chapter 25 hw

Lipid Catabolism (Lipolysis)

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

The complete catabolism of fatty acids is through the process called

beta-oxidation

A cation that is essential for muscle contraction, nerve function, and blood clotting is

calcium

Lipogenesis

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

High-density lipoproteins (HDLs)

carry excess cholesterol from peripheral tissues to the liver.

To maintain plasma membranes

cells require lipids

The major anion in body fluids is

chloride

In the citric acid cycle, a 2 carbon molecule and a 4 carbon molecule combine to produce

citric acid

Oxygen is an important molecule in which of the following?

citric acid cycle and ETS

In the ETS, ________ accepts electrons from one molecule and transfers them to another.

coenzyme

Intermediary molecules that accept electrons and transfer them to another molecule are called

coenzymes

NAD and FAD

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

The direct transfer of heat energy from one object to another through physical contact is called

conduction

Thyroxine

controls overall metabolism

Carbohydrate metabolism

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

Donor molecule (Oxidation-Reduction Reactions)

Gives up hydrogen atoms, is oxidized, loses energy

Vitamin K

Helps synthesize several proteins, including three clotting factors

Vitamin D

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

Electron Transport System (ETS)

Is the key reaction in oxidative phosphorylation in inner mitochondrial membrane

The Absorptive State

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

The vitamin that is essential for the production of several clotting factors is vitamin

K

What two types of lipoproteins are manufactured by the liver?

LDLs and VLDLs

Glycogen

Most abundant storage carbohydrate, branched chain of glucose molecules

Triglycerides

Most abundant storage lipids, primarily of fatty acids

Nitrogen Balance

Nitrogen absorbed from diet balances nitrogen lost in urine and feces

The product of one citric acid cycle is:

One molecule of GTP (guanosine triphosphate)

Hydrolysis splits triglyceride into component parts

One molecule of glycerol, three fatty acid molecules

Coenzymes

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

Each of 2 FADH2 molecules

Produces 2 ATP + 1 water molecule

Each of 8 NADH molecules

Produces 3 ATP + 1 water molecule

Negative nitrogen balance

When excretion exceeds ingestion

C and O atoms are removed and released as CO2 in the process of

decarboxylation

Carbon and oxygen atoms are removed as carbon dioxide in a process called

decarboxylation.

When chemical bonds are broken

energy is released

Lipogenesis is common for organic molecules because the intermediate ________ is formed in most nutrient metabolic processes.

acetyl-CoA

Synthesis of fatty acids starts with __________.

acetyl-CoA

Lipogenesis generally begins with

acetyl-CoA.

The nutrients that yield the most energy per gram when metabolized are

fat

Bacterial inhabitants of intestines produce small amounts of:

fat-soluble vitamin K and five water-soluble vitamins

small percentage of total circulating lipids

free fatty acid

Enzymes in cytosol convert

glycerol to pyruvate

Select the correct sequence of steps as energy is extracted from glucose during cellular respiration.

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

Growth and repair involve primarily what type of reactions?

anabolic

Lipoproteins

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)

An element that is a component of hemoglobin, myoglobin, and cytochromes is

iron

Glycerol

is synthesized from dihydroxyacetone phosphate (intermediate product of glycolysis)

The vitamin that is part of the coenzyme NAD is

niacin.

Ketoacidosis

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

Evaporation

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

Nonessential amino acids

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

Incomplete proteins

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

N Compounds

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

Chylomicrons (lipoprotein)

- 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

Transamination

- 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

Glycolysis

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

beta-oxidation

- 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

Free Fatty Acids (FFAs)

- 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

Essential fatty acids

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

Water-Soluble Vitamins

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

Conduction

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

The Liver

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

Lipid and Amino Acid Catabolism

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

Hepatocytes

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

Thermoregulation

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

Ammonium Ions

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

Vitamin B12

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

Gluconeogenesis

- 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

An ion that is a necessary component of high-energy compounds and nucleic acids and a structural component of bone is the ________ ion.

phosphate

Lipoproteins are water-soluble because of a superficial coating of

phospholipids and proteins.

What is the function of the urea cycle?

reduce the concentration of ammonia

When NAD+ is ________ it becomes NADH. When NADH is ________ it becomes NAD+.

reduced; oxidized

If other energy sources are inadequate in protein metabolism:

- 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

Solubility

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

Glucose Breakdown

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

Deamination

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

Complete proteins

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

Amino Acid Catabolism

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

Convection

- 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

Ketonemia

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

Glycogenolysis

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

Glycogenesis

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

Oxidative phosphorylation

- 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

The Postabsorptive State

- 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

Fat-Soluble Vitamins

- 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

Radiation

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

The vitamin that plays a role in maintaining epithelia and is required for the synthesis of visual pigments is vitamin

A

Vitamin A

A structural component of visual pigment retinal

Which of the following statements about ADH (antidiuretic hormone) is correct

ADH is released by the posterior pituitary gland.

