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Foundations of Medicine > Week 2 - Cell Biology > Flashcards

Week 2 - Cell Biology Flashcards

1
Q

What are the 4 major phospholipids?

A

Phosphatidylethanolamine (ER)

Phosphatidylcholine (ER)

Phosphatidylserine (ER)

Sphingomyelin (golgi)

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2
Q

What does cholesterol do in plasma membrane?

A

Stiffens

Reduces permeability

Inhibits phase changes

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3
Q

What is a glycolipid?

A

A sugar attached to a fatty acid

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4
Q

What is the orientation of glycolipids?

A

Present only on non-cytostolic surface… so on outside of plasma membran or the lumen of organelles

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5
Q

Functions of glycolipids?

A

Protection (glycocalix)

Cell adhesion

Cell identification

Surface properties of membranes

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6
Q

What is NANA

A

A negatively charged glycolipid

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7
Q

What are phosphainositols?

A

Lipid with inositol sugar that can be phosphorylated at different positions.

Can activate and signal enzymes on cell surface

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8
Q

Flippase

A

Enzyme that can flip phospholipids from one side of membrane to the other

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9
Q

Scrambleases

A

Enzyme that can scrample phospholipids.. random.. promotes apoptosis

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10
Q

Where are phospholipds the most asymetrically distributed?

A

On plasma membrane.. most mixed up in ER and gets more asymetrical as they move from ER to Gogi to cytoplasm to cell membrane

Choline and sphigo

Serine (- charge) and ethanolamine (cytosol)

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11
Q

What is a lipid raft?

A

Specialzed patch of lipids and proteins..

Signals tranduction events and endocytosis

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12
Q

What are different types of membrane proteins?

A

Transmembrane - alpha helix and beta barrel

Cytosolic surface - GPI anchor lipid chain anchor

Peripheral membrane - binded to imbeded proteins

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13
Q

What is the glycocalix?

A

Protein covalently binded to multiple sugar groups

Protect, identify, adhesion

Non cytosolic surface of membrane

Found in intestinal cells.. harsh environments

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14
Q

What ways are proteins organized in membranes?

A

Integral proteins -

Self assembly into aggregates

Tethered to extra cellular molecules

Tethered to intracellular molecules

Bind to proteins on adjacent cells

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15
Q

Syntaxin

A

SNARE proteine used in synaptic vesicle plasma membrane fusion

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16
Q

Integrin

A

Integral membrane protein that binds to extracellular molecules such as collagen and fibronectin, or cytoskeleton

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17
Q

What to metastatic cancers to do survive?

A

interfeare with apoptoic pathway so they are not killed.. linnked to integrin

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18
Q

Glycophorin and Band 3

A

integral membrane proteins that interact with molecules made of actin and spectrin. Critical for RBC funciton and elasticiy of RBC membrane

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19
Q

Cadherin

A

Large integral membrane protein that self associate in presence of Ca - it links cells together!

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20
Q

Sec 61 translocator

A

bidirectionally gated pore that lets polypepdies in or out of membrane

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21
Q

Chaperone proteins

A

Proteins that make sure other proteins fold correctly in ER

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22
Q

ER signal sequence

A

sequence of amino acids signaling for protein to bind to ER

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23
Q

What are SRPs

A

On ER, recognize signal sequence on polypeptide.

Bind the mRNA - ribosome - SRP and transfer to Sec 61 to be brought into ER

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24
Q

RER functions

A

Protein Synthesis

Membrane (integral membrane proteins)

Luminal (ER lumin)

