Unit 2 Biology 181

What are the three phases of oxidative respiration and what (generally) occurs in each?

Three stages of oxidative respiration: glycolysis, the Krebs cycle, and electron transport chain Glycolysis: CYTOPLASM (DOES NOT REQUIRE OXYGEN) Investment phase 1.) glucose enters the cytoplasm through facilitated diffusion, breaking glucose and turning it to C-C-C-C-C-C-C 2.) 6-carbon sugars uses ATP from phosphate producing glucose-6-phosphate C-C-C-C-C-C-P; turning ATP to ADP 3.) isomerase converts glucose-6-phosphate into fructose-6-phosphate 4.) A second ATP molecule donates a high energy phosphate to fructose-6-phosphate producing fructose-1,6-biphosphate P-C-C-C-C-C-C-P; second P's ATP turns to ADP Payoff Phase 5.) glycolysis employs an enzyme (aldose) to split 1,6-biphosphate into three carbon isomers: P-C-C-C (DHAP) and C-C-C-P (glyceraldehyde-3-phosphate/PGAL); enzyme will convert DHAP to C-C-C-P; there is a net investment of energy from 2 ATP molecules in the breakdown of one glucose 6.) glycolysis oxidizes the sugar (PGAL) extracting high energy electrons which are picked by the electron carrier NAD+ producing NADH (reduced coenzyme) 7.) PGAL is phosphorylated by a second phosphate group producing 1,3-bisphosphoglycerate: P-C-C-C-P (twice) 8.) 1,3 donates a high-energy phosphate to ADP forming 1 ATP; 1,3 diphosphoglycerate is oxidized to a carboxy forming 3-phosphoglycerate C-C-C-P twice 9.) water is lost from its structure (dehydration reaction); glycolysis is catalyzed producing second ATP molecule and the compound pyruvic acid (CH3COCOOH) Produced: 4 ATP (net 2 ATP), 2 NADH, and 2 pyruvate Oxidation of pyruvate: MATRIX OF MITOCHONDRIA 1. Carboxyl group is stripped off the pyruvate releasing CO2; rest of pyruvate is oxidized to an acetyl group), electrons are picked up by NAD+ forming NADH (high-energy electrons from NADH will be used later to generate ATP); the acetyl group lashes onto coenzyme A (CoA) forming acetyl CoA PRODUCED: 2 CO2, 2 NADH Acetyl CoA to CO2: 1.)acetyl CoA delivers its acetyl group to a four-carbon molecule, oxaloacetate, to form citrate; this pathway (citric acid cycle/krebs cycle) will harvest the remainder of the extractable energy from what began as a glucose molecule CITRIC ACID CYCLE: MATRIX OF MITOCHONDRIA the citric acid cycle is a closed loop: the last part of the pathway regenerates the compound used in the first step. The eight steps of the cycle are a series of chemical reactions that produces the following from each of the two molecules of pyruvate produced per molecule of glucose that originally went into glycolysis Prior to the start of the first step, a transitional phase occurs during which pyruvic acid is converted to acetyl CoA. 1.) combining the two-carbon acetyl group with a four-carbon oxaloacetate molecule to form a six-carbon molecule of citrate C-C-C-C-C-C 2.) Produce a five-carbon molecule, α-ketoglutarate C-C-C-C-C, together with a molecule of CO2 and two electrons, which reduce NAD+ to NADH 3.) Release electrons that reduce NAD+ to NADH and release carboxyl groups that form CO2 molecule producing succinyl group which binds to CoA forming Succinyl CoA (C-C-C-C) 4.) phosphate group is substituted for coenzyme A, and a high-energy bond is formed. This energy is used in substrate-level phosphorylation to form either guanine triphosphate (GTP) or ATP which is produce by GDP; still has (C-C-C-C) 5. ) Dehydration process that converts succinate into fumarate. Two hydrogen atoms are transferred to FAD, producing FADH2. The energy contained in the electrons of these atoms is insufficient to reduce NAD+ but adequate to reduce FAD. Unlike NADH, this carrier remains attached to the enzyme and transfers the electrons to the electron transport chain directly. This process is made possible by the localization of the enzyme catalyzing this step inside the inner membrane of the mitochondrion; still has (C-C-C-C) 6.) Water is added; still has (C-C-C-C) 7.) Another molecule of NADH is produced from NAD+; still has (C-C-C-C) 8.) The last step in the citric acid cycle regenerates oxaloacetate by oxidizing malate PRODUCED: 3 NADH, 2 CO2, 1 GTP, FADH2 (TWICE/ 2X) OXIDATIVE PHOSPHORYLATION: Most of the ATP generated during the aerobic catabolism of glucose is not generated directly from these pathways (glycolysis and the citric acid cycle). Rather, it is derived from a process that begins with moving electrons through a series of electron transporters that undergo redox reactions: the electron transport chain. This causes hydrogen ions to accumulate within the matrix space. Therefore, a