module 5 Flashcards

Question

cross-linking proteins

Answer 1

Actin binding proteins promote formation of loose networks of filaments

Answer 2

Actin binding proteins decrease viscosit of cytoplasm

Answer 3

Cytokinesis Phagocytosis Cytoplasmic streaming Vesicle trafficking Cell-substratum interactions Cell locomotion Axonal growth Chnges in cell shape

Answer 4

* ATP is important * Barded end incorporates monomer at faster rate * Barded and pointed ends require different [ATP-actin monomer] to elongate: * Barded needs less * Steps: * Add preformed actin filaments to the solution of actin in the presence of ATP * If [ATP] is high, actin is added at both ends * Addition continues only at the barded end because [ATP] is only high enough for addition at that end * Addition continues at the barded end, but loss of the monomer occurs at the point end to respond to the decrease in free monomers * Addition/removal rates change to maintain free monomer concentration stable

Answer 5

* Head: * Contains: * Site that binds an actin filaments * Site that hydrolyses ATP to drive the mysosin motor * Tail: * Divergent and different in various types * Variety of light chains

Answer 6

* Primarily motors for muscle contraction * Can be found in non-muscle cells: * Move towards barded end * Function in non-muscle: * Split the cell into two * Generate tension at focal adhesion * Cell migration * Ends of tails point towards the center of the filament and the globular heads point away from the center

Answer 7

* Subdivided into 17 different classes * Contains single head * Unable to assemble into filaments in vitro * Can exert tension on plasma membrane * Unable to form filament * Operate as inidivual proteins

Answer 8

* Interphase: * G1: * Cell grows and carries out normal metabolism * Organelles duplication * S phase: * DNA replication * Chromosome duplication * G2: * Cell growth * Preparation for mitosis * Mitosis: * PMAT: * Duplicated chromosomes are separated into 2 nuclei * + cytokinesis: * Division of the entire cell into 2 daughter Cell cycles vary among different types of cell depending on the cell type and environmental conditions

Answer 9

_@ end of G1:_ * First transition pt START * If pass-\> commited to the DNA replication * Uses Cdk _@ end of G2:_ * Uses mitotic cyclins _Middle of mitosis:_ * Determines if they'll complete cell division of reenter G1 of the next cycle

Answer 10

* Ensures that DNA is not damaged * Stop the progress of cell cycle if: * DNA is damaged * Critical processes have not been properly completed * Activated by the system of sensors that recognize DNA damage or cellular abnormalities * Cell stops its progress at one of those check points via Cdk inhibitor

Answer 11

* Cells that are arrested in the state of no cell division (temporarily or permanent) preceding the initiation of DNA synthesis * Ex. nerve cells, muscle cells, RBC (b/c highly specialized and lost the ability to divide)

Answer 12

* Cyclin dependent kinases are enzymes that phosphorylate other protein and regulate cell cycle * Regulated by: * Presence of specific cyclins: * Required subunits for specific Cdk activities * Levels of cyclins that vary throughout the cell cycle partially controlling the activity of Cdks and secondarilly controlling the activities of the substrates phosphorylated by those specific Cdks * Other kinases, which phosphorylate them result in activation/deactivation depending on state of phosphorylation * Phosphatases dephosphorylate them * May inhibit/activate some Cdks * Subcellular localization may separate Cdks from their substrates or create microenvi for them * CDK inhibitors * Cdks can be targeted for degradation (ex. by ubiquitin-proteasome pathway)

Answer 13

* Chromosomes condense * Formation of compact mitotic chromosomes * Chromosomes composed of two chromatids attached together at centromere * Golgi and ER fragment * Nuclear envelope dissapeares

Answer 14

Chromosomal microtubules attach to the kinetochores pf chromosomes Chromosomes are moved to spindle equator

Answer 15

Chromosomes alligned at metaphase plate Chromosomes attached to both poles by the microtubules

Answer 16

Centromere splits Chromatids separate Chromosomes move to the opposite spindle poles Spindles poles move further apart

Answer 17

Chromosomes cluster at opposite spindle poles Chromosomes become dispersed Nuclearenvelope assembles around chromosome cluster Golgi and ER reform Daughter cells form by cytokinesis

Answer 18

* Primary constrictions in chromosomes * Residence of highly repeated DNA sequence * Serves as binding site for specific proteins * Has kinetochore:

