Zaidi Flashcards
1
Q
what is gated transport
A
between nucleus and cytosol through nuclear pore complexes (active transport and free diffusion)
2
Q
what is transmembrane transport
A
membrane protein translators directly transport specific proteins from cytosol across an organelle membrane
3
Q
what is vesicular transport
A
membrane enclosed transport intermediates move proteins between various compartments via vesicles
4
Q
protein transfer/transport to various compartments guided by ______
A
sorting signals
5
Q
describe sorting signals
A
stretch of amino acids, typically 15-60 residues long with localization on N or C terminus within protein sequence
6
Q
multiple scattered sequences in protein may form ______
A
signal patch
7
Q
what removes signal after protein reaches final destination?
A
signal peptidase
8
Q
Signal sequences are both necessary and sufficient for what?
A
protein targeting
9
Q
What are signal sequences recognized by?
A
complementary receptors
10
Q
Describe nuclear transport
A
bidirectional, selective and gated
11
Q
what are sorting signals called for nuclear?
A
nuclear localization sequence
12
Q
nuclear localization sequences are rich in what amino acids?
A
lysine and arginine
13
Q
what are nuclear pore complexes?
A
perforate nuclear envelope in eukaryotic cells which transports molecules in both directions, passive diffusion of small molecules and facilitated transport
14
Q
transport of the nuclear pore complex is facilitated by the binding of particles to _____ extending from NPC
A
fibrils
15
Q
what are nuclear localization signals (NLS)
A
sorting signals that direct molecules to nucleus, rich in lysine and arginine
16
Q
look at nuclear import and export pictures
A
slide 9
17
Q
the mitochondrial signal sequence is made up of _______ and _____ signal sequences
A
n terminal and internal
18
Q
In the mitochondrial signal sequence specific receptor proteins recognize a configuration which is what?
A
positively charged residues cluster on one end and uncharged hydrophobic on the other end to form an amphiphilic alpha helix
19
Q
review the translators in mitochondrial membrane slide
A
slide 12
20
Q
Where is the tom complex located?
A
outer mitochondrial membrane
21
Q
where is the Sam complex located
A
outer mitochondrial membrane
22
Q
Where is the Tim22 and tim23 complexes located?
A
inner mitochondrial membrane
23
Q
Where is the Oxa membrane complex located?
A
inner mitochondrial membrane
24
Q
What does the TOM do?
A
import of all nuclear encoded proteins to insert them in the outer membrane
25
what does TIM 23 do?
transports soluble proteins into matrix and helps insert membrane proteins in inner membrane space
26
what does TIM 22 do?
mediates the insertion of a specific subclass of proteins
27
What are the two components of the tom and Tim complexes?
receptors for mitochondrial precursor proteins
| translocation channels
28
What does the sam complex do?
translocates and inserts/folds beta barrel proteins in the outer membrane
29
What does the oxa complex do?
mediates insertion of all proteins synthesized in mitochondria. Also some proteins already present in matrix brought from outside
30
ER signal sequence guided to ER membrane by 2 components:
- signal recognition particle (SRP)
| - SRP receptor
31
What is the SRP large hydrophobic pocket lined with?
methionine
32
review SRP role slide
slide 17
33
proteins and other biomolecules are transported via ______
transport vesicles
34
contents of vesicles are called
cargo
35
look at vesicular transport slides
slides 20-21
36
what do Rab proteins do?
direct vesicle to specific spots on target membrane
37
what do SNARE proteins do?
mediate fusion of vesicle with membrane
38
docking and fusion of vesicle slide
slide 23
39
what are the pathways in which materials are delivered to the lysosome
phagocytosis
endocytosis
autophagy
40
lysosomal hydrolyses have sorting signal _______ attached to them in the cis Golgi network
mannose-6-phosphate
41
the mannose 6 phosphate receptor in the trans golgi network recognize a sugar and then package them into _____
clathrin coated vesicles
42
where are clathrin coated contents delivered
endosomes then to lysosome
43
sorting of lysosomal protein slide
slide 28
44
describe sub cellular fractionation
tissue: mechanical blending
homogenate: suspension of different cell types
centrifugation to separate different cell types, based on size and density
lysis of cells: osmotic shock, ultrasonic vibration, mechanical blending, forcing through small orifice
ultracentrifugation: separates organelles
45
after low speed centrifugation, what is in the pellet?
whole cells
nuclei
cytoskeletons
46
after medium speed centrifugation, what is in the pellet?
mitochondria, lysosomes, peroxisomes
47
after high speed centrifugation, what is in the pellet?
microsomes, small vesicles
48
after very high speed centrifugation, what is in the pellet?
ribosomes, viruses, large macromolecules
49
describe ion exchange chromatography
positively charged bead attract negatively charged molecules, so positively charged molecules can travel freely
50
describe gel filtration chromatography
porous beads attract small molecules, and large molecules can get through
51
describe affinity chromatography
beads have covertly attached substate, so certain proteins bind while others can go through
52
where does HaeIII cut DNA
at G-C binding
53
Where does EcoRI cut DNA
at G-A binding
54
Where does HindIII cut DNA
at A-A binding
55
in agarose gel electrophoresis, DNA is already ____
charged
56
how is DNA 'glued' together?
ligase reaction (with help of ATP)
57
homologous proteins are functionally _______
interchangeable
58
what is a blastula? and what does it give rise to?
