UNIT 3 EXAM STUDY PDF

Chapter 11: Cell-Cell Interactions Cell signaling: the ability for all cells to produce, receive, and respond to external signals (cell comms) REQUIRES TWO THINGS.. 1. Ligand: small signaling molecule that binds and forms a complex with biomolecule (receptor) 2. Receptor: protein tha...

Chapter 11: Cell-Cell Interactions Cell signaling: the ability for all cells to produce, receive, and respond to external signals (cell comms) REQUIRES TWO THINGS.. 1. Ligand: small signaling molecule that binds and forms a complex with biomolecule (receptor) 2. Receptor: protein that changes shape (conformation) upon ligand binding - Conformational changes lead to cellular response Types of Ligands (signaling molecule): 1. Amino acids 2. Proteins 3. Lipids (Hormones) 4. Nucleotides 5. Dissolved Gases 6. Neurotransmitters Plants: have three walls in extracellular space - Bc interior of plant cell has more solutes than the external environment, plant cells experience turgor pressure (hard cell) 1. Primary Cell Wall: - Creates large extracellular protection (varies based on cell type) - fibrous component in plants (plant version of ECM) - Creates long strands called microfibrils which form a crisscrossed network - Between the microfibrils' spaces, a gelatinous structure called pectin (thickens jam) is held. Pectin holds a large amount of water keeping the plant cell wall moist 2. Middle lamella: the glue that holds two cells together (think jam) 3. Secondary cell wall - is made of a lot of cellulose and is used to strengthen the cell adjacent to the primary cell wall - Ex. lignin is a secondary cell wall found in wood that helps keep the plant stable against winds and gravity Animals: - Has higher percentage of protein than carbohydrates in ECM in comparison to plant cells Extracellular matrix: - has significantly less plasma membrane than extracellular matrix in a cell - Proteoglycans: sticky shit that allows cells to stick to other cells, (looks like bird feather) that structure allows it to attract water and have a sticky side (forms a gel) - Collagen: strength and rigidity beyond extracellular structure, also anchors it to other cells Extracellular Matrix: a. fiber composite secretion that animals produce (think reinforced concrete that can withstand force lengthwise and pressure) b. Mostly made of a fibrous component called collagen (glycoprotein) 25%-33% of all protein in our body is collagen - Space between collagen is filled with gel stuff called proteoglycans - Proteoglycans is responsible for the rubber consistency of cartilage c. Ground substance is made of proteoglycans - Proteins attached to polysaccharides (attracts water and creates gel like substance) d. ECM varies among tissue types to serve different function e. Integrin binds to -> Laminins -> ECM (this links cytoskeleton to ECM effectively supporting the cell as a whole) - This is RLLY important bc it impacts signaling pathways Cells Needa Comm ?!?! Responses to signals (ions and small molecules) 1. Signals could regulate gene expression (inhibiting or catalyzing protein production) 2. Signals could also activate or inactivate particular proteins that are already functioning and existing Comms in Animal Cells Tight Junction: a. Forms waterproof seal in plasma membrane b. Is composed of specialized proteins and limits the flow of solutions between two animal cells by tightly pulling the two membranes closely together c. Commonly found in epithelial cells (linings in stomach and intestines) d. They change depending on the environment (ie, the loosen when digesting and tighten after) DYNAMIC AND VARIABLE e. Proteins holding it together (protein production can increase or decrease ie. it can be tightened and loosened) Desmosome: a. Strong cell-cell attachment particularly common in animal epithelial cells and muscles (stronger than tight junctions) b. Kinda like a nail going through both membranes holding it together through the anchoring proteins within each cell membrane c. *Cadherins: linking proteins in desmosomes (cadherins can only bind to other cadherins of the same type) d. Large protein structures e. Also add intracellular structure Gap Junctions:  a. Connect adjacent cells through the membrane creating interconnected channels allowed shit to move in between b. For plants, they create a membrane lined channel to connect the cytoplasm through the cell wall c. Allows the rapid passage of regulatory ions or small molecules (flow of information) *Selective Adhesion: cells tendency to adhere to other cells of the same type (racism)* Comms in Plant Cells Lowkey hard bc direct communication is impossible due to the thick ass cell wall SOOOOOO instead they use plasmodesmata plasmodesmata: - the membrane and cytoplasm of the two adjacent cells are continuous through a gap in the cell wall - Tubular extensions from smooth ER go through these membrane-lined channels a. The plasmodesmata is split into two parts 1. Symplast: a continuous network of cytoplasm connected by plasmodesmata 2. Apoplast: region outside the plasma membrane consisting of cell wall, middle lamella and air spaces - Small molecules move through plant tissues in either of these never crossing a membrane Cells in long-distance relationships… Signaling molecules: 1. Neurotransmitters: open or close ion channels in plasma membranes of distant cells changing the electrical property of the membrane a. Responsible for transmitting info through nervous system 1. Hormones: information carrying-molecules that are secreted through bodily fluids and act of distant target cells a. Usually small molecules (includes peptides, steroids and even gases) Signal reception: *allows coordination of activities across a multicellular organism - Signal receptor: protein that binds to a particular signaling molecule and triggers a response by the cell. - Receptor structure changing after signaling molecule binds is an indicator that the signal has been received - These can be blocked - Lipid insoluble Signal: receptors are transmembrane proteins in the plasma membrane - Most of these CANT cross the plasma membrane  - To work, they have to be recognized @ the cell surface - Receptors are usually located in the plasma membrane - Lipids soluble Signals (steroids): these are often located in the cytosol - These CAN diffuse across the hydrophobic region of the membrane and enter the cytosol of target cell - Receptors are inside the cell *** 1. RECEPTORS ARE DYNAMIC: sensitivity of a hormone can change over time because of too much/intense stimulation (decline in # of receptors) 2. RECEPTORS CAN BE BLOCKED: drugs can block the interaction between receptors and hormone Signal