concentration gradient forms in which hydrogen ions diffuse out of the matrix space by passing through ATP synthase. The current of hydrogen ions powers the catalytic action of ATP synthase, which phosphorylates ADP, producing ATP. ETC: (requires oxygen) is the last component of aerobic respiration and is the only part of glucose metabolism that uses atmospheric oxygen; Electron transport is a series of redox reactions that resemble a relay race in that electrons are passed rapidly from one component to the next, to the endpoint of the chain where the electrons reduce molecular oxygen, producing water; The electron transport chain is present in multiple copies in the inner mitochondrial membrane of eukaryotes and the plasma membrane of prokaryotes. The common feature of all electron transport chains is the presence of a proton pump to create a proton gradient across a membrane. There are four complexes composed of proteins, labeled I through IV Complex 1: t wo electrons are carried to the first complex aboard NADH; Complex I can pump four hydrogen ions across the membrane from the matrix into the intermembrane space, and it is in this way that the hydrogen ion gradient is established and maintained between the two compartments separated by the inner mitochondrial membrane; electrons inside the Complex I prodive energy to push through Q and Complex 2: Complex II directly receives FADH2, which does not pass through complex I producing FAD. The compound connecting the first and second complexes to the third is ubiquinone (Q). This enzyme and FADH2 form a small complex that delivers electrons directly to the electron transport chain, bypassing the first complex. Since these electrons bypass and thus do not energize the proton pump in the first complex, fewer ATP molecules are made from the FADH2 electrons. Complex III: Cytochrome proteins have a prosthetic group of heme. The heme molecule is similar to the heme in hemoglobin, but it carries electrons, not oxygen. As a result, the iron ion at its core is reduced and oxidized as it passes the electrons, fluctuating between different oxidation states: Fe++ (reduced) and Fe+++ (oxidized). Complex III pumps protons through the membrane and passes its electrons to cytochrome c for transport to the fourth complex of proteins and enzymes (cytochrome c is the acceptor of electrons from Q; however, whereas Q carries pairs of electrons, cytochrome c can accept only one at a time). Complex IV: This complex contains two heme groups (one in each of the two cytochromes, a, and a3) and three copper ions (a pair of CuA and one CuB in cytochrome a3). The cytochromes hold an oxygen molecule very tightly between the iron and copper ions until the oxygen is completely reduced. The reduced oxygen then picks up two hydrogen ions from the surrounding medium to make water (H2O). The removal of the hydrogen ions from the system contributes to the ion gradient used in the process of chemiosmosis. CHEMIOSOMSIS: In chemiosmosis, the free energy from the series of redox reactions just described is used to pump hydrogen ions (protons) across the membrane. The uneven distribution of H+ ions across the membrane establishes both concentration and electrical gradients (thus, an electrochemical gradient), owing to the hydrogen ions' positive charge and their aggregation on one side of the membrane. hydrogen ions in the matrix space can only pass through the inner mitochondrial membrane through an integral membrane protein called ATP synthase. This complex protein acts as a tiny generator, turned by the force of the hydrogen ions diffusing through it, down their electrochemical gradient. The turning of parts of this molecular machine facilitates the addition of a phosphate to ADP, forming ATP, using the potential energy of the hydrogen ion gradient. is used to generate 90 percent of the ATP made during aerobic glucose catabolism; it is also the method used in the light reactions of photosynthesis to harness the energy of sunlight in the process of photophosphorylation. Recall that the production of ATP using the process of chemiosmosis in mitochondria is called oxidative phosphorylation. The overall result of these reactions is the production of ATP from the energy of the electrons removed from hydrogen atoms. These atoms were originally part of a glucose molecule. At the end of the pathway, the electrons are used to reduce an oxygen molecule to oxygen ions. The extra electrons on the oxygen attract hydrogen ions (protons) from the surrounding medium, and water is formed. PRODUCES WATER ATP Ideally 38 ATP in total from all three steps

