Cell BIO Exam 4
Lamellipodia
(sheet feet) flat, sheetlike extensions from the core of growth cones, located between the filopodia
filopodia
(thread feet) long, fingerlike extensions from growth cones of axons and dendrites
Erection Pathway
*Parasympathetic signalling* --> nitric oxide released --> guanylate cyclase increases in smooth muscle cells --> increased *cGMP* --> decreased intracellular Ca --> *smooth muscle relaxation* --> increase in blood flow, filling penis --> *draining veins compressed*
Process of membrane damage causes by amyloid plaques.
- Amyloid plaques are formed - Immune system attacks the amyloid plaques and causes cell damage - The plaques activate microglial cells which activates inflammation - Inflammatory free radicals damage the membrane and activates cellular kinases. - Activated kinases hyperphosphorylate tau proteins -Tau dissociates from microtubule - The microtubule breaks down
function of intermediate filaments
- Mechanical integrity of cell and nucleus - Cell shape - Signal transduction - Adhesion - Motility - Organelle positioning
functions of microtubules
- Scaffolding (shape, cell projections "skeleton") - Transportation (in cell/of cell) Chromosomes - spindle fibers Transport of vesicles and organelles Flagella/cilia - Organization within a cell (plasma membrane is structured by microtubules)
Proteins involved in binding actin filaments
- Severing protein - Side binding protein - Myosin motor protein - Cross-linking protein - Bundling protein - Capping protein
Signal Pathway for G Protein
- Stress stimulates adrenal gland to release adrenaline - adrenaline binds to adrenaline receptor (GPCR) - GPCR activates a G-protein - G-protein activates adenylyl cyclase - Adenylyl cyclase make cAMP - cAMP activates protein kinase A - PKA adds to phosphorylase kinase - activating it - Phosphorylase kinase adds phosphate to glycogen phosphorylase - initiates the breakdown of glycogen forming glucose for blood - Getting energy for fight/flight
Process of Sooth muscle relaxation
- acetylcholine binds to receptor (activated GPCR) - The GPCR activates IP3 - IP3 helps to produce calcium which activates the nitric oxide synthase - The nitric oxide synthase produces NO which diffuses across membranes and activates cyclic GMP to relax the muscle
Lipid Hormones
- cortisol - estradiol - testosterone
Malignant cancer cells tend to:
- degrade extracellular matrix - survive in foreign tissue - evade immune system - Stimulate blood vessel growth
Describe components (stucture) of motor proteins
- globular head attached to... - tail - adaptor protein attached to.. - cargo
Components of motor protein movement
- kinesin tail - microtubule
Malignant cancer cells tend to have:
- reduced dependence on external signals - increased expression of telomerase - reduced tendency for apoptosis - reduced binding
Characteristics of adult stem cells
- undifferentiated cell - found among differentiated cells in tissues - can renew itself - can differentiate into specialized cells - maintain and repair tissue
functions of microfilaments
-Movement (vesicles, proteins, contractions, cytokinesis) - Plasma membrane structure (phagocytosis, microvilli)
PDE-5 inhibitors
-Pulmonary hypertension therapy -Include sildenafil. Inhibit cGMP PDE5 and prolong vasodilatory effect of nitric oxide. Also used to treat erectile dysfunction - can increase the calcium inside the cell
Wnt proteins
-maintain stemness (otherwise they will differentiate) -Wnt stimulates expression of certain genes
What are the main reasons for apoptosis?
1. Regulate animal cell numbers 2. Get rid of unneeded cells and severely damaged cells
How many phosphates does IP3 have?
3
How many nm do motor proteins move per step?
8 nm
What are mitotic spindles?
A cell structure consisting of microtubules, which form during early mitosis and plays a role in cell division
intermediate filaments
A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments, made of filamentous proteins.
Microtubule
A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella.
Microtubules
A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella.
G0 phase
A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly.
Myosin
A protein present in muscle fibers that aids in contraction and makes up the majority of muscle fiber
Ubiquitin
A protein that attaches itself to faulty or misfolded proteins and thus targets them for destruction by proteasomes
Transcription Factor
A regulatory protein that binds to DNA (enhancer sequence) and affects transcription of specific genes. They increase mRNA production and proteins.
