Metabolism Flashcards
What does the body do if net energy change is positive?
Stores excess energy by building fat molecules
What does body do if net energy change is negative?
Uses stored energy to compensate for energy deficit
What is the percentage of energy released from catabolic reactions as heat?
60%
Which chemical bond in ATP is broken to provide energy for cells?
The bond between second and third phosphate groups
What are the four major macromolecule groups?
- Carbohydrates
- Lipids
- Proteins
- Nucleic acids
What is the most common monosaccharide used for ATP production?
Glucose
Where is excess glucose stored in the body?
- In liver and skeletal muslces as glycogen
- In adipose cells as triglyceride
Which lipid is used most often for energy?
Triglycerides
What are some examples of catabolic hormones?
- Cortisol
- Glucagon
- Adrenaline/epinephrine
What are some examples of anabolic hormones?
- Growth hormones
- Insulin
- Testosterone
- Estrogen
Define:
Oxidation
Electron loss
Define:
Reduction
Electron gain
What are the most common coenzymes of redox reactions and what are they reduced to?
- NAD to NADH
- FAD to FADH2
Where does carbohydrate digestion begin and end?
At the mouth with salivary amylase and in the small intestine with monosaccharides absorbed across epithelium
What are the steps of cellular respiration?
- Glycolysis
- Krebs cycle
- Oxidative phosphorylation
How many molecules of ATP are consumed in glycolysis?
Two
What is the net result of ATP molecules produced in glycolysis?
Four
What are the steps of glycolysis?
- 2 ATP molecules consumed and 2 phosphates transferred to glucose
- Glucose splits into two three-carbon compounds
- Additional phosphate added to each molecule
- Phosphates then removed from both carbon molecules to produce 4 ATP molecules
What are the net products of glycolysis?
- 2 pyruvate molecules
- 2 ATP molecules
- 2 NADH molecules
What happens to pyruvate when oxygen is present?
Enters the Krebs cycle
What happens to pyruvate when oxygen is limited or absent?
Converted to lactic acid
How many pyruvate molecules are produced from glucose in aerobic respiration?
Two
How many molecules are produced with each round of the Krebs cycle?
- 3 NADH molecules
- 1 ATP molecule
- 1 FADH2 molecule
- CO2 as byproduct
What molecule is pyruvate converted into in the Krebs cycle?
acetyl-CoA
Define:
Oxidative phosphorylation
Energy passed through electron carriers to collect energy needed to attach phosphate to ADP to create ATP
How many molecules of ATP are produced from the electron transport chain?
34
Define:
Electron transport chain (ETC)
Series of electron carriers and ion pumps used to pump H+ ions out of inner mitochondrial matrix
How many ATP molecules are produced in total per glucose molecule in cellular respiration?
38
Define:
Gluconeogenesis
Synthesis of new glucose from pyruvate, lactate, glycerol, alanine, or glutamine
Where and when does gluconeogenesis take place?
In the liver during low glucose periods
Where does lipid metabolism begin?
In the intestine
Define:
Pancreatic lipases
Enzymes that break down fats after being emulsified by bile salts
Define:
Chylomicrons
Phospholipid vesicles that contain triglycerides
Where do chylomicrons go after entering the lymphatic system and being transported into the circulatory system?
- the liver
- can also be stored as adipocytes
Define:
Lipolysis
- Process of breaking down fat molecules into fatty acids and glycerol
Where does lipolysis occur in the cell?
In the cytoplasm
How does glycerol enter the glycolysis pathway?
DHAP
How much more energy per unit do triglycerides yield compared to carbohydrates and proteins?
Two times more
Function of fatty acyl carnitine?
Transports fatty acids across mitochondrial membrane where it is then converted into fatty acyl CoA and then acetyl CoA
Define:
Lipogenesis
Creation of lipids from acetyl CoA in adipocytes and hepatocytes
How are fatty acids created via lipogenesis?
Acetyl CoA adds two carbons from another CoA until fatty acids are sufficient length
What are excess proteins converted to?
Glucose or triglycerides
Process of protein metabolism?
- Enzymes in stomach and small intestine break proteins down into amino acids
- Pepsin and HCL denature proteins
- Chyme enters small intestine and pancreas releases sodium bicarbonate to neutralize low pH of HCl to protect lining
- Small intestine and pancreas release enzymes to break down proteins and amino acids transported across intestinal muscosa
What are the three metabolic states?
- Absorptive
- Postabsorptive
- Starvation
Define:
Absorptive state
Occurs after meal during digestion and nutrient absorption
Define:
Postabsorptive state
Occurs when food has been digested, absorbed, and stored
Define:
Starvation state
Body is deprived of nourishment for extended period of time
When and where does digestion begin?
When food enters the mouth
What happens to insulin and blood glucose levels during the absorptive state?
Insulin levels increase in response to increased blood glucose levels.
What happens to blood glucose and insulin levels in the postabsorptive state?
Blood glucose levels decrease, causing insulin levels to decrease
What is the order of priorities for the body in a starvation state?
- Provide glucose to brain
- Conserve amino acids for proteins
- Glycolysis shuts down in cells that can use alternative fuels
What is the set point for human body temperature?
37 degrees Celsius or 97.7 degrees Fahrenheit
What are the mechanisms of heat exchange?
- Conduction
- Convection
- Radiation
- Evaporation
Define:
Basal metabolic rate
Amount of daily energy expended by humans at rest in neutrally temperate environment in postabsorptive state
