Exam 4 Flashcards
Outer membrane vs. inner membrane of Mitochondria
Outer: very porous; folded proteins can pass through channels; General Import Pores
Inner: very tight; site of oxidative phosphorylation where generation of proton gradient exists; Tim23 and Tim22
General Import Pores
transports folded proteins
N terminal of protein has positive leader sequences that binds to negative inside of channel
Facilitated diffusion and ATP independent!
Tim23 and Tim22
found on inner mitochondrial membrane
very tight channel to protect proton gradient
Gated channels
Positive N terminus binds to outside and protein gets transported inside.
Protein is unfolded and plugs whole to prevent loss of proton gradient.
Hsp70 binds to unfolded protein and uses ATP hydrolysis to make a kink and pull protein in the channel
Fission - mito
Drp1 and Bax facilitate the pinching off and division of mitochondria
Fusion
Mfn and OPA mediate fusion of mitochondria
how many calories are made with each ATP to ADP conversion?
7.3 kcal/mol
NADH structure
Two pentose rings hooked by two phosphates
an adenosine head
Oxidized form of NADH
NAD
Reduced form of NADH
NADH
Oxidative phosphorylation
Glucose is broken into two pyruvates (3C) that occurs in lack of oxygen to make 2 ATP
Pyruvate moves to mito and diffuses across outer membrane where it goes into the TCA cycle to break down into CO2, 3 NADH, and 1 FADH.
Electron Transport Chain
NADH donates electron and gets oxidized to pump protons outside.
one NADH transfers 5 protons out and forms 1 water
ATP Synthase
driven by proton gradient
protons run through channel and phosphorylate ADP to ATP.
single glucose gives 22 ATP
ATP synthase conformations
ADP and pi
brings ADP and Pi together
Looses affinity to ATP
How is apoptosis induced in mito
by activation of cytochrome c
Cytochrome c
usually involved in oxidative phosphorylation (complex IV)
CytoC binds to form an apoptosome that signals to activate caspases.
How is apoptosomes regulated?
reducing or oxidizing cytochrome C by NADH
all healthy cells form apoptosomes, but cell changes mind if the cell has the energy to reverse the activation of cyto c.
if the cell is lacking energy, cyto C cannot be inactivated and drives to apoptosis.
Quality Control in Mitochondria
Molecular: set of proteins that detect oxidative phosphorylation enzymes that are defective and degrades them
Mitophagy: degrade the piece of mito that is defective
Apoptosis: kills the cell all together
Molecular quality control in Mito:
mAAA are proteins that detect mutations in Oxidative phsophorylation enzymes and degrades them.
Lots of mutations associated with these: hereditary spastic paraplegia.
Primary Cilia
Microtubule extension out of PM on apical surface
senses physical and biochemical environment
a 9+0 arrangement
signaling and NOT motile
Motile Cilia
used when movement of fluid is required
respiratory, neural, and reproductive
2 extra MT in center of axonomes
central pair
the extra two MT in axonemes that give the motile cilia a characteristic 9+2 arrangement
Components of cilia
Basal Body anchor Transition Zone Axeneme scaffolding Intraflagellar transport Outer Ciliary Membrane
Basal Body
anchor to the axoneme structure - incredibly stable
derived from centrosome
200nm by 500 nm
central hub with radiating modified microtubules in TRIPLET
9 subunits; 3 MT per subunit
Axoneme
scaffold structure in cilia
DOUBLET MT with central pair of MTs which makes the m more stable than singlets.
Nexin
the linker between doubles in cilia to ensure integrity
How to cilia move?
dynein arms grab onto neighboring subunits and cause a pulling force that leads to motility
Intraflagellar transport
Active mechanism that regulates which components can enter and move down the cilia through the transition zone.
Bidirectional trafficking mechanism in cilia
Proteins/vesicles must have a localization signal very similar to control of nuclear pore.
Transition Zone
the linkage domain or gatekeeper of cilia
links basal body to axoneme
ensures that proteins and membranes components of cilia are distinct from PM
contains Alar Sheets
mutated in ciliopathies
what is analogous to nuclear pore in cilia
alar sheets in the transition zone
limit cytoplasmic and diffusible proteins from entering
what stage does ciliogenesis occur
G0 or G1
First step in ciliogenesis
basal bodies from centrioles migrate to surface of cell and attach to rich cortex.
along the way they associate and fuse with ciliary membrane vesicles that fuse with plasma membrane
elongation of cilia
once at Plasma membrane, basal body nucleates outcroth of axoneme
what forms the transition zone of the cilia
distal regions of the basal body
maintenance of cilia
proteins synthezied in cyto are transported via IFT
tubulin continues to be incorportated at the tip, but cilia does not elongate further.
What drives movement to the + end in cilia?