Answer 19

* On the outer surface of centromere of each chromatid * Proteinaceous * Button-like * Function: * Residence of motor proteins involved in the chromosome motility: * Dynein * CENP-E * Depolymerase * Site of attachment of chromosome to the dynamic microtubules of mitotic spindle * Key component in the signalling pathway of an important mitotic checkpoint

Answer 20

initiate microtubule assembly that is responsible for formation of mitotic spindle

Answer 21

* Net addition of tubulin at + end (@ kinetochore side) * Net loss of tubulin @ - end * Subunits move along the chromosomal microtubules from kinetochore towards the pole * happens during metaphase

Answer 22

* Adds ubiquitin to proteins at different stages of the cell cycle targeting them for proteolysis * Adaptor protein: * Determines which proteins serve as APC substrates * APC-Cdc20: * APC-Cdh1:1 * The importance of targeted proteasome-mediated proteolysis in progression thru mitosis: * Completion of mitosis requires the cessation of activity of Cdk1

Answer 23

* In animal cells forms a furrow that moves inwards towards the center of the cell * In plants: form cell plate: * Secretory vesicles from Golgi align along the equatorial plane and begin to fuse with one another * Membrane of the vesicle become plasma membrnae * Content of the vesicle forms the cell plate separting cells * Role of actin filaments: * Becomes assembled in a ring at the cell equator * Contraction of the ring requires action of myosin -\> formation of furrow that splits the cell in two * Are concentrated in a circular equatorial band within cleavage furrows

Answer 24

Reduce # chromosomes Increase genetic variability

Answer 25

formation of tetrads (synapsis b/ homologous chromosomes) cross-over @ chiasmata movements of tetrads towards the metaphase plate begins

Answer 26

* Two homologous chromosomes of tetra are connected to the spindle fibers from opposite pole * Sister chromatids are connected to the microtubules from the same spindle * Side-by-side arrangement of kinetochores

Answer 27

Anaphase I: * Homologous chromosomes separate * Dissolution of chiasmata by proteolytic cleavage of cohesin Telophase I: * Chromosome dispersion, but don't reach very extended states * Nuclear envelope may/not reform fully

Answer 28

Kinetochores of sisters chromatids face opposite pole and are atached to the opposite sets of chromosomal spindle

Answer 29

separation of sister chromatids

Answer 30

In mitosis: * Pait of homologous chromosomes * Genetically identical to the mother cell In meiosis: * Contain one chromosomes from each pair of homologous chromosomes contained by parental cell * Have the potential to be genetically different from parent chromosomes

Answer 31

Process in which info carried by extracellular messengers is translated into changes that occur inside the cell

Answer 32

* GTP-binding proteins * Associated with: * Vesicle budding * Microtubule dynamics * Protein synthesis * Nucleoplasmic transport * Recognized by G protein-coupled receptos (GPCRs) that are composd of transmembrane alpha helices: * Capable of binding a large variety of ligands * Active when bound to GTP Inactive when bound to GDP

Answer 33

* **Ligand** binds to the receptor * Alters receptor conformation -\> i**ncreases affinity for G protein** * G protein **alpha: GDP out, GTP in** * G protein **alpha dissociates** from beta and gamma * **Alpha-GTP binds to the effector (adenyl cyclase)** * **Activation of adenyl cyclase** * **Beta and gamma G protein bind to adenyl cyclase** * **Activated adenyl cyclase: ATP-\>cAMP** * GTPase hydrolyses **GTP-\>GDP and deactivates alpha G** protein * **G alpha reassociates w/ G beta and gamma** * **Adenyl cyclase stops its activity** * GRK **( G protein-coupled receptor kinase) phosphorylates receptor with use of ATP** * **Arrestin** binds to the receptor inhibiting it from activating more G proteins * **Receptor-arrestin taken up by endocytosis**

Answer 34

Involved in: * Regulation of cell growth * Cell division * Cell differentiation * Cell survival * Attachment to extracellular matrix * Migration of the cells Expression of mutant protein tyrosin kinase can't be regulated and leads to CA

Answer 35

Less orderly than apoptosis Swelling of both cell and its internal membranous organelles Membrane breaks Leakage of cell content Inflammation

Answer 36

Neat abd orderly process: * Overall shrinkage in volume of cell and nucleus * Loss of adhesion to neighboring cell * Formation of blebs * Dissection of chromatin into small fragments * Rapid phagocytosis

Answer 37

* Process by which info is relayed across the plasma membrane to cell interior * Often this info is transmitted to the nucleus * Include: * Recognition of the stimulus * Transfer of signal across the plasma membrnae * Transmission of signal to specific effector * Cessation of the response

