Ch 7: Metabolism

Describe the difference between light reactions and dark reactions

- The light reactions convert solar energy into chemical energy in the form of ATP by photophosphorylation and NADPH. -The dark reactions incorporate CO2 into organic molecules in a process called carbon fixation. Dark reactions are also reduction synthesis because carbohydrates are produced by reducing CO2. *Both reactions take place in chloroplast

Describe the dark reactions

- light Independent. Use the ATP (energy) & NADPH ( electrons) Produced by the light reactions to reduce CO2 to carbohydrates. Although these reactions do not directly require light, they will only occur during the day when the light reactions are replenishing the supply of ATP and NADPH. * Also called Carbon fixation & reduction synthesis reactions (Calvin Cycle)

What's the difference between Glycolysis & Cellular Respiration?

-Cellular respiration is the most efficient catabolic pathway used by organisms to harvest the energy stored and glue close. Where as glycolysis yields only 2 ATP per molecule of glucose. Cellular Respiration can yield 36-38 ATP. - Cellular respiration is an aerobic process; oxygen acts as the final acceptor Of electrons that are passed from carrier to carrier during the final stage of glucose oxidation. The metabolic reactions of cellular respiration occurs in the eukaryotic mitochondria and our catalyzed by reaction- specific enzymes. - 3 stages: pyruvate decarboxylation, citric acid cycle, electron transport chain.

Fats

-Fat molecules are stored in adipose tissue in the form of triglycerides. -Activated in cytoplasm with 2 ATP - Transported into mitochondrion & taken through a series of beta-oxidation cycles that convert it into two-carbon fragments, which are then converted into acetyl-CoA -Yield the greatest amount of ATP

What is Fermentation & describe the two types

-Fermentation is the process of producing ATP in the absence of oxygen. 1. Alcohol Fermentation: Occurs in yeast & bacteria; the pyruvate produced in glycolysis is converted to ethanol. 2. Lactic acid fermentation converts the 3-carbon pyruvate to the 3-carbon lactic acid (C3H6O3) and regenerates NAD + in the process, allowing glycolysis to continue to make ATP in low-oxygen conditions. Since there is a limited supply of NAD + available in any given cell, this electron acceptor must be regenerated to allow ATP production to continue. To achieve this, NADH donates its extra electrons to the pyruvate molecules, regenerating NAD+ Lactic acid is formed by the reduction of pyruvate.

Photosystems I and II

-Photosystems are light-absorbing complexes in the thylakoid membranes that are present in photosynthetic organisms . - Each has one primary photochemical reaction center (either chlorophyll P700 or P680) and a set of accessory pigments to absorb additional light. 1)There is a special molecule called chlorophyll a P700, located in photosystem I, which absorbs light best at 700 nanometers (nm). It also contains other accessory pigments. ll) Another special chlorophyll a molecule in photosystem II is called chlorophyll a P680 because it absorbs best at 680 nm. Photosystem II also contains chlorophyll b and other accessory pigments.

Photosynthesis

-Plants use the sun's energy to convert water and carbon dioxide into glucose and oxygen in the chloroplast. -glucose can be stored as storage or use as an energy source.

Calvin Cycle

-light-independent reactions of photosynthesis in which energy from ATP and NADPH is used to build high-energy compounds such as sugar. -The cycle begins when carbon dioxide (CO2) from the atmosphere enters plant cells. An enzyme called rubisco catalyzes the first reaction, where CO2 binds to a specific 5-carbon molecule called ribulose-1,5-bisphosphate (RuBP). This reaction creates a 6-carbon molecule which then splits into two 3-carbon molecules. This part of the cycle is a form of carbon fixation. This just means that inorganic carbon is converted to organic molecules, like sugar. -The high-energy products from the light reactions are used in the next reaction. ATP and NADH donate electrons to the 3-carbon molecules, which are converted to a 3-carbon sugar called glyceraldehyde-3-phosphate (G3P). -Some of these G3P molecules leave the cycle to form glucose molecules. These will be used by the plant during cellular respiration. Three turns of the cycle are needed for one G3P molecule to exit the cycle. Glucose is made of 6 carbons, so two G3P molecules are needed to make one glucose molecule. -After three turns of the cycle, this leaves five more G3P molecules which are recycled. This allows the cycle to continue. ATP is used to convert the leftover G3P into the molecules that can bind incoming carbon dioxide and restart the cycle.

Describe enzyme characteristics

1. Enzymes do not alter the equilibrium constant. 2. enzymes are not consumed in the reaction this means that they will appear in both the reactants and the products. 3. Enzymes are PH- And temperature sensitive, with optimal activity at specific PH ranges and temperatures. *Most enzyme catalyzed reactions are reversible. The product Synthesized by an enzyme can be decomposed by the same enzyme. (An enzyme that synthesizes maltose from glucose can also hydrolyze maltose back to glucose.)

What is the maximal activity of human enzymes of most body fluids?

7.2 pH

Enzyme

A protein that is an organic catalyst. -They regulate metabolism by speeding up certain chemical reactions. -They affect the reaction rate by decreasing the activation energy. *Are very selective

Noncyclic Electron Flow

A route of electron flow during the light reactions of photosynthesis that involves both photosystems and prdouces ATP, NADPH, and oxygen. The net electron flow is from water to NADP+ *The net result of noncyclic electron flow is the production of NADPH and ATP And the photoplyis( breakdown) of water

Growth

An increase in size cause my cell division and synthesis of new material

Catalyst

Any substance that affects the rate of a chemical reaction without itself being changed.