Kinesin 2 and IFT-B
This is the end of the cilia
what drives movement to the - end of cilia?
Dynein-2 and IFT-A
returns to the base of the cilia
Basal body formations
derived from centrioles and are typically formed during cell replication.
Mother centrioles are associated with ciliogenesis
New centrioles always develop at the base of the mother centriole.
How are multi-ciliated cells made?
Must be differentiated cell
Bypass the once and only once duplication of DNA and centrioles, to make multiple centrioles.
Forms dueterosome and all migrate to build cilium structure
deuterosome
used in multi-ciliary cells and help recruit machinery to build cilia
1) daughter centriole supports procentriole nucleation via deuterosome formation.
2) deuterosomes are released into cytoplasm
3) centriole growth from deutersosome
4) centriole release and maturation for docking cilia growth
Physical benefits of Cilia
Concentration of signal localized polarized fluid mechanics charge disruption flow sensing
concentration of signal - cilia
cilia create microenvironment for signaling with high surface receptor to volume ratio
How are cilia flow sensing
mechanical bending senses fluid flows
Receptors in Cilia detect
physical stimuli, light, chemical stimuli ( hormones, chemokines, GFs, morphogens)
Result of ciliary signaling
cell proliferation, motility, polarity, growth, differentiation, tissue maintenance
Sonic Hedgehog pathway - unstimulated
PTCH1 is on surface of cilia and Gli is respressed by SUFU
SMO is sequestered to intracellular vesicle
Sonic Hedgehog pathway - stimulated
Hh binds and causes PTCH1 to no longer be on surface cilia membrane and for SMO to translocate to cilia surface
This causes Cli to be transported to tip of cilia and represses SUFU to cause activation of GliA.
GliA is transported by dynein into cytoplasm and nucleus to become TF.
Hh Signaling effects..
Limb formation - growth, digit number, polarity
Bone formation: cell proliferation, diff, growth
Neurogenesis: neural tube formation, differentiation, cell migration
Left right axis formation and cilia
gastrulation establishes anterior and posterior
Ciliary pits beat in a rotary fashion at 600 bpm at the proper angle to generate net leftward flow. This causes asymmetry of growth factors and biochemical signals.
Depends on the primary cilia to sense the mechanical flow.
Characteristics of Ciliopathies
1) Rare
2) pleiotropic
3) most affect structural elements of cilia
4) Diverse range of mutations - most occurring in transition zone
5) genetically complex
6) phenotypes overlap
Bardet-Biedl Syndrome
Mutation in gene that encodes basal body proteins in cilia
affects vesicular trafficking, MT anchor, and IFT
AR disorder
pathology: photoreceptor degradation, mental retardation, kidney defects, asomnia, obesity, diabetes
Polycystic Kidney Disease
AD and AR both exist
1:1000 (maybe more)
mutation in polycystin1 and 2
pathology: renal cysts, renal failure and liver and pancreatic cysts, intracranial aneuryisms
Polycystin 1 and 2
mutated in PKD
channel proteins located at cilia base, just above transition zone.
sense mechanical urine flow to signal for Ca release to induce proliferation and cystogenesis
Function of epithelial
barrier, absorption and transport, secretion, movement though passageways, biochemical modification, sensory reception, communication
endothelium
epithelial cells that line the blood and lymph vessels
mesothelium
epithelial that encloses internal spaces of the body cavity
Vasculature in epithelium
avascular
no direct blood supply, nutrient and oxygen
diffuse through CT, BL to reach epithelial cells
Formation of epithelium
begins with primitive epithelium, which is just a single sheet of cells.
derived from endo, meso, and extoderms
these cells receive morphogenetic signals for transformation that causes disassembly and reformation during various parts of development in uterus.
some detach and migrate to become mesenchymal
this process stops at birth but is hyper-activated in cancer
Mucosae
epithelia in most internal linings
has outer epithelium
lamina propria: CT directly under eptihelia
submucosa: deep CT
Simple vs Stratified epithelia
simple: single sheets
stratified: multiple sheets
Squamous vs. cuboidal vs. columna
squamous: outer layer is flat (long but short)
cuboidal: cube shaped
columnar: tall cells
Pseudo-stratified Epithelia
all cells remain in contact with BL, but not all reach free surface
Transitional epithelia
stratified, but histologically look like a single layer
found in bladder
Function of epithelial polarity
unidirectional secretion or absorption
transcytosis
transport of vesicles in epithelia that is unidirectional - movement though the cell
Apical surface specializations
Microvilli and Cilia
Microvilli
located on apical surface.
extension of actin that increase surface area.
Stereocilia is most common: found in epididymis and in ear.
