cell metabolism & cell membrane transport

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condensation

joining together of two or more smaller molecules to from a larger one, water is generated as a product. A-OH + H-B ->A-B + H2O ADP + Pi → ATP + H2O

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hydrolysis

water reacts with molecules, causing breakage of the bonds that link a molecule together. A-B + H2O ->A-OH + H-B Protein + H2O → Amino acids.

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oxidation

removal of electrons (or H) from any molecules; reaction of any molecule with oxygen. C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O HA-BH → A-B + 2H

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reduction

addition of electrons (or H) to a molecule. Monounsaturated fatty acid + 2H → Saturated fatty acid. FAD + 2H → FADH2 A-B + 2H → HA-BH

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phosphorylation

A protein kinase catalyzes. addition of a phosphate group. A + Pi -> A-P Protein + Phosphate → Protein - Phosphate

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dephosphorylation

removal of a phosphate group. A-P -> A + Pi

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What can affect reaction rates and how?

a.Reactant and product concentration: an increase in the concentration of reactants relative to products will increase the net rate in the forward direction.

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2.What can affect reaction rates and how?

Conversely, an increase in the concentration of products relative to reactants will decrease the net forward rate. b.Temperature:

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3.What can affect reaction rates and how?

c.he height of the activation energy barrier: the rate of a reaction increases as the height of the barrier decreases.

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[E] and [S]

increasing enzyme concentration= increase reaction rate increasing substrate concentration= increase reaction rate

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activation energy barrier

the activation energy barrier increases, the reaction rate will decrease

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affinity

is the measure of the strength of interactions between a ligand and binding site.describes the strength of binding between a protein and a ligand.Higher affinities=higher rates for enzymes-catalyzed rxns

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temperature

increasing the temperature, increases the reaction rate

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Role of Enzymes in Chemical Reactions

E + S <- -> E.S <- -> P + E •Enzymes: Proteins that function as catalysts for reactions in biological systems •Enzymes function by decreasing activation energy for a specific chemical reaction

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Enzymes function

by decreasing activation energy for a specific chemical reaction

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Enzyme Properties

•Enzymes are specific for one set of substrates or a group of similar substrates •Enzymes are not changed in the reaction •Enzymes are not consumed in the reaction •Enzymes are identified by the suffix -ase are not going to change anything except spe

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Enzymes: Substrate Specificity

-Only if a substrate molecule closely fits and binds to its active site, can the enzyme act on the substrate and catalyze the reaction. -Lock-and-key model

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2. Enzymes: Substrate Specificity

-Induced-fit model: Active site approximately fits substrates As substrate(s) begins to bind, conformation change in enzyme allows for better fit Reaction takes place

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What is a cofactor?

nonprotein componentsof some enzymes necessary for them to hold normal conformation during metabolic reactions

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Cofactor: Its function?

Some enzymes require trace metals to function.Trace metals must be present in the enzyme in order for the enzyme to bind substrate.

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what is the most important energy-transferring compound in cells?

Adenosine triphosphate (ATP)

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The greater the attractive forces between substrate and enzyme, that enzyme is said to have a higher ________ for the substrate.

affinity

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What is a coenzyme?

organic molecules derived from vitamins that function in the transfer of a chemical group

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Coenzyme function?

transfer small chemical grps.

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NAD, FAD, and coenzyme A is derived from ___ vitamin.

NAD= vitamin B3 (niacin) FAD=vitamin B12 (riboflavin) coenzyme A= vitamin B5 (pantothenic acid)

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What is enzyme saturation?

An enzyme is saturated when the active sites of all the molecules are occupied most of the time. At the saturation point, the reaction will not speed up, no matter how much additional substrate is added.

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Allosteric regulation

-Reversible binding of a modulator molecule to regulatory site and alters the active site, thus the activity of the enzyme

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covalent regulation

Changing state requires formation of a covalent bond between protein (enzyme) and chemical group. Most common chemical group used in covalent modulation = phosphate group

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example of covalent regulation?