Processing: the way the cell processes the signal is dependant on where the receptor is located (membrane or cytosol) Processing Lipid Soluble Signaling Molecules: - Ex. estrogen, testosterone, and cortisol - These molecules must be carried through the bloodstream by hydrophilic molecules until they are dropped off @ the target cell to diffuse through the plasma membrane - Hormone-receptor complex is formed in the cytosol and then transported to the nucleus where it triggers changes in gene expression - Cell now produces different proteins that affect function and shape of cell - NO protein in phospholipid bilayer to facilitate these molecules bc they dont need them 1. Arrival of signal 2. Signal entry: diffusion of hormone across plasma membrane into cytosol 3. Signal reception: hormone binds to receptor inducing conformational change 4. Direct signal response: Processing Lipid Insoluble Signaling Molecules: - These types of hormones do not directly participate in intracellular activities such as change in gene expression Signal Transduction: process where an extracellular signal is converted into an intracellular signal (signal transduction pathway) 1. Signal reception: protein on plasma membrane receives extracellular signaling molecule 2. Signal Transduction: extracellular signal -> intracellular signaling molecules (this causes the signal to be amplified as it goes down the pathway (relay molecules) 3. Signal Response: a. Intracellular signaling molecule attaches to DNA to create different gene expression b. can lead to changes in cytoplasmic protein activity c. may lead to changes in gene expression Types of Signal Transduction: - Both open ion channels (conformational change)  - Coupled with phosphorylation cascades (proteins become activated by phosphorylation) - Ligand gated ion channel (ligand = signaling molecule) - Ligand binding to ion channel allows ions to move down concentration gradient - Ligand dips if electronegativity (electrochemical gradient) changes or reaches equilibrium bc the amino acids don't like the positive charge in the interior of the cell and therefore closes kicking off the ligand 1. Signal Transduction: G-protein-coupled receptors: initiate the production of intracellular second messengers which then amplify and diversify the signal a. G-proteins are found in the plasma membrane inside the cell b. Receptor is coupled with inactive G protein c. When signaling receptor protein binds to signal molecule, G protein and GDP are kicked off during conformational change and is moved to an enzyme with a new GTP - G protein binds to enzyme substrate which then amplifies and creates secondary messengers - GDP is an allosteric inhibitor (when GDP is bound to G protein, it is inactive) - GTP is an allosteric catalyst (when GTP is bound to G protein, it is active) d. When activated by a receptor, they produce a second messenger (small non-protein signaling molecule that creates an intracellular response 2. Phosphorylation Cascade: Enzyme-linked receptors: activate series of proteins inside the cell w/ phosphate groups (phosphorylate proteins inside target cells) - Has two enzymes (active sites) for the molecules to bind to - I will be asked about phosphorylation cascades on the next two exams - Phosphorylation cascade: when a protein is taken in a substrate, becomes phosphorylated and then a substrate is produced. That product becomes the next protein for the next reaction - Uses product from previous enzymatic reaction as a substrate for the next enzymatic reaction - Reaction is turned on by using enzyme complex - Is a series of reactions that occur in order to amplify the signal - TDK ^^^^ Cross Talk: enzymatic pathway negative feedback loop (phosphofructokinase) - Can promote or inhibit other enzymatic pathways Signal Deactivation: - When G-protein needs to be deactivated it is hydrolyzed (inorganic phosphate group is reattached to the G protein to return it to its inactive state - This is referred to as a phosphorylation cascades where enzymes called phosphatases removes phosphate groups from the proteins to stop the signal transductions (protein is reverted back to its inactive state) Chapter 46: Cell-Cell Interactions Types of signals: 1. Autocrine signal: a. same cell is receiving and secreting cell (cancer cells) b. Ex. growth factors that tell the cell when to divide c. Insulin and glucagonen 2. Paracrine signal: diffuse locally to cells in similar area 3. Endocrine signal: a. difference in tissue types b. long distance signaling c. Hormone carried through the bloodstream or other bodily fluids d. Coordinates activity in different cell areas 4. Neural signal: a. Local signaling occurs in the animal nervous system (neurons transmit signals along dedicated routes connecting specific locations in the body) b. Short distance between neurons 5. Neuroendocrine signal a. Refers to (neurohormones) b. Hormones released from neurons c. Carried by blood or other bodily fluids Homeostasis: how are hormones involved in homeostasis 1. Sensory receptors monitor conditions 2. Integrator processes information from sensor nad compares it to the normal value 3. Effector cells return the condition to the set point *These messages often travel from integrators to effectos in the form of hormones Negative feedback loop: - most common in maintaining homeostasis - Stimulus (impacts cell) -> releases hormone -> inhibits stimulus - Antagonistic pathway - decreases/inhibits a signal/response Positive Feedback Loop: - Oxytocin (love) is a positive feedback loop esp during childbirth - increase/amplifies a signal/response Amino acid derivative - Extracellular protein that works as a receptor - Most are not lipid soluble and bind to receptors on the surface of the target cell peptide/polypeptide: - Binds to receptors on the outside of the target cell Steroids: - Lipid soluble and binds to receptors found WITHIN the target cell Epinephrine: - FIGHT OR FLIGHT response - Needs increased oxygen and sugar for cellular respiration (body releases glucose from the liver to power cellular respiration) - Secreted by adrenal glands - Epinephrine have two different receptors (alpha and beta) beta is not only found on a blood vessel but also a liver cell. alpha is only on the blood vessel - Blood vessels have both alpha and beta receptors (negative & positive loop) Phosphorylase: - Once phosphorylated, it cleaves one glucose molecule from glycogen - Can be turned off/on by presence of ______ Phosphorylation cascade (amplification) Cyclic AMP (cAMP) Neuron: takes extracellular signal and turns into an intracellular response (electricity) Information processing Sensory input -. Motor output Axon hillock (funnel for intracellular signal to accumulate in an area for a certain response Voltage gated ion channel is closed (elctrongradient) - Think QRS complex in heart (potential energy) - Both r closed at resting potential - -55mV - High concentration of outside (opposite charge in cell)n allows movement down electrochemical gradient - Goes from neg to pos hcarge as - Voltage gaited ion channel for sodium a. Has extra structure called inactivation loop b. Allows movement of sodium to go in only one direction 1. Activation of inactivation loop (stops movement of anything into the cell) 2. Potassium dips cell (rapid drop of potential energy depoloiztion) membrane potential drops a LOT Charge changes when a lot of molecules Chapter 12: The Cell Cycle Prokaryotic Cells: - Divide through binary fission 1. Single, circular bacterial chromosome is replicated 2. Replication begins at the origin of replication and proceeds bi-directionally 3. New chromosomes are partitioned to opposite ends of the cell 4. A septum is formed to divide the cell into 2 cells Eukaryotic Cells (Gametes & Somatic Cells): - Divides through cell division 1. Gametes: has one set of chromosomes 2. Somatic Cells: has two sets of chromosomes Structures in Eukaryotic Chromosomes: 1. Cohesin: complex of proteins holding replicated chromosomes together at the kinetochore 2. Sister Chromatids: 2 copies of the chromosome within the replicated chromosome 3. Centromere: where the microtubles of the spindle attach Eukaryotic Cell Cycle: - Length of complete cell cycle varies among cell type, species, metabolic activity, etc. 1. G1 (Gap Phase 1) - Generally the longest phase - Cell growth!! 2. S (Synthesis) - Chromosomes are fully extended and uncoiled for DNA replication 3. G2 (Gap Phase 2) - Time of increased synthesis of proteins, mitochondria and other orgnalles - microtubule-organizing centers begin forming in cytoplasm a. Actin filament: two coiled strands that separates two animal cells from first original cells b. Intermediate filament: fiber wound into thicker cables (rope) c. Microtubles: hollow tube made of alpha and beta subunits (straw) - Chromosomes condense 4. M (Mitosis) a. Prophase: - Nuclear envelope begins to disappear - Chromosomes continue to condense (sister chromatids clearly there) that contains a kinetochore b. Prometaphase: - Nuclear membrane completely breaks down  - Kinetochores begin attaching to microtubles - Mitotic spindles move to the poles of the cell (aster) c. Metaphase: - Chromosomes line up along the metaphase plate 1. Polar microtubles: extend from poles to equatorial region (overlaps) 2. Kinetochore microtubles: extend from poles to kinetochore d. Anaphase: - Sister chromatids break - Chromatids become true chromosomes - (microtubles pull chromosomes from the kinetochore) e. Telophase: - Chromosomes arrive at the poles - New nuclear membrane appears - Spindle microtubles disappear - Returns to interphase serenity 5. C (Cytokinesis) - Division of cytoplasm to yield 2 daughter cells a. Cleavage furrow: in animals (looks like a butt crack) b. Cell plate: in plants bc plant cells are structurally very rigid and close together 6. G0 Phase: - “Resting state” - Where most of the cells in an animals body is at any given time Checkpoints of Cell Cycle: 1. G1/S Checkpoint - Are nutrients sufficient? - Does the cell have the appropriate environmental factors on health - Nutrients need to be sufficient (enough sugars (ATP)) - Growth factors: comms good?? Receiving extracellular signal converting to a. Proteins: growth factors that tell nucleus to make cyclin b. MPF: initiate synthesis of cyclin -> CDK is activated through cyclin creates kinases that activates 5phase proteins leading to cell division (DNA synthesis) c. Cycklins concentration changes throughout the cycle d. CDK catylizes phosphorylation of other proteins to start M phase (regulatory enzyme for cell division) binds to cyclin to control how cells divide e. CDK remains at the same density throughout the process f. RB turns off E2F (binds onto CDK-Cyklin enzyme) which removes the inactivation phosphate group (RB and E2F get phophorylated) g. E2F can activate G1 checkpoint allowed cell cycle to continue  h. Overall needs 2 ATP i. Multiple checkpoints needed for a protein to copy DNA - 2. G2/M Checkpoint - NO DNA damage - Chromosome replication is successfully completed 3. Late metaphase (spindle) checkpoint - Are all chromosomes attached to mitotic spindle PDGF: signals received from platlids during injury (sends signal to other cells to increase cell division so wound can be cut off from external environment) - intercellular signal for nucleas to smt smt - Cell size (animal): - Undamaged DNA - Mature cells do not divide - Needs to have attachment point in substrate in order to divide n grow (exception: platlids) Cancer: lack of control of cell cycle 1. One of the checkpoints r violated so cell division continues a. Transformation: how a cell is transformed in terms of it’s checkpoints b. Benign tumor: unregulated growth that is localized n does NOT move throughout the body c. Malignant: invades other tissue types to continue metastasis ie. cause additional tumors d. Do not stop growing in response to checkpoint n density e. Will continue growing and create their own growth factors (autocrine signal) f. They are IMMORTAL: as long as nutrients are present, they will continue to divide indefinitely (HeLa cells: first cells to successfully be grown on a petri dish was harvested from a woman with cervical cancer rlly sad bro wtf is wrong with Dr. Gage (proof that cancer cells will live forever)) g. Normal cells go through apoptosis (programmed cell death), cancer cells DO NOT have apoptosis h. Two kinds of genes that can disturb the cell cycle when mutated 1. Tumor suppressing genes: a gene/genes that regulate divergence from og DNA code based off environmental factors (radiation, smoke, etc, etc) - P53: guardian of genome (found in genome) protects it by calling other proteins when DNA is damaged and repairing it or causing apoptosis in the cell if unrepairable - If p53 protein is damaged/abnormal, DNA production cannot be regulated and the transformation continues to replicate - Lucky elephants bc they have extra p53 genes (humans only have one) 2. Proto-oncogenes: p53 pathway  - Based upon proteins in cytoplasm, takes intercellular signals into nucleus to turn on/off proteins - Transduction pathways: amplify signal into nucleus incase intermediate protein is unfunctional - Apart of the receptors that stop/start cell division Chapter 43: Neurons Neurons: nerve cells that transfer information within the body 1. Electrical signals: (long distance) 