Basolateral specializations
lack structural organization
still has folds to increase surface area
Tight Junctions
Zonula Occludens
uses claudins and occludins
appear like a belt surrounding cells
Limit paracellular transport and promote Transcellular transport.
work intracellularly to regulate cyto proteins that monitor gates
Adhearence Junctions
Zona Adherens
Cadherins that connect to actin skeletal
cadherins recruit kinases and phosphatases to regulate gene expression control cell division and polarity
Desmosomes
also use cahderins, but bind to Intermediate filaments
Promote structural integrity of epithelium
mutations cause blistering
Gap Junctions
actual channels that promote rapid communication between the cells through channels.
allow flow of ions, second messengers.
Non-specific!
Basal Lamina Components
collagen, glycoproteins, laminins, entactin
high variable depending on cell type.
Function of Basal lamina
epithelial attachment, selective filtration, polarity, highways for migration, barrier to invading materials, control gene expression, tissue scaffolding
Attachments to basal lamina
Hemidesmosomes and Focal Adhesions
Hemidesmosomes
link internally with integrins to intermediate filaments and provide structural connection.
Focal Adhesions
use integrin to attach to actin cytoskeleton.
have signaling capabilities to provide role in polarity
Exocrine Glands
secretes from apical surfaces of epithelia
multicellular
begin as sheet of epithelia that invaginates and elongates but remains connected as it grows.
Contains Acini that flow into the ducts
Acini
secretory units in exocrine glans that are located at the base and secrete into the ducts.
Endocrine glands
secrete hormones into bloodstream from BL side
start with primitive epithelium that invaginates, but there is a detachment from the apical surface.
Hormones must travel through BL of gland and then through another BL of the vessel to get into bloodstream
Transit Amplifying cells
intermediates in the process of differentiation of epithelial cells.
these cells have a shortened lifespan to divide rapidly and then differentiate.
much faster than stem cells.
WNT pathway in colon
WNTs are secreted ligands that bind to receptors to regulate downstream protein that regulates beta-catenin to stimulate cell division and inhibits differentiation.
APC
ACP inhibits B-catenin by sequestering it in the nuclues
WNT 7A
when gene expression of WNT7a is increased, associated with loss of function of APC in colon cancer, but not lung!
Decreased WNT-7s is not associated with colon cancer, but it is associated with Lung cancer.
WNT7A in lung
WNT7A acts on beta catenin to inhibit cell division and promote differentiation.
Cadherin and squema cell carcinoma
1) mutations in cadherin disrupt junctions in eptihelial to make more migratory
2) change in signaling pathways to change gene expression
3) it could be that low Cadherin is the effect of squema carcinoma and not the cause…
what binds to the antigen
the variable region
what gins to the antibody
the epitope
Superficial Fascia
CT near body surface with lots of fat; easily dissected
Deep Fascia
tougher deeper region of CT
Prominent thick epimysium (outer covering of muscles) and ligaments, tendons, joint capsules.
Connective Tissue Function
Mechanical strength, regulation of nutrient and metabolism between organs and blood vessels, control behavior and function of cells contacting ECM
Types of CT
Resident and Immigrant
Resident CT
produce and secrete ECM and proliferate to produce new CT
mesenchymal, fibroblasts, myofibroblasts, Adipocytes, osteoblasts, osteocytes, chondorcytes, smooth muscle
Mesenchymal cells
Resident CT
the precursors to all CT found primarily in embryogenesis
high telomerase activity
give rise to fibroblasts
Fibroblasts
Resident CT
pre-eminent cells in most CT
synthesizes fibrous proteins, proteogycans, and ECM components
capable of cell division
Sensory and proliferation is highly regulated - scarring is hypertrophy of fibroblasts
many different types of fibroblasts depending on cell type.
Can transform into variety of CT (adipocytes, Smooth muscle, chondrocytes, osteoprogenitors) - though this has not been proven in live human cells.
Myofibroblasts
Resident CT
derived from fibroblasts, capable of smooth muscle like function
Found at wound sites to contribute to retraction and shinkage of scar tissue.
Adipoctyes
Resident CT
fibroblasts derivatives or primitive mesenchymal
store fat and energy
Brown Fat: found in newborns with many mito to convert FA into heat.
Chondrocytes
Resident CT
cells that make cartilage
Immigrant blood derived CT
originate from precursors circulating in blood;
produced form hematopoietic cells in marrow and migrate into blood and CT
acct as part of immune system
Lymphocytes, macrophages, neurophils, esosinophils, mast cells, osteoclasts
Lymphocytes
immigrant CT
acquired immunity
Macrophages
immigrant CT
phagocytose cells, ECM, and non-cellular material
stimulate angiogenesis, remove damage tissue, remodel normal developing tissue
Neurophiles and eosinophils
immigrant CT
defense against microoorganisms
Mast Cells
immigrant CT
secretory, release vasodilators to promote swelling