Au Cell Biology - Exam 3

Front 1

5 types of cell signals and description

Back 1

Endocrine - hormones are sent across blood stream
Paracrine - local mediator
Neuronal - muscle move
Contact-Dependent - right next to each other, no diffusion
Autocrine - self

Front 2

4 results of signals

Back 2

survive, divide, differentiate, die

Front 3

2 most common secondary messengers

Back 3

cAMP and Ca2+

Front 4

4 steps in information flow and where located

Back 4

1. Receptor ligand binding - outside
2. Signal transduction via second messengers - cytosol
3. cellular responses - cytosol
4. changes in gene expression (from step 2) - nucleus

Front 5

2 receptor locations with description and example

Back 5

1. cell surface - hydrophilic signal molecule - peptide hormones
2. intra cellular receptors - steroid hormones

Front 6

Describe the dissociation constant Kd

Back 6

this is the concentration of ligands at which half of the receptors are occupied, similar to Km

Front 7

Examples of fast and slow response time

Back 7

altered protein function is fast - insulin
altered gene expression is slow - lactose

Front 8

3 receptor types

Back 8

1. ion channel linked receptor
2. g-protein-linked receptor
3. enzyme-linked receptor

Front 9

2 ways receptors can become desensitized to high ligand concentration

Back 9

the affinity for ligand changes - Kd increases
the receptor no longer initiates cell changes

Front 10

describe the structure of the G protein-linked receptor

Back 10

amino end outside, the segment that interacts with g-proteins is between loops 5-6 on the inside, the messenger binding site is on the outside between 6 and 7, finally the carboxyl end is on the inside, 7 loops total

Front 11

2 types of molecular switches with description

Back 11

phosphorylation - slow, kinase activates via ATP->ADP and phosphorylase deactivates
GTP-binding protein - fast, GTP binding activates via one GDP falling off and another GTP adding. GTP hydrolysis inactivates

Front 12

describe the 6 steps in the g-protein activation/inactivation cycle

Back 12

1. ligand binds to receptor on the outside
2. G-alpha releases GDP and binds GTP activating G protein
3. subunits separate with G-alpha connected to GTP
4. G-protein subunits activate or inhibit target proteins
5. G-alpha hydrolyzes GTP to GDP and becomes inactive
6. subunits recombine to form G protein

Front 13

describe the 4 steps in the production of cAMP

Back 13

1. ligand binds and G-protein activates by the exchange of GDP for GTP
2. the active G-alpha separates and activates Adenylyl cyclase which produces cAMP from ATP
3. GTP hydrolyzes and separates from adenylyl cyclase, inactivating it
4. phosphodiesterase converts cAMP to AMP w/H20

Front 14

What does caffeine do to the cell signaling process

Back 14

Inhibits phosphodiesterase so cAMP are kept high since it is not converted to AMP

Front 15

Describe the activation of PIP2

Back 15

Activated G-protein (GTP alpha complex) activates phospholipase c, this converts a PIP2 into IP3 and DAG. IP3 causes the release of Ca2+ ions from intracellular stores in the cytosol, DAG causes the activation of protein kinase C in the membrane

Front 16

Describe everything that Ca2+ ions do in the cell

Back 16

Ca ATPases in the PM pump Ca2+ out of the cell, other Ca ATPases in the ER membrane pump Ca2+ into the ER. IP3 receptor channels in the ER are gated ion channels that allow Ca2+ to flow out of the ER into the cytosol. The sodium/calcium exchanger in the PM moves 3 Na+ in for every 1 Ca2+

Front 17

What is calmodulin

Back 17

dumbbell shaped calcium binding protein that activates kinases and phosphatases

Front 18

describe the role of calcium in sea urchins

Back 18

activated sperm binds to the egg surface, calcium releases form inside the egg, cortical granules containing protein and enzymes release contents causing the creation of fertilization envelope

Front 19

describe the 6 steps in signaling involving nitric oxide

Back 19

1. The neurotransmitter acetylcholine activates a g-linked protein receptor in an endothelial cell lining a blood vessel.

2. this makes IP3 which stimulates the release of Ca2+ ions from the ER,

3. this activates Calmodulin which activates NO synthases, NO is made

4. NO rapidly diffuses across the membrane to smooth muscle cells and activates guanylyl cyclase.

5. GTP is converted to cGMP

6. cGMP activates protein kinase G which stimulates muscle relaxation and the dilation of blood vessels

Front 20

MOA of viagra, cialis and levitra

Back 20

they inhibit phosphodiesterase, resulting in high levels of cGMP leading to dialation of blood vessels

Front 21

describe how receptor tyrosine kinase works

Back 21

EGF binds to the outside, partner tyrosines are phosphorylated

Front 22

difference between plasma and serum

Back 22

plasma contains no rbc or wbc but does have platelets

serum is plasma w/o platelets

Front 23

Prokaryotes version of 3 cytoskeleton components

Back 23

Microfilaments - MreB proteins
Intermediate Filaments - Crescentin
Microtubules - Ftsz proteins