2. Chemical Signals (short distance) Neuron Structure: Dendrites: A highly branched group of relatively short projections - Converts chemical signals to electrical signals Cell body (soma): includes the nucleus - Integrates incoming electrical signals Axons: long projections - Conducts electrical signals The neurons of most vertebrates require supporting cells called glial cells. - Surround nucleus and holds them in place - Supplies nutrients and oxygen to neurons - Insulates neurons from one another - Destroys pathogens and removes dead neurons Membrane Potential: Neurons transmit electrical signals which muscles then respond to by contracting Split into two types of nervous systems… 1. Nerve net: diffused arrangement of neurons throughout the body found in cnidarians and ctenophores (simple NS) - These neurons are generally in radial symmetry centered at a central axis in the organism 2. Central Nervous System: includes a large number of neurons aggregated into clusters called ganglia - Most animals with a CNS have a brain (large cerebral ganglion) - Invertebrates’ CNS have both a brain and spinal cord - Sensory neurons, interneurons, and motor neurons are all a part of the CNS  2a. Peripheral Nervous System: all other components of the nervous system - Generally, sensory information is transmitted from PNS to CNS where it’s processed. Then a response is transmitted back through PNS to the target (reflex) 1. Sensory Neuron: nerve cell that carries sensory signals to the CNS 2. Interneurons: a neuron that passes signals from one neuron to another (integrates information from sensory neuron to CNS) 3. Motor Neurons: a nerve cell that carries the signal from CNS to effector cells (cells that cause a physiological change in an organism) in a muscle or gland Nerves: long strands of nervous tissue containing axons of neurons wrapped in connective tissue (carries signal between CNS and other parts of the body) Neuron Structure: 1. Cell body (soma): includes the nucleus - Integrates incoming electrical signals 2. Dendrites: A highly branched group of relatively short projections that receives signals from other neurons (usually 2mm or less of length) - Converts chemical signals to electrical signals - Receives signal from other axons (neurons) 3. Axons: long projections - Conducts electrical signals away from cell body to another neuron or effector - Contains Nodes of Ranvier: points where signals can be transmitted along myelinated axon - The myelinated sheath is made of Schwann Cell which insulates axons - The synaptic terminal is what relays signals to another neuron or effector Membrane Potentials: **Because there is unequal distributions of ions between the cytoplasm and extracellular fluids, there will be a difference in charge (electrical potential/voltage). When there is electrical potential across a plasma membrane, the separations of charges are called “membrane potential”. Membrane potential is measured in units called millivolts (1/1000) of a volt. In addition, MP is expressed in terms of inside relative to outside because there are usually more negatively charged ions on the inside compared to the outside: ie. membrane potential is usually negative (-65mV). Neurons use the electrochemical gradient of ions to power signals down the axon** Resting Potential: - Interior has LOW concentrations of Na+ and Cl- ions but HIGH concentrations of K+ n other stuff - Extracellular fluid is predominantly Na+ and Cl- ions - In resting neurons, the membrane is selectively permeable to K+ Diffusion across the membrane (Resting potential):  - The sodium-potassium pump actively pumps Na+ out and K+ into the cell making the potassium concentration INSIDE the cell higher and the sodium concentrations OUTSIDE the cell higher - At rest, K+ ions leak out the membrane through leak channels due to the concentration gradient established by the sodium-potassium pump BUT THEN bc there’s only negatively charged ions in the cell, potassium GOES BACK IN. bruh ikr, anyways this makes potassium reach an equilibrium potential in which there is no longer any net movement - Basically, neurons have a negative resting membrane potential bc the Sodium potassium pump creates a concentration gradient that favors the exit of potassium through leak channels Action Potential: - Rapid temporary change in membrane potential which allows neurons to communicate with other neurons, muscles, or glands - Stages of Action Potential: 1. Depolarization: membrane potential changes from highly negative to a lill positive - must surpass the threshold potential in order for an action potential to occur - Sodium channels open quickly during depolarization allowing Na+ to flow into the neuron and then closes quickly after 1-2msec. (causes cell to be more positive bc positively charged ions r entering) - This is a positive feedback loop bc as the cell depolarizes more, more Na+ channels open which depolarizes the membrane further opening more Na+ channels - Sodium channels experience refractory states (sodium channels don't work for a while after they do their thing) which prevents action potentials from propagating backwards - -65mV 2. Repolarization: occurs rapidly and changes the membrane potential back to negative - At +40mV. Repolarization occurs - Potassium (K+) flows out of the cell during repolarization (causes the cell to be more negative) 3. Hyperpolarization: membrane potential is slightly more negative than resting potential Things that affect speed: - If the axon diameter is larger, the signal travels faster since the cations can move down faster - Myelinated Axons: prevents leakage of ions (cations needed for action potential) 1. Oligodendrocytes (CNS): type of glial cell that wraps around axons of some neurons in the CNS to form a myelin sheath 2. Schwann Cells (PNS): type of glial cell that wraps around axons in PNS to form a myelin sheath  3. Node of Ranvier: a gap in the myelin sheath that is dense in voltage-gated ion channels (Na+ and K+) so new action potential can be generated - Action potential ‘jumps’ from node to node in myelinated axons - Unmyelinated axons have channels all throughout it’s length causing the action potentials to be less efficient since they happen all the time - Multiple Sclerosis: The immune system destroys myelin in CNS impairing electrical signaling How does depolarization spread down the membrane?? 