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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
Q

SER Functions

A

Lipid synthesis

Ca regulation

Detoxification

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26
Q

Ribosomes

A

Synthesize protiens

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27
Q

Polysomes

A

Multiple ribosomes on an mRNA can be free floating or attached to ER

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28
Q

Glycosylation

A

Covalent linkage of oligosachcharide chaine to certain amino acids

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29
Q

Cytosolic Proteins

A

Not made in ER.. made by special cytosolic ribosomes*

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30
Q

Glycosilation functions

A

Protein folding

Sorting and transport

Protection

Cell signaling

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31
Q

Types of glycosilation

A

O-linked

N-linked

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32
Q

N-linked glycosylation

A

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…

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33
Q

O-linked Glycosylation

A

Occurs in golgi

attached to serine of threonine

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34
Q

What are proteoglycans?

A

Heavily glycosylated proteins (O-linked)

GAG sugar chains usually negatively charged

This charge attracts water to make hydrated gels..

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35
Q

Proteasome

A

Ubiquinate and destroy misfolded proteins in CYTOPLASM

Dysfunction causes disease like Alzheimers, Parkinsons, Cystic Fibrosis, Gauchers..

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36
Q

Heat Shock Response

A

Response to an acuumulation of misfolded proteins in cytoplasm

Increases chaperones

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37
Q

Unfolded protein response

A

Response to an accumulation of misfolded proteins in ER

Increases ER chaperones

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38
Q

Ca distribution in cells

A

Cytoplasm - low Ca

ER - Active transport of Ca from cytoplasm into ER lumen

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39
Q

Detoxification of cells in SER

A

Carried out by cytochrome P450 enzymes

Render foreign compounds more hydrophilic so they are released into bloodstream and eliminated by the kidneys

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40
Q

What are the three sensors to ditect unfolded proteins?

A

IRE1

PERK

ATF6

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41
Q

What is membrane trafficking?

A

The supply of lipds and proteins to other membrane bound organells.. Supplied by ER

42
Q

Membrane Flow

A

It is the formation and transport of membrane-bound vesicles by the ER, golgi, lysosomes, and plasma membrane

43
Q

What cell pathway is defective in familial hypercholesterolemia

A

The endocytic pathway

44
Q

Golgi

A

Post office of cell.

Recieves lipids or proteins from ER

Returns escaped proteins to ER

Modifies glycoproteins

45
Q

What are two faces of golgi?

A

Trans face - Where material leaves the golgi

Cis face - recieves product from ER in memrane bound vesicles

46
Q

What are primary routes of travel from the golgi?

A

Lysosomes

Secretory vesicles

Plasma membrane

47
Q

Vesicular transport

A

Movement of material betweein ER, Golgi, lysosomes, and plasma membrane

48
Q

ER - Golgi trasport involves what?

A

Both tubules and vesicles

49
Q

What is budding and fusion?

A

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
Q

Coat proteins

A

Specific coat proteins are needed to facilitate vasicle formation between ER and Golgi

51
Q

COP I and COP II

A

Coat proteins

COP I -> Golgi to ER and Intra to Golgi

COP II -> ER to Golgi

52
Q

How are coat protein coated vesicles formed?

A

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
Q

Sar 1 and Arf

A

Membrane bound protein for formation of coat proteins

Arf - for formation of COP I

Sar 1 - for formation of COP II

54
Q

GED

A

Guanine nucleotide exchange factor

Catalyzes membrand proteins Sar1 and Arf in coat protein vesicle formation

55
Q

Sec 13/31

A

Forms cage like strucure around vesicle in coat protein vesicle formation (COP I&II)

56
Q

Sanflippo Syndrome organell defect

A

Defect in lysosomes

57
Q

KDEL

A

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
Q

What proteins/lipds are involved to grab fusion vesicles and insure correct delivery?

A

Rabs

Rab effectors

SNAREs

Lipid content of membrane

59
Q

Rabs and Rab effectors

A

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
Q

SNARE

A

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
Q

Phosphatydleinositol in fusion of vesicles

A

Plays important role in identifying corrct membranes for fusion vesicles to fuse into

62
Q

What are the paths of golgi proteins?

A

Can remain in golgi

Returned to ER

Take path out of golgi to cytoplasm

63
Q

What are three paths out of golgi to cytoplasm?

