What are the characteristics of microtubules?

Largest filament, hollow tubes made of tubulin dimers (dimers made of protofilaments) , outer diameter of 25nm, more rigid than actin filaments

What are the functions of microtubules?

Facilitates intracellular transport, guides organelle movement, separates chromosomes in cell division, form structural basis for cilia & flagella (dyneins)

____________ is the main protein of microtubules

Tubulin

What are the characteristics of intermediate filaments?

Medium-sized filament made of fibrous proteins

What are the functions of intermediate filaments?

provides structural support, anchors organelles (nucleus), maintains cell to cell connections. Make up the nuclear lamina beneath the inner nuclear membrane, in epithelial tissue they span the cytoplasm from cell-cell junction

___________, ____________, & _____________ are the main proteins in intermediate filaments

Keratin, vimentin, lamins

What are the characteristics of microfilaments?

thinnest filament, helical polymers of the protein actin

What are the functions of microfilaments?

mainly involved in cell movement, muscle contraction, and maintaining cell shape, highly conc. in cortex (beneath plasma membrane)

__________ is the main protein of microfilaments

actin

Fimbrin is a-

actin linking protein in parallel bundle (doesn’t allow for myosin II). Abundant in GI tract

a-actinin is a-

actin-linking protein for support in cardiac and skeletal muscle (allows for myosin II).

Filamin is-

found in the nervous system, mutation can cause failure in neuron ventricles (aggregates)

Dyenin is a-

motor protein, moves retrograde (transports back to cell body, - end)

Kinesin is a-

motor protein that moves anterograde (away from the cell body, +end )

Mutation in vimentin can cause?

cataracts, cloudy lens, glaucoma

Mutation in desmin can cause?

mutations in cardiac muscle that can cause cardiomyopathy, enlarge heart chambers, leading to heart failure

Mutations in keratin can cause?

can cause loss of structure, can cause epidermolysis bullosa which is the development of blisters on the body and internally.

Mutations in lamins/desmin can cause?

muscular dystrophy, damage causes muscles to weaken, and can cause deformities in the skeletal system

Alexander disease is when-

leukodystrophy affects white matter of CNS

_____________ generates force by coupling ATP hydrolysis to conformational changes

Myosin

The sliding of myosin II along actin causes -

muscle contraction

when _____ is hydrolyzed, myosin ________ to troponin

ATP, binds

Where is Ca2+ released from during a muscle contraction?

released from lumen of SR --> cytosol --> lumen of t-tubule (extracellular space)

What is the purpose of mitosis, and what does it produce?

produces two identical daughter cells that have the same number of chromosomes as the parent cell, occurs in somatic cells, produces identical cells for growth and repair

What is the purpose of meiosis and what does it produce?

produces four different daughter cells with half the number of chromosomes as the parent cells, occurs in gametes, crossing over of homologous chromosomes leads to genetic diversity

What occurs in interphase?

cell growth and DNA replication

What occurs in the G1 phase?

cell growth

What occurs in the S phase?

DNA replication

What occurs in the G2 phase?

cont. cell growth, preparation for mitosis

What occurs in the M phase?

cell physically divides into two daughter cells by separating replicated chromosomes and dividing the cytoplasm

What occurs in prophase?

chromosomes made of sister chromatids condense

What occurs in prometaphase?

breakdown of the nuclear envelope, chromosomes attach to spindle microtubules

What occurs in metaphase?

chromosomes aligned at equator of the spindle; kinetochore attaches sister chromatids via. microtubules

What occurs in anaphase?

sister chromatids separate to form two daughter chromosomes, move to opposite poles

What occurs in telophase?

two sets of daughter chromosomes arrive at opposite poles and decondense, and a new nuclear envelope is formed

What is cytokinesis?

division of cytoplasm, divided into two by a contractile ring of actin and myosin filaments

What are the characteristics of a cyclin?

concentration varies, synthesized and degraded at certain points in the cell cycle

What are the characteristics of Cdks?

is INACTIVE without the cyclin, stable concentration, phosphorylates for activation

What is the function of the G1/S cyclin and where does it have the highest concentration?

initiates DNA replication through the transition of G1 -->S, highest conc. late G1

What is the function of the S cyclin and where does it have the highest concentration?

induction of DNA replication, highest conc. S --> G2, ends early mitosis

What is the function of the M cyclin and where does it have the highest concentration?

triggers cells' entry into mitosis, highest conc. at G2/M transition

What is a type of CKI?

p27

What is the function p27?

suppresses G1/S-Cdk and S-Cdk activites in G1, helps cells withdraw from cell cycles.

