Prokaryotic vs. Eukaryotic Cells

• Prokaryotic cells are simpler and smaller than eukaryotic cells.
• Most prokaryotes are unicellular and possess one circular chromosome.
• Prokaryotic cytoplasm is enclosed by a plasma membrane and a peptidoglycan cell wall
• Prokaryotes lack membrane-bound organelles, an endomembrane system, and distinct interior compartments.
• Protein synthesis in prokaryotes occurs via ribosomes in the cytoplasm.
• Eukaryotic cells feature a distinct, membrane-encased nucleus and are characterized by compartmentalization, membrane-bound organelles, and an endomembrane system.
• The nucleus in eukaryotes facilitates intense rRNA synthesis, having a bilayer structure with its nuclear membrane continuous with the ER; the nuclear pore complex enables larger molecules to traffic in and out.
• Eukaryotic ribosomes assemble in nucleoli; which are the site of protein synthesis.
• The endomembrane system includes the ER where the rough ER (rER) secretes proteins, and the smooth ER (sER) synthesizes lipids; the Golgi apparatus, derived from the ER, collects, packages, and distributes molecules from its cis to trans face.
• Vesicles from the rER and sER transport proteins.
• Lysosomes contain hydrolytic enzymes and maintain an acidic environment.

Chapter 1 Key Points

• Fluorescence microscopy allows human and mouse proteins to be distinguished when tagged with different fluorescent markers.
• Cell Theory states that cells are the smallest unit of life, organisms consist of one or more cells, and cells arise from pre-existing cells via growth and division.
• Mitochondria and the nucleus are unique eukaryotic cellular components that evolved through endosymbiosis.
• All cells possess a cell membrane and ribosomes.
• The cell wall is an antibiotic target in bacterial cells.
• Proteins controlling cell division in yeast and humans are functionally equivalent and highly conserved over a billion years.

Chapter 8 Enzyme Activity Study

• Researchers measured enzyme F activity in mouse tissues by quantifying product per milligram of tissue per unit of time.
• Liver tissue exhibits more product generation than kidney and muscle tissues.
• Observed differences arise from variations in gene transcription, post-translational modifications, and mRNA translation among tissue types.
• Genes expressed in both organs encode for housekeeping proteins.
• Altered complementary nitrogenous bases would diminish interaction integrity due to impaired hydrogen bond formation.
• While expressing different genes and proteins; liver and brain cells contain the full organism's instructions.
• CAP but not the Lac repressor binds to the Lac operon's regulatory DNA and expresses the Lac operon when lactose is present but glucose is absent in E. coli.
• High intracellular tryptophan levels activate the tryptophan repressor to halt the tryptophan operon expression in bacterial cells.
• Tryptophan repressor protein gene expression is constitutive.

Key Membrane Terms

• Amphipathic molecules possess both hydrophobic and hydrophilic regions, like phospholipids and detergents.
• Phospholipids, the primary lipid in cell membranes, typically comprise two fatty acid tails linked to a phosphate-containing polar group.
• Phosphatidylcholine is an abundant phospholipid in cell membranes, featuring choline attached to a phosphate head group.
• Membrane protein are proteins associated with the lipid bilayer of a cell membrane.
• Membrane domain are functionally and structurally specialized regions in the membrane; the distinctive proteins characterize them.
• Cholesterol is a rigid lipid in animal cell plasma membranes that reduces bilayer flexibility.
• Bacteriorhodopsin is a pigmented protein abundant in the plasma membrane of Halobacterium halobium.
  • Bacteriorhodopsin uses light energy to pump protons out.
• Detergents are amphipathic substances; used to solubilize lipids and membrane proteins.
• Glycocalyx is a protective carbohydrate layer on the cell's exterior, formed by sugar residues of glycoproteins, proteoglycans, and glycolipids.
  • Glycocalyx is covalently bonded, and provides protection, lubrication, cell recognition, and adhesion.
• Cell cortex is a specialized cytoplasmic layer on the inner plasma membrane face; rich in actin filaments, it governs cell shape and movement in animal cells.
• Glycoprotein is a protein with carbohydrate attached.
• Proteoglycan is a core protein with more than one sugar chain attached
• Glycolipid is a lipid with carbohydrate attached; exclusively on ECF side
• Glycosylation involves adding sugar groups to proteins (in ER) and lipids (in Golgi apparatus).
• Flippases select specific phospholipids and move them to the cytosolic monolayer, resulting in asymmetry in the Golgi.
• Scramblases are non-specific; transition phospholipids from cytoplasmic to extracellular.

