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Cell Biology-Test 4
Chapters 17,18,20
| Question | Answer |
|---|---|
| Cilia and flagella contain stable microtubules moved by | dynein |
| The main supporting structure | microtubules |
| What is dynein | a motor protein |
| Dynein walk along | microtubules |
| In normal flagellum dynein causes | microtubule bending |
| In isolated doublet microtubules dynein produces | microtubule sliding |
| Microtubules all originate from | the basal body |
| What are the 3 major types of protein filaments | Intermediate filaments, microtubules, and actin filaments (microfilaments) |
| Microfilaments (Actin) are involved in | movement, plasma membrane structure |
| Microfilaments involvement in movement includes | vesicles, proteins, contraction, and cytokinesis |
| Microfilaments involvement in plasma membrane structure include | phagocytosis and microvilli |
| Actin filaments are | thin and flexible |
| Actin utilizes | ATP |
| Cell crawling depends on | actin |
| The plus end of actin filaments are the | growing ends |
| Proteins bind to actin and aid in | polymerizing, depolymerizing or binding with something |
| Nucleating proteins and monomer sequestering proteins are | regulating |
| When don't want a single actin filament to move much use | side-binding proteins |
| Bundling proteins make for | a stronger structure of a bunch of actin filaments |
| When want a sheet of actin filaments use | cross-linking proteins |
| To break up actin filaments and get them to begin depolymerizing use | severing proteins |
| Actin- rich cortex underlies | plasma membrane of most eucaryotic cells |
| Structure of plasma membrane is determined by | what it is wrapped around |
| Tread-milling motion of actin filaments (polymerization) | ATP- actin with bound ATP- acting with bound ADP- ADP moves it forward (removes from the back and add to the front) |
| Actin polymerization to push out | pseudopods to move forward |
| Contractile bundles | positive and negative ends are in opposite directions |
| Lamellipodium | monomers being added on to end, moving forward |
| Membrane ruffling exemplifies | membrane fluidity, how membrane is shaped by underlying cytoskeleton, and rapid restructuring of microfilaments |
| What is the basis of amoeboid movement | actin meshwork in leading edge of lamellipodium |
| Each monomer added requires | an ATP |
| Extracellular signals control the | arrangement of actin filaments (can restructure) |
| Depending on which GTP binding protein is activated will determine | the arrangement of actin filaments |
| If you're not prepared to be wrong, you'll never come up with anything original | Ken Robinson |
| Actin associates with what to form contractile structures | myosin |
| In muscle contraction | myosin filaments pull on actin filaments |
| Cytokinesis in animal cells is carried out by | contractile bundles of actin and myosin |
| Creative people have much more confidence in their imaginative leaps. Their intuition. | Laurel Cutler |
| Typical cell division is | nuclear replication (mitosis) and cell division (cytokinesis) |
| Cells can divide without | DNA replication |
| Cells can replicate the DNA without | cell division |
| Cell cycle | 1. cell growth and chromosome replication 2. chromosome segregation 3. cell division |
| Interphase | M phase, G1 phase, S phase, G2 phase |
| Apoptosis may be initiated internally by | cell damage or stress |
| Apoptosis may be initiated externally by | pro-apoptotic factors like tumor necrosis factor |
| One thing that leaks out of the mitochondria when the cell becomes damaged | cytochrome c |
| Synthesis of cyclin is stimulated prior to | mitosis and concentration builds |
| cyclin may be | MPF |
| The cell cycle control system depends on cyclically activated protein kinases called | cyclin dependent kinases (cdks) |
| CDK activity is regulated by | cyclin concentration and cdk phosphorylation/dephosphorylation |
| What initiates DNA replication | s-cdk |
| s-cdk helps block | re-replication |
| cdk phosphorylates cdc which allows | dna polymerase to replicate the DNA |
| cyclin concentration depends on | rate of synthesis and breakdown |
| Proteolysis | cyclin is quickly recognized for breakdown, ubiquitin molecules added, cyclin broken down becoming inactive |
| Mitogens inhibit | mitosis inhibitor (tumore supressor protein) Rb |
| Rb is a tumor supressor protein that blocks | transcription of cell cycle proteins |
| Rb is regulated by | phosphorylation by cdk |
| p53 is a transcription factor for | cdk inhibitors |
| cdk inhibitors are | tumor supressor proteins |
| cdki's block | asesembly and action of cyclin/cdks |
| Some extracellular signal proteins inhibit | cell survival, division, or growth (lack of myostatin) |
| programmed cell death (apoptosis) helps regulate | animal cell numbers and get rid of severely damaged cells that may act inappropriately |
| animal cells require _________ to survive, grow, and divide | extracellular signals |
| necrosis | random cell decay, harmful |
| apoptosis | systematic dismantling of cell components, helpful |
| following apoptosis, resulting "blebs" are removed by | phagocytic cells |
| animal cells require what to avoid apoptosis | survival factors |
| Bcl-2 family includes | pro-apoptotic proteins and anti-apoptotic proteins |
| Bad sequesters | cell death |
| phosphorylation of bad, release of active Bcl2 inhibits | apoptosis |
| What proteins can stimulate apoptosis through mitochondrial leakage of cytochrome C? | Bcl-2 proteins Bax and Bak, key indicator of cell damage |
| apoptosis is signaled by a | proteolytic cascade of caspases |