channel protein vs. carrier protein

channel protein- membrane protein that allows a substance to pass through its hollow core across the plasma membrane carrier protein- membrane protein that moves a substance across the plasma membrane by changing its own shape

Transport protein

(passive transport) membrane protein that facilitates passage of substances across a membrane by binding it

gated passive

(passive transport) transporter changes shape when a specific molecule binds to it

Define endergonic, exergonic, and activation energy

(we can predict whether a reaction requires or releases energy by comparing the bond energies of reactants with those of products) endergonic (energy in)- reactions that require a net input of free energy exergonic (energy out)- reactions that end with a net release of free energy activation energy- the minimum amount of energy for a reaction to occur

cellular respiration

A series of metabolic pathways, collectively called cellular respiration, extracts the energy form the bonds in glucose and converts it into a form that all living things can use

In terms of cell respiration, why would choking (the inability to inhale and exhale) ultimately lead to death?

A waste product of cell respiration (carbon dioxide) would build up to toxic levels and ATP would not form because a reactant for cell respiration (oxygen) would stop entering the body.

Why is ATP an effective energy storage molecule?

ATP is an unstable molecule therefore it releases the energy stored readily and quickly, this is essential for metabolic processes in the cell such as active transport and protein synthesis. As well as being unstable ATP is a very small molecule this means the energy is in manageable packages and can be released as required, this reduces waste. When the energy from ATP is used it is converted to ADP and Pi (inorganic phosphate), this is a reversible reaction meaning ATP can be recycled depending on demand

What is ATP synthase, during which part of oxidative respiration is it used and what does it do?

ATP synthase- membrane-embedded protein complex that adds a phosphate to ADP with energy from protons diffusing through it During which part- Oxidative phosphorylation is the process in which ATP is formed as a result of the transfer of electrons from NADH or FADH 2 to O 2 by a series of electron carriers. This process, which takes place in mitochondria, is the major source of ATP in aerobic organisms Do- ATP synthase is a complex which makes use of the proton potential created by the action of the electron transport chain in mitochondria. It transports a proton down the gradient and uses the energy to complete the phosphorylation of ADP to ATP

What is the definition of metabolism?

All the chemical reactions that take place inside cells (including anabolism and catabolism)

catabolism vs. anabolism

Anabolism refers to the process which builds molecules the body needs; it usually requires energy for completion. Catabolism refers to the process that breaks down complex molecules into smaller molecules; it usually releases energy for the organism to use.

What is the difference between respiration in your lungs and oxidative respiration?

Breathing involves inhale of oxygen from the atmosphere into the lungs and exhale of carbon dioxide from the lungs into the atmosphere ; whereas cellular respiration involves breakdown of glucose into carbon dioxide and water in living cells, releasing energy

Enzymes can be inhibited or competition can occur. Explain each of these.

Competitive inhibition- type of inhibition in which the inhibitor competes with the substrate molecule by binding to the active site of the enzyme Noncompetitive inhibitors (allosteric)- bind to another part of the enzyme causing the enzyme to change shape, making the active site less effective Feedback inhibitor- end product of a metabolic pathway, shuts down pathway thus preventing cells from wasting chemical resources by synthesizing more product that is needed

hydrolysis vs. dehydration synthesis

Dehydration synthesis reactions build molecules up and generally require energy, while hydrolysis reactions break molecules down and generally release energy.

What is denaturation, why is it important and what are some conditions which can cause denaturation?

Denaturation- process that changes the natural properties of a substance Important - The way proteins change their structure in the presence of certain chemicals, acids or bases - protein denaturation - plays a key role in many important biological processes. The impact of heat and radiation on proteins has its advantages as well. Food, especially meat, is cooked in order to denature the proteins within and make them easier to digest Causes of denaturation- high temperature, extreme pH values, and salinity

Describe the fluid mosaic model.

