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