Energy Metabolism Flashcards
Metabolism
the entire network of chemical processes involved in maintaining life and encompasses all these sequences of chemical reactions that occur in the bodies cells
or the sum of chemical reactions that occur in the body to make energy
Pathway
progression of metabolic chemical reaction
Intermediates
compounds formed from a pathway
Anabolic Pathway
building of compounds; uses energy
start with small compounds build larger ones, requires the input of energy
Catabolic Pathway
breaking down compounds into smaller components; releases energy
breakdown of larger compounds into smaller compounds
What are the end products of a catabolic reaction (energy metabolism)?
H20 CO2 and ATP
What are the three major categories of work that use ATP?
Mechanical Work
Synthetic Work
Transport work
(also heat)
Mechanical work
muscular contraction
Chemical/Synthetic Work
biosynthesis, chemical work, turn over cells, create proteins and enzymes
Osmotic/Transport Work
Active transport around the body (into/out of cells)
Glycolysis
Glucose metabolism: break down glucose to pyruvate; 6 carbon glucose into 2 3 carbon pyruvates
a series of chemical reactions catalyzed by enzymes that degrades monosaccharides, generates energy, provides building blocks for synthesizing other compounds
generates some ATP, NADH
reversible but requires ATP
Sources of Glucose
diet
glycogen stores-mostly liver (also muscles)
gluconeogenesis: use AA to form glucose, (the opposite of glycolysis), occurs in the liver
Lactate (cori cycle)
Cori Cycle
converts lactate back to glucose, lactate travels to liver gets turned into pyruvate
TCA cycle
Pyruvate is converted to acetyl CoA after glycolysis and before entering TCA cycle
Acetyl CoA enters and generates NADH, FADH2, GTP and CO2
Electron Transport Chain
chains of electron carrier molecules
converts NADH, FADH2, to ATP
NADH, FADh2 deliver hydrogen (protons) to a series of reactions and at the end you get the generation of ATP and water (generates H20)
Lipolysis & beta oxidation
the breakdown (metabolize) of fat
triglycerides are stored in adipose cells and are catabolized into glycerol and fatty acids
reaction is catalyzed by hormone sensitive lipase (HSL)
Glycerol enters one of the three carbon intermediate compounds in glycolysis: produce pryuvate, generate acetyl CoA, enter TCA cycle, and eventually produce atp
fatty acid chain goes through beta oxidation broken down into two carbon molecules at the beta carbon
produces one NADH and one FADH2 and one acetyl CoA and it enters teh TCA cycle when ATP is needed
Incomplete Oxidation
Incomplete oxidation of fat
we cannot get glucose from fat because we need carbohydrates for fatty acid oxidation
absence of carbohydrates means any fatty acids you have cannot be metabolized into ATP
Ketosis
- Ketones are products of incomplete fatty acids oxidation
- Low CHO intake, insufficient insulin
- Acetyl CoA cannot enter the TCA cycle
- Acetyl CoA accumulates form ketones or ketone bodies
- can be reversed with the consumption of carbohydrates
- ketosis can occur when fasting
What two conditions cause Ketosis?
Low Carb Diets
Diabetes
Urea Cycle
AA will form amonia
Build up of Ammonia is toxic to cells
Liver forms Urea
Urea is excreted via Kidneys
How is metabolism regulated?
Enzymes
Hormones: insulin, glucagon, epinephrine, hormones can control regulate glucose metabolism
Blood glucose levels
ATP concentration
Glycogenolysis
when fasting, the blood glucose levels decrease.