| Activation of procaspase-9 within apoptosome leads to | caspase cascade leading to apoptosis |
| procaspase is cleaved and assembled into a complex resulting in | one active caspase molecule (not a random process) |
| signal molecule in cell division acts as a | growth factor |
| RTK in cell division acts as a | growth factor receptor |
| What factor in the cytoplasm of mitotic cells was shown to stimulate mitosis in "quiescent" cells? | MPF |
| Proteolysis is involved in cells how | digestion for food and remodeling removal of unfolded or damaged proteins activation of proteins made in a precursor form signal transaction breakdown of proteins no longer needed |
| Replicative senescence | the permanent inactivation of proliferation after programmed number of divisions |
| Exceptions to replicative senescence | gametophytes, regenerating tissues (gut lining, skin) |
| Germ cells and stem cells express telomerase to | maintain telomere and extend lifespan |
| The world is but a canvas to the imagination | Henry David Thoreau |
| Its kind of fun to do the impossible | Walt Disney |
| Cells become different through | differentiation/ differential gene expression |
| The genes in a single cell are replicated for all | progeny cells |
| What are the three main factors determining cellular organization of tissues? | communication, adhesion, memory |
| Adhesion | whether cells are bound and what they bind to influences which genes are expressed and how much |
| How do cells remember how many times they have divided? | telomeres |
| Gene expression and protein synthesis depend on | chromosome packing |
| Chromosome packing depends heavily on | epigenetic modifications to histones and DNA |
| What determines chromatin packing and gene expression | phosphorylation, methylation and acetylation of histones and methylation of DNA |
| Stem cells generate a continuous supply of | terminally differentiated (tissue) cells |
| Blood cells are continually replaced from | bone marrow stem cells |
| In epithelium, Wnt maintains | stemness (being a stem cell) |
| What cells can become any body cell? | cells in inner cell mass of blastocyst |
| Chemical signal determine | which route of differentiation is taken |
| What is a way to provide personalized embryonic stem cells | therapeutic cloning |
| Process of therapeutic cloning | patients cell nucleus is injected into an enucleated egg, grown in culture to blastocyst, certain cells are grown in defined medium to push cells to differentiate into needed cell type |
| In reproductive cloning the embryo is implanted into | surrogate mother and leads this embryo to develop into a clone |
| Cancer is a disease of | mitosis, excessive cell division |
| Most cancers are stopped by | cellular senescence, apoptosis or the immune system |
| Viruses can cause | gene duplications, translocations to other promoters, mutation |
| Chemical carcinogens can induce | mutations, or affect gene over-expression |
| Cancer cells may | proliferate, invade, or metastasize |
| Chromosomal rearrangements due to genetic instability are common in | malignant cancers |
| Cancers develop by an | accumulation of genetic mutations |
| Tumor suppressor genes block | cell division, too inactive |
| Proto-oncogenes promote | cell division- too active |
| BRCA1 | breast cancer |
| Intermediate filaments provide | resistance for/to mechanical stress in cell and attachment and provide an underlayerment for the nuclear membrane |
| Intermediate filaments are | strong and rope like complexes of filament proteins |
| Intermediate filaments strengthen cells by helping create a | protein network that permeates a tissue right through cell membrane via transmembrane proteins |
| The nuclear envelope is supported by | meshwork of intermediate filaments |
| Microtubules provide what 3 things | scaffolding, transportation, organization within cell |
| What is the site of microtubules origination | the centrosome (a mass of amorphous proteins) |
| Centrioles are small clusters of | microtubules |
| What powers the maintenance of microtubules | GTP |
| Alzheimers disease is characterized by aggregation of | beta-ameloid proteins into ameloid plaques |
| Plaques activate the immune system thereby | activating inflammation |
| The inflammation in Alzheimer's disease damages the neurons and causes | phosphorylation and self aggregation of tau |
| Tau dissociates from | microtubules causing microtubule breakdown and neurite retraction |
| Drugs that stabilize or destabilize microtubules in mitosis disrupt | spindle fiber function and lead to cell death (useful in treating cancer) |
| What drives intracellular transport? | motor proteins |
| Motor proteins use what to move | ATP |
| KInesins move toward the | plus end |
| dyneins move toward the | negative end |
| Rho, Rac and cdc42 are all | GTP binding proteins |
| Go is when cells | exit cell cycle and become quiescent |
| S checkpoint checks | density, attachment problems, cell shape, cell damage, nutrients |
| MPF activity is highest in which phase? | M phase |
| Cyclically activated protein kinases are called | cyclin-dependent kinases (cdks) |
| p53 is a transcription factor for | cdk inhibitors |
| cdki's block assembly and action of | cyclin/ cdks |
| Tumor Necrosis Factor produces | a lot of inflammation and induces apoptosis |
| Bax and Bak can stimulate apoptosis through | mitochondrial leakage of cytochrome C which is a key indicator of cell damage |
| plant cell walls are built primarily of | cellulose (glucose polymer) |
| What gives the plant wall its tensile strength? | microfibrils |
| INK4 | melanoma, pancreatic |
| RB | retinal |
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