Chapter 25 - Metabolism and Nutrition Flashcards
What are the three main fates of food molecules that are absorbed by the GI tract?
- Supply energy
- Serve as building blocks
- Stored for future use
What does metabolism refer to?
All of the chemical reactions that occur in the body
What is catabolism?
Chemical reactions that break down complex organic molecules into simpler ones
Are catabolic reactions exergonic or endergonic?
Exergonic
- produce more energy than they consume
What is anabolism?
Chemical reactions that combine simple molecules to form complex structural and functional components
Are anabolic reaction exergonic or endergonic?
Endergonic
- consume more energy than they produce
What is the function of ATP?
Participates in energy exchanges in living cells
What happens during oxidation reactions?
Electrons are removed from an atom or molecule
- results in a DECREASE in the potential energy of the atom of molecule
What happens during reduction reactions?
Electrons are added to an atom or molecule
- results in an INCREASE in the potential energy of the molecule
What is phosphorylation?
The addition of a phosphate group to a molecule
What are the three mechanisms of phosphorylation to generate ATP?
- Substrate-level phosphorylation
- Oxidative phosphorylation
- Photophosphorylation
What is the formula involving ADP, ATP, energy and a phosphate group (P)?
ADP + P + energy –> ATP
What is the body’s preferred source for synthesizing ATP?
Glucose
What are the four possible rates of glucose in the body?
- ATP production (glucose is oxidized to produce ATP)
- Amino acid synthesis
- Glycogen synthesis (glucose monomers are combined to form the polysaccharide glycogen)
- Triglyceride synthesis (hepatocytes transform glucose to glycerol and fatty acids)
How is glucose absorption accomplished in the GI tract?
Via secondary active transport
- Na+ glucose symporters
How is glucose absorption accomplished in the body (other than GI tract)?
GluT molecules (via facilitated diffusion) - insulin increases insertion of GluT into the plasma membrane, therefore, rate increases
What is the oxidation of glucose to produce ATP known as?
Cellular respiration
glucose catabolism
What are the four sets of reactions involved in cellular respiration?
- Glycolysis
- Formation of acetyl coenyzme A
- Krebs cycle
- Electron transport chain
What happens during glycolysis?
One glucose molecule is oxidized and it produces two molecules of pyruvic acid, two molecules of ATP and two (NADH + H+)
- ANAEROBIC CELLULAR RESPIRATION
What is anaerobic cellular respiration?
A way to produce ATP without oxygen
What happens during the formation of acetyl coenzyme A?
Pyruvic acid is prepared for entrance into the Krebs cycle
- also produces energy-containing NADH + H+ and carbon dioxide
What happens during the Krebs cycle reaction?
Oxidize acetyl co enzyme A and produces carbon dioxide, ATP, NADH + H+ and FADH2
What happens during the electron transport chain reaction?
NADH + H+ and FADH2 are oxidized, and transfer their electrons through a series of electron carriers
What are the two sets of reaction that require oxygen during cellular respiration?
Krebs cycle and electron transport chain
What is pyruvate dehydrogenase?
An enzyme
- converts pyruvic acid to a 2-carbon fragment called an acetyl group
Where does the Kerbs cycle occur?
In the matrix of mitochondria
- a series of oxidation-reduction reactions and decarboxylation reactions release CO2
Where does the electron transport chain reaction occur?
In the inner mitochondrial membrane
What is the overall reaction of cellular respiration?
Glucose (C6H12O6) + 6 oxygen molecules (6O2) + 36 or 38 Phosphate groups + 36 or 38 ADP –> 6 carbon dioxide molecules (6CO2) + 6 water + 36 or 38 ATP!
What happens if glucose is not needed immediately? What does it get made into?
Combines with other molecules to form glycogen
What is glycogenesis?
What hormone stimulates it?
Synthesis of glycogen
- insulin (from pancreatic beta cells) stimulates hepatocytes and skeletal muscles
Is glycogenesis catabolic or anabolic?
ANABOLIC!
What is glycogenolysis?
Process of splitting glycogen into its glucose subunits
What is gluconeogenesis?
Process where glucose is formed from noncarbohydrate sources
- triglycerides, lactic acid, certain amino acids