Liver glycogen is converted back to glucose; circulated back into blood, provides energy to glucose dependent tissues/organs. Skeletal muscle glycogen converted back to glucose; and used for ATP production within its own cells
Body’s glycogen stores may be depleted after 1 hour of strenuous exercise or after 24 hours of fasting, most restored over half the day
Wasting Metabolism
Suppressed appetite
Slowed metabolism
Lowered body temperature
Reduced resistance to disease
breakdown on protein
AA are deaminated
nitrogen group is excreted via the kidneys as urea
carbon skeletons yield acetyl CoA or intermediary compound
most enter TCA cycle
metabolic consequence of excess (feasting) CHO intake
storage!
first used to maximize glycogen stores, once glycogen stores are full carbohydrates consumed in excess will be stored in they body as fat
metabolic consequence of excess (feasting) Lipid intake
lipids consumed in excess go immediatly into storage of adipose tissue as triglycerides
Lipogenesis
metabolic consequences of excess (festing) protein intake
first fill any AA needs then converted to triglycerides and stored as fat
fate of nutrients when fasting
when macronutrients from a meal are no longer available to provide energy (2-3 hours after finishing a meal) the body draws on its glycogen and fat stores (ATP)
3-24 hours after eating glycogenolysis glycogen will be used for red blood cells, nerve cells, brain cells
fatty acids from adipose tissue supply acetyl CoA
TCA cycle will go forward and supply ATP as long as glucose lasts
fate of nutrients when fasting
glycogen stores are depleted after 24 hours of fasting
body begins to break down protein to AA to produce glucose (to supply brain and nervous system)
fatty acids converted to ketones (alternate energy source for cells) which slows breakdown of body proteins (liver)
proteins meet glucose needs (gluconeogenesis)
wasting metabolism
Shift to ketosis during starvation
suppression of appetite, slowing metabolism, adaption to prolonged fast can maintain life for 2 months
Define ATP
adenosine triphosphate
the main form of energy the body uses
major end product of energy metabolism
Give an example of an anabolic reaction
- Glucose to glycogen
- Glycerol and fatty acids to triglycerides
- AA to proteins
Give an example of a catabolic reaction
- Glycogen to glucose
- Triglyceride into glycerol and fatty acids
- Protein to AA
Identify where energy metabolism occurs in the cell
ATP IS PRODUCED IN MITOCHONDRIA Glucose enters the cell Glycolysis occurs in the cell cytoplasm Pyruvate enters mitochondria and is irreversibly converted to acetyl CoA TCA cycle occurs inside the mitochondria ETC in mitochondrial membrane
Identify 3 major metabolic pathways through which macronutrients are converted to energy
Glycolysis • Glucose to Pyruvate • Uses and generate ATP • Reversible, but requires ATP (Irreversible conversion of pyruvate to acetyl CoA) TCA Cycle • Cycle generates NADH, FADH2, GTP and CO2 ETC • Oxidative phosphorylation • NADH, FADH2, converted to ATP • H20 generated
Examine the general differences in breakdown of CHO FAT PRO to ATP
Carbohydrates
• Digested into glucose
• Glucose broke down to 2 3 carbon pyruvate molecules
• Pyruvate the Acetyl CoA
• Acetyl CoA enters the tca cycle
• Generates NADH FADH2 GTP and CO2
• Electron transport chain
• Converts NADH and FADH2 to ATP and h20
Proteins
• AA are deaminated
• Nitrogen group is excreted via the kidneys as urea
• Carbon skeletons yield pyruvate or acetyl CoA or intermediary compound
• Most enter TCA cycle
Lipids
• Breadown of fat Lipolysis
• Triglycerides stored in adipose cells are catabolized into glycerol and fatty acids
• Reaction is catalyzed by HSL hormone sensitive lipase
• Glycerol enters one of the three carbon intermediate compounds in glycolysis
• Produce pyruvate
• Generate acetyl CoA
• Enter tca cycle and
• Eventually produce ATP
• Fatty acids chain goes through beta-oxidation
• Fatty acid chain broken down into two carbon molecule at the beta carbon
• Produces one NADH one FADH2 and one acetyl CoA and it enters the TCA cycle when atp is needed
Besides ATP, list the other 2 compounds produced in cells after food is completely metabolized
CO2 and H20