What are some types of protein kinases/phosphatases?

Wee & Cdc25

What is the function of wee?

Phosphorylates inhibitory sites in Cdks, suppresses Cdk1 activity before mitosis

What is the function of Cdc25?

removes inhibitory phosphates from Cdks, mainly involved in controlling Cdk1 activation at the onset of mitosis

What is a type of ubiquitin ligase?

APC/C

What is the function of APC/C?

catalyzes ubiquitination of regulatory proteins involved in exit from mitosis (securing and S- & M-cyclins

What is centrosome duplication?

creates the poles of the mitotic spindle (S phase)

Cohesin-

holds sister chromatids together during DNA replication (until cell reaches anaphase)

What is the purpose of the kinetochore?

attaches chromosomes to spindle microtubules to ensure separation during cell division

Apoptosis is __________________ cell death

programmed

What are some characteristics of apoptosis?

Active process, a natural process that occurs during development and aging, non-inflammatory, cell shrinks and nucleus condenses, plasma membrane blebs but remains intact

What are some characteristics of necrosis?

Passive process, inflammatory, caused by external factors such as injuries, infections, diseases, cell and mitochondria swells, plasma membrane loses its integrity, Can be fatal if left untreated

Necrosis is ________________ cell death

accidental

Initiator caspases 8 & 9 are-

key enzymes in the apoptotic pathway, acting as the first step in triggering programmed cell death by activating downstream executioner caspases

Initiator 8 is mainly involved in-

apoptotic pathway triggered by death receptors

Initiator 9 initiates a pathway triggered by what?

mitochondrial damage

Executioner caspases 3,6,7 are-

key enzymes responsible for the direct cleaving and dismantling various cellular proteins to execute cell death, amplifies response via proteolytic cascade

The adaptor binding domain allows-

binding to other proteins, acting as a bridge to connect different signaling molecules within a cellular pathway

Which enzyme is responsible for breaking down DNA during apoptosis?

Caspase-activated deoxyribonuclease (CAD)

What acts as a chaperone protein that keeps CAD inactive until it is cleaved by caspases?

Inhibitor of Caspase-Activated Deoxyribonuclease (ICAD)

Fas and TNF (tumor necrosis factor) are-

proteins that play crucial roles in cell death pathways

What is the function of Fas?

induces cell death through interaction with Fas receptor

What is the function of TNF?

can trigger various cellular responses including inflammation and apoptosis depending on the receptor it binds to

The Fas death receptor is a-

homotrimer protein located on the target cell that triggers apoptosis (after it is activated by the FAS ligand on a lymphocyte)

What is FADD ( Fas-associated protein with death domain)

an adaptor protein that is a central component of the death-inducing signaling complex (DISC) that mediates that activation of caspase 8

The death effector domain is a-

protein-protein interaction domains that regulate apoptosis, component of the DISC to trigger apoptosis

What is DISC (death-inducing signaling complex)?

a multiprotein complex that triggers apoptosis, composed of: death receptor, FADD, procaspase-8, cFLIP

What occurs in the intermembrane space in apoptosis?

cytochrome C floats around as an apoptotic stimulus

What occurs in the outer mitochondrial membrane in apoptosis?

allows the release of pro-apoptotic proteins like cytochrome C from the intermembrane space into the cytosol, triggering the cascade of events leading to cell death

What is the function of cytochrome C in apoptosis?