Membrane Lipid Characteristics & Behavior

• Lipids undergo glycosylation in the Golgi, with oligosaccharides added to the lumen side.
• Cholesterol, glycolipids, and phospholipids are amphipathic.
• Hydrophilic regions contain charged or uncharged polar groups.
• Hydrophobic regions are uncharged and nonpolar, exhibiting no favorable interaction with water, thus water forms a cage-like structure to maximize hydrogen bonding.
• Triglycerides consist of three fatty acid tails and are nonpolar molecules like animal fats and plant oils, this is the hydrophobic effect.
• Phospholipid bilayers spontaneously close to form sealed compartments.
• Phospholipid movement includes lateral diffusion, flexion, rotation, and infrequent flip-flop due to weak hydrophobic interactions.
• Membrane fluidity is influenced by temperature, saturation + tail length, and cholesterol.
  • Desaturase enzyme-add a double bond.
  • Increased saturation implies removing double bonds.
  • Shorter tails reduce hydrophobic tail interaction, increasing fluidity.
• New membranes form as ER-bound enzymes manufacture phospholipids on the cytosolic surface of the ER, then scramblases prevent accumulation on one side by transferring randomly phospholipids to the other, resulting in symmetric growth.
• The Golgi contains flippases, which consume energy to transfer specific phospholipids, creating asymmetry.
• Glycolipids, located exclusively on the ECF side, receive their sugar groups in the Golgi.
• The majority of membrane functions are carried out by membrane proteins.
  • Transport, anchoring, receptors, and enzymatic activity are all responsibilities of proteins.
• There are four categories of membrane proteins

Membrane Proteins: Types

• Transmembrane proteins are amphipathic.
  • Hydrophobic regions interact with fatty acid tails and contain 17-20 nonpolar amino acids in alpha-helices or beta-barrels.
• Monolayer-associated alpha-helices are mostly in the cytosol, and anchored by an amphipathic alpha-helix.
• Lipid-linked proteins are found outside of the bilayer via covalent attachments.
• Protein-attached peripheral proteins attach through interactions with other membrane proteins.