Describes the organization of cell membranes; phospholipids drift and move like fluid; the bilayer is a mosaic mixture of; the membrane's lipids and proteins can move laterally within the bilayer, like a boat on the ocean.

How do proteins work in the PM

Embedded in cell membrane, some help cell attach to other surfaces or cells, others interact with other proteins and lipids, some protein (integral) are permanently attached in the membrane

Define free energy

Energy that is available to do work

Facilitated diffusion vs. active transport

Facilitated diffusion- materials diffuse across the plasma membrane with the help of membrane proteins (no ATP consumed) Active transport- requires energy input (usually ATP), moves a solute against its concentration gradient One of the main comparisons is that active transport occurs against the concentration gradient whilst, facilitated diffusion occurs down the concentration gradient.

What molecules can move freely across the PM?

Gases and nonpolar molecules diffuse freely across a lipid bilayer; ions and large polar molecules require more mechanism; Oxygen is a small molecule and it's nonpolar, so it easily passes through a cell membrane. Carbon dioxide, the byproduct of cell respiration, is small enough to readily diffuse out of a cell. Small uncharged lipid molecules can pass through the lipid inwards of the membrane.

What does glycolysis literally mean, and what does this process produce?

Glycolysis literally means to break down glucose; glyco- glucose, -lysis: breaking up Glycolysis is the first step in the breakdown of glucose to extract energy for cellular metabolism; the breakdown of glucose by enzymes, releasing energy and pyruvic acid Glycolysis: 6 glucose are turn into two pyruvates (3 glucose each), 4 ATP made (uses two ATP = 2 ATP net, makes two NADH

In which part of the cell or mitochondrion does each of the following occur: glycolysis, Krebs cycle, ETC ?

Glycolysis takes place in the cytoplasm (between the plasma membrane and the nuclear envelope; fills the space between organelles) of both prokaryotic and eukaryotic Krebs cycle (citric acid cycle) takes place in the matrix of mitochondria ETC (electron transport chain) is found in the inner mitochondrial membrane

What are the three main stages of aerobic cellular respiration?

Glycolysis, Krebs cycle, oxidative phosphorylation

Glycolysis vs Krebs Cycle

Glycolysis- process of breaking glucose into two three-carbon molecules with the production of ATP and NADH (a co enzyme that has the ability to transfer electrons) Krebs cycle- (alternative name for citric acid cycle) series of enzyme-catalyzed chemical reactions of central importance in all living cells Glycolysis is the breakdown of a molecule of glucose to yield two molecules of pyruvate, whereas Kreb cycle is the process where acetyl CoA, produces citrate by adding its carbon acetyl group to oxaloacetate.

What happens to a cell when it is exposed to a hypertonic solution ? Explain how each of this solution differs from other in terms of solvent and solute.

Hypertonic- Solute concentration higher outside the cell; cell will shrink; alot of water goes out few goes in

What happens to a cell when it is exposed to a hypotonic solution?Explain how each of this solution differs from other in terms of solvent and solute.

Hypotonic- solute higher concentration inside cell; cells will swell or burst; a lot of water goes in few comes out

ADP vs. ATP

If a cell needs to spend energy to accomplish a task, the ATP molecule splits off one of its three phosphates, becoming ADP (Adenosine di-phosphate) + phosphate. The energy holding that phosphate molecule is now released and available to do work for the cell. When the cell has extra energy (gained from breaking down food that has been consumed or, in the case of plants, made via photosynthesis), it stores that energy by reattaching a free phosphate molecule to ADP, turning it back into ATP. The ATP molecule is just like a rechargeable battery. When it's fully charged, it's ATP. When it's run down, it's ADP.

What happens to a cell when it is exposed to an isotonic solution? Explain how each of this solution differs from other in terms of solvent and solute.

