Chapter 25 Hw

metabolism

transport hydrogen atoms to coenzymes

reduced; oxidized

coenzymes

anabolic

glycolysis → acetyl CoA → citric acid cycle → electron transport chain

glycosis

This process splits glucose in half and produces 2 ATPs for each glucose.

This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.

This process produces some ATP and carbon dioxide in the mitochondrion

remove hydrogen atoms from organic molecules and transfer them to coenzymes

coenzyme

acetyl-CoA

the citric acid cycle

2

the movement of hydrogen ions through channels in the inner mitochondrial membrane.

mitochondrial matrix.

citric acid cycle and ETS

electron transport system

citric acid

gluconeogenesis

gluconeogenesis

decarboxylation.

NAD and FAD

mitochondria

LDLs and VLDLs

acetyl-CoA.

carry excess cholesterol from peripheral tissues to the liver.

very-low-density lipoproteins.

beta-oxidation

acetyl-CoA

phospholipids and proteins.

acetyl-CoA

high-density lipoproteins

reduce the concentration of ammonia

transferred to a keto acid

urea

urea

the liver forms glucagon

muscle proteins are used as an energy source

ketoacidosis

ADH is released by the posterior pituitary gland.

potassium

chloride

calcium

phosphate

iron

zinc

A

D

E

K

riboflavin

niacin.

A

liver

fat

thermoregulation

convection

conduction

2 pyruvate molecules with a net gain of 2 ATP molecules

the breakdown of organic substrates that releases energy used to synthesize high-energy compounds (e.g., ATP)

Most abundant storage carbohydrate, branched chain of glucose molecules

the synthesis of new organic molecules, in energy terms: is an "uphill" process that forms new chemical bonds

Most abundant storage lipids, primarily of fatty acids

Generates ATP and other high-energy compounds by breaking down carbohydrates Glucose + Oxygen -> Carbon dioxide + Water

- occurs in small steps which release energy to convert ADP to ATP - one molecule of glucose nets 36 molecules of ATP

- breaks down glucose in cytosol into smaller molecules used by mitochondria - does not require oxygen (anaerobic reaction)

1. Glucose molecules 2. Cytoplasmic enzymes 3. ATP and ADP 4. Inorganic phosphates 5. NAD (coenzyme)

decarboxylation

To remove hydrogen atoms from organic molecules and transfer them to coenzymes

two carbon atoms regenerating 4-carbon chain

One molecule of GTP (guanosine triphosphate)

- is the generation of ATP within mitochondria - a reaction requiring coenzymes and oxygen - produces more than 90 percent of ATP used by body Results in 2 H2 + O2 -> 2 H20

Is the key reaction in oxidative phosphorylation in inner mitochondrial membrane

loss of electrons, electron donor is oxidized

gain of electrons, electron recipient is reduced

coenzymes in the citric cycle that remove hydrogen atoms from organic substrates, each hydrogen atom consists of an electron and a proton

Travel through series of oxidation-reduction reactions ultimately combine with oxygen to form water

Play key role in oxidation-reduction reactions and act as intermediaries, accept electrons from one molecule, transfer them to another molecule

Enter electron transport system, transfer to oxygen, H2O is formed Energy is released and synthesize ATP from ADP

Accepts hydrogen atoms, is reduced, gains energy

Gives up hydrogen atoms, is oxidized, loses energy

Accepts two hydrogen atoms from citric acid cycle, gaining two electrons

Accepts two hydrogen atoms, gains two electrons, releases one proton, forms NADH + H+

Does not produce ATP directly, creates steep concentration gradient across inner mitochondrial membrane

As they pass from coenzyme to cytochrome and from cytochrome to cytochrome

- energy of one electron pair removed from substrate in citric acid cycle by NAD - pumps 6 hydrogen ions into intermembrane space - reentry into matrix generates 3 molecules of ATP

- energy of one electron pair removed from substrate in citric acid cycle by FAD - pumps 4 hydrogen ions into intermembrane space - reentry into matrix generates 2 molecules of ATP

- the most important mechanism for generation of ATP - requires oxygen and electrons - rate of ATP generation is limited by oxygen or electrons - cells obtain oxygen by diffusion from extracellular fluid

Produces 3 ATP + 1 water molecule

Produces 2 ATP + 1 water molecule

28 ATP

1. Breaks down 2 pyruvic acid molecules 2. Produces 2 ATP by way of GTP 3. Transfers H atoms to NADH and FADH2 4. Coenzymes provide electrons to ETS

- is the synthesis of glucose from noncarbohydrate precursors 1. Lactic acid 2. Glycerol 3. Amino acids - Stores glucose as glycogen in liver and skeletal muscle

- the breakdown of glycogen - Occurs quickly - Involves a single enzymatic step

- the formation of glycogen from glucose - Occurs slowly - Requires high-energy compound uridine triphosphate (UTP)

Triglycerides

Breaks lipids down into pieces that can be: converted to pyruvate or channeled directly into citric acid cycle

One molecule of glycerol, three fatty acid molecules

glycerol to pyruvate

- breaks fatty acid molecules into 2-carbon fragments - occurs inside mitochondria Each step: 1. Generates molecules of acetyl-CoA and NADH 2. Leaves a shorter carbon chain bound to coenzyme A

can use almost any organic substrate because lipids, amino acids, and carbohydrates can be converted to acetyl-CoA

is synthesized from dihydroxyacetone phosphate (intermediate product of glycolysis)