Front 24

3 research methods for cytoskeleton

Back 24

microscopy - visualize
drugs - structure and function
mutants - function

Front 25

4 functions of microtubules

Back 25

1. cell motility
2. organization and maintanance of cell shape
3. chromosomal movements
4. disposition and movement of organelles

Front 26

6 functions of microfilaments

Back 26

1. muscle contraction
2. amoeboid movement
3. cell locomotion
4. cytoplasmic streaming
5. cell division
6. maintenance of animal shape

Front 27

5 functions of intermediate filaments

Back 27

1. structural support
2. maintenance of animal cell shape
3. formation of nuclear lamina and scaffolding
4. strengthening of nerve cell axons
5. keeping muscle fibers in register

Front 28

components of microtubule structure

Back 28

alpha and beta - share 40% amino acid identity but have same 3-D structure

GTP binds at N terminus, MAP at c terminus

Front 29

2 types of motor MAP

Back 29

kinesin and dynein

Front 30

type of non motor MAP

Back 30

tau, gives neurons distinct shape

Front 31

5 steps in microtubule assembly

Back 31

1. tubulin dimers (non covalent heterodimers)
2. oligomers
3. protofilament
4. sheets of protofilament
5. closing microtubule
6. elongating microtuble

Front 32

3 phases of microtubule assembly

Back 32

1. lag phase
2. elongation phase
3. plateau phase

Front 33

describe the structure of centrosomes

Back 33

pair of centrioles at the center, nucleating sites of gamma tubulin, anchors negative end of microtubules

Front 34

describe microtubules in a neuron

Back 34

axons tubules have negative end near nucleus, dendrites go both ways

Front 35

describe how the two types of motor proteins move

Back 35

kinesins move toward the plus end, dyneins move toward negative end

Front 36

describe components of microfilament

Back 36

monomers of g-actin (globular) bind to atp then form f-actin (filament) w/ADP

Front 37

2 categories of microfilaments

Back 37

muscle specific and non-muscle specific

Front 38

3 orientations of actin in crawling cells

Back 38

1. contractile bundle - forms stress fiber
2. gel - makes cell cortex
3. parallel bundle - makes filopodium

Front 39

describe the structure of flagellum

Back 39

9+2 array of microtubules

Front 40

describe the structure of microvillus

Back 40

actin microfilaments with lateral cross-links

Front 41

what do capping proteins do

Back 41

stabilize microtubules stopping growth

Front 42

What does the spectrin-ankyrin-actin network do

Back 42

forms the cell cortex by support of the erythroyte plasma membrane, without it red blood cells would be circular

Front 43

What is unique about listeria

Back 43

it has an actin tail and since prokaryotes don't make actin, it comes from the host

Front 44

what is the significance of IF being more stable than MF or MT

Back 44

it is used more for structural purposes than movement

Front 45

two IF categories and examples

Back 45

1. cytoplasmic - keratins in epithelia, vimentin in connective tissue, neurofilaments.
2. nuclear - nuclear lamins form shape of nucleus

Front 46

why is IF identification important

Back 46

IF typing with immunofluorescent microscopy is important for cancer type diagnosis since IF type is maintained in cancer

Front 47

3 components of IF assembly

Back 47

dimer (Ns and Cs next to each other), tetramer, protofilaments

Front 48

3 types of mictrotubule associated proteins

Back 48

1. cytoplasmic dynein - moves toward minus end.
2. axonemal dynein - activation of sliding in flagellar microtubule
3. kinesin - moves toward plus end

Front 49

2 types of microfilament associated proteins (actin binding)

Back 49

myosin I - monomer, motion along actin filaments (individual cherries)
myosin II - filament, slides filaments in sarcomere of muscle (bunch of grapes)

Front 50

what does dynactin do

Back 50

helps dynein hold onto cargo

Front 51

what causes flagellum to bend

Back 51

motor proteins

Front 52

what is a bundle of muscle fibers called

Back 52

myofibril

Front 53

what is the smallest unit of muscle contraction

Back 53

sarcomere

Front 54

4 steps in muscle contraction

Back 54

1. release of Pi causes cross-bridge formation
2. release of ADP causes power stroke
3. bind of atp causes cross-bridge dissociation
4. atp hydrolysis causes cocking back of myosin head

Front 55

describe the regulation of striated muscle contraction

Back 55

tropomyosin blocks the myosin binding site on actin. Ca2+ binds to troponin which moves tropomyosin out of the way so myosin can bind

Front 56

describe 3 types of protein processing

Back 56

1. cleavage - just a cut
2. splicing intramolecular - just one molecule involved
3. splicing intermolecular - two molecules involved

Front 57

describe 2 types of intracellular protein sorting

Back 57

1. cotranslational import - into ER, golgi, vesicle then to destination
2. postranslational import - straight into various organelles

Front 58

describe the 6 steps in cotranslational import

Back 58

1. SRP binds to ER signal sequence and blocks translation
2. SRP binds to SRP receptor, ribosome docks
3. GTP binds to SRP and receptor, pore opens polypeptide is inserted
4. GTP is hydrolyzed and SRP is released
5. signal sequence is cleaved by signal peptidase as polypeptide elongates
6. polypeptide is released inside, ribosome is released, and translocon pore closes

Front 59

where is the signal sequence located

Back 59

on the N terminus

Front 60

what are the 4 components of the translocon

Back 60

1. SRP receptor
2. poor protein, ribosome
3. receptor
4. signal peptidase

Front 61

3 things that occur inside the ER

Back 61

1. glycosylation
2. BiP binding protein
3. disulfide bonds between cysteins by disulfide isomerase

Front 62

4 things about BiP

Back 62

1. most abundant chaperone in the ER
2. binds to hydrophobic regions
3. ATP hydrolysis driven
4. hydrophobic regions are unstable and lead to aggregation of unfolded proteins

Front 63

what moves proteins in mito. and chloro.