Regulating an enzyme through protein kinase-induced phosphorylation of that enzyme

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feedback inhibition

- An intermediate product of a metabolic pathway allosterically inhibits an enzyme (often a rate-limiting enzyme) that catalyzes an earlier reaction.

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what is the most important energy-transferring compound in cells?

Adenosine triphosphate (ATP)

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Study glycolysis

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glycolysis: its location,

cytosol

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glycolysis: how many ATP molecules are produced (net),

generating 2 ATP and 2 NADH + 2 H+

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glycolysis: the final products (with available oxygen, with limited oxygen).

The final product of glycolysis under aerobic conditions/with available oxygen is pyruvate. 2 pyruvate Pyruvate enters the mitochondrial matrix where it is converted into acetyl CoA.

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glycolysis: the final products (with limited oxygen).

With limited available oxygen: Pyruvate + NADH + H+ -> lactate + NAD+ Under anaerobic conditions,pyruvate is converted to lactate in the cytosol

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Study Krebs cycle: its location, its initial substrate, its production (NADH, FADH2, ATP directly, CO2, H2O) in one cycle, and its significant in terms of energy production.

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Krebs cycle: its location,

mitochondrial matrix

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Krebs cycle: its initial substrate,

Acetyl CoA

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Krebs cycle: its production (NADH, FADH2, ATP directly, CO2, H2O) in one cycle,

1 ATP, 3 NADH + 3 H+, 2 CO2, 1 FADH2

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Krebs cycle: its significant in terms of energy production.

reduces the coenzymes NAD and FAD for oxidative phosphorylation

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Study electron transport chain: location, electron movement, and hydrogen ions movement and ATP synthase

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. Study electron transport chain: location,

inner mitochondrial membrane

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. Study electron transport chain: electron movement,

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. Study electron transport chain: hydrogen ions movement a

Electrons are carried from complex I to III by coenzyme Q, from III to IV by cytochrome C. Released energy is used to transport H+ from the mitochondrial matrix to the intermembrane space against their concentration gradient.

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Study electron transport chain: ATP synthase

-H+ then flow in the opposite direction (down their concentration gradient) through the enzyme ATP synthase, in the process releasing energy to synthesize ATP. -NADH -> 3 ATP; FADH -> 2 ATP.

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What happens each time an electron is passed between the molecules of the electron transport chain is produced?

Energy is RELEASED each time an electron is passed between the molecules of the electron transport chain

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What is the first electron acceptor for an NADH and a FADH?

flavine mononucleotide (FMN)is the first component of the electron transport chain that accepts electrons from an NADH molecule. FADH2 donates its electrons to coenzyme Q which at a point down stream.

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What is the final acceptor of electrons in the electron transport chain?

last electron acceptor= O2

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Define glycogenesis, glycogenolysis, and gluconeogenesis? Where do they occur? What molecules can be converted to glucose?

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Define glycogenesis? Where do they occur?

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glycogenesis:What molecules can be converted to glucose?

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Define glycogenolysis? Where do they occur?

the breakdown of glycogen to glucose

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glycogenolysis: What molecules can be converted to glucose?

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Define gluconeogenesis? Where do they occur?

refers to synthesis of glucose and occurs in the liver

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Gluconeogenesis: What molecules can be converted to glucose?

glycerol, lactate, a.a., pyruvate substrate= amino acids and glycerol only

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Define lipolysis,

is the conversion of triglycerides(fat) to glycerol and fatty acids

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Lipogenesis

synthesize fats from other nutrients.

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What are ketones?

generated from acetyl CoA, important for the nervous system as a partial alternative to glucose.Also metabolism of fatty acids that results in the accumulation of acetyl CoA can lead to a buildup of ketones.

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Define the essential nutrients.

is any biomolecule necessary for proper body function that cannot be synthesized in cells. If it can't be produced by body then is essential

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How many ATP are generated from the complete oxidation of one glucose molecule?