- cannot be produced by the body, must be consumed - unsaturated 18-carbon fatty acid from plants - Linoleic acid and Linolenic acid

cells require lipids

- most lipids are not soluble in water - special transport mechanisms carry lipids from one region of body to another

lipoproteins

free fatty acid

- can diffuse easily across plasma membranes - in blood, are generally bound to albumin (most abundant plasma protein) - an important energy source during periods of starvation when glucose supplies are limited

- are produced in intestinal tract - are too large to diffuse across capillary wall - enter lymphatic capillaries and travel through thoracic duct to venous circulation and systemic arteries

are lipid-protein complexes that contain large insoluble glycerides and cholesterol five classes 1. Chylomicrons 2. Very low-density lipoproteins (VLDLs) 3. Intermediate-density lipoproteins (IDLs) 4. Low-density lipoproteins (LDLs) 5. High-density lipoproteins (HDLs)

- mitochondria generate ATP by breaking down amino acids in citric acid cycle - not all amino acids enter cycle at same point, so ATP benefits vary

- removal of amino group by transamination or deamination - requires coenzyme derivative of vitamin B6 (pyridoxine)

- attaches amino group of amino acid to keto acid - converts keto acid into amino acid that leaves mitochondrion and enters cytosol - available for protein synthesis

- prepares amino acid for breakdown in citric acid cycle - removes amino group and hydrogen atom - reaction generates ammonium ion

- highly toxic, even in low concentrations - liver cells (primary sites of deamination) have enzymes that remove ammonium ions by synthesizing urea

water-soluble compound excreted in urine

the reaction sequence that produces urea

1. Proteins are more difficult to break apart than complex carbohydrates or lipids 2. A by-product, ammonium ion, is toxic to cells 3. Proteins form the most important structural and functional components of cells

- amino acids made by the body on demand - requires process called amination

- focal point of metabolic regulation and control - contains great diversity of enzymes that break down or synthesize carbohydrates, lipids, and amino acids

- have an extensive blood supply - monitor and adjust nutrient composition of circulating blood - contain significant energy reserves (glycogen deposits)

Is the period following a meal when nutrient absorption is under way

- the period when nutrient absorption is not under way - body relies on internal energy reserves for energy demands - liver cells conserve glucose break down lipids and amino acids

- generate acetyl-CoA - increased concentration of acetyl-CoA causes ketone bodies to form

Three types 1. Acetoacetate 2. Acetone 3. Betahydroxybutyrate - liver cells do not catabolize these - peripheral cells absorb these and reconvert to acetyl-CoA for citric acid cycle - they are acids that dissociate in solution - fasting produces ketosis

- the appearance of ketone bodies in bloodstream - lowers plasma pH, which must be controlled by buffers

- a dangerous drop in blood pH caused by high ketone levels - may cause coma, cardiac arrhythmias, death

- provide all essential amino acids in sufficient quantities - found in beef, fish, poultry, eggs, and milk

- are deficient in one or more essential amino acids - found in plants

1. amino acids- framework of all proteins, glycoproteins, and lipoproteins 2. purines and pyrimidines- nitrogenous bases of RNA and DNA 3. Creatine- energy storage in muscle (creatine phosphate) 4. Porphyrins- bind metal ions, essential to hemoglobin, myoglobin, and cytochromes

Nitrogen absorbed from diet balances nitrogen lost in urine and feces

- are not stored in the body - must be obtained by: recycling N compounds in body or from diet

When excretion exceeds ingestion

- vitamins A, D, E, and K - are absorbed primarily from the digestive tract along with lipids of micelles - normally diffuse into plasma membranes and lipids in liver and adipose tissue

A structural component of visual pigment retinal

Is converted to calcitriol, which increases rate of intestinal calcium and phosphorus absorption

Stabilizes intracellular membranes

Helps synthesize several proteins, including three clotting factors

vitamin deficiency disease

- components of coenzymes - rapidly exchanged between fluid in digestive tract and circulating blood - excesses are excreted in urine

fat-soluble vitamin K and five water-soluble vitamins

- intestinal epithelium absorbs all water-soluble vitamins except B12 - B12 molecule is too large - must bind to intrinsic factor before absorption

energy is released

controls overall metabolism

suppresses appetite

released by adipose tissues during absorptive state and binds to CNS neurons that suppress appetite

released by empty stomach and increases appetite

- heat production - BMR estimates rate of energy use - energy not captured is released as heat - serves important homeostatic purpose

- warm objects lose heat energy as infrared radiation - depending on body and skin temperature - about 50 percent of indoor heat is lost by radiation

- results from conductive heat loss to air at body surfaces - as body conducts heat to air, that air warms and rises and is replaced by cooler air - accounts for about 15 percent of indoor heat loss

- absorbs energy (0.58 Cal per gram of water evaporated) - cools surface where evaporation occurs - evaporation rates at skin are highly variable

- direct transfer of energy through physical contact - generally not effective in heat gain or loss

1. Increased muscle tone increases energy consumption of skeletal muscle, which produces heat 2. Involves agonists and antagonists, and degree of stimulation varies with demand 3. Shivering increases heat generation up to 400 percent

1. Releases hormones that increase metabolic activity 2. Heat-gain center stimulates adrenal medullae via sympathetic division of ANS releasing epinephrine