Download Enzymes, Membranes, and Hormones: A Comprehensive Study Guide for NS 4320 Exam 1 and more Exams Health sciences in PDF only on Docsity!
NS 432 0 EXAM 1 T 10 TU WIT0% VERIFH COMPLIED!!ETE SOLUTIONS
Enzymes and membranes - ANSWER What are enzymes? -up. ANSWER Catalysts. Increase reaction rates without being used
How do enzymes speed up chemical reactions? - ANSWER lower activation energy 6 classes of enzymes -isomerases, ligases ANSWER oxidoreductases, transferases, hydrolases, lysases,
Oxidoreductases - ANSWER transfer of electrons (H atoms) Transferases - ANSWER group transfer reactions Hydrolases - ANSWER Hydrolysis reactions (transfer of functional groups to water) Lyases -removal of groups ANSWER addition of groups to double bonds, or formation of double bonds by
Isomerases - ANSWER Transfer of groups within molecules to yield isomeric forms Ligases -reactions coupled to cleavage of ATP or similar cofactor ANSWER formation of C-C, C-S, C-O, and C-N bonds by condensation
Role of enzymes and their kinetics -(ex. cellular respiration/glucose breakdown) (G<0) ANSWER Exergonic: net release of free energy
Endergonic: energy is absorbed in the reaction (ex. photosynthesis) (G>0) Draw change in energy with and without enzyme. -state in lower. ANSWER Pic 1. Catalyzed transition
Enzymes act by - ANSWER binding substrates Enzymes _________ recognize proper substrates - ANSWER selectively Enzymes produce products in - ANSWER very high yields (greater than 95%) Specificity is controlled by - ANSWER structure Enzymes do not effect - ANSWER equilibrium (G) *The overall free energy change for a reaction is related to (G) -equilibrium constant ANSWER the
*The free energy of activation for a reaction is related to the (G++) -constant (k) ANSWER rate
catalyzed vs. uncatalyzed --two free reactants single restricted transition state ANSWER UNCATALYZED BIMOLECULAR RXNS -conversion is entropically unfavorable UNCATALYZED UNIMOLECULAR RXNS
Vmax is never - ANSWER achieved in reality Vmax only if - ANSWER enzyme is completely saturated with substrate Equilibrium constant (deltaG) -reaction is at equilibrium ANSWER overall free energy change; when the
Rate constant (k) - ANSWER speed of reaction Catalytic efficiency - ANSWER kcat/km an estimate of "how perfect" the enzyme is Measures how the enzyme performs when s is low. Specificity - ANSWER unique fit of substrate with enzyme Transition state - ANSWER least stable state The effects of enzyme ihibitors - ANSWER pic 2 chemical and physical properties of membranes - ANSWER Barrier to toxin molecules
- Transport and accumulation of nutrients
- Energy transduction- Facilitation of cell motion
- Reproduction
- Signal transduction
- Cell-cell interactions Heads go toward - ANSWER water (hydrophilic) Physical Properties of Membranes - ANSWER Monolayers and bilayers iiiiiiiiiiiii <- Monolayers ¡!¡!¡!¡!¡!¡!¡!¡!¡!¡!¡!¡!¡ <- Bilayers Micelles vesicle (liposome) - ANSWER bubble of lipids that carry things to other membranes. Micelles - ANSWER monolayered -forms in the solution of amphipathic molecules that have larger head than tail -bury the nonpolar tails in the center of a spherical structure -reverse in nonpolar solvents -amphipathic lipid aggregates that form in water Physical properties of membranes - ANSWER -Dynamic and flexible structures -Can exist in various phases and undergo phase transitions
-individual molecules CAN move around Hormones and signal transduction - ANSWER 3 classes of mammalian hormones -space, diffuse to neighboring target (ex. eicosanoids) ANSWER 1. paracrine: released into extracellular
- endocrine: released to blood, carried to target cells (ex. insulin, glucagon)