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ch.4 Study concentration of solutes in ICF and ECF, focus on sodium, calcium, potassium, amino acids

table 4.1 p94

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ICF and ECF: on sodium,

ICF= 15mM and ECF: 145mM

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ICF and ECF: calcium

ICF= <0.001mM and ECF: 1.8mM

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ICF and ECF: potassium

ICF= 140mM and ECF:4mM

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ICF and ECF:amino acids

ICF= 8mM and ECF: 2mM

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ICF and ECF: chlorine

ICF= 4mM and ECF:115mM

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Define chemical,

A chemical force (ions move from higher concentration to lower concentration).

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Define electrical,

2. An electrical force: ions to be pushed in one direction or the other by the membrane potential

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Define electrochemical gradient.

Total force acting on particle,Sum of chemical and electrical forces.is Force that ultimately determines the movement of ions across the membrane

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Define Membrane potential. How is it formed?

Is a force. a reflection of the unequal distribution of positive and negative ions across the plasma membrane

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Membrane potential: How is it formed?

Due to unequal distribution of anions and cations across cell membrane

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Define cations and anions. What type of charge does intracellular fluid have? And extracellular fluid?

-Cation = particle with a (+) charge -Anion = particle with a (-) charge -ICF contains a slight excess of anions (-) -ECF contains a slight excess of cations (+)

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Define equilibrium potential

describes the membrane potential where electrical forces and chemical forces are balanced. Membrane potential (Vm), (a hypothetical value )when Electrical force = chemical force

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Define passive transport. What is simple diffusion? What molecules can move into/out of cells by it? What factors can affect its rate?

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. Define passive transport.

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passive transport. What is simple diffusion?

•No membrane proteins are needed •Transport is through the bilipid layer •Passive Transport - A random thermal molecular motion down a concentration gradient.

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simple diffusion: What molecules can move into/out of cells by it?

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simple diffusion: What factors can affect its rate?

1. The magnitude of the driving force; as the concentration gradient increases or decreases by a given factor, the flux increases or decreases by that same factor. 2. Membrane surface area:

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simple diffusion: What factors can affect its rate?

3. Membrane permeability: for any mechanism of passive transport, a higher permeability translates into a higher rate of transport, other things being equal.

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simple diffusion: Factors influencing the permeability:

a. The lipid solubility of the diffusing substance: hydrophobic (nonpolar) substances are the most lipid soluble, hydrophilic (polar or ionized) are the least lipid soluble. b. The size and shape of diffusing molecules.

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simple diffusion: Factors influencing the permeability:

c. Temperature: higher temperature increases the permeability. d. Membrane thickness: a thicker membrane would have a lower permeability.

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Define facilitated diffusion.

a molecule is moved down its concentration gradient with the assistance of a protein carrier molecule, and no energy is required

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facilitated diffusion. What molecules can move into/out of cells by it?

a.a., glucose, fructose

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Define ion channel diffusion. What molecules can move into/out of cells by it?

1. Leak channels 2. Gated channels Rate of transport through ion channels depends on: - The transport rate of individual channels: type of channels. -The number of channels in the membrane. Most ion channels: either a closed state or an open state.

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ion channel diffusion. What molecules can move into/out of cells by it?

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Compare and contrast passive transport/active transport

Active Transport - Nonspontaneous - Requires cell energy - Involves a pump (membrane protein) - Movement is uphill

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Compare passive transport/active transport

active transport: Characteristics of a Pump - A type of membrane protein - Function as transporter and enzyme - Can harness energy - Have specific binding sites - Demonstrate saturation

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contrast passive transport/active transport

Passive Transport - Including simple diffusion, facilitated diffusion, and diffusion through ion channels - Spontaneous - No cell energy is required - Downhill movement ex.simple diffusion,facilitated diffusion, ion channels diffusion

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active transport:

• Primary active transport • Secondary active transport required energy,ATP

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Compare and contrast primary and secondary active transport

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primary active transport

requires ATP directly NA+/K+ pump

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secondary active transport

requires ATP indirectly

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