Answer 38

* Substance that is released into the cell as the result of binding of the 1st messanger (hormone or ligand) to a receptor outside the cell * Include: * cAMP * IP3 * Ca2+ * DAG * Nitric oxide

Answer 39

* Is a G protein that is part of many pathway controlling cell growth * Needs to be quickly turned off after activation * In oncogenes, changes to Ras causes ot to be permanently on -\>uncontrolled growth w/t differentiation -\>tumor * Pathways are activated when growth factor bind to the extracellular domain of its receptor

Answer 40

Grow in multilayered clumps Continue to grow regardless the presence/absence of exogenous growth factors Unable to respond to inhibitory signals from neighboring cells

Answer 41

* Chemical mutagens * UV radiatino (forms thymidine dimers) * DNA- and RNA-tumor viruses: * Effects are more complicated * Some can induce transformation b/c they have appropriated cellular genes that can hinder cells' growth control function * Inherited mutation * Diet: * Can increase or decrease risk of CA

Answer 42

From DNA damage caused by normal metabolic rnx that the cell unable to repair

Answer 43

* Malignant tumors tend to metastasize * CA cells have lost their growth control, and have following growth properties: * Grow in multilayered clumps * Continue to grow regardless the presence/absence of exogenous growth factors * Unable to respond to inhibitory signals from neighboring cells * CA cell often have highly aberrant chromosomes (aneuploidy), while healthy cells have a pair of identical chromosomes *

Answer 44

tumor suppressor genes oncogenes proto-oncogenes

Answer 45

* Act as cell's brakes * Encode proteins that restrain cell growth and prevent cells from becoming malignant * If copies of the mutatte tumor suppressor genes on both homologous chromosomes -\> loss of growth control * **Loss-of-function mutatio**n **on both homologous-**\>CA

Answer 46

* Encode proteins that promote the loss of growth control and the conversion of cell to a malignant state * Accelerators of cell proliferation * Lead to genetic instability * Prevent cell from apoptosis * Promote metastasis * Act dominantly (o**nly need mutant copy on one of the homologous**

Answer 47

* Have the potential to subvert cell own activities and push the cell towards the malignant state * Encode proteins that have various function in cell normla activities * Can be converted into the oncogenes: * Mutation that will alter the properties of the gene product * Multiple duplication -\> gene amplification -\> excess products * Chromosome rearrangement -\>altered gene expression * After gain-of-function mutation-\>oncogene

Answer 48

* RB gene is ex. of tumor suppressor gene * Nonfamiliar ex of disease: * Sporadic cases * Person begins life w/ normal RB genes in zygote * Retinoblastoma occurs only in whom a given retinal cell accumulates independent mutation in both alleles of the gene * Familiar ex of disease: * Ex inherited * Abnormal allele in the zygote of the RB gene (usually present as a deletion) * All cells of the retina have at least one unfunctional RB gene * If the other gene is inactivated (ex. point mutation)-\>CA

Answer 49

Receptor for growth factors Protein kinases and proteins that activate proteins kinass Proteins that regulate cell cycle Transcription factors Proteins that modify chromatin Metabolic enzymes Proteins that inhibit apoptosis

Answer 50

mutant forms of cytoplasmic protein kinases Receptor protein kinases GTP-binding proteins

Answer 51

* A benign tumour is composed of cancer cells that lack the capability to invade normal tissues or metastasize to distant cells * a malignant tumour tends to metastasize.

Answer 52

* A tumour-suppressor gene encodes proteins that restrain cell growth and prevents cells from becoming malignant, * an oncogene encodes proteins that promote the loss of growth control and the conversion of a cell to a malignant state.

Answer 53

* Proto-oncogenes are a variety of genes that have the potential to subvert the cells own activities, and push the cell toward a malignant state. They can be converted into oncogenes. * An oncogene encodes proteins that promote the loss of growth control and the conversion of a cell to a malignant state.

Answer 54

Progression of a cell through the cell cycle Adhesion of a cell to its neighbours Apoptosis Repair of DNA damage Cell-to-cell communication

Answer 55

* A gene mutation alters the structure and function of the encoded protein. * A mutation in a nearby regulatory sequence alters the expression of the gene. * A rearrangement of DNA brings a new DNA segment closer to the proto-oncogene, which results in an inappropriate transcription of the proto-oncogene by the promoter of the transposed gene.

module 5 Flashcards

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