- autocrine: affect the cell where they are produced (but bind to surface receptors) Insulin is a - ANSWER peptide hormone epinephrine is a - ANSWER amine hormone glucose regulation of insulin secretion (pic 3) -metabolism of glucose in the cell raises intracellular ATP, closing K+ channels in the ANSWER when BG level is high, active plasma membrane and thus depolarizing the membrane in response to this membrane-depolarization triggered by high ATP, voltage-gated Ca2+channels open, allowing Ca2+ to flow into the cell
cytosolic Ca2+ is now high enough to trigger insulin release by exocytosis Know about the effects of key hormones in metabolism - ANSWER What are some metabolic effects of insulin and the enzymes it targets? -Insulin stimulates glucose uptake in muscle and fat ANSWER Glucose --> glucose 6-phosphate
In liver, insulin stimulates glycogen synthase, inactivates glycogen phosphorylase Glucose 6-phosphate --> glycogen Also in liver, insulin stimulates glycolysisGlucose 6-phosphate --> acetyl-CoA
increase glycogen breakdown -Target enzyme: glycogen phosphorylase (increase) ANSWER Effect of glucagon: glycogen---> glucose
decrease glycogen synthesis -glycogen ANSWER Effect of glucagon: Less glucose used as target enzyme: glycogen synthase (decrease) decrease glycolysis - ANSWER Effect of glucagon: less glucose used as fuel in liver target enzyme: PFK-1 (decrease) increase gluconeogenesis -glycerol ANSWER Effect of glucagon: amino acids, oxaloacetate, target enzymes: pyruvate kinase (decrease); PEP carboxykinase (increase) What is a receptor? -complex, which exerts a physiological effect (intrinsic effect) after binding its natural ANSWER A membrane-bound or soluble protein or protein ligand. G-protein coupled receptors - ANSWER Epinephrine receptor Enzyme-linked receptors - ANSWER Insulin receptor
- cAMP is degraded, reversing the activation of PKA (down-regulation of cAMP occursby the hydrolysis of GTP in the a-subunit of the G-protein)
signal amplification -the signal in proportion to the amount of target in the reaction. ANSWER The use of specific detection ways to directly increase
What is cAMP? --Allosterically activates cAMP-dependent protein kinase A (PKA) ANSWER a secondary messenger
-PKA activation leads to activation of enzymes that produce glucose from glycogen insulin-signaling cascade - ANSWER pic 5 Carbohydrates and their metabolism - ANSWER 3 monosaccharides - ANSWER glucose, fructose, galactose 3 disaccharides - ANSWER sucrose, maltose, lactose sucrose - ANSWER glucose + fructose maltose - ANSWER glucose + glucose lactose - ANSWER glucose + galactose Know the scientific principles of carbohydrate nutrition -metabolism provides substrates that can be used for fat synthesis. ANSWER -Glucose
-Acetyl-CoA -->Fatty acids -->Triglycerides -Glycerol-3-phosphate --> Triglycerides Conversion of excess glucose to fat Glucose is one of two signals that stimulate the expression of genes for lipogenicenzymes, such as acetyl-CoA carboxylase and fatty acid synthase.
Serves as a glucose sensor - ANSWER Glucokinase CHO digestion mouth -starch and glycogen to disacharides ANSWER Begins in mouth with salivary amylase breaks down
CHO small intestine -disaccharides into monosacchiride. ANSWER continues in pancreas with pancreatic amylase,breaks
ends in small intestine with "brush border" enzymes -ASE - ANSWER Breaks things down. Maltase, Sucrase, Lactase. CHO absorption -the GI epithelial cells to enter blood and lymph. ANSWER is the process by which molecules are transported through
Glucose / Galactose is absorbed by - ANSWER SGLT Fructose is absorbed by - ANSWER GLUT
GLUT4 - ANSWER muscle, adipose tissue, heart Activity increased by insulin GLUT5 -primarily fructose transport ANSWER intestine, testis, kidney;
4 pathways of glucose utilization - ANSWER storage, glycolysis, PPP, Structure Know the feeder pathways for glycolysis and their importance -(glucose, fructose) ANSWER Sucrose Lactose (glucose, galactose) Mannose Glycogen or starchAll needed to make pyruvate
What are the products of glycolysis (pyruvate) and their fates? -conditions: converted to acetyl coenzyme A ---> TCA cycle-->CO2 ANSWER normal
