals regulated secretion
38
receptor-mediated endocytosis
ligand/receptor interaction
39
phagocytosis
ingestion of large particles, microorganisms, or cells
40
pinocytosis
internalization of external fluid maintains SA/volume ratio
41
what are coated vesicles
vesicles with protein coats on the cytosolic side helps to determine location
42
examples of coated vesicles
clathrin-coated: from TGN to endosomes COPI-coated: from golgi back to ER COPII-coated: from ER to golgi caveolin-coated: unknown, may be involved w/cholesterol uptake
43
what are lysosomes
activated endosomes than contain digestive enzymes capable of degrading all macromolecules
44
how do lysosomes form
enzymes are fused into endosomes until they can no longer fuse, and the pH drops, then activating lysosome
45
lysosome function
to degrade foreign material brought into cell by phagocytosis and receptor-mediated endocytosis; soluble materials are released into cytosol; insoluble materials remain in lysosome = residual bodies (CELLULAR AGING) breakdown of damaged/unneeded cellular parts extracellular digestion (release of enzymes to the outside of the cell)
46
macrophagy
when an entire organelle is broken down by lysosome
47
microphagy
when cytoplasmic molecules are broken down by lysosome
48
lysosomal storage disease
when lysosomes lack a functional enzyme to breakdown a particular substance, so that substance accumulates diagnosed prenatally
49
vacuole location
in plant cells
50
provacuole is analogous to _____ vacuole formation is analogous to ______
endosome lysosome formation
51
vacuole functions
store hydrolytic enzymes maintain turgor pressure regulate cytosolic pH protein storage malate storage (CAM plants) anthocyanin storage (flower color) toxin storage
52
peroxisomes
contain catalase that degrade hydrogen peroxide and release water not derived from ER
53
what is the cytoskeleton
a network of interconnected filaments and tubules that extends throughout the cytosol increases internal organization and maintains cell shapes
54
functions of the cytoskeleton
``` cell movement cell division organelle and mRNA movement cell signaling cell to cell adhesion ```
55
what are the elements of the cytoskeleton and their relative size
microtubules, intermediate filaments, and microfilaments from biggest to smallest
56
what are the subunits for microtubules
alpha and beta tubulin heterodimers
57
what are the subunits for intermediate filaments
occur as single filaments or any bundles
58
what are the subunits for microfilaments
actin monomers
59
function of microtubules
moving components within cells or moving fluid outside of cells
60
types of microtubules
cytoplasmic (inside cell) | axonemal (outside cell)
61
examples of cytoplasmic microtubules
nerve cell axons spindle fibers "interstate system"
62
examples of axonemal microtubules
cilia flagella basal bodies
63
what is microtubule structure
long, hollow cylinders w/outer wall of 13 protofilaments doublets (2 microtubules) are found in cilia and flagella triplets (3 microtubules) are found in basal bodies and centrioles
64
how are microtubules formed
nucleation + elongation alpha and beta tubulin dimers are formed and then joined together to form alternating rings all dimers face same direction, giving polarity dimers add to positive end more often
65
where do microtubules originate
at the microtubule-organizing center (MTOC)
66
microtubules-associated proteins (MAPs)
bind along microtubules so it may interact with other cellular structures ex: Tau protein in axons
67
+ - TIP proteins
stabilize the + end of the microtubule to decrease the likelihood of disassembly
68
catastrophins
promote microtubule disassembly
69
functions of microfilaments
muscle contraction cell migration maintain cell shape produce cleavage furrow during cell division
70
microfilament structure
globular (single actins) has ATP filamentous (helical strands of globular actin) has ADP
71
types of actin
muscle-specific (alpha actin) nonmuscle-specific (beta and gamma actins)
72
actin-binding proteins
1. thymosin beta-4: binds the free ATP of G-actin 2. formin promotes the addition of G-actin 3. gelsolin breaks up microfilaments 4. capz prevents + elongation 5. filamin splices crisscrossed filaments so they may connect 6. actinin stabilizes ordered arrays
73
what are microvilli
microfilaments that line intestinal cells to increase SA for digestion and absorption
74
function of intermediate filaments
to provide structure and allow for tension in animal cells
75
examples of intermediate filaments
keratin in epithelial cells vimentin in connective tissue desmin in muscle cells
76
intermediate filaments are usually how many protofilaments
8
77
plectin proteins
help connect the 3 cytoskeleton elements
78
what are the three levels of movement
tissue level, cellular level, and intracellular level
79
what is tissue level movement
cells in muscle tissue contracting ex: bending limbs, beating heart, uterine contractions
80
what is cellular level movement
motility of one or a few cells ex: cilia, flagella, amoeboid movement, cancer invasion, actin dependent migration
81
what is intracellular level movement
components within the cell need to be shuttled ex: chromosome separation during anaphase, RNA movement, vesicles moving
82
how are microtubule interactions mediated
by kinesins and dyneins
83
how are microfilament interactions mediated
by myosins
84
what are kinesins and dyneins
microtubule-associated motor proteins that "walk" along the microtubule kinesins move toward + end dyneins move toward - end
85
how do kinesins move
leading globular head binds to ATP other globular head swings forward and binds

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