1. Depolarization (positive charge in cell) opens the sodium channel, so Na+ enters the cell 2. Na+ ion attracts negative charges and pushes positive charges further down the axon 3. Positive charge spreads down the axon initiating depolarization at another node which then opens another sodium channel Neurotransmitter: chemical messengers that transmit information from one neuron to another neuron, muscle, or gland Axon Structure: 1. Synaptic Cleft: space separating neurons from other neurons, muscles, or effectors 2. Synaptic vesicles: ends of axons that store neurotransmitters Presynaptic Neuron: neuron that transmits a signal by releasing a neurotransmitter to another neuron, muscle, or gland cell at a synapse Postsynaptic Neuron: cell that receives signal at the synapse Synaptic Transmission: 1. Action potential reaches end of axon near synaptic cleft 2. Depolarization opens calcium channel at the synapse in the plasma membrane of the presynaptic neuron causing an inflow of Ca2+ ions 3. Bc theres sm Ca2+ ions in the axon, synaptic vesicles fuse with the presynaptic membrane and release neurotransmitters into the synaptic cleft through exocytosis 4. Neurotransmitters (ligand) bind to receptors on postsynaptic cell causing ion channels to open. This leads to a change in membrane potential which triggers an ACTION POTENTIAL!! 5. Response ends when the neurotransmitter unbinds from the receptor causing the ion channels in the postsynaptic membrane to close Postsynaptic Potentials: 1. Excitatory postsynaptic potentials: changes in membrane potential that make the postsynaptic cell MORE likely to produce an action potential - Usually when a neurotransmitter binds to a logan-gated sodium channel on a postsynaptic membrane  - Depolarization occurs with a Na+ inflow 2. Inhibitory postsynaptic potential: changes in membrane potential that make the postsynaptic cell LESS likely to produce an action potential - If neurotransmitter-receptor binding leads to an outflow of K+ ions or inflow of Cl- ions - Hyperpolarization occurs with a K+ outflow or Cl- inflow 3. Simultaneous EPSP and IPSP cancel each other out but multiple EPSP IPSP occurs at the same time called summation - Both EPSP and ISPS are spectrums and depend on the amount of neurotransmitter that is released at the synapse (ie. higher concentration of neurotransmitter = larger EPSP or IPSP)) Axon Hillock: site in neuron where an axon joins the cell body and where action potentials are first triggered (abundant in sodium channels) Metabotrophic Receptor: - The binding of neurotransmitter to a metabotropic receptor activates a signal transduction pathway in the postsynaptic cell involving a second messenger (slower but lasts longer in comparison to logan gated channels) - Original ligand causes many conformational changes resulting in the release of a second messenger - Ex. cyclic AMP (cAMP) Chapter 37: Information Processing in Plants Steps in Information Processing: 1. Sensory Cell: perceives external stimulus and transduces the information to an internal signal 2. Cell-Cell signal: released by sensory cells travels throughout the body 3. Target Cell: receives the cell-cell signal and changes activity Signal Transduction (a cell's response to a cell-cell signal): 1. Signal arrives 2. Receptor protein changes in response to a signal 3. Receptor or associated protein catalyzes phosphorylation reaction 4. Phosphrylated protein triggers phosphorylation cascade OR releases second messengers 5. Phosphorylated proteins or second messengers initiate response 6a. activate/repress translation 6b. Change ion flow through the channel or pump 6c. Activate or repress transcription PHOT1 Gene: blue light receptor protein (when phosphorylated, it can produce two different responses) 1. Opening of stomata 2. Reorientaes chloroplasts within the plant so it faces the light 3. Produces auxin(?) PHOT2: mutant of PHOT 1 that does not make plants grow towards light (natural selection) Auxin is the signal response that makes plants bend toward light. Produced at the top of the plant in the top of the coleoptile, auxin moves to the lower part of the plant where it bends - Increases # of membrane proton pumps in the plasma membrane (makes cell wall more acidic) note acid-growth hormone - Responsible for fruit production - Senescence Acid-Growth Hypothesis: Plants Phototropic Response 1. Proton pumps acidify the cell wall outside the plasma membrane 2. Wall ‘loosens’ as activated expansins unzip hydrogen bonds connecting cellulose microfibrils to other cell wall polymers. The electrochemical gradient brings ions into the cell causing water to enter the cell as well 3. Water follows by osmosis increasing the turgor pressure and pushing the loosened wall out therefore elongating the cell - Auxin moves in one direction and is VERY slow (dependent on size) - This is all a result of auxin which allows plants to grow in the direction of the sun Statohypothesis: Gravitropic Response w/ Auxin 1. Auxin flows to the end of the root where it then distributes in an upside-down umbrella fashion 2. If the root is not growing straight down, auxin distribution is uneven 3. The root knows to bend when there is pooling of auxin Thigmotropic Response: plants' response to touch (carnivorous plants) - Thigmonastic movement generates - Auxin independent - Pressure-gated ion channel (when its touched by something, it opens an ion channel which changes the charge inside the cell and creates a response (opens channel)) - Abscisic Acid (ABA): inhibits seed growth - the hormone used to close somatic cells Gibberellins: a hormone that promotes growth (stimulates growth) - Amylase: storage molecule for starch - Is found in the cell and is released when a seed is in contact with water, causes the How stomata opens in response to blue light: - Blue light strikes PHOTO1 starting up the hydrogen pump - Protein brings in chloride and potassium into the guard cell to increase solute concentration inside the cell - H2O enters the cell through osmosis How stomata close in response to ABA: - ABA binds to receptor on guard cell -> hydrogen pump stops pumping in hydrogen ions - Potassium and chloride dips outta the cell - Bc concentration is higher outside the cell, water moves down the gradient and the cells begin to shrivel and close 4 ethylene senescence: - Abcision zone: location on a leaf that lacks auxin in response to external environments (fall) that is sensitive to ethylene - Fruit ripening - A compound produced in the cell and is released as a gas (THE THING WHERE U PUT A BANANA WITH AN UNRIPE FRUIT TO RIPEN IT UP) Cytokinins: - Mitosis promoting factor How do plants sense and respond to herbivores/predators: 1. Standing defenses: mechanisms that are continually present and produced (spines on a plant) 2. Induced defense: being induced by prey, herbivore, or fungus, that penetrates through root or guard cells that eat the plant from the inside out so the plant has a hypersensitive