is released into the cytoplasm when a cell receives apoptotic signals, where it then binds to Apaf-1 to activate the caspase cascade

___________ activates after binding to cytochrome c, forming a complex called the apoptosome, which recruits Caspase-9 and activates initiating the caspase cascade

Apaf-1 (apoptotic protease activating factor-1)

What is the role of caspases in apoptosis?

activate via proteolytic cleavage during apoptosis, dismantle the cell into apoptotic bodies

The Bcl-2 protein family -

regulates apoptosis by acting as either inhibitors or promoters of cell death. Bcl –2 -> anti-apoptotic

Inhibitor or apoptosis proteins (IAPs) are-

a family of proteins that regulate cell death and survival by blocking caspases

What is the function of a tight junction?

seals gap between epithelial cells, prevents substances from seeping through, found towards apical surface

What is the function of an Adherens junction?

connects actin filament bundle in one cell with one in the adj cell

What is the function of desmosomes?

connects intermediate filaments in one cell to those in the next cell.

What is the function of gap junctions?

allows the passage of small water-soluble molecules from cell to cell, electrically connects cells to each other/ communication

What is the function of hemidesmosomes?

anchors intermediate filaments in a cell to the extracellular matrix (basal layer)

Cadherins are-

transmembrane cell adhesion proteins, form connections between adjacent cells, more cadherins = connection stability

Catenins are-

intracellular proteins that link cadherins to actin cytoskeletons, anchors cells together for coordinated cell behavior in a tissue by maintaining adhesion and communication.

Proteoglycans-

made of GAG (glycosaminoglycan chains)

Fibrous proteins consist of __________

collagen

Glycoproteins consist of ____________

integrins

Integrin α 7 β 1 is a ___________ found in __________. An α mutation can cause __________________ while a β mutation can cause ___________________

Lamin, muscle, muscular dystrophy, embryo death at implantation

Integrin α L β 2 is a ___________ found in __________. An α mutation can cause __________________ while a β mutation can cause ___________________

Ig superfamily counterreceptor (ICAM), white blood cells, impaired recruitment of leucocytes, leucocyte adhesion deficiency & impaired inflammatory responses.

Integrin α IIb β 3 is a ___________ found in __________. An α mutation can cause __________________ while a β mutation can cause ___________________

Fibrinogen, platelets, Bleeding, no platelet aggregation (Glanzmann’s disease), Mild osteoporosis (otherwise same as the α mutation)

Integrin α 6 β 4 is a ___________ found in __________. An α mutation can cause __________________ while a β mutation can cause ___________________

Laminin, hemidesmosomes, Severe skin blistering and defects in other epithelia , Same as α mutation

(matching) Adherens junction

Cell junction in which the cytoplasmic face of the plasma membrane is attached to actin filaments.

(matching) Anaphase promoting complex (APC/C)

Ubiquitin ligase that catalyzes the ubiquitylation and destruction of securin and M- and S-cyclins, initiating the separation of sister chromatids in the metaphase-to-anaphase transition during mitosis.

(matching) Apoptosome

Heptamer of Apaf1 proteins that forms on activation of the intrinsic apoptotic pathway; it recruits and activates initiator caspases that subsequently activate downstream executioner caspases to induce apoptosis

(matching) Cadherin

Member of the large cadherin superfamily of transmembrane adhesion proteins. Mediates homophilic Ca2+-dependent cell–cell adhesion in animal tissues.

(matching) Caspase

Intracellular protease that is involved in mediating the intracellular events of apoptosis

(matching) Cell cycle

Reproductive cycle of a cell. The orderly sequence of events by which a cell duplicates its chromosomes and usually the other cell contents, divides into two.

(matching) Cell division cycle 25C (Cdc 25):

Protein phosphatase that dephosphorylates Cdks and increases their activity

(matching) Centriole

Short cylindrical array of microtubules, closely similar in structure to a basal body. A pair of centrioles is usually found at the center of a centrosome

(matching) Centrosome

Centrally located organelle of animal cells that is the primary microtubule-organizing center (MTOC) and acts as the spindle pole during mitosis

(matching) Chromosome

Structure composed of a very long DNA molecule and associated proteins that carries part (or all) of the hereditary information of an organism.

