Psu Bmb 252 Test 2

Front 1

ARP

Back 1

Actin Related Protein
A nucleation/capping protein of actin at the (-) end. Binds to actin filaments at 70° --> branching. Often at the leading edge of migrating cells. Form in the dendritic nework.

Front 2

Formins

Back 2

A nucleation protein of actin at the (-) end. Responsible for bundles. Often connected to the plasma membrane.

Front 3

Alpha-actin

Back 3

Goes between actin filaments to form a contractile bundle which is loose and allows myosin II to enter. Form in stress fibers.

Front 4

Fimbrin

Back 4

Goes between actin filaments to form parallel bundles which are tight and do not allow myosin II to enter.

Front 5

Profilin

Back 5

Binds to actin monomers making them available for filament addition.

Front 6

Thymosin

Back 6

Binds to actin monomers making them unavailable for filament addition.

Front 7

Filamin

Back 7

Cross-links with actin to form a gel that fills the lamellipodia cell projection. Filamin fills it in.

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Myosin II

Back 8

Motor protein that moves along actin and is responsible for contraction. Most move to (+). Form bipolar filaments.

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Myosin V

Back 9

Motor protein that carries cargo, things with suffix "somes". Moves to the (+) end.

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Myofibrils

Back 10

Cylindrical structure that spans a muscle's length, there are several per muscle cell (muscle fiber)

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Sacromere

Back 11

A band in the myofibril between Z disks (+) that contains a dark band of myosin II and two light side half-bands that are composed of actin

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Titin

Back 12

The spring-like protein that pushes the Z disk away from the myocin (relaxing)

Front 13

Tropomyosin

Back 13

Twists around actin. In it's usual binding place it allows myosin to bind

Front 14

Troponin

Back 14

Pulls tropomyosin out of its regular spot into a spot that blocks myosin. Occurs with low Ca2+ and relaxes muscles

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Sarcoplasmic reticulum

Back 15

modified ER that surrounds each myofibril

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T tubules

Back 16

Surround each myofibril and release some Ca2+ which binds to SR which releases a lot of Ca2+

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Alpha-tubulin

Back 17

One of the molecules of the tubulin heterodimer. Binds to GTP which cannot be lost or hydrolized.

Front 18

Beta-tubulin

Back 18

One of the molecules of the tubulin heterodimer. Binds to GTP and is a GTPase.

Front 19

MAPs (2 examples)

Back 19

Microtubule Associated Protein

Stabilizes microtubule ends for growth

Ex: MAP2 (longer) and tau (shorter and angled)

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Catastrophe factors

Back 20

Destabilize microtubules by bending the ends

Front 21

Stathmin

Back 21

Binds to tubulin subunits to block their addition to the microtubule. Becomes inactive and releases the tubulin when phosphorylated. The concentration of tubules is constant.

Front 22

Gamma-tubulin

Back 22

A protein part of the gamma-TuRC (tubulin related complex) that nucleates/caps microtubules at the (-) end

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Centrosome

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A MTOC (Microtubule organizing center) that is near the nucleus. Made of centrosome matrix and 50+ Gamma-TuRC. Plants and fungi don't have them

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Centrioles

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Short modified mictrotubules that are at right angles to one another in the centrosome. Duplicate in the S-G2 phase

Front 25

Kinesins

Back 25

Motor proteins that move to the (+) end of microtubules. Extend the ER

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Dynesins

Back 26

Motor proteins that move to the (-) end or microtubules. Faster than kinesins. Shaped like a ring on a stalk which connects to a microtubule. Turning of the ring powers movement. Keep the Golgi near to the centrosome

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Kinesin-1

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Carries cargo on mictrotubules

Front 28

Kinesin-3

Back 28

Carries membrane-enclosed organelles on microtubules

Front 29

Kinesin-5

Back 29

Slides microtubules in opposite directions

Front 30

Kinesin-13

Back 30

A kinesin motor protein turned catastrophe factor

Front 31

Kinesin-14

Back 31

Moves to mictrotubule (-) end

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Cytoplasmic intermediate filaments

Back 32

Not in all eukaryotes. Subject to mechanical stress

Front 33

Nuclear intermediate filaments

Back 33

In all eukaryotes. On the interior of the nuclear membrane. One kind: lamins

Front 34

Vimentin-like intermediate filaments

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Vinmentin, desmin (muscle)