response that causes apoptosis where the plant is being eaten - Ex. Irish famine a. Pathogen enters and binds to plant receptor protein b. A signaling molecule is produced and sent to the rest of the plant (phosphorylation cascade) c. Protein is created that makes chemicals/molecules that make the plant taste bad or make the predator nauseous Hypersensitive Response: - The rapid and localized death of cells surrounding the site of infection, thus starving a pathogen 1. Pathogen binds to a receptor protein in the plant causing HR (rapid and localized death of cells) 2. Surrounding cells produce poisonous chemicals and hormones to prepare the rest of the plant for attack  3. The hormone reaches target site and creates pathogenesis-related loci (PR) that protect tissues distant from the initial site of infection (these are all called SARS: systemic acquired resistance) Chapter 44: Information Processing in Animals 1. Mechanoreception: response to pressure (statocyst) - In animals, the pressure protein is composed of calcium(?) 2. Hair Cell: literally the best thing to happen in evolution - Stereocilia: connected to one another through polypeptide thread in which a potassium channel is attached - Responds to pressure waves that bend the stereocilia (pushes them over) that activates potassium ion channels and allows movement of potassium into hair cells (causes depolarization) - Potassium channels open in response to bending causing membrane depolarization -> inflow of Ca2+ -> synaptic vesicles fusing with plasma membrane -> neurotransmitter is released - Hair cell is rlly important for detecting predators and prey esp in fishes (lateral line) - Lateral Line: series of canals running along the head and body of fish with a bunch of hair cells attached 3. Chemoreception: response to smells - Chemicals binds to chemoreceptors which initiate action potential in sensory neurons 4. Photoreception: response to light - Species' sensory abilities correlate with the environment and its needs in life - Some species don't got or NEED eyes LOL - Ommatidia eyes in insects are a bunch of eyes that function independently - Human eyes: The pupil allows light to come in (there are no photoreceptive cells behind the optic nerve - Octopus eyes: A higher quantity of optic nerves allows them to see 180’ (total of 360) - Scallops apparently have 120 eyes surrounding the shell: but their eyes r SIMPLEEEE compared to other marine organisms 5. Electroreception: can detect electrical current only in water tho (they can detect OTHER ANIMALS NEURONS) - Mainly found in sharks, used to find prey (Ampullae of Lorenzini which is located on the nose of a shark) - Electrogenic fishes can produce electrical fields so they can locate items that disrupt the current (think echolocation) Chapter 34: Plant Structure, Chapter 35: Nutrition, Chapter 36: Animal Nutrition and Chapter 41: Homeostasis Plant Vascular Tissue System: 1. Xylem: - Functions as straws - Transports water and nutrients up to rest of plant and provides structural support - Consists of two types of cells: Tracheids and Vessel members a. Xylems are dead at maturity b. Water proof cell walls remain c. Both found in vascular tissue d. Pits: allow water diffusion e. Unidirectional flow 1. Tracheids: long tapered cells with pits, constricting flow as it moves up 2. Vessel elements: short and wide with perforations as well as pits 2. Phloem: - Alive at maturity - Has limited quantity of organelles - Transports sugars, amino acids, hormones, etc up to rest of the plant and provides support a. Sieve-tube elements: long thin cells with perforated ends called sieve plates - Bi-directional flow - Lack nuclei and are directly connected to adjacent companion cells by plasmodesmata b. Companion cells: connect and maintain the cytoplasm and plasma membrane of sieve-tube elements - Contains majority of organells and helps transportation How does water move into roots? - Water travels from soil through the cortex (waxy substance) to epidermis which eventually goes to the xylem - Water travels from root hairs to the xylem through three different roots 1. Symplastic route: via plasmodesmata (ie. water goes through holes in the cell) 2. Transmembrane route: vie water channels (ie. aquaporins) 3. Apoplastic route: within porous cell walls (ie. around the plasma membrane) - Casparian strip: cell walls impregnated with wax; impermeable to water - Casparian strips blocks the apoplastic route at the endodermos causing water to take a detour by either entering through symplastic or transmembrane route Cohesion-Tension Theory: - Idea that water is drawn from soil through the process of capillary action (cohesion)  - Water is being continuously lost from leaves through transpiration, this transpiration creates a negative pressure (tension) which ultimately draws water up the xylem - Root -> leaves -> atmosphere Translocation: bidirectional movement of sugars through a plant from sources to sinks through the phloem - Source: tissue where sugars enter the phloem (found in leaves) - Sink: tissue where sugar is being utalized or stored (roots and flower) - Sugar concentration is high at the source (mature leaves) and low in sinks Pressure-Flow Hypothesis: - Pressure potential gradient is created in the phloem caused by events at source and sink tissues - Phloem sap: (high concentration of sucrose) moves vertically, passing through pores in sieve-tube elements - Water in phloem sap moves down this pressure gradient caring sugar along by bulk flow and then returns to the xylem after the sucrose reaches the sink - Turgor pressure: water entering phloem causes huge pressure pushing phleom sap bidirections Moving sugar from Source Cell (leaf) to Companion Cell - Sugar moves against concentration gradient (source ie. leaf -> companion cell) through facilitated diffusion - Hydrogen proton pumps hydrogen ions into source cell creating an electrochemical gradient. This incites hydrogen ions to move down the gradient into the companion cell through a proton-sucrose symporter (brings in both hydrogen ion and sucrose) - Osmotic gradient: water leaves xylem through pits to the phloem bc of osmotic gradient (phloem has way more concentration) and creates turgor pressure pushing the pleom sap to a sink cell Phleom Unloading: moving sugar from Companion Cell to Sink Cell (root or flower) - Sugar moves with concentration gradient (passive transport) 1. Root cells have a large vacoule that stores sucrose surrounded by a membrane called the tonoplast - Hydrogen ion pumps ions into the vacoule of sink cellp to create an electrochemical gradient. When hydrogen ion leaves vacoule bc of the gradient, it leaves through