Module 1

Question 1

Types of Multipotent Cells

Answer 1

Hematopoietic, Mesenchymal, Skin, Neural, and Epithelial

Question 2

Stem cell commitment

Answer 2

is a stepwise process, transcription factors turn certain developmental pathways on and shut others off (this determines what cell type it will become)

Question 3

Asymmetric cell division

Answer 3

maintains stem cell populations by creating two different daughter cells from mitosis. one daughter cell is a stem cell while the other has the ability to differentiate (due to cell polarity during cell division this daughter cell does not have any proteins that help keep the cell in stem cell form)

Question 4

Induced pluripotent stem cells

Answer 4

aka cellular reprogramming, this is done by the overexpression of stem cell maintenance proteins in somatic (unipotent) cells

Question 5

Where are stem cells found in the human body?

Answer 5

Umbilical cord blood, dental pulp of mandibular third molars, deciduous teeth that have been shed, and periodontal ligament cells

Question 6

Stem cell niche

Answer 6

saves stem cells from depletion and protects the human from overproduction of stem cells. ECM interactions are known to play an important role in maintaining the niche

Question 7

Glycoaminoglycans (GAG) structure

Answer 7

Repeating dissacharide chains of acidic sugar-acetylated sugar
Negative surface charge
covalently attach to proteins to form proteoglycans
proteoglycan aggregates –> fir tree appearance

Question 8

Collagen Synthesis

Answer 8

1. translation into RER
2. vitamin C dependent hydroxylation of pro and lys residues
3. some hydroxylysine residues are glycosylated
4. triple helix formation
5. secretion into ECM and cleavage
6. formation of mature collagen

Question 9

Elastin

Answer 9

enables skin to stretch without tearing (lungs, arteries etc)
contains little hydroxyproline and no hydroxylysine
interacts with fibrillin in ECM
form desmosine cross links

Question 10

Fibrous Proteins and disease

Answer 10

Scurvy - vitamin C deficiency
Osteogenesis Imperfecta - abnormal collagen (type 2 lethal) or decreased collagen (type 1)
Ehlers-Danlos Syndrome - defects in collagen causing stretchy skin
Marfan Syndrome - defect of fibrillin-1 tall and thin long fingers
a1-antitrypsin deficiency - reduced ability to inhibit elastase from neutrophils in lungs which causes breakdown of lung tissue

Question 11

Adhesive proteins

Answer 11

join ECM components to eachother and cells to the ECM
fibronectin - connective tissues
laminin - epithelial tissues

Question 12

Cell adhesion molecules

Answer 12

Cadherins
Selectins
Immunglobulin Superfamily
Integrins

Question 13

Cadherins

Answer 13

Ca2+ mediated cell-cell adhesion
1 cadherin binds to another in the ECM by joining actin of the cytoskeletons
major role in holding cells together and tissue integrity

Question 14

Selectins

Answer 14

transiet cell-surface binding
connects cells by binding protein on surface of one cell to carbohydrate on the surface of another
important in the bloodstream with WBC

Question 15

Immunoglobulin Superfamily

Answer 15

cell-cell adhesion with transient expression

important during development and regeneration

Question 16

Integrins

Answer 16

Both cell-cell AND cell-ECM adhesion
integrins bind to fibronectin and laminin in the ECM (depends on tissue type)
multiple weak adhesions due to low binding affinity

Question 17

Hetero vs euchromatin

Answer 17

heterochromatin = more tightly packed and less transcription
euchromatin = less tightly packed and more genes are located within this region

Question 18

Ribosomes

Answer 18

40% protein and 60% rRNA

Question 19

Treacher Collins Syndrome

Answer 19

genetic disorder affecting ribsome biogenesis

defective treacle gene causing improper trxn of rRNA for 28S subunit

Question 20

Rapid growth (RER vs SER)

Answer 20

during rapid growth there is a lower concentration of RER which means less proteins are being secreted outside of the cell to meet the metabolic demands inside the cell

Question 21

Cystic Fibrosis

Answer 21

mutations in the CFTR gene that distrupt normal protein conformation and traps proteins in the ER (which normal deals with the unfolded protein response to correctly fold proteins)

