ANS 100- Midterm 1 Review

Acclimation vs. Acclimatization vs. Adaptation

-refers to the process of change in resonse to a controlled environmental variable (usually in a lab setting; ex. if you take a fish at 15C and leave it in water at 5C) -refers to the process of change in response to natural environmental variation (ex. comparing a fish that you capture in summer with mean temp of 15C with a fish captured in winter with mean temp of 5C) -refers to the product or process of evolution by natural selection, that is, a change in a population or group of organisms over evolutionary time. Sometimes used as a synonym for acclimatization (ex. when referring to phenotypic plasticity contexts)

3 properties of enzymes

1. Active at low concentrations 2. increase the rate of reactions but are not altered, act as catalysts 3. do not change products Enzymes lower the activation energy so more substrate molecules possess enough energy to reach the transition st and the rxn is accelerated/ enabled to happen (substrate molecule may have conformation change caused by enzyme to enable rxn)

Phenotypic plasticity How can you tell if a trait is: plastic? Irreversible/ reversible Explain using specific example:

Ability of one genotype to produce multiple phenotypes, depending on environmental conditions. Observed most commonly at the population level. Ex. coat color of arctic fox cold environment to warm= reversible trait Developmental plasticity is an ex. of irreversible plasticity (cannot be changed in the adult org by subsequent changes in the environment). Ex. of rxn norm: continuum of helmets/ spiny tails of water fleas when raised in the presence/ absence of predators.

Ligand-receptor interactions are specific; however, there are many ligand mimics that act as agonists or antagonists. What happens when an agonist binds to a receptor? What about when an antagonist binds?

Agonist: Activates/ allows a reaction, down-regulates receptors made (ex. heroin) Antagonist: Blocks a reaction by binding to a receptor but not stimulating a signaling event, interferes with the binding of nat'l ligand, up-regulates receptors (ex. caffeine)

What does a graph of ligand-receptor binding look like?

Effect of messenger concentration Graph: y-axis: % receptors bound x-axis: [M] + curve, asymptote at 100 High-affinity receptor has steeper curve to 100

Explain the statement "Transformation of high-grade energy is inefficient". What is a measure of the inefficiency?

Efficiency of energy transformation= Output of high-grade energy/ input of high-grade energy Conversion of chemical bond energy in a fuel molecule (e.g. glucose) to chemical bond energy of ATP Glucose to ATP= ~70% (rest lost as heat) ATP to muscular motion= ~25-30%

Endocrine system cell-to-cell signaling:

Endocrine secretory cell; most cells in body target cells; chemical signal type; long max signaling distance; circulatory system transport; slower speed; longer duration of response

Natural selection acts on an animal's phenotype, which is a product of its genotype and environment. Explain the importance of each component and how they interact from the basis of selection.

Evolution by natural selection requires variation in phenotype, heritability (genotype not just environmental morphologies), and differential mean of repro success (fitness based on ability to survive and reproduce in environment).

How are depolarization, hyperpolarization, and repolarization illustrated?

Depolarization= becoming less negative Repolarization= returning to resting membrane potential Hyperpolarization= becoming more negative (then repolarizes back to resting membrane potential)

Law of mass action: How does this chemical law modulate the transport of hydrophobic messengers

law stating that the rate of any chemical reaction is proportional to the product of the masses of the reacting substances, with each mass raised to a power equal to the coefficient that occurs in the chemical equation. M+C ←→ M-C where M= messenger and C= carrier protein Adding more M drives towards messenger bound to carrier protein, removing M drives towards unbound

Direct cell signaling vs. Indirect cell signaling

Direct- signaling cell and target cell connected by gap junctions, signal passed directly from one cell to another Indirect- signaling cell releases chem messenger which is carried in extracellular fluid (some may be secreted to environment), binds to receptor on target cell, activation of signal transduction pathway leads to response in target cell

How can you measure metabolic rate both directly and indirectly? Many factors affect metabolic rate. What are these factors and how does each factor specifically affect metabolic rate?