Protein for secretion by cell

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25
SER Functions
Lipid synthesis Ca regulation Detoxification
26
Ribosomes
Synthesize protiens
27
Polysomes
Multiple ribosomes on an mRNA can be free floating or attached to ER
28
Glycosylation
Covalent linkage of oligosachcharide chaine to certain amino acids
29
Cytosolic Proteins
Not made in ER.. made by special cytosolic ribosomes\*
30
Glycosilation functions
Protein folding Sorting and transport Protection Cell signaling
31
Types of glycosilation
O-linked N-linked
32
N-linked glycosylation
Attatched to asparagine Glycosylated in ER 14 sugar oligosaccharide attached on a membrane lipid called a dolichol, then transfered to growing polypeptide chain This is why glycosylation is always on LUMINAL side...
33
O-linked Glycosylation
Occurs in golgi attached to serine of threonine
34
What are proteoglycans?
Heavily glycosylated proteins (O-linked) GAG sugar chains usually negatively charged This charge attracts water to make hydrated gels..
35
Proteasome
Ubiquinate and destroy misfolded proteins in CYTOPLASM Dysfunction causes disease like Alzheimers, Parkinsons, Cystic Fibrosis, Gauchers..
36
Heat Shock Response
Response to an acuumulation of misfolded proteins in cytoplasm Increases chaperones
37
Unfolded protein response
Response to an accumulation of misfolded proteins in ER Increases ER chaperones
38
Ca distribution in cells
Cytoplasm - low Ca ER - Active transport of Ca from cytoplasm into ER lumen
39
Detoxification of cells in SER
Carried out by cytochrome P450 enzymes Render foreign compounds more hydrophilic so they are released into bloodstream and eliminated by the kidneys
40
What are the three sensors to ditect unfolded proteins?
IRE1 PERK ATF6
41
What is membrane trafficking?
The supply of lipds and proteins to other membrane bound organells.. Supplied by ER
42
Membrane Flow
It is the formation and transport of membrane-bound vesicles by the ER, golgi, lysosomes, and plasma membrane
43
What cell pathway is defective in familial hypercholesterolemia
The endocytic pathway
44
Golgi
Post office of cell. Recieves lipids or proteins from ER Returns escaped proteins to ER Modifies glycoproteins
45
What are two faces of golgi?
Trans face - Where material leaves the golgi Cis face - recieves product from ER in memrane bound vesicles
46
What are primary routes of travel from the golgi?
Lysosomes Secretory vesicles Plasma membrane
47
Vesicular transport
Movement of material betweein ER, Golgi, lysosomes, and plasma membrane
48
ER - Golgi trasport involves what?
Both tubules and vesicles
49
What is budding and fusion?
Budding is when a vesicles forms out of donor compartmetn membrane in vesicular transport Fusion is when that vesicle fuses into the target compartment
50
Coat proteins
Specific coat proteins are needed to facilitate vasicle formation between ER and Golgi
51
COP I and COP II
Coat proteins COP I -\> Golgi to ER and Intra to Golgi COP II -\> ER to Golgi
52
How are coat protein coated vesicles formed?
GEF catalyzes receptor Arf or Sar1 (phosphorilizes GDP to GTP on protein) which extends hydrophobic tail into bilayer Arf or Sar1 recruit proteins to concentrate cargo and curve membrane Sec13/31 is recruited to form cage like structure and pinch of formed vesicle with cargo inside
53
Sar 1 and Arf
Membrane bound protein for formation of coat proteins Arf - for formation of COP I Sar 1 - for formation of COP II
54
GED
Guanine nucleotide exchange factor Catalyzes membrand proteins Sar1 and Arf in coat protein vesicle formation
55
Sec 13/31
Forms cage like strucure around vesicle in coat protein vesicle formation (COP I&II)
56
Sanflippo Syndrome organell defect
Defect in lysosomes
57
KDEL
KDEL is a protien receptor on Golgi that detects proteins and lipds that should remain in ER but escape.. Escaped material is packaged and returned to ER by COP II
58
What proteins/lipds are involved to grab fusion vesicles and insure correct delivery?
Rabs Rab effectors SNAREs Lipid content of membrane
59
Rabs and Rab effectors
Proteins involved with delivery of fusion vesicles on receiving membrane Rabs - identify proper location (Rab GTP) Rab effector - Effector proteins are bound to Rab GTP to bind the vesicle to correct target site
60
SNARE
Involved with accurate fusion of vesicles to recieving membrane Binding of v-snare with its corresponding t snare (on fusion vesicle) bind and pull vesicle in close enough to facility fusion
61
Phosphatydleinositol in fusion of vesicles
Plays important role in identifying corrct membranes for fusion vesicles to fuse into
62
What are the paths of golgi proteins?
Can remain in golgi Returned to ER Take path out of golgi to cytoplasm
63
What are three paths out of golgi to cytoplasm?
Sortred to lysosomes (requires specific signal) Sorted to secretory granules (Specific signal) Packaged into vesicles for direct exocytosis (defult if no signal)
64
Lysosome
Compartments filled with hydrolytic enzymes that carry out digestion of cellular materials
65
What enzymes to lysosomes contain?
Proteases nucleases glycosoidases lipases phosphatases sulfatases
66
What is the safety mechanism in lysosomes?
All enzymes in lysosomes are acid hydrolases.. so they must have a low pH to function (4.5 - 5) So... if they escape into cell they will become inactive They contain a proton pump to produce acidic lumen and are highly glycosylated