(matching) Cohesin

Complex of proteins that holds sister chromatids together along their length before their separation

(matching) Collagen

Fibrous protein rich in glycine and proline that is a major component of the extracellular matrix in animals, conferring tensile strength.

(matching) Connexon

Water-filled pore in the plasma membrane formed by a ring of six connexin protein subunits. Half of a gap junction: connexons from two adjoining cells join to form a continuous channel through which ions and small molecules can pass

(matching) Cyclin dependent kinase (Cdk):

Protein kinase that has to be complexed with a cyclin protein in order to act. Different cyclin–Cdk complexes trigger different steps in the cell-division cycle by phosphorylating specific target proteins

(matching) Cyclins

Protein that periodically rises and falls in concentration in step with the eukaryotic cell cycle. Cyclins activate crucial protein kinases (called cyclin-dependent protein kinases, or Cdks) and thereby help control progression from one stage of the cell cycle to the next.

(matching) Cytoskeleton

System of protein filaments in the cytoplasm of a eukaryotic cell that gives the cell shape and the capacity for directed movement. Its most abundant components are actin filaments, microtubules, and intermediate filaments

(matching) Death receptor

Transmembrane receptor protein that can signal the cell to undergo apoptosis when it binds its extracellular ligand

(matching) Desmosome

Anchoring cell–cell junction, usually formed between two epithelial cells. Characterized by dense plaques of protein into which intermediate filaments in the two adjoining cells insert.

(matching) Elastin

Extracellular protein that forms extensible fibers (elastic fibers) in connective tissues.

(matching) Fimbrin

cytoskeletal protein that crosslinks actin filaments

(matching) Gap junction

Communicating channel-forming cell–cell junction present in most animal tissues that allows ions and small molecules to pass from the cytoplasm of one cell to the cytoplasm of the next.

(matching) Glycosaminoglycan (GAG):

Long, linear, highly charged polysaccharide composed of a repeating pair of sugars, one of which is always an amino sugar

(matching) Inhibitor of caspase-activated DNase (iCAD):

a protein that prevents the DNA-degrading enzyme caspase-activated deoxyribonuclease (CAD) from breaking down DNA.

(matching) Interphase

Long period of the cell cycle between one mitosis and the next. Includes G1 phase, S phase, and G2 phase.

(matching) Kinesin

Member of one of the two main classes of motor proteins that use the energy of ATP hydrolysis to move along microtubules.

(matching) Kinetochore

Large protein complex that connects the centromere of a chromosome to microtubules of the mitotic spindle.

(matching) Laminin

Extracellular matrix fibrous protein found in basal laminae, where it forms a sheetlike network.

(matching) Meiosis I

The first of two rounds of chromosome segregation following meiotic chromosome duplication; segregates the homologs, each composed of a tightly linked pair of sister chromatids.

(matching) Meiosis II

The second of two rounds of chromosome segregation following meiotic chromosome duplication; segregates the sister chromatids of each homolog

(matching) Mitosis

cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus typical of ordinary tissue growth.

(matching) Motor protein

Protein that uses energy derived from nucleoside triphosphate hydrolysis to propel itself along a linear track

(matching) Myosin

Type of motor protein that uses the energy of ATP hydrolysis to move along actin filaments.

(matching) Proteoglycan

a molecule consisting of one or more glycosaminoglycan chains attached to a core protein.

(matching) p53

A transcription regulatory protein that is activated by damage to DNA and is involved in blocking further progression through the cell cycle

(matching) Sister chromatid

Tightly linked pair of chromosomes that arise from chromosome duplication during S phase. They separate during M phase and segregate into different daughter cells

(matching) Tight junction

Cell–cell junction that seals adjacent epithelial cells together, preventing the passage of most dissolved molecules from one side of the epithelial sheet to the other.

(matching) Tubulin

The protein subunit of microtubules