Electrons along ETS release energy

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

Leptin

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

Ghrelin

released by empty stomach and increases appetite

Cholecystokinin (CCK) and adrenocorticotropic hormone (ACTH)

suppresses appetite

Catabolism

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

The carbon dioxide of respiration is formed during

the citric acid cycle

In oxidative phosphorylation, energy for the synthesis of ATP is directly obtained from the

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

Urea Cycle

the reaction sequence that produces urea

Anabolism

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

The term ________ refers to the homeostatic process that allows us to maintain a constant body temperature.

thermoregulation

In transamination, the amino group of an amino acid is

transferred to a keto acid

What is the role of NADH in metabolism?

transport hydrogen atoms to coenzymes

The two most important coenzymes for glycolysis and the citric acid cycle are

NAD and FAD

In order for glycolysis to proceed, which of the following need not be present?

acetyl-CoA

Heat loss to the cooler air that moves across the surface of your body is called

convection

Most of the ATP from metabolism is produced in the

electron transport system

Reduction

gain of electrons, electron recipient is reduced

FAD and ATP Generation

- 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

NAD and ATP Generation

- 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

Oxidative Phosphorylation

- 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

Citric Acid Cycle

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

Glycolysis Factors

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

In glycolysis, each molecule of glucose that is catabolized gives a net yield of how many molecules of ATP

2

Coenzyme (Oxidation-Reduction Reactions)

Accepts hydrogen atoms, is reduced, gains energy

Coenzyme FAD

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

Coenzyme NAD

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

Fatty acids and many amino acids cannot be used for ________ because their catabolic pathways produce acetyl-CoA.

gluconeogenesis

The process of synthesizing glucose from noncarbohydrates is called

gluconeogenesis

Which of the following processes takes place in the cytosol of a eukaryotic cell?

glycosis

The smallest lipoproteins, called __________, transport cholesterol from peripheral tissues to the liver.

high-density lipoproteins

The condition where the blood pH drops because of ketone bodies in the blood is called __________.

ketoacidosis

The major cation in cytoplasm is

potassium

The function of the citric acid cycle is to

remove hydrogen atoms from organic molecules and transfer them to coenzymes

The vitamin that is part of the coenzyme FAD is

riboflavin

During the absorptive state,

the liver forms glucagon

The element that is necessary for the proper function of the enzyme carbonic anhydrase is

zinc

the vitamin that is required for proper bone growth and for calcium absorption and retention is vitamin

D

Shivering Thermogenesis

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

Three Factors against Protein Catabolism

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

Nonshivering Thermogenesis

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

N Compounds include:

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

Glycolysis produces how many pyruvate molecules and how many ATP molecules?

2 pyruvate molecules with a net gain of 2 ATP molecules

Total yield from citric acid cycle to ETS

28 ATP

Taking excess vitamins can be dangerous. It is possible to overdose on vitamin

A

ATP Generation and the ETS

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

The vitamin that prevents breakdown of vitamin A and fatty acids is vitamin

E

Electrons (Oxidation-Reduction Reactions)

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

Vitamin E

Stabilizes intracellular membranes

Which statement describes the citric acid cycle?

This process produces some ATP and carbon dioxide in the mitochondrion

Which statement describes glycolysis?

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

Which statement describes the electron transport chain?

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

Ketone Bodies

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 function of the citric acid cycle is:

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

Electrons

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

the most abundant lipid in the body

Triglycerides

most lipids circulate through bloodstream as

lipoproteins

Fat-soluble vitamin overdoses primarily affect which organ

liver

Oxidation

loss of electrons, electron donor is oxidized

The sum of all of the biochemical processes going on within the human body at any given time is called

metabolism

Where does beta-oxidation take place?

mitochondria

The citric acid cycle occurs in the

mitochondrial matrix.

During starvation,

muscle proteins are used as an energy source

One citric acid cycle removes

two carbon atoms regenerating 4-carbon chain

The amino group that is removed from an amino acid during deamination is converted to the less toxic form of __________.

urea

The conversion of ammonia into a less toxic substance produces

urea

Lipoproteins that are primarily sent to skeletal muscles and adipose tissues are called

very-low-density lipoproteins.

Avitaminosis

vitamin deficiency disease

urea

water-soluble compound excreted in urine