Chapter 9 - Energy Metabolism Flashcards
Metabolism
Chemical processes in the body that provide energy in useful forms and sustain vital activities
Metabolic Pathway
Series of chemical reactions occurring in a cell
Intermediate
Compound formed in a metabolic pathway
Anabolic
Pathways that use small, simple compounds to build larger, more complex compounds.
ex: glucose, fatty acids, cholesterol, amino acids
Catabolic
Pathways that break down large compounds into smaller compounds. Energy is usually released.
ex: glycogen
Cells use energy to…
- build compounds
- contract muscles
- conduct nerve pulses
- pump ions
How do catabolic processes release energy?
By breaking the chemical bonds in carbs, fats, proteins, and alcohol
Adenosine Triphosphate (ATP)
Main energy currency for cells. ATP energy is used to promote ion pumping, enzyme activity, and muscular contraction.
Adenosine Diphosphate (ADP)
Breakdown product of ATP. ADP is synthesized into ATP using energy from foods and a phosphate group (P1)
Adenosine Monophosphate (AMP)
Breakdown product of ADP when a phosphate group is removed. AMP is produced when ATP is in short supply.
How many pounds of ATP does the body contain at any given time?
0.22 lbs
How many pounds of ATP does a sedentary adult use every day?
~ 88 lbs
How much ATP is used during an hour of strenuous exercise?
66 lbs
Oxidize means to _____ an electron, while reduced means to _____ an electron
lose ; gain
What removes hydrogen from energy-yielding compounds or their breakdown products?
Dehydrogenases
Coenzyme
Compound that combines with an active protein (apoenzyme) to form a catalytically active protein (holoenzyme). In this manner, coenzymes aid in enzyme function.
ex: niacin, riboflavin
Cellular Respiration
Oxidation (electron removal) of food molecules resulting in the eventual release of energy, CO2, and water.
Aerobic
Requiring oxygen.
More efficient at producing ATP.
Anaerobic
Not requiring oxygen.
Cytosol
Water-based phase of a cell’s cytoplasm; excludes organelles, such as mitochondria
What are the 4 stages of aerobic cellular respiration?
- Glycolysis
- Transition Reaction
- Citric Acid Cycle
- Electron Transport Chain
Stage 1 of Aerobic Cellular Respiration: Glycolysis
Glucose is oxidized and forms 2 molecules of the 3 carbon compounds pyruvate, produces NADH + H+, and generates a net of 2 molecules of ATP.
- Occurs in cytosol
Stage 2 of Aerobic Cellular Respiration: Transition Reaction
Pyruvate is further oxidized and joined with conezyme A (CoA) to form acetyl-CoA.
Produces NADH + H+ and releases CO2 as a waste product.
- Occurs in mitochondria
Stage 3 of Aerobic Cellular Respiration: Citric Acid Cycle (or Krebs Cycle, Tricarboxylic Acid Cycle (TCA Cycle))
Acetyl-CoA enters the citric acid cycle, resulting iin the production of NADH + H+, FADH2, and ATP.
CO2 is released as a waste product.
- Occurs in mitochondria
Stage 4 of Aerobic Cellular Respiration: Electron Transport Chain
The NADH + H+ produced in stages 1 - 3 and FADH2 from stage 3 enter the electron transport chain.
The NADH + H+ is oxidized to NAD+. and FADH2 is oxidized to FAD.
At the end of the electron transport chain, O2 is combined with hydrogen ions (H+) and electrons to form water.
Most ATP is produced in the electron transport chain, so the mitochondria are the cell’s major energy-producing organelles.
Mitochondria
Main sites of energy production in a cell that also contains the pathway for oxidizing fat for fuel, among other metabolic pathways.
Roles of Glycolysis
Break down carbs to provide energy and provide building blocks for synthesizing other compounds
The transition reaction requires coenzymes from…
thiamin, riboflavin, niacin, and pantothenic acid
Oxidative Phosphorylation
Process by which energy dervied from the oxidation of NADH + H+ and FADH2 is transferred to ADP + P1 to form ATP
Cytochrome
Electron-transfer compound that participates in the electron transport chain
ex: iron
Anaerobic Glycolysis
Pyruvate + NADH + H+ —> Lactate + NAD+
What is the only method for making ATP in cells without mitochondria?
Anaerobic glycolysis
Lactate is also created during what?
Intensive exercise
Lipolysis
Breakdown of triglyercides to glycerol and fatty acids
Fatty Acid Oxidation (AKA Beta-Oxidation)
Breakdown of fatty acids into compounds that enter the citric acid cycle.
- Occurs in mitochondria
Carnitine
Compound used to shuttle fatty acids from the cytosol of the cell to the mitochondria
Pyruvate can synthesize ______ for the citric acid cycle.
Oxaloacetate
Ketone Bodies
Incomplete breakdown products of fat, containing 3 or 4 carbons. Most contain a chemical group called a ketone.
ex: acetoacetic acid
Ketosis
Condition of having a higher concentration of ketone bodies and related breakdown products in the bloodstream and tissues.
Can lead to diabetic ketoacidosis.
Where does metabolism protein take place?
Liver (except amino acids leucine, isoleucine, valine)
Glucogenic Amino Acids
Amino acid that can be converted into glucose via gluconeogenesis
Ketogenic Amino Acids
Amino acid that can be converted to acetyl-CoA and form ketones
Gluconeogenesis
Generation of new glucose from glucogenic amino acids.
The catabolism of amino acids creates ________, which must be excreted
ammonia (NH3)
What is the main pathway or alcohol metabolism?
Alcohol dehydrogenase (ADH)
Alcohol is mainly metabolized in the ______, although 10-30% of it may be metabolized in the _________
liver ; stomach
Steatosis
Accumulation of fat in the liver
What is a pathway to metabolize excess alcohol?
Micromosal Ethanol Oxidizing System (MEOS)
What is a minor pathway for alcohol metabolism?
Catalase pathway
The liver is important for what metabolic processes?
- conversions between various forms of simple sugars
- fat synthesis
- production of ketone bodies
- amino acid metabolism
- urea production
- alcohol metaolism
- nutrient storage
What vitamins are needed for metabolic pathways to operate? (9)
- B-vitamins
- thiamin
- riboflavin
- niacin
- pantothenic acid
- biotin
- vitamin B-6
- folate
- vitamin B-12
What minerals are needed for metabolic pathways to operate?
iron, copper
When your lean body mass declines by __%, after ___ to ___ weeks of fasting, you will die
50% ; 7 to 10 weeks
Lipogenesis
Synthesis of fat from excess carb or protein intake
Phenylketonuria (PKU)
Enzyme phenylalanine hydroxylase doesn’t function efficiently in the liver to convert phenylalanine into tyrosine
Galactosemia
2 specific enzyme defects lead to a reduction in the metabolism of galactose into glucose
Glycogen Storage Disease
Liver is unable to convert glycogen to glucose