67
What are the three paths into the lysosomes?
Autophagy Phagocytosis Endocytosis
68
Phagocytosis
Engulfment of large particles by cell, then moved to lysosome
69
What are two classes of phagocytes
Macrophages and neutrophils
70
Endocytosis
Formation of lysosomes from golgi and ensdosomes Coated vesicle is formed containing material to be digested. Coat is removed, the vesicle fuses to endosome (early) Transport vesicles are removed and returned to membrane through budding The early endosome receives hydrolitic enzymes from Golgi Eventually it turnes into late endosome where most digestion takes place then finally turnes into the classic lysosome
71
Clathrin
Coat protein for Golgi to Plasma membrane or visa versa Binds to adaptor proteins during formation of encocytotic vesicle, creates coat Clathrin then deforms membrane and invaginates material forming the vesicle Dynamin pinches vesicle off The clathrin coat then falls off and is recycled to make early endosome
72
Mast Cell
Big cell used in exocytosis.. common signal for realease is Ca spike
73
Mitochondria
Powerhouse of cell ATP production
74
Where do mitochondria localize?
Along microtubules Near sites that require lots of ATP (near myofibers in muscles) (wrapped around sperm tail)
75
Mannos 6 Phosphate
Is a tag on acid hydrolysis containing vesicles going from trans face golgi to endosomes
76
Pinocytosis
Cell 'drinking'
77
Transcytosis
Mediated of transport of material from one side of cell to the other Ex. transportation of antigens form one side of gut epithelial cells to the other...
78
How are nuclear-encoded cytosolic mitochondrial proteins recognized and imported into mitochondria?
Requires signal sequence on polypeptide AND Receptor on outside of mitochondria (TOM) then TIM (2) inside mitochondrial membrane transport into mitochondria
79
TOM and TIM and OXA
TOM trasporter on outer mitochondral membrane for INcoming proteins TIM (2 of them) transporter on inner mitochondral membrane for INcoming proteins OXA transports proteins OUT of mitochondria
80
Cardiolipin
Phospholipid found in abundent quantities on inner mitochondral membrane
81
Perioxisome
Spherical structures bound by single membrane to produce and remove hydrogen perioxide
82
Nucleus
Reposatory of genetic information (non mitochondral) Site of DNA synthesis and gene expression (transcription) occur
83
Nucleolus
Site of transcription in nucleus Made of nuclear organizing regions of chromosomes Site of ribosome production
84
Lamins
Filamentous scaffolding structure to provide sites of attatchment for chromosomes
85
MARs/SARs
Areas of SOME chromosomes that bind to muclear matrix Areas of TOPO I and II (topoisomerase) activity - to reduce torsional stress\*
86
Large looped domain of chromosomes
Area between MARS on chromosome used for transcription Prouces Ribosomes
87
Nuclear envelope
Nucleus is bounded by nuclear envelope Contains: Outermembrane Innermembrane Nuclear pores Nuclear lamina
88
Nuclear pores
Semi-permiable Permiable for particles up to 5kDa Proteins between 5kDa and 60kDa can be transported but is slower and requires specific receptor proteins
89
Nuclear Localization Signal (NLS)
Amino acid sequence in proteins that move nuclear bound proteins into the nucleaus (because, like all proteins are synthesized IN CYTOPLASM) Not the signal that matters but actual folding (lysine rich)
90
What is Ran
It is a small G-protein It binds to GDP in cytoplasm to transport proteins into nucleus, then dissociates in presence of GTP to release protein in nucleus Exact opposite to export proteins.. Ran binds to GTP in nucleus, transports protein out of nucleus, then dissociates in GDP Cytoplasm: GDP rich Nucleus: GTP rich
91
Microfilaments
Muscle of cell Suport/organize plasma membrane Cell Shape Cell division Cell motility Actin filaments\* Microvillus\*
92
Microtubules
Railroad tracks Organize cytoplasm Intracellular transport Cell Division Cilia/glagellae motility (sperm) Centrosome (microtubules anchored in it)
93
Intermediate filaments
Strenghthen Cytoplasm/tissues Support nucleus Epidermal appendages (nails, hair) Cell to Cell junctions
94
Actin
Double helix of dimers of globular proteins Actin + ATP leads to addition of + end Actin + ADP.. will fall off..
95
Tubulin
Medium sized globular proteins make tall stacks then form cylinder Tubulin + GTP adds to + end and grows GDP makes it fall off, GTP much more stable Makes microtubules
96
Intermediate filament proteins
Vary in size Over 50 gene products in 4 subfamilies Polymerization appears to be regulated by phosphorylation Make a coiled coil NO polarity
97
Polymerization/Depolymerization of tubulin and actin..
Tubulin and actin polymerize in presense of GTP/ATP and grow from + end GDP/ADP will depolymerize and make them dissasemble and shrink from + end..
98
What causes polymerization of actin?
Nucleotide hydrolysis
99
What is the Rho family of actin
Rho - stress fibers (parallel bundles with myocin) Rac - lamellipodia (meshworks stabilized with filamin) Cdc42 - Filopodia (parallel bundles stabilized with cross linking)
100
What are the actin associated motor proteins?
Myocin Type I and Type II Type II polimerize for muscles...
101
What helps cell movement?
The polymerization of actin proteins
102

Foundations of Medicine (42 decks)

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