Chapter 12 Membrane Transport

• Action potential is a self-propagating wave of electrical excitation in neurons and excitable cells, also known as a nerve impulse.
• Inactivation gates regulate ion channel activity.
• Ion channels are transmembrane proteins forming pores for specific inorganic ions to diffuse down electrochemical gradients.
• Voltage-gated ion channels are channel proteins that respond to changes in membrane potential to permit passage of ions like Na+ and are common in nerve and muscle cells.
• Ligand-gated channels are ion channels stimulated to open upon binding by a small molecule, for example, a neurotransmitter.
• Mechanically gated channels are ion channels that open in response to physical perturbation.
• Transmitter-gated ion channels are transmembrane receptor proteins/complexes that open upon neurotransmitter binding, allowing specific inorganic ions to pass and potentially trigger an action potential in the postsynaptic cell.
• Voltage-gated Na+ channels are plasma membrane proteins in electrically excitable cells that open upon membrane depolarization, allowing Na+ influx and initiating action potentials.
• The voltage-gated K+ channel is also present.
• Na+ or K+ leak channels are K+ permeable ion channels that flicker between open and closed states, influencing resting membrane potential in animal cells.
• Patch clamp recording is a technique to monitor ion channel activity in a membrane, in which a tight seal is between a glass electrode tip and cell membrane area.
• EPSP and IPSP mediate synaptic transmission.
• Active transport moves solutes against their electrochemical gradient, requiring energy like ATP hydrolysis.
• Passive transport involves a solute's spontaneous movement down its concentration gradient via a membrane transport protein, channel, or transporter.
• ATPases mediate active transport.
• Na+/K+ ATPase actively pumps Na+ out and K+ in, using ATP hydrolysis, maintaining a Na+ gradient.
• The Ca2+ pump actively expels Ca2+ from the cell cytosol via ATP hydrolysis.
• Pumps are transporters using an energy source (ATP hydrolysis, sunlight) to actively move a solute against its electrochemical gradient.
• Transporters/transport proteins mediate solute movement across a cell membrane via conformational changes.
• Osmosis involves passive water movement across a membrane from high to low concentration.
• Synaptic transmission is a specialized junction, at which a nerve cell communicates with another cell (muscle, nerve, gland), usually via nerve cell-secreted neurotransmitter at synapse.
• The synaptic cleft is involved.
• Refractory period occurs.
• Antiport is a type of coupled transporter that moves two different ions or small molecules across a membrane in opposite directions simultaneously or sequentially.
• Symport is a transporter moving two different solutes in the same direction.
• Coupled pumps also exist.
• Electrochemical gradient drives ion movement across a membrane; contains ion concentration gradient and membrane potential influences.
• Membrane potential is the voltage difference across a membrane due to slight positive/negative ion excess on either side.
• Graded potential is variable in size
• Resting membrane potential is the voltage difference across the plasma membrane when a cell is unstimulated.
• De-/re-hyperpolarization shifts the membrane potential, such that the inside of the cell is less negative.
• Neurotransmitters are signaling molecules secreted by neurons at synapses to transmit information to postsynaptic cells; examples include acetylcholine, glutamate, GABA, and glycine.
• A neuron is an electrically excitable cell that integrates and transmits information as part of the nervous system.
• Nerve terminal occurs
• Axons conduct electrical signals from the nerve cell body to target cells.
• Dendrites extend from the neuron surface and receive signals from other neurons.
• Alongside Na+ channels, are voltage gated K+ channels, which help to return the depolarized membrane to its resting state.
  • Channels open in response to depolarization, and K+ ions flow OUT of the cell, DOWN their electrochemical gradient.
• Hyperpolarization occurs.
• Both transporters and channels can mediate passive transport, in which uncharged solute moves spontaneously down its concentration gradient.
• Electrochemical gradient determines movement of charged solutes during passive transport.
• Transporters can act as pumps to mediate active transport, in which solutes are moved uphill against their concentration/electrochemical gradients.
  • This process requires energy from ATP hydrolysis, a downhill flow of Na+/H+ ions, or sunlight.
  • A conformational change occurs during the process.
• The Na+ pump in the plasma membrane of animal cells is an ATPase; it actively transports Na+ out of the cell and K+ in, maintaining a steep Na+ gradient to drive other active transport processes and convey electrical signals.
• Inorganic ions of appropriate size/charge cross the membrane using ion channels. Most are gated, opening transiently in response to a particular stimulus.
• Even when activated, ion channels do not remain open continuously
  • They flicker randomly between open and closed conformations
  • An activating stimulus increases the proportion of time that the channel spends in the open state.
• Membrane potential is determined by the unequal distribution of charged ions on a cell membrane; it is altered when these ions flow through open ion channels.
• Action potentials propagate via voltage-gated Na+/K+ channels sequentially responding to plasma membrane depolarization.