How are amyloid plaques formed?
AB proteins stick together outside the neurons
What lead to Beta Amyloid proteins (AB protein)
APP or gamma secretase mutation
What is the basis of ameboid movement?
Actin meshwork, actin filament treadmilling.
What does the proteins added to RTK do?
Activate Ras-GEF which activates the RAS protein by changing GDP to GTP.
Phospholipase C Pathway Activation
Activates protein kinase C and triggers a rise in intracellular Ca2+
What can intracellular signaling cascades achieve ?
Astonishing speed, sensitivity, and adaptability
What ion signal triggers many biological processes?
Ca2+
Chemotaxis
Cell movement that occurs in response to chemical stimulus
Pluripotent
Cells that are capable of developing into most, but not all, of the body's cell types
What drugs binds tubulin dimers and prevents their polymerization?
Colchicine (colcemid) and Vinblastine (vincristine)
Microtubule-associated proteins (MAPs)
Cross-linking proteins that stabilize bundles of permanent microtubules (e.g. the microtubules that run the length of nerve axons) by binding to the sides of the microtubules.
What are the components of MPF?
Cyclin and CDK complex
What causes the disconnect between neurons in Alzheimer's disease?
Dismantled microtubules
Hutchinson-Guilford Progeria Syndrome
Early aging caused by lamin gene mutation
What recognizes the abnormal surface of proteins?
Enzymes
What does chromosome packaging depend on?
Epigenetic modifications to histones and DNA (carried out by enzymes)
What controls the arrangement of actin filaments?
Extracellular signals
True or False: Stem cells cannot repair damaged tissues
False, Stem cells can repair damaged tissues.
Actin filament treadmilling
G-actin monomers assemble at the (+) end of the filament growing in length while disassembling and shrinking at the (-) end Actin polymerization is ATP dependent
What hydrolyzes GTP back to GDP?
GAP
What exchanges GDP for GTP?
GEF
What doe tubulin dimers bind to?
GTP, this to allows them to be added to the positive end of microtubule.
What does Receptor tyrosine kinases activate?
GTP-Binding protein (RAS)
What is an example of an mitogen?
Hormone
what does medicine like viagra target?
Inhibit PDE-5
What binds to ER receptor, allowing the channel to open and release Ca2+?
Inositol triphosphate (IP3)
What is significant about the activation of origin of replication?
It allows activation of DNA polymerase so DNA can be replicated.
What happens when Rb becomes phosphorylated?
It becomes inactive and it releases E2F to transcribe mitosis genes.
What is p21 and what does it do?
It is a cdk inhibitor, it blocks the assembly of cyclin/cdk, this process stops the cell cycle for DNA repair
What does RAS activate?
MAP kinase kinase kinase
What factor in the cytoplasm stimulates mitosis in quiescent cells?
MPF
MPF
Maturation-promoting factor (M-phase-promoting factor); a protein complex required for a cell to progress from late interphase to mitosis. The active form consists of cyclin and a protein kinase.
What is the difference between microtubules and intermediate filaments?
Microtubules have distinct ends and are much larger than intermediate filaments.
What is the basis of muscle contraction?
Myosin filaments pulling on actin filaments
Yamanaka factors
Oct4, Sox2, Klf4, c-Myc
What else other than phosphorylation can make cyclin/cdk inactive?
P27 (a cyclin/cdk inhibitor)
What activates protein kinase C (PKC) and triggers a rise in intracellular Ca2+?
Phospholipase C
Bundling proteins
Proteins which cross-link unbranched actin filaments into parallel arrays
Pathway to mitosis
Ras signaling --> MAP kinase kinase kinase --> MAP kinase kinase --> MAP kinase --> Activates mitosis
Rb
Retinoblastoma, osteosarcoma Inhibits E2F; blocks G1 to S phase
What phase of mitosis does DNA replicate?
S phase (interphase)
What initiates DNA replication and blocks re-replication?
S-cdk
Motor Proteins
Specialized proteins that use energy to change shape and move cells or structures within cells.
Totipotent
Stem cells with the potential to differentiate into any type of cell.
How does the ends of intermediate filaments differ from one another?
THEY DONT, both ends are the same. (They align based on amino end and carboxyl end)
What does the cell-cycle control system do?
