Chapter 26 Nutrition and Metabolism

nutrient

any chemical taken into the body used for metabolic processes

macronutrients

required in significant amounts

examples of macronutrients

water, carbohydrates, lipids, and proteins

micronutrients

required in smaller amounts, as reactants or enzyme components

examples of micronutrients

vitamins and minerals

Vitamins

are carbon-containing molecules required by the human body for proper function

minimal quantities of what are required?

minimal quantities of vitamins

How many vitamins are there?

13

water-soluble vitamins

vitamins B1-3, 5-7, 9, 12, and C

fat-soluble vitamins

A, D, E, K

where can you get nutrients from?

nuts, grains, and dark green leafy vegetables often contain large amounts of useful vitamins

vitamin c defincency leads to what

poor wound healing and scurvy

minerals

non-carbon-containing molecules with specific elements that are essential to life

examples of minerals

calcium, phosphorous, magnesium, potassium, sulfur, sodium, and chlorine (in the form of chloride) are required in significant quantities

trace minerals

minerals required in quantities similar to vitamins.

trace minerals examples

iron, iodine, copper, zinc, manganese, fluorine (in the form of fluoride), molybdenum, chromium, selenium, and cobalt.

ATP is used as what?

an energy storage molecule

ATP is broken down into what

ADP and a phosphate group

Catabolic reactions

may remove ATP

Anabolic reactions

often consume ATP

phosphorylation

ATP is converted into ADP and phosphate, the phosphate group often forms a covalent bond with another molecule

proteins can be activated or deactivated using what?

phosphorylation

Glucose

the conventional starting point of carbohydrate catabolism

Glucose catabolism

aerobic respiration, anaerobic fermentation, glycolysis

aerobic respiration

uses oxygen to oxidize glucose into carbon dioxide

anaerobic fermentation

temporarily results in the production of lactic acid in the absence of oxygen

glycolysis

the splitting of glucose into pyruvate, occurs in the cytoplasm

Matrix reactions

occurring in mitochondrial matrix

pyruvate processing

Krebs cycle

Membrane reactions

occurring on inner mitochondrial membrane

electron transport chain

chemiosmosis

in glycolysis, one glucose molecule yields =

two pyruvate molecules, two ATP molecules, and two NADH molecules

pyruvate

formed in glycolysis is transported to the mitochondrial matrix, Krebs cycle

pyruvate molecule is converted into what, and produces what?

converted into an acetyl-coenzyme A molecule, produces NADH

NADH

the enzyme that catalyzes pyruvate dehydrogenase

The Krebs cycle

named for Hans Krebs, a German-British scientist who first described this metabolic process in the 1930s. citric acid cycle, takes place in the mitochondrion

One acetyl-CoA molecule

results in the formation of 2 CO2 molecules , 3 molecules of NADH, 1 molecule of FADH2 , and 1 molecule of ATP

One molecule of glucose

generates a net total of 6 molecules of carbon dioxide, 10 molecules of NADH, 2 molecules of FADH2 , and 4 molecules of ATP

Acetyl-CoA

covalently bonded to oxaloacetate to generate a molecule of citrate co

Citrate

proceeds through the cycle, losing carbon dioxide molecules and electrons until it becomes oxaloacetate

Oxaloacetate

bonds to a new molecule of acetyl-CoA, and the cycle starts again

Oxidative phosphorylation

the process of phosphorylating ADP to form ATP through energy generated by redox reactions.

the electrons carried by NADH and FADH2 are

removed from the electron carriers and used to generate energy for ATP synthesis

electron transport chain

consists of multiple membrane proteins that oxidize NADH and FADH2 . electrons removed from the electron carriers

what happens when electrons are removed from the electron carriers

pump protons across the plasma membrane to generate an artificial proton gradient

electrons end up with what

oxygen

the final electron acceptor in the electron transport chain is what

oxygen

Chemiosmosis

the process of using the proton-motive force to synthesize ATP

Mitochondrial ATP synthase

a membrane protein found on the inner membranes of mitochondria that uses the proton-motive force to synthesize ATP

the movement of protons through the enzyme complex causes what

conformational changes in the enzyme, allowing for the production of ATP from ADP and phosphate.

Oxygen

required in aerobic respiration as the final electron acceptor in the electron transport chain, forming water

Without oxygen

electron transport chain becomes bogged down, and non-functional, electron carriers NADH and FADH2 become stuck in their reduced state

Without NAD+

glycolysis is unable to proceed

anaerobic fermentation

an energy-generating metabolic process that also uses redox reactions to drive ATP synthesis, requires converting NADH back to NAD+ to be re-used in glycolysis

when is anaerobic fermentation used

in occasions where oxygen is absent or in low supply

anaerobic fermentation electrons do not end up with what

oxygen

In muscle cells, fermentation results in what

results in the formation of lactic acid from pyruvate under anaerobic conditions

Glycogenesis

glucose into glycogen, it is stimulated by insulin, and chains glucose monomers together

Glycogenolysis

breaking down stored glycogen into glucose, it is stimulated by glucagon and epinephrine, and the liver cells can release glucose back into the blood

glycogenolysis provides glucose when?

in between meals

Gluconeogenesis

produces glucose from noncarbohydrates like glycerol and amino acids, it occurs in the liver, and can occur in the kidneys if necessary

Fats

broken down into glycerol and fatty acids, glycerol, fatty acids

Glycerol

converted to a glycolysis intermediate

Fatty acids are broken down into what?

broken down into acetyl-CoA molecules

Proteins are broken down into what?

broken down into amino acids

what happens to excess amino acids

are converted into pyruvate or intermediates in the Krebs cycle

Nucleic acids and steroids

can not be metabolized for energy

Lipogenesis

synthesis of fat from other types of molecules

Lipolysis

breaking down fat for fuel

Lipolyisis is stimulated by what hormones

Epinephrine  Norepinephrine  Glucocorticoids  Thyroid hormone  Growth hormone

protein metabolism

Proteins can be broken down into amino acids

Excess amino acids

converted into pyruvate or intermediates in the Krebs cycle

Amination

the addition of an amino group

Deamination

the removal of an amino group

Transamination

the migration of an amino group from one molecule to another

Excess amino groups

become ammonia

converted into urea by the liver

Steroids and nucleotides

can not be used to fuel ATP synthesis

Steroids

converted into a hydrophilic form and are excreted in urine

Nucleotides

stripped of the sugar and phosphate groups and are converted into uric acid

steroids are synthesized from where

acetyl-CoA molecules

Nucleotides are synthesized from where

a ribose base and several nitrogen-containing compounds