Chapter 15 Key Terms

• Autophagy is a mechanism for cells to digest/recycle obsolete or damaged molecules/organelles.
• Rab proteins are small GTP-binding proteins on transport vesicles/organelles
  • Rab proteins serves as molecular markers to ensure fusion occurs with the correct membrane.
• A signal sequence is an amino acid sequence that directs a protein to a specific location in the cell, such as the nucleus or mitochondria.
• Endocytosis uptakes material through plasma membrane invagination, enclosing it in a membrane-bound vesicle.
• Endosomes are eukaryotic compartments for material ingested via endocytosis en route to lysosomes.
• Exocytosis secretes molecules from eukaryotic cells.
  • Secreted molecules are packaged in membrane-bound vesicles that fuse with the plasma membrane, releasing their contents.
• Phagocytosis engulfs particulate matter by cells/macrophages.
• SNARE proteins mediate selective vesicle fusion with a target membrane inside the cell.
• Tethering proteins, filamentous transmembrane proteins, dock transport vesicles to target membranes.
• Vesicular transport is the movement of material between organelles through membrane-enclosed vesicles.
• Clathrin coats transport vesicles budding from the Golgi-secretory pathway or plasma membrane-endocytic pathway.
• The endomembrane system is an interconnected network of membrane-enclosed organelles
  • ER, Golgi, lysosomes, peroxisomes, and endosomes.
• Lysosomes break down worn-out proteins, organelles, and molecules taken up by endocytosis and contain digestive enzymes active at an acidic pH.
• The unfolded protein response is a molecular program triggered by the accumulation of misfolded proteins in the ER.
  • The unfolded protein response expands the ER and promotes production of molecular machinery to restore proper protein folding and processing.
• Pinocytosis is a type of endocytosis in which soluble materials are taken up from the environment.
• Receptor-mediated endocytosis selectively uptakes material by animal cells via macromolecule binding to plasma membrane receptors and entry in clathrin-coated vesicles.
• Transport vesicles are membrane vesicles transporting proteins between intracellular compartments like the ER and Golgi.

Chapter 15 Essential Concepts

• Nuclear localization signals direct nuclear protein transport from the cytosol into the nucleus through nuclear pores. Proteins are fully folded during this transport.
• Most mitochondrial and chloroplast proteins are synthesized in the cytosol and transported into organelles by protein translocators. Proteins are unfolded during this process.
• The ER produces most cellular lipids and many proteins. Ribosomes direct proteins to the ER with a signal recognition particle (SRP) recognizing an ER signal -hydrophobic- On the growing polypeptide chain.
• Water-soluble proteins pass entirely into the ER lumen for secretion or organelle lumen destination, while transmembrane proteins remain anchored in the lipid bilayer via alpha helices.
• Proteins fold, assemble, form disulfide bonds, and undergo glycosylation in the ER lumen.
• Exit from the ER functions as a quality control step.
  • Proteins that do not properly fold or assemble are retained by chaperones, which prevent aggregation and aid folding.
  • Unsuccessful proteins are degraded in the cytosol via ubiquitin and proteasome.
• Excess misfolded proteins trigger an unfolded protein response.
• Protein transport from ER to Golgi and Golgi to other destinations relies on transport vesicles in vesicular transport.
  • Coated vesicles quickly shed their coat to dock and fuse.
• The Golgi receives proteins and modifies their oligosaccharides.
  • The proteins are sorted and dispatched from the trans Golgi network to plasma membrane, lysosomes (via endosomes), or secretory vesicles.
• Transport vesicles constantly bud from the trans Golgi network in all eukaryotic cells; constitutive exocytosis delivers proteins to the cell surface for secretion and incorporates lipids/proteins to plasma membrane.
• Specialized secretory cells regulate exocytosis, in which concentrated and sorted molecules inside secretory vesicles are released by exocytosis due to signaling.

Chapter 16 Smart Work

• Ion-channel-coupled receptors, the simplest cell-surface receptors, activate and triggers a response in milliseconds.

• Adenylyl cyclase activation via a G protein Gs subunit is not part of the amplification of the original signal.