Digestion

Breakdown of food substances into simpler forms that can be absorbed and used

What is the source of carbon for carbohydrate production in the Calvin cycle?

CO2

Ingestion

Consumption of food and raw materials

Carbohydrates

Disaccharides are hydrolysis into monosaccharides, most of which can be converted into glucose or glycolysis intermediated. Glycogen stores in the liver can be converted, when needed, into a glycolytic intermediate.

Describe Enzyme Specificity

Enzyme action and reaction rate depend on several environmental factors including temperature, pH, and the concentration of enzyme and substrate. Heat alters the shape of the active site of the enzyme molecules And activated.

What is the net reaction for Glycolysis?

Glucose+ 2ADP + 2Pi + 2NAD+ -----> 2 Pyruvate + 2ATP + 2NADH + 2H+ + 2H20 -Depending on the capabilities of the organism, pyruvate degradation can proceed in 2 directions. 1. Anaerobic Conditions: Pyruvate is reduced during the process of fermentation. 2. Aerobic Conditions: pyruvate is further oxidized during cellular respiration in the mitochondria.

Ammonia

Is a toxic substance in vertebrates. Fish can excrete Ammonia, where as insects and birds convert it to iris acid, And mammals converted to urea for excretion.

Cellular Respiration

Metabolic pathway that breaks down glucose and produces ATP. The stages of cellular respiration include glycolysis, pyruvate oxidation, the citric acid or Krebs cycle, and oxidative phosphorylation. *Essentially, sugar (C6H12O6) is burned, or oxidized, down to CO2 and H2O, releasing energy (ATP) in the process

Induced Fit Theory

More widely excepted theory describes the active site as having flexibility of shape. When the appropriate substrate comes in contact with the active site the confirmation of the active site changes to fit the substrate.

Glycolysis

One Glucose (C6H12O6) is broken down to 2 molecules of pyruvic acid (3 Carbon) . Results in the production of 2 ATPs for every glucose, the production of ATP, & the reduction of NAD + into NADH in the cytoplasm.

Electron Transport Chain

The NADH & FADH2 made in other steps deposit their electrons in the electron transport chain, turning back into their "empty" forms (NAD + & FAD). As electrons move down the chain, energy is released and used to pump protons out of the matrix, forming a gradient. Protons flow back into the matrix through an enzyme called ATP synthase, making ATP. At the end of the electron transport chain, oxygen accepts electrons and takes up protons to form water.

Proteins

The body The grades proteins only one not enough carbohydrate or fat is available

Assimilation

The building up of new tissues from digested food materials

Transportaion

The circulation of essential compounds required to nourish the tissues in the removal of waste products from tissues

Respiration

The consumption of oxygen by the body. Cells use oxygen to convert glucose into ATP, a ready source of energy for cellular activities

Regulation

The control of physiological activities. The body's metabolism functions to maintain its internal environment in a changing external environment. The steady state of the internal environment is known as homeostasis and includes regulations by hormones and the nervous system. Irritability is the ability to respond to a stimulus and is part of regulation

Synthesis

The creation of complex molecules from simple ones (anabolism)

Reproduction

The generation of additional individuals of a species

Absorption

The passage of nutrient molecules through the lining of the digestive tract into the body. Absorbed molecules pass through cells lining the digestive tract by the fusion or active transport

Glucose Catabolism

The production of ATP is achieved through the oxidation of glucose molecules. In oxidation, the electrons are stripped from a glucose molecule to reduce NAD+ and FAD. NAD+ and FAD possess a high energy potential to drive the production of ATP in the electron transport chain. ATP production occurs in the mitochondria of the cell. There are two methods of producing ATP: aerobic and anaerobic.

Pyruvate Decarboxylation

The pyruvate form during glycolysis is transported from the cytoplasm into the mitochondrial matrix word is the decarboxylated (loses CO2) & the Acetyl Group that remains is transferred to Coenzyme A to form Acetyl-CoA. *In the process NAD+ is reduced to NADH

Excretion

The removal of waste products ( Such as carbon dioxide, water, and urea) Produce dear metabolic processes like respiration in assimilation

Metabolism

The sum of all chemical reactions that occur in the body. Can be divided into catabolic reaction, which break down large chemicals and release energy. Anabolic reactions, which build up large chemicals and require energy.

Lock and Key Theory

This spatial structure Of an enzyme's active site is exactly complementary to the spatial structure of its substrate. The two fit together like a lock and key.

Cyclic Electron Flow

Under certain conditions, the photoexcited electrons take an alternative path called cyclic electron flow, which uses photosystem I (P700) but not photosystem II (P680). This process produces no NADPH and no O2, but it does make ATP. This is called cyclic photophosphorylation.

When are many of the active sites on the enzyme unoccupied?

When the concentration of both enzyme and substrate are low.

Citric Acid Cycle ( Krebs Cycle)

When two- carbon acetyl group from acetyl-CoA combines with oxaloacetate, a four- carbon, molecule to form the six-carbon citrate. Through a series of reactions, two CO2 are released and oxaloacetate is regenerated for use in another turn of the cycle.

pancreatic enzymes

Work optimally in the alkaline conditions of the small intestine with a pH of 8.5.

Pepsin

Works best in the highly acidic conditions of the stomach with a pH of 2.

What are the 4 stages of Respiration?

glycolysis, pyruvate oxidation, citric acid cycle, oxidative phosphorylation (electron transport chain)

oxidative deamination

removes an ammonia molecule directly from the amino acid.

transamination reaction

when amino acids lose an amino group to form an alpha-keto acid