exam 2 Flashcards
What is metabolism?
sum of all chemical reactions that occur in the body
what is bioenergetics
metabolic process converting foodstuffs like carbs, fats and proteins into energy in a biologically usable form
what are three forms of energy?
electrical, mechanical, chemical
what is atp
energy stored in the form of a phosphate bond
what is atpase?
breaks the phosphate bond which liberates energy to do work, resulting in the formation of ADP and P
ATP -> ADP + P + energy
what is the synthesis of atp? hint: arrows
ADP + P -> ATP
how does metabolism work?
protons and electrons move between the cytosol and mitochondria often by carrier proteins (NAD+, FAD+)
difference between oxidation and reduction?
coupled reactions
molecules that gain electrons or have their full compliment – reduced
molecules that lose or lack electrons –oxidized
molecule cannot be oxidized unless it donates electrons to another atom
- *often involves transfer of hydrogen atoms rather than free electrons (hydrogen atoms contain 1 electron)
- molecule losing hydrogen also loses electron ->oxidized
what is key to metabolism (coupled reactions)?
coupling of:
Oxidation of ADP to form ATP
Reduction of oxygen to form water
Oxidized and reduced forms of NAD and FAD?
O: NAD+
R: NADH
O: FAD
R: FADH2
what are enzymes?
catalysts that regulate speed of chemical reactions (lowers activation energy, the energy required to start a reaction)
what two factors alter enzyme activity?
temperature and pH
*optimal range exists, away from this range there is diminished enzyme activity
what is diagnostic value of enzymes?
damaged cells releases enzymes into the blood
many enzymes not normally found in blood
*enzyme levels in blood indicate disease or tissue damage
How many forms of oxidation of carbs, lipids, and proteins exist? How many kcal of energy?
carb: 3 // 1 g = 4 kcal
lipid: 4 // 1 g = 9 kcal
Protein: 1 // 1 g = 4 kcal
How are monosaccharides formed?
by gluconeogenesis – simple sugars such as glucose and fructose
synthesis of glucose from AA, lactate, glycerol and other short chain molecules
How are monosaccharides broken down (2 ways)?
glycolysis – breakdown of glucose into pyruvate and lactate; occurs in sarcoplasm of muscle cell
krebs cycle – breakdown metabolic pathway in the mitochondria in which energy is transferred from carbs, fats and AA to 3 NADH and 1 FADH for subsequent production of ATP in the electron transport chain
How are disaccharides formed?
combine 2 monosaccharides; mostly sucrose (table sugar)
Whatt are polysaccharides?
complex carbs containing three or more monosaccharides; mostly cellulose and starch
What is the storage from of glucose? How is it broken down?
glycogen stored in both the muscle and liver (a polysaccharide)
name the examples each of monosaccharides, disaccharides and polysaccharides.
mono – glucose, fructose
di – sucrose (table sugar)
poly – cellulose, starch
what is the prototype or carbohydrates and fats? Hint: Carbon and hydrogen and oxygen counts
Carbohydrates prototype: glucose C6H12O6
Fats prototype: palmitate C16H32O2
what are the 4 forms of fat?
fatty acids
triglycerides
phospholipids
steroids
fatty acids are broken down by what?
beta oxidation – breakdown of free FA to form acetyl-CoA; occurs in mitochondria
primary substrate for metabolism
what are triglycerides?
3 FAs linked by a glycerol backbone; broken down by lipolysis: breakdown of triglycerides in adipose tissue to FA and glycerol for subsequent transport to tissues for metabolism
What are phospholipids?
lipids with phosphoric acid unit
important structure of cell membranes
not used as as energy source by skeletal muscle during exercise
What are steroids?
most common is cholesterol
component of cell membrane;; sex hormone synthesis
not used an energy source during exercise
What are the number of amino acids in the body?
20 total but 9 cannot be synthesized by humans (essential aa) and must be consumed in food
how are amino acids formed?
by linking aa by chemical bonds called peptide bonds
How can proteins be utilized in two ways?
alanine can be converted into glucose in liver which can then be used to synthesize glycogen
liver glycogen can be broke n down to glucose and transported to working skeletal muscle via circulation
many AA can be converted into metabolic intermediates and directly used as fuel in bioenergetic pathways
greatest to least amounts of primary nutrients used for energy during exercise?
fats
carbs
proteins contribute relatively small amounts
fatty acids (primary form of fat) stored how in muscle and fat cells?
as triglycerides
Why must metabolic pathways exist in the cell with the ability to produce ATP rapidly?
muscle cells store limited amounts of ATP. Therefore, because muscular exercise requires a constant supply of ATP, metabolic pathways must exist in the cell with the capability to produce ATP rapidly
What are systems that generate ATP?
ATP-PCr (anaerobic)
glycolysis (anaerobic)
oxidation (aerobic)
formation of ATP by PCr breakdown?
PCr +ADP —————————–creatine kinase—-> ATP + Cr
Donation of a phosphate group and its bond energy from PCr to ADP to form ATP
Intracellular source of “bond” energy to rebuild ATP
**LIMITED CAPACITY SYSTEM
Why is ATP-PCr (phosphagen) system a limited capacity system?
provides energy for muscular contraction at the onset of exercise
Provides energy for 3-15 seconds of “all out” conditions like sprinting 50 meter, high jump
simple one enzyme reaction -> ATP
Why does regeneration occur during exercise recovery?