Isotonic- Fluids have the same solute concentration; cell will stay the same; equal amount of water is going in and out of the cell

Krebs cycle vs. ETC

Krebs- occurs in the mitochondrial matraix, ETC occurs in the mitochondrial inner membrane; Krebs- 2 ATP net gain per glucose, ECT 32 ATP net gain per glucose; krebs- aerobic process oxygen not directly involved, ETC aerobic oxygen directly involved; Krebs- CO2 is released as waste product, ETC water is released as waste product

lactic acid fermentation vs. alcohol fermentation

Lactic acid- Muscle fatigue; this type of fermentation is used routinely in mammalian red blood cells and in skeletal muscle that has an insufficient oxygen supply to allow aerobic respiration to continue (in muscles used to the point of fatigue). In muscles, lactic acid accumulation must be removed by the blood circulation and the lactate brought to the liver for further metabolism. The chemical reactions of lactic acid fermentation are the following: Pyruvic acid + NADH <--> Lactic acid+ NAD+ , pyruvate receives electrons and hydrogen from NADH, forming NAD+ (oxidized) and lactate; enzyme used in this reaction is lactate dehydrogenase (LDH). alcohol fermentation produces ethanol, an alcohol. The first chemical reaction of alcohol fermentation is the following (CO2 does not participate in the second reaction): pyruvic acid--> CO2 + acetaldehyde + NADH --> Ethanol +NAD+; pyruvate is spilt into acetaldehyde and CO2, acetaldehyde receives electrons and hydrogen from NAD, forming NAD+ and ethanol

What is the induced-fit model of enzymes?

Model describing a more dynamic interaction between enzyme and substrate (the chemical reactants to which an enzyme binds are the enzyme's substrate); as the enzyme and the substrate come together, their interaction causes a mild shift in the enzyme's structure that confirms an ideal binding arrangement between the enzyme and the transition state of the substrate, this ideal binding maximizes the enzyme's ability to catalyze its reaction

What happens to the NADH and FADH2 which are produced during the citric acid cycle?

NADH and FADH2 produced in the citric acid cycle must transfer their electrons to the next pathway in the system which will use oxygen; they travel down the electron transport chain releasing the electrons that they once had, the end result is loads of energy

Is glucose the only molecule which can be used to make ATP in your body? Explain your answer.

No, energy can be obtained from complex carbohydrates, fats, and proteins Complex carbohydrates: enzymes break starch and other complex carbohydrates down to monosaccharide, monosaccharide are taken up by cells and converted to glucose-6-phosphate, which continues in glycolysis Energy from fats: enzymes split fats into glycerol and fatty acids, glycerol products enter glycolysis, fatty acids are converted to acetyl Co-A and enter the Krebs cycle, compared to carbohydrates, fatty acid breakdown yields more ATP per carbon atom Energy from proteins: enzymes split dietary proteins into amino acid subunits, which are used to build proteins or other molecules; the amino group is removed and converted into ammonia (NH3) a waste product eliminated in urine; acetyl CoA, pyruvate or an intermediate of the Krebs cycle forms, depending on the amino acid

Simple diffusion vs. osmosis

One big difference between osmosis and diffusion is that both solvent and solute particles are free to move in diffusion, but when we talk about osmosis, only the solvent molecules (water molecules) cross the membrane

oxidation vs reduction reactions

Oxidation reaction strips an electron from an atom in a compound (lost electron) and the addition of this electron to another compound is a reduction reaction (gained electron)

What are the fundamental differences between active and passive transport? Why does a cell require both types of transport?

Passive transport- no ATP needed; substances move from an area of higher concentration to an area of lower concentration. Active transport- ATP needed; if a substance inside the cell is greater than it concentration gradient (if the concentration of the substance inside the cell is greater than its concentration in the extracellular fluid and vice versa), the cell must use energy to move the substance Why- is to protect the cell's internal environment and to keep its balance of salts, nutrients, and proteins within a range that keeps the cell and the organism alive

3 parts of plasma membrane

Phospholipid bilayer, proteins, and cholesterol

What does it mean to say that the PM is selectively permeable?