Question 22

Peroxisomal disorders

Answer 22

X-linked adrenoleukodystrophy

Zellweger syndrome

Question 23

Lipids in each leaflet

Answer 23

Outer - SM and PC

Inner - PI, PE, PS

Question 24

FRAP

Answer 24

shows that proteins can redistribute throughout the lipid bilayer

Question 25

Lipid rafts

Answer 25

cholesterol enriched microdomains in the plasma membrane | functions include cholesterol transport, endocytosis, signal transduction

Question 26

spectrin

Answer 26

actin binding protein that provides stability, strength, support for the plasma membrane spectrin forms dimers and then tetramers with itself

Question 27

Actin

Answer 27

regulation of physical state of cytosol (gel/sol state) cell movement contractile rings during cell division G-actin monomers hydrolyze ATP to polyermize into F-actin. eventually reaches a steady state where rate of addn to the PLUS end=rate of sub to the MINUS end

Question 28

Actin binding proteins

Answer 28

1. regulators of gel/sol state 2. spectrin (association requires ATP & important in RBC) 3. dystrophin (in skeletal muscle cells)

Question 29

intermediate filaments

Answer 29

do not disassemble and assemble rapidly like actin and microtubules stable & intact structures in the cell fibrous and provide structural support

Question 30

microtubules

Answer 30

motility, chromosomal movements, organelle and vesicle transport protofilaments form cylindrical structure and GTP bound heterdimers (composed of alpha and beta tubulin) add to the plus end, this is called the GTP cap Once the GTP cap is gone, the microtubule cannot grow any longer dynamic instability

Question 31

General mechanism for all G-protein receptors

Answer 31

ligand binds to receptor and causes a conformational change on the cytoplasmic side of the plasma membrane which binds and activates G-protein (alpha subunit) by replacing GDP with GTP Alpha subunit then goes on to react with an enzyme regulated by G protein --> relays the signal from the first message (ligand) to deeper into the cell by producing mediators aka second messengers The secondary messenger activates a Ser/Thr kinase that phosphorylates proteins (amplifies signal from original primary messenger) which results in a biological response

Question 32

types of receptors

Answer 32

1. g protein receptors 2. catalytic receptors 3. intracellular receptors

Question 33

Adenylyl cyclase

Answer 33

once the alpha subunit of g protein binds to adenylyl cyclase, ATP gets converted to cAMP which acts as a secondary messenger in the cell cAMP then goes on to regulate protein kinase A (PKA) PKA phosphorylates proteins which have biological affects in the cell

Question 34

Aberrant activity of Gs and Gi proteins

Answer 34

Cholera - modifies alpha subunit on Gs in intestinal cells which makes it so it cannot be shut off. this results in the overpdn of cAMP and diarrhea and dehydration Pertussis - modifies Gi in the respiratory tract so it inhibits the alpha subunit from shutting adenylyl cyclase off

Question 35

Phospholipase C

Answer 35

regulated by G protein 2 secondary messangers produced: IP3 and DAG(anchored in the membrane) IP3 then binds to ER to release calcium Ca and DAG work together as secondary messengers by activating protein kinase c (PKC) PKC phosphorylates proteins in the same way that PKA does

Question 36

Catalytic receptors

Answer 36

3 domains: ligand binding, transmembrane, effector region (within cell) upon binding of ligand, two receptors form dimers each receptor tail tyrosine phophorylates the other in the dimer SH2 (adaptor protein) then is able to bind to the phosphorylated tyrosines

Question 37

Ras

Answer 37

homologous to the alpha subunit of G protein Ras binds to SH2 containing domains that are already bound to the phosphorylated tyrosines Ras activates the MAP kinase cascade (much longer lived that tyrosine phos.) Final enzyme: MAP kinase gets phosphorylated and translocates to the nucleus to act as a trxn factor

Question 38

STATs

Answer 38

signal transducers and activators of trxn SH2 containing proteins that can bind directly to the phosphorylated tyrosines (unlike Ras) STATs get tyrosine phosphorylated and form dimers --> translocate to nucleus to act as trxn factor

Question 39

inhibitors of DNA synthesis

Answer 39

5-Fluroruracil | methotrexate