  • When the α subunit hydrolyzes its bound GTP, it will dissociate from adenylyl cyclase, rendering the enzyme inactive once again.

• Ligand binding to the G-protein-coupled receptor, activated Gα influencing target proteins, and Gα exchanging GDP for GTP are required for G-protein signaling pathway activation.

• Activation of PKC occurs through binding to DAG and the continuing presence of Ca2+.

• RTKs can activate the enzyme phosphoinositide 3-kinase, which phosphorylates inositol phospholipids.

  • This serves as a docking site that recruits specific intracellular signaling proteins to the plasma membrane

• Blocking binding of the EGF ligand to the overexpressed EGFR would not be effective in treating glioblastomas because the receptor is active even in the absence of the ligand. Ligand is not needed to activate the signaling pathway, drive cell cycle progression, and promote tumor growth.

• Inhibiting Ras GEF, serine threonine kinase activity, and blocking phosphorylation sites on AKT would all lessen the signaling through the pathway and could be effective anti-cancer treatments.

• Nitric oxide (NO) produces penile erection by activating guanylyl cyclase and cyclic GMP formation

  • Drugs like Viagra inhibit phosphodiesterase to prolong NO effects.

• Inhibition of GTP hydrolysis will maintain Ga in an active state

  • Inhibition of cAMP breakdown will maintain PKA in an active state, increasing signaling through the pathway and CREB activation.

• If regulatory subunits don't bind PKA's catalytic subunits, PKA won't be inhibited and will phosphorylate CREB.

• In the cyclic AMP dependent pathway, extracellular signal molecules activates GPCR to activate Gs protein; Gs alpha subunit activates ADENYLYL CYCLASE (produces cAMP from ATP).

  • CAMP mainly activates CYCLIC-AMP-DEPENDENT PROTEIN KINASE in animal cells.

• The PIP2 inositol pathway includes extracellular signal activation of GPCR to activate Gq protein and beta-gamma complex, which then activates the membrane-bound enzyme PHOSPHOLIPASE C.

Chapter 16 Key Terms

• Nuclear receptors are proteins inside a eukaryotic cell
  • These proteins bind to a signal molecule, enters the nucleus, and regulates transcription.
• Enzyme-coupled receptors are transmembrane proteins that activate an intracellular enzyme when stimulated by ligand binding.
• Receptor tyrosine kinases (RTKs) are enzyme-coupled receptors
  • These receptors' intracellular domains have tyrosine kinase activity activated upon ligand binding to the receptor's extracellular domain.
• MAP kinase signaling occurs which allows cells to respond to extracellular signal molecules that stimulate proliferation and includes mitogen-activated protein kinase (MAP kinase).
• Ras GTPase is a small GTP-binding protein that helps relay signals from cell surface receptors in the nucleus and contains an overactive mutant in many human cancers.
• CELL SIGNALING is a molecular mechanism where cells detect/respond to external stimuli and send messages to other cells
• An extracellular signal molecule is any molecule present outside the cell
  • This molecule elicits a cell response upon binding to a receptor.
• A local mediator is a secreted signal molecule that acts over a short range on adjacent cells.
• Hormones are extracellular signal molecules
  • Hormones are secreted and transported through the bloodstream to target tissues.
• Nitric oxide (NO) is a locally acting gaseous signal molecule
  • NO diffuses across cell membranes.
  • NO affects intracellular protein activity.
• A neurotransmitter is a small signaling molecule secreted by a nerve cell at a synapse
  • A neurotransmitter transmits information to a postsynaptic cell.
• A GAP & GEF occurs