Plasma membranes are amphiphilic which helps the movement of some materials (lipid soluble low molecular weight, fat soluble vitamins, fat soluble drugs, hormones, and oxygen and carbon dioxide) through the membrane and hinders the movement of others (polar substances, small ions- sodium, potassium, calcium and chloride) -ability of a cell to control which substances and how much of them enter or leave the cell; allows the cell to maintain a difference between its internal environment and extracellular fluid, supplies the cell with nutrients, removes wastes and maintains volume and pH

Define cellular respiration

Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen;how we derive energy from fuel or from what we eat (glucose)

Why is oxidative respiration important? In other words, what does it produce?

Produces energy

What is the purpose of the Krebs cycle and what does it produce?

Purpose- It finishes the sugar-breaking job started in glycolysis and fuels the production of ATP in the process. The eight steps of the cycle are a series of redox, dehydration, hydration, and decarboxylation reactions that produce 2 CO2 molecules, 1 GTP/ATP, and reduced forms of NADH and FADH2

What is pyruvate and where is it produced and which reaction produces it?

Pyruvate: three-carbon sugar that can be decarboxylated and oxidized to make acetyl CoA, which enters the citric acid cycle under aerobic conditions; the end product of glycolysis Produce: Pyruvate is produced by glycolysis in the cytosol (cytoplasm) of the cell Reaction: oxidation

chemical bond energy

Reaction- a chemical change that occurs with atoms, ions, or molecules Reactants- atoms, ions, or molecules that enter a reaction Product- atoms, ions, or molecules remaining at the end of a reaction

types of endocytosis

Receptor-mediated endocytosis- specific molecules bind to the surface receptors, which are then enclosed in an endocytic vesicle Phagocytosis- Larger target particles such as microbes or cellular debris are engulfed by pseudopods which merge as a vesicle, which fuses with a lysosome in the cell Pinocytosis- a less selective endocytic pathway that brings small volume of fluid into the cell

The Na+/K+ pump is very important for all cells. Explain the job of this protein and why that function is so important.

Sodium-potassium pump (Na+/K+ ATPase) moves K+ (2)into the cell while moving Na+ (3)out at the same time. This results in the interior being slightly more negative to the exterior; the difference in charge is important in creating the conditions necessary for the secondary process. Therefore the sodium potassium pump is an electrogenic pump (a pump that creates a charge imbalance), creating an electrical imbalance across the membrane and contributing to the membrane's resting potential in the cell

How does the structure/composition of the plasma membrane relate to its functions? Include the lipid and the protein components. What types of functions do different proteins perform?

Structure: The primary function of the plasma membrane is to protect the cell from its surroundings. Composed of a phospholipid bilayer with embedded proteins, the plasma membrane is selectively permeable to ions and organic molecules and regulates the movement of substances in and out of cells. Proteins Integral: function as transporters, channels Peripheral: may serve as enzymes or as cell's recognition sites (the body recognizes its own proteins and attacks foreign proteins associated with invasive pathogens). Lipids (phospholipids): phospholipids form an excellent two-layer cell membrane that separates fluid within the cell from fluid outside the cell (separates the water and other materials on one side of the barrier from the water and other materials on the other side)

what can affect the rate of diffusion?

Temperature, size of the molecules, steepness of the concentration gradient, solvent density, solubility, surface area and thickness of plasma membrane, and distanced traveled

concentration

The amount of solute in a solevent

When fermentation occurs, what product(s) is/are produced?

The end products of fermentation are ethanol (alcohol), gas (carbon dioxide), and lactic acid; it occurs when materials run out of oxygen during the gylcosis stage

What is a mitochondrion and what are its component parts?

The eukaryotic cell structure where cellular respiration occurs; The mitochondrion is a double-membrane-bound organelle found in most eukaryotic organisms; it consists of an outer membrane, inner membrane and gell-like material called matrix

Imagine that the pH decreased (meaning the concentration of H+ increased) in the mitochondrial intermembrane. What might happen to ATP production as a result?

The high external acid concentration causes an increase in H+ in the inter membrane space leading to increased ATP production by ATP synthase.

Define osmosis.

The movement of water down it concentration gradient; moves from lower solute concentration to a region of higher solute concentration; must pass through selectively permeable membrane (water will go to where there is more "stuff")

Explain how protons are used to make ATP. In your discussion be sure you define what a gradient is and how a gradient helps in ATP production.