low O2: pyruvate--> lactate Alcoholic ferm: pyruvate--> ethanol How is glucose phosphorylated in cells? - ANSWER first phase of glycolysis -job: phosphorylate glucose and keep it in the cell INhibited by G-6-P
HEXOKINASE:
-ubiquitous -low Km for glucose-regulated
GLUCOKINASE: -liver -high Km for glucose What is the fate of pyruvate in presence of oxygen? -A-->TCA cycle--> CO2 ANSWER acetyl coenzyme
Summary of Glycolysis -from glucose ANSWER breaks glucose in half and extracts a little energy
creates: 2 pyruvate, 2 ATP, 2NADH Gluconeogenesis is the process in which ________. -noncarbohydrate molecules ANSWER glucose is formed from
Gluconeogenesis occurs in the - ANSWER liver and kidneys Gluconeogenesis is regulated by -Allosteric regulation (F-1,6-bisPase) ANSWER Reciprocal control with Glycolysis Substrate regulation (G-6-P) Importance of gluconeogenesis -source of energy. ( Brain, Testies, Kidneys.) ANSWER some organs can only use glucose as a
-TPP
-CoASH -lipoic acid-FAD -NAD+ What are the regulated steps of the TCA cycle? How are they regulated? -PDH, citrate synthase, Isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase ANSWER
- Activated by substrate availability -Inhibited by product accumulation With the complete oxidation of 1 glucose molecule, how many ATP's are generated? -ANSWER 2 ATP before ETC; 28 after ETC
When ATP is low, .... (CAC) - ANSWER citric acid cycle is stimulated --> produces ATP When ATP is high, ... (CAC) - ANSWER Citric acid cycle is inhibited Acetyl-CoA is used for fatty acid synthesis instead of entering CAC 3 irreversible reactions mediated by ______________, ______________, and__________________ - ANSWER citrate synthetase, Isocitrate dehydrogenase,and α-ketoglutarate dehydrogenase
regulated by ATP or NADH
1 NADH produces ______ ATP - ANSWER 2.5 ATP 1 FADH2 produces _________ ATP - ANSWER 1.5 ATP TCA cycle - ANSWER Pic 6 ETC and ATP Synthesis -(the final electron acceptor) and form water. ANSWER Electrons move from NADH and FADH2 to oxygen
This reaction releases energy which creates a proton gradient (via 3 proton pumps) todrive ATP synthesis.
Complex I-IV and ATP synthase Describe the protein complexes involved in ETC and the major electronacceptors/donators (coenzymes) - ANSWER Complex 1-
Complex 1 - ANSWER NADH dehydrogenase Receives electrons from NADHdonates to ubiquinone 4 protons Complex 2 - ANSWER succinate dehydrogenase Receives electrons from FADH2donates to iron-sulfur cluster 0 protons
reversable P/O ratio for NADH - ANSWER 2. P/o ratio for FADH2 - ANSWER 1. P/O ratio is defined as: -through electron transport chain. ANSWER molecules of ATP formed per two electrons flowing
Oxidative phosphorylation inhibitors -Oligomycin ANSWER Rotenone, Cyanide, Azide, CO,
Rotenone inhibits - ANSWER Complex I Cyanide, Azide, CO inhibit - ANSWER Complex 4 Oligomycin inhibits - ANSWER ATP synthase Uncouplers -electron transport; dissipates the proton gradient; Allowing transport in the absence of ANSWER disrupt the coupling between oxidative phosphorylation and phosphorylation. Shuttle back and forth across membrane carrying protons to dissipate the gradient. uncoupler (thermogenin) -drops. ANSWER uses energy to create more heat when temperate
Energy totals worth 10 points - ANSWER Pic 7 Glycogenesis - ANSWER
fate of glucose - ANSWER storage- starch Glycolysis- pyruvateppp- Ribose-5-Phosphate structure- cell wall Glycogen storage - ANSWER 10% liver 1-2% muscleonly different from starch is number of branches
Glycogen branching - ANSWER Highly branched via Alpha-1,6 Glycosidic linkages. the more branches the more sites for phosphorylase attack. branches provide a mechanism for quick release or storage for metabolism. Glycogen synthesis - ANSWER pic 8 Control of glycogen synthesis - ANSWER is done by insulin signaling pathway. when blood glucose is high insulin is secreted from the pancreas to the liver andstimulates glycogen synthesis.
