BIOL 4100 EXAM 4

METABOLISM

all the chemical reactions that occur within a cell

ANABOLIC

Increase in molecular order; decrease in local entropy

ANABOLIC

Pathways that produce cellular components

ANABOLIC

Synthesize polymers in order to store energy

Endergonic

energy requiring reaction

Exergonic

energy liberating reaction

CATABOLIC

Pathways that breakdown cellular components

CATABOLIC

Decrease in molecular order; increase in local entropy

CATABOLIC

Release free energy; produce small molecule building blocks

exergonic

ATP Hydrolysis is Highly _____

Respiration

The flow of electrons, either through or within a membrane, from reduced coenzymes to an external acceptor, usually accompanied by the generation of energy in the form of ATP

36 atp

total net ATP yield from complete oxidation of substrate (glycolysis and respiration)

Mitochondria

perform most of the cellular oxidation reactions and produce the bulk of the ATP produced in an animal cell.

IMM

surrounds the innermost space, the matrix and forms the cristae of the mitochondria

Cristae and Matrix

the major working parts of the mitochondria

electrochemical gradient

drives H+ back into the matrix where the force is harnessed to produce ATP and for selective transport of metabolites across the IMM.

Fusion

rescues stress by allowing functional mitochondria to complement dysfunctional mitochondria by diffusion and sharing of components between organelles.

Hyperfusion

Stress-induced ___________ yields maximal potential, whereas under relaxed conditions cells are able to segregate the damaged ones.

Fusion/Fission

Allows redistribution of mitochondria throughoutthe cell.

Fusion/Fission

Maintains healthy mitochondria.

Fusion/Fission

Plays prominent roles in many disease related processes (apoptosis, mitophagy, etc.)

Mitochondrial Matrix

Almost void of non-coding DNA, variation in genetic code, relaxed codon usage

Mitochondrial Matrix

has a high protein concentration

Mitochondria

Generates reducing power and carbon building blocks for cellular growth, Performs two critical steps in the urea cycle, Adapting metabolic pathways to different nutrient conditions, Membrane biosynthesis, Calcium buffer system.

Proton Motive Force (PMF)

form of potential energyconsisting of charge (Δψm) and chemical (ΔpH)components, that together drive ATPproduction

TCA Cycle

Oxaloacetate → x3 NADH, x1 FADH2 → Oxaloacetate

3, 1

TCA produces __ NADH and __ FADH2 from one pyruvate

2, 2, 2

Glycolysis produces __ pyruvate, __ NADH, and __ ATP from one glucose

8, 2, 4

Glycolysis + TCA produces __ NADH, __ FADH2, and __ ATP

Redox Potential

a Measure of Electron Affiliates

7

NADH produces enough energy to make __ molecules of ATP by donating electrons to diatomic oxygen

1 Electron

Cytochromes and Iron-Sulphur Clusters carry _________

Quinones

These electron carrying cofactors can carry up to two electrons at a time

Quinones

Coenzyme Q and Ubiquinone are examples of these E- Carrying Cofactors

phobic

Coenzyme Q is hydro____

NADH Dehydrogenase (Complex 1)

Largest of the respiratory enzyme complexes. Accepts electrons fromNADH and passes them to ubiquinone.

NADH Dehydrogenase (Complex 1)

Reduces Ubiquinone to Ubiquinol to oxidize NADH to NAD+

NADH Dehydrogenase (Complex 1)

takes in 6H+ and pumps 4H+ out

Succinate Dehydrogenase Complex (Complex 2)

Oxidizes a molecule of succinate to fumarate to generate reduced ubiquinone

Cytochrome c Reductase Complex (Complex 3)

Completely REDUCES Cytochrome C – picks up electrons

Q Cycle

2 Ubiquinol + 2 Cytochrome C³⁺ + 2 H⁺ (in) → 2 Ubiquinone + 2 Cytochrome C²⁺ + 4 H⁺ (out) (+ 1 ubiquinol??)

Cytochrome c Oxidase Complex (Complex 4)

Completely OXIDIZES Cytochrome C – gives away electrons

Cytochrome c Oxidase Complex (Complex 4)

4 Cyt C²⁺ + 8H+ (in) + O₂ → 4 Cyt C³⁺ + 2 H₂O + 4H+ (out)

Proton Pumps

conformational change transporting H+ from the matrix to the IMS

Asp, Glu, Ser, Thr

These 4 amino acids serve as proton wires

Reactive Oxygen Species (ROS)

chemically reactive chemical species containing oxygen

Superoxide (O₂^-)

product of the one-electron reduction of dioxygen O2

Superoxide (O2-)

Reduction in the NADH pool, Reverse Electron Transport, and Normal mitochondria activity all lead to production of:

8000, 400

ATP synthase works at ____ RPM, and produces ___ molecules of ATP per second

ATP Synthase

The c Subunits of ___ _______ determines proton usage per molecule produced

dimerization

__________ of ATP synthase is required for proper cellular respiration

ETC

contains three respiratory enzyme complexes through which electrons pass on their way from NADH to O2.

NADH, Succinate, Ubiquinone, Cytochrome C, Oxidase

NADH → ______ Dehydrogenase Complex → _______ Dehydrogenase → _________ (Coenzyme Q) → __________ Reductase → Cytochrome c → Cytochrome c ______ → ATP + H20 + O2

H+

flows back into the matrix through ATP Synthase, providing the basis of ATP production in the cell.