Back 63

translocase, TOM TIM, TOC TIC

Front 64

4 important factors in posttranslational import into the mitochondrion

Back 64

1. involves heat shock proteins that are chaperiones.
2. ATP hydrolysis driven removal of chaperones
3. Only unfolded proteins can pass
4. transit sequence and transit pepsidase

Front 65

3 purposes of smooth ER

Back 65

1. lipid synthesis
2. drug detoxification
3. calcium storage

Front 66

2 purposes of rough ER

Back 66

1. quality control for protein folding
2. glycosylation

Front 67

How does the smooth ER detoxify drugs

Back 67

monooxygenases add OH groups to make them more soluable to pass in urine

Front 68

what does the smooth ER do in the liver

Back 68

removes Pi from glucose after it is created from glycogen so it can pass through the membrane

Front 69

how many enzymes for protein modification per golgi stack

Back 69

3-8

Front 70

5 steps in lysosomal enzyme synthesis

Back 70

1. enzyme is created and carbo is added in the ER
2. in the golgi sugar is phosphorylated by phosphotransferase
3. manose binds to receptor
4. low ph in lysosome causes dissation of enzyme to receptor.
5. receptor is recycled

Front 71

2 types of secretory vesicles

Back 71

1. constitutive secretion is always on, mucus from intestinal cells
2. regulated secretion is controlled, neurotransmitters, digestive enzymes

Front 72

what helps pinch off clathrin coated pit

Back 72

dynamin

Front 73

origin and destination for coated vesicles

Back 73

clathrin - TGN/endosomes
clathrin - PM/endosomes
COPI - Golgi/ER or Golgi
COPII - ER/Golgi
Caveolin - PM/?

Front 74

what helps SNAREs bind and release

Back 74

Rap GTPase helps bind, SNAPs and NSF help break up

Front 75

describe the break down of glycogen

Back 75

ephedrine binds to receptor causing the activation of g-protein, GTP-alpha activates adenylate cyclase creating cAMP, this activates several phosphorylases which cleave glycogen

Front 76

describe the major steps in apoptosis

Back 76

chromatin condenses, cytoplasm shrinks, nucleus fragments, blebbing, apoptotic body is phagocytized

Front 77

what are caspases

Back 77

cistine, aspartic acid, apoptosis specific proteases

Front 78

what is the organelle of apoptosis

Back 78

mitochondria

Front 79

how does withdrawal of survival factors initiate apoptosis

Back 79

cytochrome c is released from mitochondria, calcium is released and caspase is activated

Front 80

5 stages of mitosis and what happens in each

Back 80

1. prophase - nucleoli disappears, cetrosomes duplicate, starburst of MTs asters
2. prometaphase - nuclear envelope fragments, centrosomes to opposite poles.
3. metaphase - metaphase plate
4. anaphase - shortest phase, topoisomerase II loosens centromere
- anaphase a: chromosomes pull apart
- anaphase b: poles move apart, polar MT lengthens
5. telophase - nuclear envelope formes, chromosomes uncoil, nucleoli returns, cytokinesis

Front 81

what links the chromosome to the microtubule

Back 81

kinetochore

Front 82

3 types of MTs

Back 82

kinetochore - pull
polar - push
astral - go off in space

Front 83

4 influences of restriction point

Back 83

growth factors
nutrients
cell size
DNA damage

Front 84

G2-M transition influences

Back 84

cell size
dna damage
dna replication

Front 85

metaphase-anaphase transition influence

Back 85

chromosome attachmet to spindle

Front 86

what does cdk stand for and what is it called later

Back 86

cyclin dependent kinase, MPF

Front 87

4 things stimulated by active mitotic cdk-cyclin

Back 87

1. nuclear envelope breakdown
2. chromosome condensation
3. mitotic spindle formation
4. targeted protein deradation (via anaphase promoting factor)

Front 88

what holds sister chromatids together and what breaks down

Back 88

cohesin and separase

Front 89

2 functions of anaphase promoting complex

Back 89

degrades securin (stablizes separase) and degrades mitotic cyclin

Front 90

describe the activity of g1 cdk

Back 90

phosphorylates Rb protein twice causing it to release E2F which is a transcription factor

Front 91

describe g1 cell arrest

Back 91

dna damage from xrays occurs, p53 (tumor suppressor) is phosphorylated and binds to the regulatory region for the gene p21, this is a cdk inhibitor protein

Front 92

what is a mitogen

Back 92

growth factor used with g1 cdk and Rb