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Epithelial intermediate filaments

Back 35

Keratins

Front 36

Axonal intermediate filaments

Back 36

Neurofilament proteins

Front 37

Plectin

Back 37

Links intermediate filaments to themselves or other fibers/structures

Front 38

Septins

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Filaments that are non-polar, form rings and cages, recruit the actin myosin ring in cell division, and keep proteins localized

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Adult cells that divide

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Epidermis, epithelial, bone marrow, liver, neurons

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Cell cycle phases

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G1, S, G2, M

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Late G1 checkpoint

Back 41

Growth factors/Mitogens signal the cell to continue. Fix DNA before replication. Implied in cancer. P53 increases P21 that inhibits G1/S and S-Cdks if there is unfixed DNA damage. Passes the checkpoint when there is no negative signal.

Front 42

Late G2/ G2M checkpoint

Back 42

Check replicated DNA for errors (ssDNA). If there are errors then cdc25 is inhibited which then fails to activate M-Cdk. Passes the checkpoint when there is no negative signal

Front 43

Metaphase/Anaphase checkpoint

Back 43

Check all chromosomes are attached to the spindles. M-Cdk activates cdc20 which activates APC. APC ubiqutinates securin which releases separase which initiates anaphase

Front 44

Cyclins

Back 44

Manage the cell cycle through binding to Cdks which activate other proteins and are directed by the cyclins. Go through cycles of synthesis and degredation

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Cdk

Back 45

Cyclin dependant kinase. Phosphorylates other proteins. Has constant concentrations

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CAK

Back 46

Cdk-activating kinase, increases Cdks activity by phosporylating a Cdk with cyclin bound

Front 47

G1 cyclins

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Promote start in G1

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G1/S cyclins

Back 48

Bind Cdks at the end of G1

Commit the cell to replication

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S cyclins

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Bind Cdks during S phase. Needed for replication initiation

Front 50

M cyclins

Back 50

Promote mitosis

Front 51

Wee1

Back 51

A kinase that adds an inhibitory phosphate to M-cyclin-Cdk. Is inhibited by active M-Cdk. Positive feedback (M-Cdk increase causes more M-Cdk to be active)

Front 52

Cdc25

Back 52

A phosphatase that removes the inhibitory phosphate from M-Cdk. Is inhibited in the late G2 checkpoint by incomplete replication. In a positive feedback loop and activated by M-Cdk so if one activity falls both fall.

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p27

Back 53

A CKI (Cyclin-Cdk Inhibitor)

Binds to cyclin-Cdk and blocks its activity. A mutation could cause cancer

Front 54

APC

Back 54

Anaphase Promoting Complex

Ubiquitinates the cyclin of M-Cdk and the cyclin gets released into the proteasome because M-cyclin must be low at the metaphase/anaphase interface. Inhibited by unattached kinetochores. Ubiquitinates securin which frees separase and the chromosome separates

Front 55

Cdc20

Back 55

Binds to APC activating it to ubiquitinate M-Cdk. Is activated by M-Cdk. Think caterpillar and grass

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ORC

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Origin replication complex. Caused to fire by phosphorylation by S-Cdk and does not fire twice due to the phosphate.

Front 57

Prophase

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Chromosomes condense. Mitotic spindle forms

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Prometaphase

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The nuclear envelope breaks down. The centrosomes align at the poles. Kinetochores attach to the mictrotubules from the closer pole for movement, not division yet.

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Metaphase

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Chromosomes line up at the equator walked there by kinesins from one pole. The kinetochores become attached to both poles. Metaphase/anaphase checkpoint

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Anaphase

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Chromosomes are split and moved towards the poles. Kinetochore mictrotubules shorten and the centrosomes move towards opposite membranes

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Telophase

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The nuclear envelope reforms and chromosomes decondense. Contractile ring is developing for cytokinesis

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Cohesins

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Hold sister chromatids together along their whole length

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Condensins

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Help chromosome condensation

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Astral microtubules

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Connect centrosomes to the plasma membrane. Dyneins attached to the membrane pull the centrosomes towards the membrane (anaphase movement A)

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Kinetochore microtubules

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Connect chromosomes to the poles

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Interpolar microtubules

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Attach to a microtuble of the opposite pole. Are walked apart by kinesins (anaphase movement B)

Front 67

Ndc80

Back 67

Attach microtubules to the kinetochore when dephosphorylated. Are not phosphorylated when there is tension so tension leads to pulling apart of the chromatids.