The cell cycle control system controls cell cycle by activating and inactivating key proteins - this regulation is mostly carried out by phosphorylation and dephosphorylation
what is happening during G1 and G2 of interphase?
The cell is growing
What triggers progression through the cell cycle?
The cell-cycle control system
What happens when Ca2+ concentration decreases in muscle?
The muscle relaxes, allowing more blood flow
What end are tubulin dimers added to microtubules?
The positive end
How does microfilaments (actin filaments) change?
The process of treadmilling. Actin with bound ATP added to the plus end, while Actin is remove from the minus end (ADP).
What does each cell type in a single organism have in common?
They have the same genes
What is the role of receptors?
They may be an enzyme or can be used to bind to an enzyme.
How is actin polymerized?
Through nucleating proteins
How does CDK become active?
Through the removal of phosphate performed by phosphatase.
What is the purpose of DNA checkpoints?
To help prevent the replication of damaged DNA
True or False Ca2+ is a cofactor for many enzymes and acts as an allosteric switch.
True
True or False: There are different cyclins and cdks that trigger different steps in the cell cycle.
True
what are p53 and cki?
Tumor suppressor proteins. They inhibit replication of cells when they are damaged.
How does motor proteins work?
Use ATP to move along pulling adaptor protein and "cargo" (vesicles, organelles, chromosomes, RNA, Ribosome, cytoskeleton)
How are organelles moved?
Using microtubules
Meiosis
When cells divide without DNA replication.
What is cancer the product of?
a damaged single cells that divided too much
Cancer
a disease of mitosis (excessive cell division)
Mitogen
a molecule that initiates mitosis
induced pluripotent stem cells
a pluripotent stem cell that was generated by manipulation of a differentiated somatic cell
What occurs after phosphates are added to RTK?
a scaffold is made to add other protein to the RTK which can be activated to perform other functions.
actin filaments (microfilaments)
a thin, flexible type of protein filament composed of actin proteins that forms part of the cytoskeleton and supports the plasma membrane and plays a key role in cell strength, shape and movement
What does cell crawling depend on?
actin filament polymerization
What makes up the basic structure if microtubules?
alpha and beta tubulin
Phospholipase C
an enzyme that catalyzes the splitting of a specific type of phospholipid into IP3 and DAG (both of which act as second messenger molecules).
Cytoskeleton
an extensive network of several types of proteins that permeates the cell and influences most aspects of cell function
What type of division allows two daughter cells to become different?
asymmetrical division
severing proteins
break actin filaments all along the length of the filament
Mitosis
cell division in which the nucleus divides into nuclei containing the same number of chromosomes
Multipotent
cell with limited potential to develop into many types of differentiated cells (adult stem cells)
Where do microtubules originate from?
centrosome
What causes cancer?
changes in DNA due to viruses, man-made chemicals, natural chemicals, and ionizing radiation
Alzheimer's disease
characterized by beta-amyloid protein aggregation (amyloid plaques)
What determines the route of differentiation a cell takes?
chemical signals
What does epigenetics influence?
chromatin structure/packing
What does gene expression and protein synthesis depend on?
chromosome packing
How does cilia differ from flagella?
cilia are not motile but are purely sensory
Phospholipase
cleaves fatty acids from phospholipids
Microtubule doublets
configurations of the microtubule that make up the axoneme (cilia and flagella: for motility)
myosin motor proteins
convert the potential energy in ATP into the kinetic energy of mechanical work
What regulates cdk activity?
cyclin concentration and the phosphorylation/dephosphorylation of cdk
What activates PKC?
diacyglycerol and Ca2+
How do cells become different?
differentiation by differential gene expression (this determines what proteins are made and what the cell will do.)