PCr reformation requires ATP formation and occurs only during recovery from exercise
What happens with depletion of PC?
may limit short-term, high-intensity exercise
What happens with creatine monohydrate supplementation?
increased muscle PC stores
some studies showed improved performance in short-term, high-intensity exercise (inconsistent results may be due to water retention and weight gain)
- *Does not appear to pose health risks
- may be variant in supplement purity
Breakdown of glucose or glycogen during glycolysis forms how many molecules of pyruvic acid or lactate?
2
Glycolysis has how many net gain of ATP?
2 if using glucose
3 if using glycogen
If glycolysis begins with glycogen as the substrate, the addition of only 1 ATP is required
The energy investment phase of glycolysis requires how many ATP?
2 ATP
Energy generation phase produces what?
4 ATP
2 NADH
2 pyruvate
2 lactate
How many reactions occur in glycolysis?
12 total reactions
First 5 involve conversion of C-6 units, requiring energy
Last 7 steps cause conversion of C-3 units, resulting in energy regeneration
What happens during the first 5 steps involve conversion of C-6 units that require energy?
“energy investment phase” where ATP used to form sugar phosphates
What happens during the last 7 steps cause conversion of C-3 units, resulting in energy regeneration?
“energy generation phase”
NAD and FAD: hydrogens and associated electrons are frequently removed from nutrient substrates and transported by “carrier molecules”; both NAD and FAD transport hydrogens and their associated electrons to mitochondria to be used to generate ATP aerobically
**for glycolysis to continue, need adequate amounts of NAD to accept hydrogen atoms
Key reactions in glycolysis include formation of what?
**glucose-1-phosphate – split from glycogen
glycogen –(phosphorlyase)–> glucose-1-phosphate
**glucose-6-phosphate – common form of glucose and glycogen
glucose –hexokinase—-> glucose-6-phosphate
*requires ATP
**fructose-1, 6-biphosphate - important regulatory step
fructose-6-phosphate —-phosphofructokinase–> fructose-1, 6-biphosphate
*requires ATP
What is the relationship between ATP, ADP, PC (phosphocreatine) and bond energy?
PC +ADP —(creatine kinase)-> ATP +C
donation of a phosphate group and its bond energy from PC to ADP to form ATP
Stored PC in muscle cells is small/limited, called ATP-PC system, at onset of short-term, high-intensity exercise, providing energy for the muscle contraction. PC reformation requires ATP and occurs only during recovery form exercise
What are the two methods of ATP production rapidly without O2?
ATP-PC system and glycolysis
how many molecules of pyruvate or lactate and net gain of ATP are formed from the breakdown of glucose or glycogen in glycolysis?
2 pyruvate or lactate molecules + 2 net gain ATP
Describe NADH conversion to NAD so that glycolysis can continue (sex metaphor).
see study guide
what are the three anearobic, metabolic pathways that muscle cells can produce ATP?
atp-pc system
glycolysis
oxidative formation of ATP
What are the two aerobic ATP production?
krebs cycle
electron transport chain
one mole of ATP equal to how many kcal of energy
7.3 kcal
32 moles of ATP form how many molecules of glucose?
32 moles of ATP = 1 molecule of glucose
potential energy released from one mole of glucose is how many kcals per mole?
686 kcal/mole
when exercise begins, the increase in ADP and Pi level increase which limiting enzyme? this increases glycolysis.
PFK (phosphofructokinase)
which energy system has the greater contribution during short-term, high-intensity activities? anaerobic or aerobic?
anaerobic; aerobic contributes more to long-term, low-to moderate-intensity exercise
what percent of metabolic energy is lost as heat?
60 to 70%
What is BMR (basal metabolic rate)?
minimal energy expenditure following prolonged rest or sleep
What is BMR affected by?
thermoregulation, age, stress, hormone
what is calorimetry?
a device for measuring heat produced by the body; heat produced is removed by stream of cold water flowing through coils
H2o temp leaving – H2O temp entering = heat production
what are the advantages to direct calorimetry?
measures heat directly
provide accurate measures of total body energy expenditure
What are the disadvantages to calorimetry?
large
expensive to construct
slow to generate results
cannot follow rapid changes in energy releases; thus, energy metabolism during intense exercise cannot be studied
How do you measure Indirect calorimetry (VO2) ?
All energy metabolism ultimately relies on utilization of O2. Direct relationship between O2 consumed and amount of heat produced in body – measuring O2 consumption to provide an “indirect” estimate of metabolic rate (your caloric expenditure can be estimated by measuring your respiratory gases”
The oxygen consumption indicator of energy is supplied by which two possible things?
oxidative phosphorylation or index of aerobic ATP production
O2 utilization and CO2 production are recorded as an estimate of what?
tissue use
equipment required for indirect calorimetry (VO2)?
volume measurement
gas analysis
Determination of substrates in indirect calorimetry are what 3 factors?
requires calculation of RER (RQ) [respiratory exchange ratio]
VCO2/VO2
RER varying according to fuel being used
Fat and carbs differ in the amount of O2 used and CO2 produced during what? what are the statistics?
oxidation;
indicates fuel utilization
- 70 = 100% fat
- 85 = 50/50 fat, CHO
- 00 = 100% CHO
During steady state exercise, VCO2 and VO2 are reflective of what?
O2 consumption and CO2 production at the cellular level
Increased RER increased role of carbs. Decreased RER (respiratory exchange ratio) increases the role of what?
fats
oxygen uptake increases linearly with increasing work rate until what is reached?
VO2max