a proton-sucrose antiporter that brings in a sucrose cell as the hydrogen leaves 2. Developoing leaf cells get sucrose through passive transport in accordance to the sucrose concentration gradient Soil Types and Plant Survivability: - Anions dissolve in solid water and ARE immediately available for plant use - Cations dissolve in soil water but are not immediately available for plant use Nutrient Uptake: 1. Hydrogen pumps ions outside root cell creating an electrochemical gradient that brings in anions through a symport cotransporter and cations through regular channels 2. Mycorrhizal Fungi: fungi that has a symbiotic relationship with plant roots - Efficient bc networks for filamentous hyphae increase SA - Fungi can acquire nutrients from macromolecules in soil that other plants cannot - Increases surface area of roots so they can acquire more nutrients Animals Nutrient Requirements: - Essential amino acids - Essential fatty acids - Vitamins (organic compounds that are vital for health but only need limited amounts) - Minreals (inorganic substances used as components of enzyme cofactors) - These process in which these are obtained is… 1. Ingestion 2. Digestion 3. Absorption 4. Eliminaation Types of Jaws: these have all adapted through natural selection 1. Filter feeder: filter through water to get food Ex. baleen 2. Substrate Feeder: chewing on leaves - Ex. caterpillar 3. Fluid feeder: mosquitoes 4. Bulk feeders: us Jaw Adapations: 1. Cichlid: pharyngeal jaw can bite more effectively 2. Non-cichlid: pharyngeal jaw doesnt bit as effectively - Teeth dictate diet: teeth for biting, tearing, grinding, etc Metabolic Process of Nutrient Acquisition: 1. Carbohydrates: - Salivary amylase in mouth begins break down 2. Lipids - Lingual lipas in mouth begins break down 3. Proteins - Pepsin in stomach begins breakdown Chemical digestion of Food: - CO2 + H2O -> H2CO3 -> H+ + HCO3- - Hydrogen proton pump moves ions from inside cells to stomach lumen - Antiporter moves bicarbonate out and chloride inside the cell - Chloride moves down concentration gradient into lumen Small Intestines Nutrient Absorption: - Cells lining the small intestines absorb released sugars - Microvilli: increases surface area of small intestines to enhance efficiency of nutrient absorption - Sodum potassium pump pumps potassium into epithelial cell that then leaves through a leak channel - Glucose travels from lumen -> epithelial cell -> blood Large Intestines AKA Colon: - Most of the nutrients and water have been absorbed - Primary function of colon is to compact wastes that remain and absorb enough water to form feces Energy Allocation: - Biogenetics: flow and transformation of energy in an animal that determines the nutritional needs - Metabolic Rate: animals energy use per unit of time Chapter 40: Homeostasis Osmoregulation, Water and Electrolyte Balance in Animals Osmoconformer: - Spend less energy on maintaining constant osmolarity within body - Negs??: Have to deal w? drastic shifts in salinity (hurricnase that bring in a lot of freshwater) - Most often found in stable ocean habitats Osmoregulator: - Can mostly maintain constant molarity within body even if external concentration of salt changes through active protein processes that utilize ATP to move water and salt against concentration gradient - Can acclimate to different salinities but must be done slowly otherwise they'll die (if gradient is too large) Nitrogenous Waste: 1. Urea (Mammals):  - intermediate in terms of solubility; - intermediate toxicity; - intermediate amount of energy needed to produce 2. Ammonia (Aquatic): - the most soluble in water; - MOST toxic; - requires LEAST amount of energy to produce 3. Uric Acid (Reptiles & Birds): - lowest solubility in water; - LEAST toxic; - requires MOST amount of energy to produce bc its concentration is so high (white shit from birds n its white bc oF THE SALT) Osmoregulation Shark: rectal gland holds excess salt and is then excreted into water (if water is super salty, you know a sharks there), ions can be concentrated this way only if they are actively transported against concentration gradient Rectal Gland (evolutionary basal) Protein System: goal is to concentrate the ions in the rectal gland 1. Sodium potassium pump: is pumping potassium into the cell and moving sodium out (goal is to create a concentration gradient of sodium on basal lateral side of epithelial tissue 2. (high concentration of sodium at bottom will move sodium potassium and chloride from interstitial tissue to membrane) leak channels of chloride allow chloride out of the apical membrane 3. Potassium leak channel allows potassium to leave epithelial cell 4. Sodium moves through interstitial space to diffuse through the lumen into shark rectal gland Marine vertebrates: have hypotonic cells bc there's waters moving out of the cells - To combat this: they drink LOTTSS of water to replace what is being lost to the environment - Little production of urine (scant) - Excess salts from the water is excreted through the chloride cells, skin, and kidney (think back to rectal gland) Freshwater Fish: have hypertonic cells bc theyre absorbing a lot of water into their tissue - To combat this: waterproofing (body w/ scales) - Lots and lots of dilute urine (urine with less electrolyets) - Chloride cells and ……. - Does the opposite process of rectal gland (moving salts into body tissue) Chloride Cells: - Uptake of salts (FreshWater)  - Excretion of salts (SaltWater) - Rich in mitochondria bc they need lts of ATP Salmon have BOTH chloride cells because they live in both FW and SW environments Terrestrial Organisms - Land animals have to regulate water and electrolytes too on the DL 1. Filtrate: filtrates blood in kidneys to take out excess water and ions 2. Reabsorption: reclaiming valuable solutes or water 3. Secretion: adds nonessential solutes and water from the bodies fluids to the filtrate 4. Excretion: releasing processed filtrate containing nitrogenous wastes from the body Excratory Process in Invertebrates: 1. Flame bulb cells: excretoratory site found in flatworms - Filter out bodily fluids inside protonephridia - Cillia wrings itself like a towel to move fluids through membranes so it can be excreted 2. Insects have Malpighian Tubules to regulate water and electrolyte balance - Open circulatory system - Hemolymph: fluid circling in insects body - To filter it, insects have a malpighian tubules that take in hemolymph, water, electrolytes, and nitrogenous waste - Electrolytes and water are reabsorbed back into hemolymph to conserve and retain water in insects Excratory Process in Vertebrates: - Kidney functions in both osmoregulatoin and excretion - Kidney consists of tubules arranged in organized array and in contact with a network of capillaries - Bowmans Capsule is permeable to water and small solutes BUT NOT blood cells or large molecules - Filtrate produced there contains slats, glucose, amino acids, vitamins, nitrogenous waste, and other small molecules - Starts filtration - Proximal Tubule: a. where reabsoption of ions, water, and nutrients occurs b. Molecules are transported actively ans passively from the filtrate into the interstitial fluid and then capillaries Vertebrates: (mammals) - Nephron, cortical nephron, an - Healthy kidneys should filter 1600 L of blood per day producing 180 L of filtrate 1. Glomerulus: oxygenated blood comes in and leaves. Capilarries are pitied allowing blood to move out, smt slits that allows blood to move Lumen of Proximal Tubule 1. Sodium potassium pump: moves sodium out into blood vessel and moving potassium in - Goal: To create sodium gradient 2. Descending loop of Henle: filtrate moves down while water passively moves out the filtrate (filtrate becomes more concentrated 3. Ascending Loop of Henle: salts move out of filtrate through concentration gradient (passive and active transport) 4. Henle Loop descends again ADH (antidiuretic hormone): saves water - Collecting ducts are temporarily more permeable to water allowing conservation of water - Water leaves loop of henle more than usual Chapter 42: Gas Exchange Homeostasis is dependant on respiratory and circulatory systems 1. Ventilation 2. Diffusion 3. Circulation 4. Diffusion 5. Cellular respiration How do organisms obtain O2 and release C2 - These gas exchanges between the environment and the cells is based on diffusion - In water: gases dissolve in water from the atmosphere but it depends on several factors - (Frick’s Law of Diffusion: the rate of diffusion of a gas is dependant on 5 parameters) 1. Solubility of gas 2. Temperature 3. Surface area available for diffusion 4. Differences in partial pressures of the gas across the gas-exchange surface 5. Thickness of the barrier in diffusion - Diffusion through membrane will increase if the surface area increases, thickness of cell membrane decreases, concentration gradient increases, or membrane permeability increases Aquous Environment: - Not all aqueous organisms have gills, some use preform simply diffusion through their skin 1. Parapodium: walking legs that function as gills 2. Coelom: found in starfish, have gills embedded in their coelom 3. Fish Gills: use a countercurrent exchange system where blood flows in the opposite direction to water passing over the gills  a. Ram ventilation - Swims with its mouth open to push water over its gills - These organisms are highly energetic (ie. have a lot of ATP) b. Buccal Pumping - Operculum: structure that creates partial pressure in mouth and gill cavity - This partial pressure pushes water across gills and then into the opercular cavity How fish are able to oxygenate: (chloride cells are found in the GILL STRUCTURE) 1. Countercurrent exchange system ensures constant concentration gradient - Gill arch holds gill filaments which hold multiple gill lamella that increases surface area - Oxygen rich water enters the gill and then oxygen poor water leaves the gill Respiration in Terrestrial Environment: - Trachea: air filled tubes found in insects, connected to the outside through pores called spiracles - Birds: utalize one-way airflow through avian lungs a. Increased surface area for gas exchange in a bird in order to maximize oxygen uptake ie. ATP production 1. Air goes into posterior air sacs 2. Air moves into parabronchi space where gas exchange occurs 3. Air is pushed out of air sac - Mammalian organism: a. Capillary action where gas exchange occurs How do mammals under a lot of pressure deal with gas exchange?? 1. Supporting cartilage (Epiglottic Cartilage) surrounds their lungs unlike human lungs 2. Laryngeal Sac: Circulation and Gas Exchange: 1. Open circulatory system: mechanism that bathes organs in hemolymp to provide oxygen and nutrients to organs - Most invertebrates have this - Hemolymph: fluid that transports nutrients around the body (fills up space and it NOT contained in a system) 2. Closed circulatory systems - Blood is completely contained within blood vessels and flows in a continous circuit throughout the body under pressure created by the heart - Capillaries: increased surface area here which increases quantity of gases, electrolytes, potassium, chloride, etc that is delivered to the cells - Velocity is decreased at capillaries (slower flow) allowing diffusion of nutrients to increase across the cell membrane Respiratory Pigments: - Pigments that circulate in blood and it increases the amount of oxygen transported by alot - Mainly consists of a metal bound to the protien hemoglobin Hemoglobin: - A single hemoglobin can carry four molecules of O2, one molecule for each iron containing heme group - Hemoglobin binds oxygen reversibly, loading it in the gills/lungs and releasing it in other parts of the body - They bind COOPERATIVELY! - Single hemoglobin subunit binds to one oxygen inducing conformational change which kicks the other three subunits into love state for oxygen - When one subunit releases O2, the other subunits release their O2 more readily - Cooperativity can be demonstrated by the dissociation curve for hemoglobin - As pressure increases, oxygen saturation increases - Oxygen saturation is at its highest at rest bc your body doesnt really need the oxygen - Assists in preventing harmful changes in blood pH and plays a minor role in CO2 transport - Most of CO2 is transported in blood plasma bound to hemoglobin or as bicarbonate ion Bohr Shift: - CO2 produced during cellular respirations lowers the bloods’ pH decreasing the affinity of hemoglobin for O2 Thermodynamics: - Ectotherm organisms exchange heat by four physical processes (organisms that cant regulate their own temp) 1. Radiation: sun hitting them to warm them up 2. Evaporation: water moving off the body 3. Convection: wind blows to cool them off 4. Conduction: - Some organisms move solutes out of their body to limit the amount of water inside cells Endotherms: organisms able to regulate internal temperature utalize negative feedback loops - Classes of Animals: 1. Homeotherm: body remains the same temperature irregardless of the external environment 2. Poikilotherm: temperature varies based upon seasonality or time of day (bears) 3. Heterotherm: temp varies Countercurrent Heat Exchange: - Artery blood (warm) is transferred to vein (colder blood)  - Warm blood transfers heat to adjacent veins Billfish: have heater cells that warm up neuron for eye cells