blastula consists of a sheet of epithelial cells facing the external medium, which gives rise to the ectoderm
59
what is the ectoderm?
precursors to nervous system and epidermis, gives rise to endoderm
60
what is the endoderm
precursor of gut, lung and liver
| gives rise to mesoderm
61
what is the mesoderm
precursor of muscles and connective tissue
62
where are the instructions for producing a multicellular animal?
non-coding regulatory DNA
63
Cells make developmental decisions long before they show signs of ______
differentiation
64
what are determined cells
Cells that are fated to develop into a specialized cell type despite changes in the environment
65
What are completely undetermined cells
cells that can change rapidly due to alterations in the environment
66
What are committed cells
cells that have some attributes of a particular cell type but can change with environment
67
most important environmental cues are from where?
signals from neighboring cells
68
describe a short range signal
cell-cell contacts
69
describe a long range signal
substances that can diffuse through the extracellular medium
70
What is a morphogen
long range inductive signal that imposes a pattern on a filed fo cells, forms gradients of different concentrations
71
What is the morphogen gradient formed by?
localized production of an inducer that diffuses away from its source
localized production of an inhibitor that diffuse away from its source and block the action of a uniformly distributed inducer
72
describe phase 1 of neural development
different cell types develop independently at widely separate locations in embryo according to local program and are unconnected
73
describe phase 2 of neural development
axons and dendrites grow out along specific routes setting up a provisional but orderly network of connections between various parts of the system
74
describe phase 3 of neural development
continues into adult life, connections are adjusted and refined through interactions with distant regions via electric signals
75
neurons are produced in association with ______ cells
glial
76
CNS is derived from what?
neural tube
77
PNS is derived from what?
neural crest
78
tip of axon/dendrite has irregular, spiky enlargement called the ______
growth cone
79
what is growth cone behavior dictated by?
its cytoskeletal machinery
80
monomeric GTPases ____ and ____ control the assembly and disable of actin filaments, which control _____ of growth cone
Rho and Rac, movement
81
growth cones travel toward target cells along predictable routes by exploiting two major cues to find their way. What are these?
extracellular matrix environment: sensed by receptors present on membrane
chemotactic factors: related by neighboring cells, attractive or repulsive
82
what are chemotactic factors?
guidance factors at strategic points along path and are attractive or repulsive
83
What are examples of chemotactic factors?
netrin
slit
semaphorin
84
look at mechanism of commissural neuron guidance
slide 64
85
once axonal growth cone reach eventual target cells what does it do?
halt, communicate and make synapses with target cells
| signal form target tissue regulate which growth cone synapses and where
86
synaptic remodeling is dependent upon 2 rules that create spatial order. What are these?
- axons from cells in different regions of retina compete for tectal neurons
- axons from neighboring sites which are excited at same time cooperate/collaborate to retain and strengthen synapses with tectal neurons
87
What does activity dependent synaptic remodeling depend on?
electrical activity and synaptic signaling
88
What are the characteristics of stem cells?
```
not terminally differentiated
can divide without limit
ability to renew themselves
when divide each new cell has ability to remain a stem cell or become differentiated into a different cell type
undergo slow division
```
89
totipotency
ability of a cell to give rise to all cells of an organism, including embryonic and extra embryonic tissues (zygote)
90
pluripotency
ability of cel to give rise to all cells of the embryo and subsequently adult tissues (embryonic stem cells)
91
multi potency
ability of a cell to give rise to different cell types of a given lineage (adult stem cells)
92
asymmetric division
creates 2 cells, one with stem cell characteristics and another with ability to differentiate
93
independent choice
division makes 2 identical cells but he outcome is stochastic and/or influenced by environment
94
describe epidermis
forms outer covering of skin
creates water barrier
made of epithelial cells
continuously repaired and renewed
95
describe dermis
second layer, rich in collagen, provides toughness
96
describe hypodermis
fatty subcutaneous layer
97
what is the only dividing cells in the epidermis
basal cell layer
98
look at epidermis layer picture
slide 77
99
renewal of epidermis slide
slide 78-79
100
describe the olfactory neuron
bipolar neurons with a dendrite facing extracellular environment and an axon that travels along the olfactory nerve. Hair like cilia protrude from dendrite.
101
describe the odorant receptors of the olfactory neurons
on the free surfaces of cilia, and are a type of G protein coupled receptors
102
describe the process of what happens when an olfactory receptors is activated
activates intracellular G protein (Golf)
activates adenylate cyclase which produces cyclic AMP
opening of ion channels in plasma membrane which results in influx of sodium and calcium
influx of positive ions cause neuron depolarization, generating action potential
103
individual olfactory neurons survive only for _____
a month
104
what do embryonic stem cells develop into?
different cell types with characteristics appropriate for that site
105
look at derivation of ES cell slide
slide 91
106
what is a different source of human embryonic stem cells?
somatic cell nuclear transfer (SCeNT)
107
strategies to induce ES cell like properties in adult somatic cells
induced pluripotent stem (iPS) cells
108
describe SCeNT
nucleus taken from somatic cell of patient and injected into oocyte of a donor, replaces oocyte nucleus. Blastocyst generated form hybrid oocyte and ES cells isolated
109
descrive iPS cells
somatic cells can be reprogramed to form iPSC by exposing them to defined, limited sets of transcription factors (genes for stem-ness)