Direct: Calorimetry on vertebrates, measures animals heat production Indirect: Oxygen analyzer Factors: temp- activity- starvation- feeding increases mr (heat increment of feeding/ SDA) repro state- increases during prego dormancy- near zero time of day- nocturnal vs. diurnal

Neurons have a resting membrane potential like other cells. What sets up this resting membrane potential? How is it maintained?

Membrane potential is negative at rest.

Metabolism scales to the exponent of 0.75, what does this number tell you specifically about how much metabolic rate changes with size?

Metabolic rate decreases and body mass increases.

Define metabolism. How does metabolism differ from metabolic rate? What goes into determining metabolic rate of an animal?

Metabolism- the sum of all chemical reactions in a biologic entity Metabolic rate- An organism's rate of energy consumption; the rate at which it converts chemical-bond energy to heat and external work Determined by: maintenance, temperature balance, digestion, movement

Km

Michaelis constant (Km) The concentration of substrate that yields half maximal velocity in an enzymatic reaction; measure of dissociation/ affinity : low Km= high affinity for substrate bc overpowering top # ([ES] breaking apart)

Paracellular transport vs. transcellular

Paracellular- molecules must be able to move through the band of tight septate junctions; in many epithelia, only very small molecules are able to do this, restricting the paracellular path to such molecules. Transcellular- molecules must cross both apical and basolateral cell membranes

Be able to explain the structure of a phospholipid membrane. Why is it called a phospholipid bilayer? How does the structure of the bilayer influence the transport of molecules? Explain two mechanisms used by ectotherms to maintain membrane fluidity at cold temperatures?

Phospholipid membrane is called a bilayer because it is composed of two layer of phospholipids. The phospholipids have a hydrophilic head and a hydrophobic tail. The structure of the bilayer influences the transport of molecules because anything polar cannot penetrate the middle (where the hydrophobic tails are) and thereby needs a channel. ***Two mechanisms ectotherms use to maintain membrane fluidity at cold temperatures are adding double bonds (pushes the phospholipid out and takes up more space which prevents it from becoming a gel) and changing the head groups by having more PE.***

What is the difference between a polar and a non-polar molecule? Define hydrophilic and hydrophobic. Which one is polar and which one is non-polar?

Polar molecules have electrons that are unevenly distributed which leads to positive and negative regions. Nonpolar molecules have evenly distributed electrons. Hydrophilic: water loving and have a positive and negative end. Polar Hydrophobic: water hating and electrons are distributed evenly. Nonpolar

What is "Unity in Diversity"?

Refers to the phenomenon that although animals display a large diversity of adaptations in response to varying environmental stimuli, there are many similarities and commonalities amongst the proximate and ultimate causes behind physiological processes. This is due to both common ancestry and common environmental challenges.

3 environmental factors representing the greatest challenges to homeostasis and why

The Big 3: 1. Temperature- Effects orgs at the molecular level - measure or "heat" or energy in a system - energy is what controls the movement of atoms in molecules, and the bonds among those atoms which is the basic architecture of all bio matter - Lowest temp: -1.86°C - Highest: ~50°C 2. Oxygen: the e- acceptor -allows energy to flow through biological systems -protons (H+) are transferred from reduced, energy rich compounds to oxygen during cellular respiration: (4H+ + 10O2 ->2H2O) - Air ~ 21%O2 at all altitudes -High altitude air is less dense 3. Water: Universal solvent -ions and molecules are "dissolved" in water -Challenge to maintain appropriate water balance -Terrestrial (*xeric= desert) orgs must conserve water or be able to withstand seasonal desiccation/ dehydration

How are gradients formed and what maintains them, delaying diffusion?