Endocrine Signals

Long range signal produced at distances from their target and carried by the circulatory system to the site of activation (e.g. Hormones)

Paracrine Signals

Short range signal produced locally andreach their target by diffusion to nearby tissues (e.g. Growth Factor)

Juxtacrine Signals

signals that require physical contact between sending and receiving cell

Autocrine Signals

signaling in which sending and receiving mediators are located on the same cell

Ligands

signaling molecules that trigger a signal cascade by bindingto receptor proteins

Receptors

proteins responsible for detecting stimuli

Signal Transduction

The ability of a cell to translate receptor-ligand interactions to change cellular behavior or gene expression.

Primary Messenger

ligand that initiates the signal cascade by binding to the initial receptor protein

Second Messenger

additional molecules in the cell that receive and relay the signal from one location to the next

Ligand Binding

Receptor conformation changes, clustering, or BOTH, cause this

Pre-Programmed Response

a predetermined sequence of events that occur within a cell depending on specific ligand binding to a receptor.

Dissociation Constant (K_d)

amount of ligand needed to produce a state where exactly half of the receptors are occupied (10⁷ – 10¹⁰nM)

agonists

ligands that bind to their receptors and activate a signaling cascade.

Antagonists

ligands that bind to receptors and prevent naturally occurring messengers from binding and activating the receptor.

Signal Amplification (Upregulation)

The strong response of a target cell to the signaling cascade initiated by ligand binding to its receptor.

Downregulation

one method of this is to reduce the concentration of free ligand available to the receptor (neurons/neurotransmitters)

Neurotransmitter Reduction

Preventing reuptake of neurotransmitter at neuronal synapses

Downregulation

one method of this is to reduce the amount of receptor or the sensitivity of the receptor for the ligand (Receptor desensitization)

Receptor Desensitization

cells in general are geared to sense CHANGES in ligand concentrations rather than fixed ligand concentrations

G proteins

guanine nucleotide binding proteins

Amino terminus

located in extracellular space and location of unique ligand binding sites in G-protein coupled receptors

Carboxy Terminus

located in cytosol and location of unique specific G-protein binding sites in G-protein coupled receptors

G Protein Coupled Receptor Kinases (GCRKs)

enzymes that phosphorylate GPCRs affecting their ability to interact with G-proteins

Large Heterotrimeric G proteins

These proteins are activated by G protein-coupled receptors and are made up of alpha (α), beta (β) and gamma (γ) subunits, the latter two referred to as the beta-gamma complex.

small monomeric G proteins

These proteins are homologous to the alpha (α) subunit found inheterotrimers, but exist as monomers. (e.g. Ras)

Regulators of G Protein Signaling Proteins (RGSs)

proteins that stimulate the catalysis of GTP hydrolysis by G-alpha protein subunits.

Acetylcholine (Ach)

In the absence of _________, aG proteins associated with the _________ receptor is bound to GDP and inactive. (same term)

acetylcholine (Ach)

Upon binding of ______, the G protein is activated by dissociation of G-alpha and the G-beta-gamma complex. The G-beta-gamma complex subunit interacts with a K+ ion channel causing it to open.

signaling cascades

Depending on situation, BOTH G and G/ can result in the initiation of ______ ________

Primary

________ messengers are often hydrophilic or charged in nature

Second Messengers

molecules that relay signals received at receptors on the cell surface — such as the arrival of protein hormones, growth factors, etc. — to target molecules in the cytosol and/or nucleus. (e.g. cAMPand Ca+2)

This second messenger propagates signal from extracellular messengers which cannot pass through the plasma membrane

cAMP

This second messenger regulates ion channel function and is involved in the activation of downstream protein kinases

Gs

Adenylate Cyclase Stimulatory Protein Coupled Receptor

Phosphodiesterases

cAMP molecules in the cytosolare hydrolyzed to AMP by ___________

cAMP, phosphodiesterase

PKA activity can be increased by increasing ____ production or blocking _________

extracellular signals

All cells communicate through ___________ _________ that initiate signal transduction pathways

calcium ions

The concentration of ______ inside a cell can act as an “on v. off switch” for many different cellular processes

Ligand-Receptor

______—_______ interactions are very similar to enzyme-substrate interactions.

G-Protein Coupled Receptors (GPCRs)

coupled to trimeric G proteins. Interaction causes conformational changes that switch the G protein complexes “on” or “off” depending on their interactions with GDP/GTP

G-Protein Coupled Receptors (GPCRs)

can regulate ion channels and control the in flow of ions into the cytosol of the cell.

adenylyl cyclase, cAMP

Ligand binding of GPCRs can activate Gs-alpha and result in the activation of ______ ______ which converts ATP to _____.

cAMP

binds to the regulatory subunit of protein kinase A (PKA) releasing the catalytic subunits which mediate diverse effect in most cells.

Tyrosine Kinases

phosphorylate Tyrosine (Y) residues

Serine/Threonine Kinases

phosphorylate Serine (S) and/or Threonine (T) residues

Dual Specificity Kinases

phosphorylate Serine (S) or Threonine (T) residues AND Tyrosine (Y)