Front 68

Cytokinesis

Back 68

The actin myosin contractile ring tightens. Interphase microtubules are nucleated by the centrosomes. The ring gets smaller by disassembling of actin/myosin filaments. ER is cut in two, mitochondria are randomly distributed.

Front 69

Cell plate

Back 69

The new cell wall that forms between two daughter cells in plants guided by a phragmoplast of overlapping microtubules

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Somatic cells

Back 70

Divide by mitosis (2n --> 2n)

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Germ cells

Back 71

Precursors to eggs and sperm that divide by meiosis (2n --> 1n, not a part of the cell cycle)

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Phases of Meiosis

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G1, S, G2, Meiotic division 1, Meiotic division 2

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Bivalent

Back 73

Two matching pairs of sister chromatids lined up (one maternal one paternal) and held together by cross-overs. The daughters get one of the pair by random

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Chiasma

Back 74

Cross-overs. Hold together the bivalent

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Meiotic prophase 1 stages

Back 75

Leptotene, zygotene, pachytene, diplotene, diakinesis

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Leptotene

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1st phase of prophase 1

Sister chromatids bundle together and form visible strands in the nucleus

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Zygotene

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2nd phase of prophase 1

Synapsis (coming together) of homologs by assembly of the synaptonemal complex. Zygo = pairing

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Pachytene

Back 78

3rd phase of prophase 1

A tetrad forms from the pairs of sister chromatids on either side. This is the bivalent. Chiasmata form

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Diplotene

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4th phase of prophase 1

The synaptonemal complex degrades leaving homologs attached by just the chiasmata. How mammal eggs are kept until ovulation

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Diakinesis

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5th phase of prophase 1/1st phase of metaphase 1

Nuclear membrane disintegrates and the metotic spindle begins to form

Front 81

Mitogens

Back 81

Stimulate DNA replication by triggering G1-CDK and G1/S-Cdk. Signal through RTK (so do growth factors)

Front 82

Myc

Back 82

A gene regulatory protein that activates G1-Cdk which adds inhibitory phosphates to Rb causing it to release E2F which causes transcription of G1/S and S-cyclins leading to S phase. Expression is increased by mitogen/GF binding to RTKs.

Front 83

p53

Back 83

Phosphorylated in the event of DNA damage, and causes transcription for the translation of p21 which inhibits G1/S and S-Cdks preventing DNA synthesis. Mutated in half of cancers

Front 84

Blebs

Back 84

Irregular cell buds on a cell undergoing apoptosis

Front 85

Phosphatidylserine

Back 85

Signal that promotes phagocytosis

Front 86

Procaspases

Back 86

Cleave themselves to form capsases by induced proximity or are cleaved by capsases. Induced proximity is signaled for externally or caused by cytochrome C assembling the apoptosome wheel internally.

Front 87

Cytochrome C

Back 87

Released from a mitochondria that received an internal apoptosis signal (Bcl-2) and causes the apoptosome to form inducing the caspase cascade.

Front 88

CAD

Back 88

Caspase Activated DNAse

Released from its inhibitor iCAD by an executioner caspase and cuts DNA

Front 89

Bcl-2 family

Back 89

Effector: Will aggregate on the mitochondrial membrane which causes cytochrome C release resulting in apoptosis

Anti-apoptopic: inhibit aggregation of the effector Bcl-2 proteins so apoptosis does not occur

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IAP

Back 90

Inhibitor of Apoptosis

An external survival factor inhibits anti-IAPs so IAPs are free to inhibit apoptosis

Front 91

Cadherins (4 types)

Back 91

Link cells together through their extracellular domains in the presence of Ca2+ which makes them rigid (Ca-adherents). Differences are responsible for tissue segregation by type.

Classical: N- (nerve), P- (placenta, epidermis), E- (epithelial)

Non-classical: desmosomes and involved in neurons

Front 92

Integrins

Back 92

Link cells to the ECM. On the ECM side the link is mostly to laminin, fibronectin, and collagen. Allows for signaling both ways. Can also bind to other cells through Ig-like CAMs. Ca2+ or Mg2+ dependent. Active when the alpha-beta-glycoprotein heterodimer is straight

Front 93

Adherins junctions

Back 93

A type of cadherin. Link actin from one cell to another

Front 94

Desmosome junctions

Back 94

A type of cadherin. Link intermediate filaments from one cell to another

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Focal adhesions

Back 95

Link actin filaments to the ECM

Front 96

Hemidesmosomes

Back 96

Link intermediate filaments to the ECM

Front 97

Malignancy

Back 97

The spreading of cancer. 90% of cancer is epithelial. If malignant it stops expression of E-cadherin, detaches from the epithelia, and migrates elsewhere.