A

Sortred to lysosomes (requires specific signal)

Sorted to secretory granules (Specific signal)

Packaged into vesicles for direct exocytosis (defult if no signal)

64
Q

Lysosome

A

Compartments filled with hydrolytic enzymes that carry out digestion of cellular materials

65
Q

What enzymes to lysosomes contain?

A

Proteases

nucleases

glycosoidases

lipases

phosphatases

sulfatases

66
Q

What is the safety mechanism in lysosomes?

A

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
Q

What are the three paths into the lysosomes?

A

Autophagy

Phagocytosis

Endocytosis

68
Q

Phagocytosis

A

Engulfment of large particles by cell, then moved to lysosome

69
Q

What are two classes of phagocytes

A

Macrophages and neutrophils

70
Q

Endocytosis

A

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
Q

Clathrin

A

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
Q

Mast Cell

A

Big cell used in exocytosis.. common signal for realease is Ca spike

73
Q

Mitochondria

A

Powerhouse of cell

ATP production

74
Q

Where do mitochondria localize?

A

Along microtubules

Near sites that require lots of ATP

(near myofibers in muscles)

(wrapped around sperm tail)

75
Q

Mannos 6 Phosphate

A

Is a tag on acid hydrolysis containing vesicles going from trans face golgi to endosomes

76
Q

Pinocytosis

A

Cell ‘drinking’

77
Q

Transcytosis

A

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
Q

How are nuclear-encoded cytosolic mitochondrial proteins recognized and imported into mitochondria?

A

Requires signal sequence on polypeptide

AND

Receptor on outside of mitochondria (TOM)

then TIM (2) inside mitochondrial membrane transport into mitochondria

79
Q

TOM and TIM and OXA

A

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
Q

Cardiolipin

A

Phospholipid found in abundent quantities on inner mitochondral membrane

81
Q

Perioxisome

A

Spherical structures bound by single membrane to produce and remove hydrogen perioxide

82
Q

Nucleus

A

Reposatory of genetic information (non mitochondral)

Site of DNA synthesis and gene expression (transcription) occur

83
Q

Nucleolus

A

Site of transcription in nucleus

Made of nuclear organizing regions of chromosomes

Site of ribosome production

84
Q

Lamins

A

Filamentous scaffolding structure to provide sites of attatchment for chromosomes

85
Q

MARs/SARs

A

Areas of SOME chromosomes that bind to muclear matrix

Areas of TOPO I and II (topoisomerase) activity - to reduce torsional stress*

86
Q

Large looped domain of chromosomes

A

Area between MARS on chromosome used for transcription

Prouces Ribosomes

87
Q

Nuclear envelope

A

Nucleus is bounded by nuclear envelope

Contains:

Outermembrane

Innermembrane

Nuclear pores

Nuclear lamina

88
Q

Nuclear pores

A

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
Q

Nuclear Localization Signal (NLS)

A

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
Q

What is Ran

A

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
Q

Microfilaments

A

Muscle of cell

Suport/organize plasma membrane

Cell Shape

Cell division

Cell motility

Actin filaments*

Microvillus*

92
Q

Microtubules

A

Railroad tracks

Organize cytoplasm

Intracellular transport

Cell Division

Cilia/glagellae motility (sperm)

Centrosome (microtubules anchored in it)

93
Q

Intermediate filaments

A

Strenghthen Cytoplasm/tissues

Support nucleus

Epidermal appendages (nails, hair)

Cell to Cell junctions

94
Q

Actin

A

Double helix of dimers of globular proteins

Actin + ATP leads to addition of + end

Actin + ADP.. will fall off..

95
Q

Tubulin

A

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
Q

Intermediate filament proteins

A

Vary in size

Over 50 gene products in 4 subfamilies

Polymerization appears to be regulated by phosphorylation

Make a coiled coil

NO polarity

97
Q

Polymerization/Depolymerization of tubulin and actin..

A

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
Q

What causes polymerization of actin?

A

Nucleotide hydrolysis

99
Q

What is the Rho family of actin

A

Rho - stress fibers (parallel bundles with myocin)

Rac - lamellipodia (meshworks stabilized with filamin)

Cdc42 - Filopodia (parallel bundles stabilized with cross linking)

100
Q

What are the actin associated motor proteins?

A

Myocin Type I and Type II

Type II polimerize for muscles…

101
Q

What helps cell movement?

A

The polymerization of actin proteins

102
Q
A

Foundations of Medicine (42 decks)

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