The proton gradient produced by proton pumping during the electron transport chain is used to synthesize ATP. Protons flow down their concentration gradient into the matrix through the membrane protein ATP synthase, causing the conversion of ADP to ATP.

What is acetyl co-A and where is it produced and which reaction produces it?

The pyruvate molecules produced at the end of glycolysis are transported into the mitochondria, there the pyruvate will be transformed into an acetyl group that will be picked up and activated by a carrier compound called coenzyme A (CoA) resulting in the compound called acetyl CoA Produced- mitochondrial matrix Reaction: oxidization

uniporter vs. symporter vs. antiporter

Uniporter- transporter that carries one specific ion or molecule; symporter- transporter that carries two different ions or small molecules, both in the same direction; antiporter- transporter that carries two ions or small molecules in different directions

How does ATP assist enzymes which catalyze endergonic reactions?

When ATP or a phosphate group from ATP is added to a substrate or enzyme that participates in an endergonic reaction, the potential energy of the substrate or enzyme is raised enough to make the reaction exergonic and thus spontaneous. In this way, ATP drives reactions that otherwise would not occur.

ATP

a nucleotide with a 3 phosphate groups; transfers a phosphate group and energy to other molecules

Phosphorylation

a phosphate-group transfer; ADP binds phosphate in an endergonic reaction to replish ATP (ATP/ADP cycle)

aerobic respiration vs. anaerobic respiration vs. fermentation

aerobic respiration- process in which organisms convert energy in the presence of oxygen; metabolic pathways are used by most eukaryotic anaerobic respiration- process in which organisms convert energy for their use in the absence of oxygen; metabolic pathways are used by prokaryotes and protist in anaerobic habitats fermentation- An anaerobic pathway for breaking down glucose; process of regenerating NAD+ with either an inorganic or organic compound serving the final electron acceptor, occurs in the absence of oxygen; fermentation pathways breakdown carbohydrates without using oxygen; occurs in the cytoplasm aerobic respiration and formation both begin with glycolysis, which converts one molecule of glucose into two molecules of pyruvate

How is energy stored?

all cells store and retrieve energy in chemical bonds of the molecules of life; when bonds break chemical energy is released sucrose (reactant)---reaction---glucose + fructose (products)

Tonicity

amount of solute in a solution; the ability of a solution to cause a cell to gain or lose water

types of metabolic pathways

anabolic pathways- pathways build molecules ; consume enerfy using stored energy from e- in bonds catabolic pathways- pathways break apart molecules; release energy Cyclic pathways- pathways regenerate a molecule from the first step

How do enzymes bind to substrates?

binding at enzyme active sites may bring on the transition state by four mechanisms - helping substrates get together - orienting substrates in positions that favor reaction - inducing a fit between enzyme and substrate (induced-fit model) - shutting out water molecules

How are plant cells different

cell walls help maintain water balance ( will not burst because of the cell wall) plant cell in hypotonic solution (swells, becomes turgid, very firm), plant cells in isotonic solution (become flaccid, limp, may wild), plants in hypertonic environment (lose water, membrane pulls away from wall-plasmolysis)

What are some non-protein helps of enzymes?

co-factors- inorganic ions (iron, magnesium) that help molecules bind to enzyme (doesn't have carbon) eg. DNA polymerase (enzyme used to build DNA requires zinc ion) coenzyme- organic helper molecules; common source is dietary vitamins (does have carbon) e.g. vitamin c (build collagen fibers)

Compare and contrast the following terms: phagocytosis, receptor-mediated endocytosis and pinocytosis.

common characteristic: the plasma membrane of the cell invaginates forming a pocket around the target particle, the pocket pinches off resulting in the particle being contained in newly created intracellular vesicle formed from the plasma membrane; they are all active transports Different: phagocytosis("cell-eating")- is the process by which large particles (large macromolecules, whole cells, or cellular structures), are taken in by a cell Pinocytosis("cell drinking")- a process that takes in small molecules (liquids/water) , which the cell needs from the extracellular fluid potocytosis- used to bring small molecules into the cell and to transport these molecules through the cell for their release on the other side of the cell; receptor-mediated endocytosis- employs receptor proteins in the plasma membrane that have a specific binding affinity for certain substances, transports large quantities of marcromolecules

controls over metabolism

concentrations of reactants or products can make reaction proceed forward or backward feed back mechanisms can adjust enzyme production, or activate or inhibit enzymes