Cell-Signaling Proteins

• G proteins are membrane-bound GTP-binding proteins involved in intracellular signaling.
  • Composed of three subunits, it is usually activated by the binding of a hormone.
• G-protein coupled receptors (GPCRs) are cell surface receptors that associate with an intracellular trimeric GTP-binding protein after activation by an extracellular ligand.
  • They are embedded in the membrane by seven transmembrane alpha helices.
• Adenylyl cyclase catalyzes cyclic AMP formation from ATP.
  • It is an essential component in intracellular signaling pathways.
• Cyclic AMP (cAMP) is a small intracellular signaling molecule generated from ATP in response to hormonal stimulation of cell surface receptors.
• Protein kinase A (PKA) phosphorylates target proteins due to increased intracellular cAMP.
• Protein phosphatase catalyzes the removal of phosphate groups from a protein.
• Protein kinases catalyzes a ATP to a specific amino acid side chain.
• Ion channel-coupled receptors are transmembrane receptor proteins/complexes that open in response to a ligand’s binding to its external face.
  • This allows passage to specific inorganic ions.
• Second messengers occur.
• A molecular switch is an intracellular signaling protein
  • This toggles between active or inactive states.
• Signal transduction converts stimuli from one form to another.
  • Stimuli in cell biology includes cells respond to an extracellular signal.
• Phospholipase C is an enzyme associated with the plasma membrane that generates two small messenger molecules.
• Phosphatidylinositol 4,5-bisphosphate (PIP2) is a minor plasma membrane lipid with a role in cell signal transduction.
  • Cleavage yields two small messenger molecules (IP3 and diacylglycerol).
• Diacylglycerol (DAG) is a small messenger molecule produced by membrane inositol phospholipid cleavage
  • Resulting from response to extracellular signals, and helps activate protein kinase C.
• Inositol 1,4,5-triphosphate (IP3) is a small intracellular signal molecule
  • IP3 triggers Ca2+ release.
  • IP3 occurs due to signal molecules activating phospholipase C.
• Protein kinase C (PKC) phosphorylates target proteins
  • PKC occurs in response to increased diacylglycerol and Ca2+ ions.
• Calmodulin is a small Ca2+ binding protein
• It modifies activity of proteins.
• CaM kinases phosphorylates target proteins due to rise in Ca2+

Essential Concepts of Cell signaling for Cell-Surface Receptors:

• There are three main classes of cell-surface receptors: ion channel coupled receptors, g protein coupled receptors, and enzyme coupled receptors.
• GPCRs activate GTP binding proteins in this process.
• G proteins directly regulate ion channels/enzymes.
  • These proteins activate/inactivate adenylyl cyclase
  • This increases/decreases the second messenger cyclic AMP concentration and generate 2nd messengers (inositol triphosphate and diacylglycerol).
• IP3 opens Ca2+ channels, releasing Ca2+.
  • The Ca2+ itself acts as a 2nd messenger
  • The Ca2+ alters activity of Ca2+ responsive proteins (calmodulin, CaM kinases).
• Elevated cAMP activates cyclic AMP-dependent protein kinase (PKA)
  • Ca2+ and diacylglycerol both activate protein kinase C (PKC).
• PKA, PKC, and CaM kinases phosphorylate and alter the activity of proteins on serines and threonines.
  • Each cell type contains a set of the proteins which affects the proteins within the cell type to react in their particular ways.
• Enzyme-coupled receptors are associated with intracellular enzymes
  • Many are tyrosine kinases (RTKs).
  • RTKs phosphorylate themselves and certain signaling proteins on tyrosine
  • Phosphotyrosines become docking sites for various proteins.
• Most RTKs activate Ras, this activates a three-protein MAP kinase
• RTKs stimulate cell growth/survival.

Chapter 17: Cytoskeleton Key Terms

• Intermediate filaments are fibrous cytoskeletal elements, approximately 10nm in diameter, forming ropelike networks in animal cells, which help cells resist tension applied from outside
• Alpha helix monomer components present
• Coiled coil dimer present
• Tetramer components exist
• Plectin is present
• Nuclear lamina occurs as a fibrous layer of the inner nuclear membrane. It is formed by a network of intermediate filaments made from nuclear lamins.
• Nuclear lamins occurs
• Progeria exists.
• Keratin is a class of intermediate filaments abundant in epithelial cells, providing tensile strength.The Main structural component of hair, feathers, and claws.
• Desmosome are specialized cell-cell junction, and is usually formed between epithelial cells, that serves to connect the ropelike keratin filament of the adjoining cells, providing tensile strength.
• Epidermolysis bullosa also occurs.