When is MPF activity the highest?
during M phase
reproductive cloning
embryo is implanted into surrogate mother and leads this embryo to develop into a clone
Protein Kinase C
enzyme that phosphorylates certain intracellular proteins when activated by diacylglycerol
terminal differentiation
final stage of a cell in which it is highly specialized; can no longer divide and make more cells
terminal differentiation
final stage of a cell in which it is highly specialized; can no longer divide and make more cells, common in nerve cells
what forms the nucleation site of the tubule?
gamma tubulin complex
A signal molecule is also known as a(n) _____.
growth factor
malignant
harmful
What are blood cells continually replaced from?
hematopoietic stem cells
Heterochromatin
highly condensed chromatin
What binds to receptors?
hormone or neurotransmitter
Mitogenesis
initiation of mitosis
IP3
inositol triphosphate
cytoplasmic intermediate filaments
keratins (epithelial cells), vimentin and vimentin-related (connective tissue and muscle cells) , and neurofilaments (nerve cells)
Dyneins in cilia and flagella
large motor proteins which are responsible for bending movements in an organelle, also drives microtubule sliding by hydrolyzing ATP
inositol phospholipid
lipid present at small concentrations in the plasma membrane that is converted into a second messenger; it has inositol (a carbohydrate) as its hydrophilic head group
Euchromatin
loosely packed chromatin
Are cytoplasmic Ca2+ concentrations low or high at rest?
low (they are high when active)
3 types of cytoskeleton
microfilaments (actin filaments), intermediate filaments, microtubules
Cilia and flagella are based on what?
microtubule complexes covered by plasma membrane
Where does microtubules originate from?
microtubule-organizing center
Order the three types of cytoskeleton based on size.
microtubules > intermediate filaments > microtubules
What is MAP?
mitogen activated protein
Dyneins
move toward - end (cell center)
Kinesis
move toward the + end (away from cell center)
What makes the structure of cilia and flagella strong?
multiple, microtubule doublets
Benign
not life threatening
Ran
nuclear import
What is the nuclear envelope supported by?
nuclear lamina
nuclear intermediate filaments
nuclear lamins (only in animal cells)
Microtubules
organize the interior of a cell
What does Cdk phosphorylate and activate?
origin of replication
P53 stimulates what?
p21 expression
What does DNA damage lead to?
p53 phosphorylation
Hormones that bind to intracellular receptors must be able to do what?
pass through plasma membrane
Therapeutic Cloning
personalized cells for tissue repair
What activates AKT
phosphatidylinositol 3-kinase
What does receptor tyrosine kinase activate?
phosphatidylinositol 3-kinase (which is used to phosphorylate inositol lipid)
What lipid docking site is produced from phosphatidylinositol 3-kinase?
phosphatidylinositol bis phosphate
How are microtubules maintained?
polymerization (powered by GTP hydrolysis) and depolymerization (GDP)
Proteins bind to actin and modify its properties by aiding in what processes?
polymerizing and depolymerizing
cross-linking proteins
possess 2 or more actin binding sites and join microfilaments into three-dimensional networks
Apoptosis
programmed cell death
What binds to actin filaments and aids in binding with other actin filaments?
proteins
RTK
receptor tyrosine kinase (phosphorylates tyrosine)
RTK
receptor tyrosine kinase, a growth factor receptor
Amyloid precursor protein (APP) made in the neurons are cleaved by what?
secretase (alpha, beta, gamma) proteases.
How do tumors arise?
sequential acquisition of mutations in genes that control cell growth
How can actin be depolymerized?
serving proteins or sequestering monomers
Telomere
short DNA repeats at the end of chromosomes that contain no genes, but protect from gene loss
Ras
signal-transducing GTPase
What does mutant keratin lead to?
skin blistering
What cells are born with a certain number of potential divisions?
somatic cells
What does actin filament networks provide?
strength and structure
What drug binds to stabilize microtubules?
taxol
Cellular senescence
the permanent inactivation of proliferation after programmed number of divisions
Rhodopsin
the pigment in rod cells that causes light sensitivity (light activated GPCR)
What is useful in determining what a cell has and how much?
transcription factor binding to enhancer sequence
protein kinase A (PKA) activates what?
transcription factor, which generates a long term response
What are nuclear receptors?
transcription factors leading to the synthesis of new proteins that will perform a physiological response
What are abnormal surface amino acids marked with?
ubiquitin
Where is nitric oxide produced?
vascular endothelium, nitric oxide stimulates cGMP synthesis to stimulate smooth muscle relaxation. (decrease pressure and increase flow)
Rab
vesicle targeting
When does apoptosis occur?
when cells are extremely damaged
Order of cell development
zygote, blastula, gastrula