The nature of the molecule determines whether the PE of the gradient is primarily electrical or chemical. Uncharged molecules form chemical gradients while ions can form a chemical gradient and influence the electrical gradient. Animals can maintain a voltage difference across their cell membranes, as well as some organelle membranes, such as the mitochondrial membrane. Only 2 factors are required to establish a potential difference across a membrane: concentration gradient and a membrane that is permeable. Various gated channels and ways of transport establish the membrane differences (animals can turn on/off these mechanisms).

Diffusion is defined by Fick's equation. How can animals increase the rate of diffusion?

The net movement of a molecule throughout the available space from an area of high concentration to an area of low concentration. It is dependent on the parameters included in Fick's equation: diffusion coefficient of the solute X diffusion area X concentration gradient. **An animal can increase diffusion by increasing SA, decreasing membrane thickness, or store more PE and increasing temp.

Explain relationship between body mass and metabolic rate. Who is a prominent figure in defining this relationship and what was this contribution?

y (metabolic rate)= aM^b a= normalization coefficient b= scaling coefficient Klieber determined that b is closer to 3/4 rather than 2/3 which was previously believed

Changes in internal and external environment can affect the capacity of enzymes to catalyze reactions. Cold-adapted enzymes are different than warm-adapted enzymes. What do I mean by this statement? How is this achieved?

*Flexibility-stability tradeoff* Enzyme kinetics are affected by environmental temperature and temperature affects changes in weak bonds alter 3-D structure, changes in ionization state of amino acids within the active site, and changes the ability of the enzyme to undergo structural changes necessary for catalysis. Cold-adapted enzymes have fewer weak bonds, enzymes breathe more easily and are more vulnerable to temperature dependent unfolding. Warm-adapted enzymes need to be super stable so that they do not denature

PE

trapped energy (in chemical bonds, gradients etc.)

Provide an example that explains the role of chemistry and the role of physics in constraining animal phys

- Mechanical engineering rules apply to physical properties of animals -Chemical laws, including the effects of T, govern interactions between bio molecules -Electrical laws describe membrane fxn -Body sx affects many physio processes

Be able to explain the different types of chemical bonds and their importance for storing energy. What are reducing equivalents? During aerobic metabolism when are they formed? How are these reducing equivalents important for forming ATP during oxidative phosphorylation.

- covalent (strong bonds) individual atoms held together by the sharing of electrons - noncovalent (weak bonds) molecules organized into 3D structures (ex geckos) Energy storage: (2 forms) - Reducing energy Chemical PE (lipids, carbs, proteins & amino acids not stored as ATP) Food goes in--> metabolites --> AceCoA--> NADH and FADH2 (reducing equivalents) - High energy bonds (ATP) Mitochondrial e- transport chain builds electrochem gradient that can be used to drive ATP synthesis.

Ligand-receptor complexes must be inactivated to allow for responses to changing conditions. Explain the six ways in which this can be achieved.

-Ligand removed by distant tissue -Ligand taken up by adjacent cells -Ligand degraded by extracellular enzymes -Ligand-receptor complex removed by endocytosis -Receptor inactivation -Inactivation of signal transduction pathway

3 main strategies to regulate enzyme activity

1. Competitive inhibition- bind to active site, preventing substrate molecules from binding. Effectiveness depends on substrate concentration. When [S] is low, inhibitor outcompetes S for the active site, reducing the reaction rate. Km is increased 2. Allosteric Activation- alter enzyme kinetics by binding to the protein at locations far away from the active site. Enzymatic 3D structure is altered, including complex changes in enzyme kinetics. Enzymes often possess multiple sites for different allosteric regulators and these enzymes are often larger and more complex than other enzymes. Allosteric regulators can inhibit or activate enzyme activity, changing either Km or Vmax. 3. Convalent action- enzymes can be regulated by the covalent modicfication of critical amino acid residues within the protein. The most common is protein phosphorylation where a specific protein kinase transfers the phosphate group from ATP to an amino acid of the target enzyme. Reversible and may activate or inhibit enzymes

Explain the four sources of ATP, how these stores are produced, how quickly the ATP is available to use, how long these stores last and whether they are an efficient mechanism of ATP production.