Microtubules

• Microtubules are long, stiff, cylindrical structures of tubulin that organize the cytoplasm, directing intracellular transport of macromolecules/organelles in eukaryotes.
• Tubulin exists as aplha/betta/gamma tubulin.
• Heterodimer present
• MTOC occurs
• Centrosomes are microtubule-organizing centers
  • Centrosomes near the nucleus in animal cells.and duplicate during the cell cycle to form two mitotic spindle poles.
• Spindle poles form a centrosome from which microtubules radiate to organize the mitotic spindle.
• Basal bodies are present
• Nucleation sites occur
• Centrioles are cylindrical microtubule arrays
  • They pair at the centrosome in animal cells and occur at the base of cilia/flagella, where they're called basal bodies.
• Organization with 9+0 and 9+2 arrangements exist
• Dynamic instability switches fast between growth and shrinkage exhibited by microtubules.
• GTPase are present
• Motor proteins (myosin, kinesin) move proteins along a protein filament or polymeric molecule using energy from ATP hydrolysis.
• Dynein motor proteins uses ATP hydrolysis energy.
  • This moves towards the microtubule minus end.this form also bends cilia.
• Kinesin motor proteins that uses ATP hydrolysis energy, where it moves towards the microtubule plus end.
• Cilia are hairlike structures that are made of microtubules on eukaryotic cells; its beating can drive fluids (such as in lungs).
• Flagella are long, whiplike structure for propelling a cell through fluid via rhythmic beating.

Cell structures and components

• Actin is thin and is made from globular actin molecules that promotes movements and contractions in muscle cells.
• G-Actin and F-Actin are present.
• Polarity occurs the can refer to any structure
• ATPase occurs
• Treadmilling processes with subunits adding/losing
• Proteins bind with actin for structure/function of networks
• Thymosin, Profilin exists:
• Formin, APR ⅔ complex exist
• Spectrin exists
• Cofilin
• Capping Proteins are in certain areas
• Nucleation sites are present
• Lamellipodium exists on surface
• Filopodium also exists
• Myosin is used for movement

Essential concepts

• Microtubules grow out from organizing centers that control their location, number, and organization; y-tubulin complexes in these organizing centers function as nucleation sites that cap the microtubules' minus ends.
• Many microtubules display dynamic instability, alternating rapidly between growth and shrinkage. Shrinkage is promoted by hydrolysis of the GTP.
• Kinesins and dyneins are microtubule associated motor proteins that use the energy of ATP hydrolysis to move unidirectionally along microtubules.
• Microtubules, actin filaments are polar, with a fast growing plus end and a slow growing minus end. Their assembly and disassembly are controlled by the hydrolysis of ATP.
• Myosins are motor proteins that use the energy of ATP hydrolysis to move along actin filaments. In nonmuscle cells, myosin I can carry organelles or vesicles along actin filament tracks, and myosin II can cause adjacent actin filaments to slide past each other in contractile bundles.
• In skeletal muscle cells, repeating arrays of the overlapping filaments of actin and myosin II form highly ordered myofibrils, which contract as these filaments slide past each other.