Front 98

Beta-catenin

Back 98

When Wnt is present it is stable and helps to link classical cadherins to actin

Front 99

Alpha-catenin

Back 99

Helps to link classical cadherins to actin. When stretched it had more room to bind vinculin which binds more actin.

Front 100

Transcellular network

Back 100

Actin/myosin bundles around cells (belts) that are connected and can contract to form invaginations

Front 101

Tight (occluding) junctions

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Selectively permeable barrier between cells that pinches together at the apical surface and keeps apical (active) and basal membrane (passive) pumps separate

Front 102

Paracellular vs Transcellular transport

Back 102

Paracellular: passive, small molecules go through tight junctions between cells

Transcellular: active/passive, molecules go through the cells

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Claudins and occludins

Back 103

Form tight junctions by homophilic interactions. Claudins can form paracellular pores

Front 104

ZO

Back 104

Zonula Occludins

Serve as a scaffold for tight junctions

Front 105

Gap junctions

Back 105

Channels between cells that allow through molecules <1000 Da (1 Da = 1g/mol). Gap junction signalling is faster than through synapses but less regulated. Allows for synchronous contractions of heart/smooth muscle

Front 106

Connexins/Connexons

Back 106

Connexins are monomers that make up connexons (6 connexins). Connexons from opposite cells link to form a continuous channel. There are several thousand channels per gap junction

Front 107

Selectins (3 types)

Back 107

A type of CAM (Cell adhesion molecule) that weakly binds to oligosaccharides. Responsible for immune responses. Ca2+ dependent

Types: L- (leukocytes), P- (platelets), E- (endothelial (blood vessels))

Front 108

Immunoglobulin superfamily

Back 108

A type of CAM (Cell adhesion molecule) that have Ig-like domains that are not Ca2+ dependent and can bind to themselves or to integrins

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Fibroblasts

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Cells that secrete extracellular matrix

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Connective tissue ECM

Back 110

Consists of fibrous polymers, ex: collagen, fibronectin, etc.

Front 111

Extracellular matrix components

Back 111

Proteoglycans, fibrous proteins, and glycoproteins

Front 112

Proteoglycans

Back 112

Consist of GAGs attached to proteins linked through a serine amino acid (99% saccharides)

Front 113

GAGs

Back 113

Repeated unbranched disaccharides that are negatively charged

Front 114

Hyaluronan

Back 114

A GAG that along with proteoglycans forms hydrating gels. It is negatively charged so attracts Na+ which attracts water because of osmotic pressure

Front 115

Aggrecan aggregate

Back 115

A core protein attaches a lot of hyaluronan which attaches a lot of proteoglycans which have a bunch of GAGs. The major proteoglycan in articular cartilage

Front 116

Collagen

Back 116

The major protein of connective extracellular matrix. Three intertwined L-alpha-helixes that make a right-handed spiral. Every third residue is glycine. Assemble into stiff fibrils

Front 117

Fibronectin

Back 117

A glycoprotein. Glycoproteins are about half protein and half polysaccharide and help with extracellular matrix orgaization by binding to components of the matrix and to integrins

Front 118

Basal lamina

Back 118

A type of ECM made of glycoproteins and proteoglycans in a thin mat that underlies epithelial cell sheets and tubes, surrounds individual muscle cells, and is a selective filter in kidneys

Front 119

Basal lamina synthesis

Back 119

Made by cells on both sides, i.e. epithelial and stroma (cells in the connective tissue (connective ECM))

Front 120

Basal lamina connections

Back 120

Epithelial side: through integrins

Connective tissue side: through fibronectin

Front 121

Laminin

Back 121

A heterotrimer glycoprotein responsible for basal lamina organization (sheet structure)

Front 122

Talin

Back 122

Recruited by thrombin in blood clotting. Is an adapter between active integrin and actin on the intracellular side. This makes extracelluar side sticky (blood vessel walls). When talin is pulled it has room to bind vinculin which recruits extra actin