1. Free ATP -instant, only a few secs 2. Phosphagen -Very fast ATP production for short duration -Creating phosphate (vertebrates), Arginine phosphate (invertebrates) -Fast Enzymatic replenishment: Creatine Kinase (CK activity limits burst performance potential 3. Anaerobic Glycolysis -Fast ATP production for moderate duration -Glucose, glycogen supply in musce -Energy inefficient 4. Oxidative using O2 in environment -Slow ATP production for long duration (whole lifetime) -Energy efficient

What are the 4 unifying themes of physiology?

1. Physiological processes obey the laws of chemistry and physics. 2. Physiological processes are usually regulated. 3. Physiological phenotype is the product of the genotype and the environment. 4. A genotype is the product of evolution, acting through natural selection and other evolutionary processes.

What are the four functional zones of a neuron? Be able to sketch and label a typical motor neuron.

1. Signal reception -Dendrites and the cell body (soma) -Incoming signal received and converted to change in membrane potential 2. Signal integration -Axon hillock -Strong signal is converted to an action potential (AP) 3. Signal conduction -Axon (some wrapped in myelin sheath) -AP travels down axon 4. Signal transmission -Axon terminals -Release of neurotransmitter

4 different types of junctions

1. Tight junctions- A type of intercellular connection that is capable of preventing the free movement of molecules between the cells. Occlude the space between two cells because not only do the cell membranes meet or fuse at such junctions, but also the junctions form continuous bands around cells. Cell membrane of the two cells make contact at ridges. 2. Septate Junctions- Like tight junction (both occluding junctions) but looks like a ladder 3. Gap junction- Aqueous pore between two cells that allows ions and small molecules to move freely from cell to cell; formed by proteins called connexins in the vertebrates and innexins in the invertebrates. 4. Desmosomes- A type of cell-cell junction common in epithelial tissues. Localized spot where the contact between cells is strengthened. *Occluding junctions form continuous rings around cells and it is where cell membranes meet or fuse and they occlude intracellular space

3 classes of simple epithelia

1. squamous 2. cuboidal 3. columnar

4 features of an adaptive trait

1. variation in trait 2. heritability 3. trait must increase fitness 4. relative fitness of the different genotypes depends on the environment

electrical gradient

A charge gradient across a membrane arising from unequal distribution of charged particles. In cells, the electrical gradient is called the membrane potential.

electrochemical gradient

A gradient composed of the concentration gradient of an ion and the membrane potential; the driving force for the movement of that ion across the membrane.

Chemical gradient

An area across which the concentration of a chemical differs, often across a membrane.

Types of gated channels

Aquaporins- water channel proteins, strictly passive Voltage-gated channels- change of membrane potential opens Stretch/tension-gated- stretches via cytoskeleton Phosphorylation-gated channel- attachment of PO4^2- opens Ligand-gated- has a receptor site to which ligand binds then opens

What is equilibrium potential? How does it affect the degree to which membrane potential can change?

As permeability to a specific ion increases, membrane potential will approach that ion's equilibrium potential. The membrane potential at which an ion is at its equilibrium distribution across a membrane. Net movement stops when the equilibrium potential is reached.

How do endotherms and ectotherms differ in their metabolic rates? Why does this difference exist?

At the same body temp, similar sized endotherms and ectotherms differ in oxygen consumption by at least 4/5 fold. Endotherms have a higher demand for food (energy) than ectotherms.