Chapter 18: Cell Cycle Key Terms

• M Phase is a period when Cells split
• Interphase is along period when the cycle is prepared
• G1,s and G2 phases present
• Mitosis divides nucleus
• Cytokenisis divides cytoplasm
• Centrosome occurs
• Mitotic spindle formed between ends and separates
• There a protein complexs that attaches chromosomes
• Microtubules is also used

Addtional Key Terms

• Spindle pole helps organize
• Contrile ring helps pinches cell
• Cylcin helps control cycle by binding
• CDK triggers cycle when complexed to clyclin proteins
• g1/s and s-cdk forms the proteins phase on cycle
• There are mitositic Cdks for specific phases
• There a regulators that controls phase with damage
• If damage goes too high the protein induces sucicide in cell
• Condesins are used to compaact and segregate
• A protein complex is that triggers sister cell to separate
• Ubiquitin the protien complex targets it
• A nuclear lamina also occurs

Key Concepts for Cell Cycle

• Cell cycle control depends on kinases.
• There are cyclin-cdk complexes for various step (including division)
• APC/c controlls different stages
• S-CDk initiates DNA replications which can be delayed due to a phase.

Cell Junctions, Cancer & Tissues

• Tight junctions seal cells preventing the movement of molecules
• Occludins are present
• Claudins is also present
• Basal lamina is mat that cells sits on
• Laminin is present.
• Triple collagen is a component
• Apical occur on top
• Basal is located at base
• Basolateral occurs adjacent
• Gap junctions are special connection
• Cxonneson is present
• C adherin is mediate attachments
• There intermediate filaments used
• Integral promotes adhesions
• Linker protien used
• Desmonses connected with adjacent filament
• Some cells have structures anchor basal lamina
• The Cytoplasmic place is present
• Kertain also is present
• Sheet junctions acts with cell

Cancer Terminology

• Oncogene is a gene that is activated and may turn the cell cancerous
• The process for most cells contains normal
• A proto oncogene mutated
• Cancer cells are inaffective but don't harm
• Mutations can cause the proto one to become cancer.

Other Cellular Concepts

• There three classes of cell junctions?
• For junctions what their role what does proteins help?
• Discuss general gap role and composition?
• tight junction roles what composes?

Final Exam Breakdown:

• Module 1 covers: -- Chapters 1: 4-6, -- Chapter 5: 6-9, -- Chapter 7: 10-12, -- Chapter 8: 7-12.

• Module 2 covers: -- Chapters 11: 6-10, -- Chapters 12: 6-10, -- Chapters 15: 12-15, -- Chapter 10: 4-6.

• Module 3 covers: -- Chapters 16: 18-24, -- Chapters 17: 18-24, -- Chapters 18: 18-24, -- Chapter 20: 14-20.

• Nucleosome diagrams in chapter 5 occur

• RNA splicing diagrams are in chapter 7

RNA Processes and snRNP Action

• In RNA splicing, introns are removed. This happens during transcription elongation which occurs adjacent to a nucleotide sequence. There are three sites of imports site splice site is an end of intron.

1. Branch is cut, this promotes cut of back bone.
2. There are OH links that are covalently linked
3. The exons react with sequecnes first.
4. Exons now from a link.

• RNA functions with snRNPS which a few protiens and 5 types.
• There complimentary base pairing which ensures introns are spliced.

Protein Sythesis and Translation

• TRNA helps synthases attach correcct Trnas.
• Initiations moves the tRNA and methionie to the P site of subunits
• mRNA bonds to end and moves until AUG
• Dissosciate allows subunits to then come together.
• Elgongations: A amino acid bonds, then a chain is moved in a peptide chain then transferse releases its from ribozyme. The translocar has 3 steps forward to release tRNA.
• MRNA is formed FROM 5 to 3.
• A termination occurs.

Protein Movement

• Coating proteins transport materials from Gogi network through plant related cells.

Protein Cotranslocation

• Ribosomes are going to bond to emerging Er then translate. It also pause the translation

• Amino trna bonds ER sequence and bond to protein. Which directs ribosomes and translocated polypeptide.

• Translocation continues

##Cell Interactions

• Extracellular signals cannot defuse
• Pcracine is for closer cells

Actions potenail:

• Resting point: is stead the state
• There a depolarization going in
• A polarizaution occurs