Methods of transport, energy requirement, and types of transported material

diffusion (passive)- small-molecular weight material osmosis (passive)- water Facilitated transport/diffusion (passive)- sodium, potassium, calcium, and glucose Primary active transport (Active)- sodium, potassium, and calcium secondary active transport (Active)- amino acids and lactose Phagocytosis (Active)- large macromolecules, whole cells, or cellular structures Receptor-mediated endocytosis (Active)- Large quantities of marcromolecules

second law of thermodynamics

during every energy transfer or transformation some energy is unusable and is often lost as heat; when you exert yourself, your body releases the stored energy in your body (heat is lost)

first law of thermodynamics

energy is neither created nor destroyed; can be transferred from one form to another

How enzymes work?

enzyme (catalysis)- an enzyme makes a specific reaction occur much faster than it would on its own Substrate- the specific reactant acted upon by an enzyme active site- locations on the enzyme molecule where substrates bind and reactions proceed

exergonic vs. endergonic

in an exergonic reaction, energy is released to the surroundings. The bonds being formed are stronger than the bonds being broken. In an endergonic reaction, energy is absorbed from the surroundings

What is an enzyme? What does it mean to say enzymes catalyze reactions? How do enzymes do this?

enzyme- special molecules that catalyze (helps chemical reaction) biochemical reactions enzymes catalyze reactions- they perform the critical task of lowering the activation energies of chemical reactions inside the cell How- Enzymes do this by binding to the reactant molecules, and holding them in such a way as to make the chemical bonding-breaking and bond-forming processes takes place more readily

How does a cell move larger items across the PM?

exocytosis- the fusion of a vesicle with the cell membrane, releasing its contents to the surrounding (materials exiting cell) Endocytosis- the formation of a vesicle from cell membrane, enclosing materials near the cell surface and bringing them into the cell (materials entering the cell)

electrochemical gradient

gradient produced by the combined forces of an electrical gradient and chemical gradient

What is the purpose of the ETC and what does it produce?

main purpose is to build up a surplus of hydrogen ions (protons) in the intermembrane space so that there will be a concentration gradient compared to the matrix of the mitochondria to generate ATP Produce- at the end of the chain the electrons are taken up by oxygen molecules to make water. This is why oxygen is known as the final electron acceptor

The sum of all the biochemical reactions in an organism is called

metabolism

Amphiphilic barrier

molecule possessing a polar or charged area and a nonpolar or uncharged area capable of interacting with both hydrophilic and hydrophobic environments

what is diffusion

passive process (no energy required)of transport of low-molecular weight material according to its concentration gradient; moving of solutes across the membrane

Metabolic pathways

series of enzyme-mediated reactions by which a cell builds, rearrange or breaks down an organic substance; all of the chemical reactions that transpire inside cells including that use and release energy

Simple diffusion vs. facilitated diffusion

simple diffusion- an unassisted type of diffusion in which a particle moves across the plasma membrane; can only move substance in the direction of concentration gradient Facilitated diffusion- transport of substances across the membrane through a concentration gradient by means of a carrier molecule; can move substance with and against concentration gradient

What two things make up a solution?

solute and solvent

What are some other types of carrier proteins?

symporter- carries 2 different ions or molecules Uniporter- one specific ion or molecule Antiporter- Also carries two different ions or molecules, but in different directions

Effects of temp, pH and salinity

temp- raising the temp boosts reaction rates by increasing a substrate's energy, but raising it too high denatures enzymes pH- each enzyme has an optimum pH range; in human most enzymes work at pH 6 to 8 Salinity- salt levels affect the hydrogen bonds that hold enzymes in their 3 dimensional shape

Concentration gradient

the difference in concentration between two adjacent regions(difference in 2 areas); area of high concentration adjacent to an area of low concentration

Osmosis

the movement of water down its concentration gradient; moves from lower solute concentration to a region of higher solute concentration; must pass through selectively permeable membrane (water will go where there is more stuff)