Cell signaling types

Autocrine/ Paracrine Nervous Endocrine Exocrine

3 different time scales in which animals can respond to a stressor or change in environment: Use ex. of endurance in humans, be able to daw figure, labeling

Concept of Time, Environmental stressor: 1. Sort-term modulation (acute response) msec/min 2. Acclimation/ Acclimatization, days to weeks 3. Adaptation, 100s to 1000s of generations Acute Response- (endurance ex.) men were unable to continue walking 100 min in hot environment when first exposed Chronic Response- After a week of heat exposure, dramatically increased endurance; 23/24 men could walk for 100 min. x-axis: Endurance measured as # of men who could walk for 100 minutes y-axis: days of heat exposure

Conformer vs. Regulator Pros and cons Can animals be both?

Conformer- allows internal conditions to change along with changes in the external environment. It is a lower cost of living, but can have fatal results if the external changes are extreme. Regulator- maintains relatively constant internal range of conditions in spite of changes in the externarl environment. It is more costly in terms of metabolic energy, but allows organisms to survive harsher environmental fluctuations. Animals could be both a conformer and regulator because they may be regulators with respect to one internal parameter, but conformers with respect to another. Ex. lizards regulate internal salinity but conform to temperatures.

What are a few reasons we need a nervous system?

Conveys information rapidly, allows reaction to danger or stimulus,

What is the difference between a graded and an action potential. Why does a threshold potential need to be reached before an action potential is generated?

Graded: -Amount of voltage change is proportional to current applied -Vary in magnitude (graded) depending on strength of stimulus -Can be excitatory or inhibitory -Conduction with decrement- decreased strength with increased distance from opened ion channel due to: leakage of charged ions across membrane, electrical resistance of cytoplasm, and electrical properties of the membrane and electronic current speeed - TRAVEL SHORT DISTANCES -Sub-threshold to elicit all-or-none response ALL-OR-NONE: -Membrane potential change above a threshold elicits a massive depolarization (AP) Action Potential: -travel long distances -triggered by net graded potential at axon hillock (trigger zone) -do not degrade over time or distance -all APs of same magnitude ** Must reach threshold potential to fire -Depolarization below threshold will not initiate an action potential

Facilitated diffusion

Hydrophilic molecules protein transporter is needed no energy is required depends on conc gradient

What affects the permeability of hydrophobic solutes (and gases)? What affects the permeability of inorganic ions (and water?)

Hydrophobic- dependent on factors that affect diffusion through lipids (molecular sz of solute) Hydrophilic- number of channels and how many are open

2 types of membrane proteins

Integral- embedded in the phospholipid bilayer Peripheral- noncovalently bonded to integral proteins or lipids, but are not within the bilayer. Some help anchor the cell membrane to filaments of their cytoskeleton If a peripheral protein was yanked out of the bilayer, it would not change the membrane's conformation bc of the weaker association of peripheral proteins. Whereas the embedded proteins would if taken out.

Contrast the four different types of receptors in chemical messenger signaling and how they differ in transducing the signal to the target cell.

Intracellular receptors: Ligand diffuses across cell membrane and binds to a receptor in the cytoplasm or nucleus. The ligand binding changes the shape of the receptor that activates it. L-R complex binds to specific DNA sequences and regulates the transcription of target genes. Ligand-Gated Ion Channels: Ligand binds to the receptor and the receptor changes shape opening a channel. Concentration and electrical gradients dictate the direction of ion movement and movement of ions change ion concentrations which alters the membrane potential. Receptor Enzymes: a ligand binds to the receptor changing its shape and the transmembrane domain transmits this shape change across the membrane, activating the catalytic domain of the enzyme which starts a phosphorylation cascade. G-Protein-Coupled Receptors: Ligand binds to the receptor causing a conformational change and the activated receptor signals to an associated G protein, causing the alpha subunit to release GDP and bind GTP. The activating alpha or beta-gamma subunits move through the membrane and interacts with an amplifier enzyme. The activated amplifier enzyme converts an inactive second messenger to its active form. The activated second messenger activates or inhibits cellular pathways.

Types of facilitated diffusion

Ion channels- small pores for specific ions, open and close in response to cellular conditions, "gated channels" Porins- like ion channels, but for larger molecules Permeases- function more like an enzyme, carries molecule across membrane

Passive diffusion

Lipid soluble molecules no specific transporters no energy required depends on conc. gradient with steeper gradients resulting in faster rates

What equation calculates an ion's equilibrium potential? What equation calculates the equilibrium potential of all ions?

Nernst Goldman

Nervous system cell-to-cell signaling:

Short duration responses; rapid speed; synapse transport; long intracellularly & short across synapse is the max signaling distance; electrical and chemical signal type; neuron, muscle, and endocrine target cells; neural secretory cell

What is the step-by-step signal transduction pathway of how a peptide chemical messenger vs. a steroid is released by the signaling cell, transported to the target cell, transduced through the target cell to elicit the appropriate response.

Signal Transduction by intracellular receptors: 1. Hydrophobic ligands pass through membrane 2. inside cell, ligand binds to l-binding domain of the intracellular receptors 3. ligand binding changes the shape of the receptor 4. the r-l complex translocates to the nucleus 5. the DNA-binding domain of the receptor binds to responsive element DNA sequences, and the transactivating domain interacts with other transcription factors bound in this region. 6. Together, there transcription factors alter the rate of transcription of the target genes into mRNA

G-coupled Receptors

transmembrane protein that interacts with intracellular G proteins which are named for their ability to bind guanosine nucleotides, activate second messengers (Cyclic AMP signaling)

Define homeostasis

The stable internal conditions maintained by animals despite changes in the environment through coordinated physiological processes.

Neurons are excitable. What do I mean by this statement? How is this achieved?

They can rapidly change their membrane potential through depolarization, repolarization, and hyperpolarization which act as electrical signals

Why do small animals have a higher mass specific metabolic rate than larger animals? Why can't we have endothermic animals smaller than a hummingbird or a shrew?

To meet energy needs: Shrews and small hummingbirds must maintain enormous mass specific mr's to regulate body temps near 37-40 degrees C. Can only pack so many mitochondria into a cell and can only supply metabolic fuels up to a certain rate

Auto-/Paracrine system cell-to-cell signaling:

Various secretory cells; most cells in body as target cells; chemical signal type; short max signaling distance; extracellular fluid transport; rapid speed; short duration of response

Exocrine system cell-to-cell signaling:

Various secretory cells; sensory and neural target cells; chemical signal type; very long max signaling distance; external environment transport; various speeds and durations of response

KE

energy of movement

Primary and Secondary Active transport

protein transporter is needed energy is required (hydrolysis of ATP provides energy, ATPases are transporters) molecules can be moved from low to high concentration Primary- direct use of exergonic rxn Secondary- couples the movement of one molecule to the movement of a second

4 components of transducers

receiver- ligand binding receptor transducer- conformational change of the receptor amplifier- signal transduction pathway increases the number of molecules affected responder- something that responds to the signal

Hydrophilic messengers storage: secretion: transport: receptor: effects:

storage: intracellular vesicles secretion: exocytosis transport: dissolved in extracellular fluid receptor: transmembrane effects: rapid = peptides and most amines and purines can travel through the lipid membrane using pores; typically involves the movement of ions (changes in membrane potential); opening and closing can be regulated

Hydrophobic messengers: storage: secretion: transport: receptor: effects:

storage: synthesized on demand secretion: diffusion across membrane transport: short distances: dissolved in extracellular fluid; long distances: bound to carrier protein receptor: intracellular or transmembrane effects: slower or rapid = steroids, lipids, and few amines and purines

What is the difference between kinetic and potential energy? What are the different categories of energy, provide a brief explanation of what they are and whether they are potential, kinetic or both potential and kinetic energy.

• Heat - Radiant energy- transmitted from one object to another - Thermal energy- movement of molecules, also called molecular kinetic energy • Mechanical energy - movement of objects • Electrical energy - movement of charged particles down a charge gradient • Chemical energy - within chemical bonds